James Hamilton, a data center manager at Amazon questions whether solar panels installed at computer data centers make any sense.
In a recent blog post, Hamilton — who also served as a data center architect at Microsoft — asks whether such solar farms are “really somewhere between a bad idea and pure marketing, where the environmental impact is purely optical.”
My take on all solar installations (subsidized with tax dollars paid by you and me): Their only real beneficial purpose is to create the demand for solar panels that will cause manufacturers to go down learning curves to lower their costs. At some future date solar photovoltaics will start making economic sense. One hopes that date comes sooner rather than later. But be clear: that date has not yet arrived.
As for companies that spin their solar installations as examples of good corporate citizenship and responsibility: Oh get off it. Some people prone to want to swallow feel-good arguments are going to be taken in by this rhetoric. But resist that impulsive and let us be real: If something is expensive for what it produces (and solar is more expensive than wind power or efficiency measures for example) it takes a lot of resources to build. Using more resources is worse for the environment than using less resources, all else equal.
Is there a flaw in my unsentimental take on this? Please comment if you see an error in my logic.
While I'm at it: If we are going to have solar installations built at higher cost then can we at least put them where the sun shines the most? I realize various governments want to crow about their solar power capacity. But solar in Germany is pretty stupid all considered. Ditto Seattle and other relatively dark places. Though if the Germans want to subsidize the development of cheaper solar power for many years (only to see most of the manufacturing move to China) then I'm not going to try to stand in their way. I'm not paying taxes to the German government or paying high German electric power rates.
Of course, there's a limit to how much reason we can expect from governments or voters. We will spend more to go down solar panel cost curves than we could have spent in a more rational system. We will also get propagandized about how governments and corporations are doing great things with our tax dollars to usher in a better future. But my advice is to resist being sentimentalized.
Polysilicon crystal is an input into making silicon-based photovoltaics. After peaking at over $400 per kilogram in 2008 due to rapidly rising demand big capital investments in polysilicon crystal manufacturing plants led to a glut. Now polysilicon crystal has fallen in price by an order of magnitude. The good news: according to that link the manufacturing cost (at least for lower cost producers) is still lower than the market price. So the current lower market price is sustainable and will lead to lower silicon PV prices as new contracts for polysilicon are negotiated.
However, oversupply in the polysilicon market pushed the spot price of silicon down from $80 per kilogram in late March 2011 to under $30 per kilogram in December, representing more than a 60 percent drop.
For the future of silicon PV what we need to know: how much further can polysilicon manufacturing costs drop? Is energy cost the biggest cost in that process? Are we need the floor for long term polysilicon prices? Can silicon PV continue to drop in cost as fast as thin films?
As I've written previously, the manufacturing and installation cost trends are what we should watch when it comes to the future of renewables. Market prices can be going up and down independent of manufacturing costs.
Update: In the comments Ronald Brakels points to a report on research to lower the energy cost of making polysilicon crystals. This has the potential to raise the energy return on energy invested (EROEI) of silicon PV.
A Bloomberg article about the sharp decline in photovoltaic (PV) panel maker First Solar highlights the big decline in market prices for PV. Does this portend more of the same? Probably not.
The spot price of solar panels has fallen 47 percent this year, according to Bloomberg New Energy Finance, while crude oil prices have gained 8 percent in New York.
Thin film solar panel maker First Solar might still be the lowest cost PV maker. But the declining cost of polysilicon has helped make silicon PV makers in China much more cost competitive against First Solar's low CdTe panels.
Solyndra declared bankruptcy Sept. 6 saying it couldn’t compete after prices for polysilicon, the raw material in traditional solar cells, fell 64 percent this year.
So have total production costs declined as fast as polysilicon costs? Probably not. Prices have fallen below production costs of many solar photovoltaic panel makers. As a result a number of firms including Solyndra, Stirling Energy Systems Inc., Evergreen Solar, SpectraWatt Solar Millennium have filed for bankruptcy liquidation or Germany's insolvency. Even many Chinese makers are losing money since they haven't cut costs as fast as market prices have dropped. China's PV makers are also headed for a shake out with the number of supplies expected to shrink just as is happening in the United States and Germany.
The price drop would be more exciting if it was caused by an equal or larger drop in costs. Low cost leader First Solar got their production costs to 98 cents per watt in February 2009 and yet wants to get to 50-54 cents per watt only by 2015. Think about how the recent rate of price drop compares to the longer run rate of cost drop. In 6 years First Solar's production costs will fall a percentage amount about the same as the amount that PV market prices fell in just 1 year.
Bottom line: rapid price declines aren't sustainable without rapid cost declines. Rapid cost declines aren't happening. Instead, excess production capacity, especially in China, has accelerated price declines. But don't expect this trend to continue absent some technological breakthroughs that enable big cost reductions.
Update: An article on First Solar's financial results provides evidence that First Solar's rate of production cost declines has decelerated. Also, to get PV wafers installed and operating requires other steps (e.g. labor at the installation site) whose costs are not affected by technological advances that lower wafer costs. Prices will probably come down further due to over capacity in the PV industry. But prices might bottom out and bounce back up a bit once enough PV makers go bankrupt. Already many Chinese PV makers have halted production as the shake-out continues.
Berkeley, CA — The installed cost of solar photovoltaic (PV) power systems in the United States fell substantially in 2010 and into the first half of 2011, according to the latest edition of an annual PV cost tracking report released by the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab).
The average installed cost of residential and commercial PV systems completed in 2010 fell by roughly 17 percent from the year before, and by an additional 11 percent within the first six months of 2011. These recent installed cost reductions are attributable, in part, to dramatic reductions in the price of PV modules. Galen Barbose of Berkeley Lab’s Environmental Energy Technologies Division and co-author of the report explains: “Wholesale PV module prices have fallen precipitously since about 2008, and those upstream cost reductions have made their way through to consumers.”
This does not mean that manufacturing costs are falling as fast as prices. For several years in the run up to the 2008 financial crisis demand for solar power was growing so fast due to government incentives (especially in Germany) that declines in production costs did not translate into declines in market prices. The recession caused a drop in demand while capacity was still growing. So prices are catching up with previous production cost declines. Companies are feeling more pricing pressures and a shake-out is going on with weaker players failing or merging.
If you are going to build a home you can get PV installed more cheaply if you design for it and do it during your construction process.
The report also found that residential PV systems installed on new homes had significantly lower average installed costs than those installed as retrofits to existing homes.
The full report (PDF) has some interesting details.
Average installed costs vary widely across states; among ≤10 kW systems completed in 2010, average costs range from a low of $6.3/W in New Hampshire to a high of $8.4/W in Utah. The country’s largest state PV markets, California and New Jersey, were near the center of this range, suggesting that, in addition to absolute market size, other state and local factors (e.g., permitting requirements, labor rates, the extent of third party ownership, and sales tax exemptions) also strongly influence installed costs.
Utility-scale solar projects are much cheaper. So people installing solar on their roofs are actually driving up average costs of solar installs.
Since wholesale module costs are now a small fraction of total installed costs it seems like the big cost reductions needed to make solar competitive mostly fall in other areas such as inverters, mounting brackets, permits, labor, and installation.
The recent decline in installed costs is, in large part, attributable to falling wholesale module prices, which fell by $0.9/W from 2008 to 2009, by $0.5/W from 2009 to 2010, and which have fallen further still in 2011 (based on Navigant Consulting’s Global Power Module Price Index).
The savings when installs are done as part of new home construction are sizable.
The new construction market offers cost advantages for small residential PV systems. Among 2-3 kW residential systems (the size range typical for residential new construction) installed in 2010 and funded through California’s incentive programs, new construction systems cost $0.7/W less, on average, than comparably sized residential retrofit systems (or $1.5/W less if comparing only rack-mounted systems).
With non-module costs now several times larger than module costs I am left wondering about the prospects for the decline of non-module costs. Will PV total installation costs decline much more slowly than we've seen in the last few years? What is needed to lower the non-module costs? Installer robots? Roof tile as PV? Inverters integrated into the modules? Anyone have insights into where the next big round of cost cutting will come from and when it will happen?
Kevin Bullis in MIT's Technology Review reports on a company that can squeeze a lot more power out of existing solar cells.
A startup called TenKsolar, based in Minneapolis, says it can increase the amount of solar power generated on rooftops by 25 to 50 percent, and also reduce the overall cost of solar power by changing the way solar cells are wired together and adding inexpensive reflectors to gather more light.
The key innovation: a method to allow solar panels to not be limited by the output from their lowest output cells.
They claim that in higher sunlight areas the result is solar for 8 cents per kilowatt-hour. If you are a high electric power user in southern California you can find yourself paying 34 cents/kwh in the higher usage tiers. So the case for PV on your roof is especially compelling in SoCal. Phoenix Arizona has more insolation but Arizona electricity is less than 2/3rds the cost of California electricity. But to decide whether solar will save you money you need to look more closely at your electric power costs. Some areas have season price differences, tiered rates with higher prices for bigger users, options for time-of-day pricing, and also even options for cheaper recharging of electric vehicles.
Some Wake Forest University researchers have developed a solar collector design that captures both electric power and heat for a higher overall efficiency.
A new polymer-based solar-thermal device is the first to generate power from both heat and visible sunlight – an advance that could shave the cost of heating a home by as much as 40 percent.
Geothermal add-ons for heat pumps on the market today collect heat from the air or the ground. This new device uses a fluid that flows through a roof-mounted module to collect heat from the sun while an integrated solar cell generates electricity from the sun’s visible light.
If this approach can be commercialized then it could lower water and home heating bills.
Only a relatively small portion of the light hitting photovoltaic (PV) material gets converted into electric power. Check out this table of average PV conversion efficiencies by type with silicon crystals at 20% on average. Much of the remaining energy in the light can be captured as heat.
The design of the new solar-thermal device takes advantage of this heat through an integrated array of clear tubes, five millimeters in diameter. They lie flat, and an oil blended with a proprietary dye flows through them. The visible sunlight shines into the clear tube and the oil inside, and is converted to electricity by a spray-on polymer photovoltaic on the back of the tubes. This process superheats the oil, which would then flow into the heat pump, for example, to transfer the heat inside a home.
Houses of the future will do more work. They will combine the German Passivhaus (Passive House) design ideas (where a house leaks very little heat) with solar panels that collect electric and heat energy. As a result houses will do more work to supply a comfortable environment and to power appliances and highly efficient lighting fixtures. Houses will also contain computers with sensors and software that will monitor your health, let you know when your kids or pets are up to trouble, do self-cleaning, and other tasks. Future houses as capital assets will have higher productivity than they do today.
Researchers at the Lawrence Berkeley lab have discovered a very manufacturable way to produce photovoltaic (PV) solar cells that can convert the Sun's full spectrum of light into electricity.
Although full-spectrum solar cells have been made, none yet have been suitable for manufacture at a consumer-friendly price. Now Wladek Walukiewicz, who leads the Solar Energy Materials Research Group in the Materials Sciences Division (MSD) at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), and his colleagues have demonstrated a solar cell that not only responds to virtually the entire solar spectrum, it can also readily be made using one of the semiconductor industry’s most common manufacturing techniques.
The new design promises highly efficient solar cells that are practical to produce. The results are reported in a recent issue of Physical Review Letters, available online to subscribers.
Using more of the solar spectrum could help reduce PV costs. Higher efficiency is especially valuable for space satellites where launch costs are such a big factor. Higher efficiency reduces the area of PV panel that has to get launched into space.
CAMBRIDGE, Mass. - Using carbon nanotubes (hollow tubes of carbon atoms), MIT chemical engineers have found a way to concentrate solar energy 100 times more than a regular photovoltaic cell. Such nanotubes could form antennas that capture and focus light energy, potentially allowing much smaller and more powerful solar arrays.
"Instead of having your whole roof be a photovoltaic cell, you could have little spots that were tiny photovoltaic cells, with antennas that would drive photons into them," says Michael Strano, the Charles and Hilda Roddey Associate Professor of Chemical Engineering and leader of the research team.
The idea with solar concentrators is to come up with concentrators that cost much less per area covered than photovoltaic (PV) cells would cost for that same area. Then use much higher efficiency PV cells to focus the light onto. The higher efficiency cells cost more per area but cost less overall of they can cover a very small area but get solar power from a larger area.
Since so many ways to lower solar power exist I expect its costs to keep on falling. In the long run solar power will become very cheap. So electric power during the day in the summer will become cheaper than electric power the rest of the time.
BOSTON, Aug. 24, 2010 — Continuous research and development of alternative energy could soon lead to a new era in human history in which two renewable sources — solar and wind — will become Earth's dominant contributor of energy, a Nobel laureate said here today at a special symposium at the American Chemical Society's 240th National Meeting.
Walter Kohn, Ph.D., who shared the 1998 Nobel Prize in Chemistry, noted that total oil and natural gas production, which today provides about 60 percent of global energy consumption, is expected to peak about 10 to 30 years from now, followed by a rapid decline. He is with the University of California, Santa Barbara.
Peak Oil is going to cause a lot of problems in the short to medium term. Why are oil companies drilling in deepwater tens of thousands of feet down? Because that's where substantial quantities of oil are still to be found. That's a sign, and not a good one.
A new energy era beckons.
The global photovoltaic energy production increased by a factor of about 90 and wind energy by a factor of about 10 over the last decade. He expects vigorous growth of these two effectively inexhaustible energies to continue during the next decade and beyond, thereby leading to a new era, the SOL/WIND era, in human history, in which solar and wind energy have become the earth's dominant energy sources.
Note that he doesn't put nuclear energy up there as the next big energy source. Whenever will fusion energy become viable?
Wind still isn't providing one whole percentage point of US energy usage. Solar's at .11 quads as compared to wind at .70 quads. So wind is much bigger than solar. Not surprising because it is substantially cheaper.
The estimated U.S. energy use in 2009 equaled 94.6 quadrillion BTUs (“quads”), down from 99.2 quadrillion BTUs in 2008. (A BTU or British Thermal Unit is a unit of measurement for energy, and is equivalent to about 1.055 kilojoules). The average American household uses about 95 million BTU per year.
Energy use in the residential, commercial, industrial and transportation arenas all declined by .22, .09, 2.16 and .88 quads, respectively.
Wind power increased dramatically in 2009 to.70 quads of primary energy compared to .51 in 2008. Most of that energy is tied directly to electricity generation and thus helps decrease the use of coal for electricity production.
Solar's cost is falling more rapidly than wind's and looks to be on path to continue to do so for years to come. So expect solar to gradually close the gap with wind.
The power output of solar panels can be boosted by 10 percent just by applying a big transparent sticker to the front. Developed by a small startup called Genie Lens Technologies, the sticker is a polymer film embossed with microstructures that bend incoming sunlight. The result: the active materials in the panels absorb more light, and convert more of it into electricity.
The article says this material works better in areas where more light is diffuse due to cloud cover. Well, Nick G recently pointed me to a good source for seeing where in America a larger fraction of the light gets redirected on its way to the surface. This pair of maps of insolation for photovoltaics and concentrating solar power provide a good visual way of seeing where a polymer film cover would work especially well to boost PV output:
Areas which shift from a hotter color in the photovolaic solar image to a cooler color in the concentrating solar image are the best candidates for benefit from using the polymer film described above.
A new process that simultaneously combines the light and heat of solar radiation to generate electricity could offer more than double the efficiency of existing solar cell technology, say the Stanford engineers who discovered it and proved that it works. The process, called "photon enhanced thermionic emission," or PETE, could reduce the costs of solar energy production enough for it to compete with oil as an energy source.
The key here is the ability to achieve the very high temperatures needed to use heat to generate electricity while still retaining the ability to convert a portion of the light directly into electricity.
If this wasted heat energy could somehow be harvested, solar cells could be much more efficient. The problem has been that high temperatures are necessary to power heat-based conversion systems, yet solar cell efficiency rapidly decreases at higher temperatures.
Until now, no one had come up with a way to wed thermal and solar cell conversion technologies.
Melosh's group figured out that by coating a piece of semiconducting material with a thin layer of the metal cesium, it made the material able to use both light and heat to generate electricity.
"What we've demonstrated is a new physical process that is not based on standard photovoltaic mechanisms, but can give you a photovoltaic-like response at very high temperatures," Melosh said. "In fact, it works better at higher temperatures. The higher the better."
Because the process works best at 200 C and above it is more suited to solar concentrators. I've been wondering whether concentrating solar or PV would win in the long run. Sounds like maybe a hybrid of the two could become the biggest winner.
Efficiency of 55-60 percent might be possible.
Melosh calculates the PETE process can get to 50 percent efficiency or more under solar concentration, but if combined with a thermal conversion cycle, could reach 55 or even 60 percent – almost triple the efficiency of existing systems.
Since this design could work with existing parabolic mirror solar concentrators and requires a fairly small amount of material the incremental capital cost for boosting conversion efficiency is fairly low. Since a large amount concentrated light hits a small target a boost to the target's conversion efficiency lowers of of electric power generation.
According to Professor Joachim Luther, chief executive officer of the Solar Energy Research Institute of Singapore (SERIS), the breakdown cost of a PV system sees BOS accounting for the lion’s share at 39%.
The BOS, or balance of system, includes the cost of cabling, mounting system and inverters.
The silicon material accounts for 12% and the cells and modules take up 16% each, among others, says Professor Luther.
At first glance this seems to pose problems for the prospects of cutting the costs of PV. Even if the solar cells were literally free the cost of PV wouldn't even fall by half.
But bigger cost reductions still seem attainable for a couple of reasons. First off, higher efficiency solar cells would cut module costs by requiring less bracketing and glass cover for the same amount of electric power. Second, PV roofing tile for new houses and for when old roofs get replaced will avoid the need for much additional labor and special brackets to hold the PV. Integrated designs combined with higher PV efficiency could just be the ticket to very low costs.
A question for anyone who might know: What are the prospects for cheaper and/or longer lasting grid tie inverters?
A UT Austin chemist claims quantum dots can hit 66% efficiency in the conversion of light into electricity.
AUSTIN, Texas—Conventional solar cell efficiency could be increased from the current limit of 30 percent to more than 60 percent, suggests new research on semiconductor nanocrystals, or quantum dots, led by chemist Xiaoyang Zhu at The University of Texas at Austin.
Zhu and his colleagues report their results in this week's Science.
The scientists have discovered a method to capture the higher energy sunlight that is lost as heat in conventional solar cells.
The maximum efficiency of the silicon solar cell in use today is about 31 percent. That's because much of the energy from sunlight hitting a solar cell is too high to be turned into usable electricity. That energy, in the form of so-called "hot electrons," is lost as heat.
If the higher energy sunlight, or more specifically the hot electrons, could be captured, solar-to-electric power conversion efficiency could be increased theoretically to as high as 66 percent.
Photovoltaic cells of such a high efficiency would lower costs substantially. Some people are skeptical about the potential for cheap solar power. But my view is that while solar is still more expensive than wind, nuclear, coal, and other sources of electric power it will eventually become competitive. Its costs (though not always its market price) have steadily fallen for decades. First Solar continues to establish new lower cost points. Even potential for further cost cutting exists that solar should become cheap as a day time power source.
Eric Wesoff of Green Tech Media reports on their projection that well over 10 gigawatts of solar cells will be installed in 2010.
In 2010, we will cross the threshold of 10 gigawatts of photovoltaic solar installed globally in a single year -- a record-setting and once-inconceivable number.
Rewind to ten years ago: the total amount of photovoltaics installed in the year 2000 was 170 megawatts. Since then, the solar photovoltaic industry has grown at a 51 percent annual growth rate, and 170 megawatts is now the size of a healthy utility installation or a small solar factory.
Contrast that with 200 gigawatts of wind installation this year. Wind continues to far surpass solar power due to lower costs.
Total new solar installations for 2010 will be around 11 gigawatts. By contrast, 7 gigawatts of solar was installed in 2009. This increase is partly driven by government policies around the world. But the rapid decline in solar photovoltaic (PV) module costs by about half from late 2008 till today also lowers the threshold for profitable solar projects.
Suntech Power VP Andrew Beebe says SunTech has a single manufacturing building in China which will have the capacity to produce 1 gigawatt of PV per year.
We have a building (that's one building!) in China that this year should be capable of cranking out one gigawatt of product per year. I think that's larger than the entire industry's capacity ten years ago.
Solar's got one big advantage over wind: electric power demand is strongest (and wholesale electric power spot market prices are highest) when the sun shines. Solar's output profile peaks earlier in the day than overall electric power demand. But solar's power output peak is much closer to peak demand than wind's night time output peak. Therefore solar doesn't have to be as cheap per kilowatt-hour to compete against wind.
Current solar troughs use glass mirrors that are formed in the shape of a parabola and then attached to a support structure made of aluminum or steel. The executives said they estimate that the all-aluminum Alcoa parabolic trough, which is being tested at the National Renewable Energy Laboratory in Colorado, will cut the price of a solar field by 20 percent due to lower installation costs.
This comes on the heels of an even more ambitious effort by Google to cut CSP costs. Bill Weihl of Google says Google has a concentrating mirror design that might cut solar thermal costs by a factor of 2 or more.
Weihl said Google is looking to cut the cost of making heliostats, the fields of mirrors that have to track the sun, by at least a factor of two, "ideally a factor of three or four."
The timelines for both these technologies range up to 3 years before they are ready. The cost of concentrating solar looks headed on a downward course.
Plastic polymer solar cells hold out the hope of lower production costs. But their lower conversion efficiencies for producing electricity require more cells and framing to mount over a larger area to get the same amount of electricity. Solarmer Energy thinks it can hit 10% conversion efficiency and eventually higher.
Solarmer Energy, based in El Monte, CA, is on target to reach 10 percent efficiency by the end of this year, says Yue Wu, the company's managing director and director of research and development. Organic cells will likely need at least that efficiency to compete on the photovoltaic market.
In collaboration with Luping Yu, a professor at the University of Chicago, the startup has previously engineered polymers that absorb a broad range of wavelengths and has made cells that convert sunlight to electricity with a record efficiency of nearly 8 percent.
Stanford materials science prof Michael McGehee is quoted in the article suggesting that polymer solar cells might one day hit 15 to 20% conversion efficiency. That's higher than the current CdTe thin films efficiency (about 11%) from industry leader First Solar. But I wonder whether polymer photovoltaics will last as long as CdTe. Anyone know?
With so many competitors rolling out innovations solar power costs are going to continue to drop.
A new manufacturing process could cut the cost of making crystalline silicon wafers for solar cells by 80 percent. The process is being developed by Lexington, MA-based 1366 Technologies, which this week showed off the first solar cells made this way. The technology is key to the company's plan to make solar power cheaper than the electricity generated from coal within 10 years.
Enough players are going at the problem of how to make solar power way cheaper that I expect some group to do it sooner or later. The question is when. This year?
A lot of scientists (e.g. MIT prof Emanuel Sachs who founded 1366 Technologies) obviously think the big disruptive advances are possible or they wouldn't be trying so hard and making such big promises for the future. I expect they understand the physics well enough to know that much cheaper solar PV is possible.
Granted cheap solar or cheap wind (if wind power costs can fall further) will still be problematic due to unreliability. But if batteries for electric cars become cheap enough then cars will become a big source of electric power demand that for the most part won't be time sensitive. People will be able to recharge their cars at night while asleep (and in most areas wind blows stronger at night). After coming home from work most cars sit for over 12 hours. The wind just has to blow sometime during that long period. Similarly, cars parked at work will be able to recharge during the day when the sun is shining.
Writing at greentechmedia.com Craig Hunter outlines an argument for why even if solar cells become almost free the current PV panel approach has so many other costs that competitive PV electric power remains a distant prospect.
Framed in this way, the litmus test for any solar energy technology is its ability in the next 10-20 years to be deployed in hundreds of gigawatts per year, delivering electricity at $.05-.07/kWh, even in areas that aren't very sunny. Given the load factors of PV installations, not to mention the possible need for storage, we need to consider a target installed system price of no more than $1/Wp.
Panel prices have indeed come down significantly, but the PV "experience curve" (15% cost reduction for each doubling of production) is too slow, requiring us to get to 40-80GW per year production just to reach sub-$1/Wp panel pricing. And unless we see disruptive improvements in conversion efficiency, the "balance-of-system" costs (i.e., all the system costs other than the solar panel itself) will make it impossible to achieve a $1/Wp system price even if the panels are nearly free.
So are PV's prospects really that bad? On homes will PV integrated into roofing tile provide the way to avoid most of the physical packaging costs of solar panels? I would expect PV tiles to enable avoidance of lots of labor costs - at least with new roofs where the labor is already getting paid to put up roofing tiles anyway. Even if that happens how much of the total cost is the panel packaging? Will grid-tie inverter costs come down far enough to enablesub-$1/Wp total system cost?
PASADENA, Calif.—Using arrays of long, thin silicon wires embedded in a polymer substrate, a team of scientists from the California Institute of Technology (Caltech) has created a new type of flexible solar cell that enhances the absorption of sunlight and efficiently converts its photons into electrons. The solar cell does all this using only a fraction of the expensive semiconductor materials required by conventional solar cells.
"These solar cells have, for the first time, surpassed the conventional light-trapping limit for absorbing materials," says Harry Atwater, Howard Hughes Professor, professor of applied physics and materials science, and director of Caltech's Resnick Institute, which focuses on sustainability research.
The light-trapping limit of a material refers to how much sunlight it is able to absorb. The silicon-wire arrays absorb up to 96 percent of incident sunlight at a single wavelength and 85 percent of total collectible sunlight. "We've surpassed previous optical microstructures developed to trap light," he says.
This is an amazing accomplishment. At a competitive price such high efficiency in photovoltaic material would allow a much smaller footprint of land area to supply a very large fraction of all the energy we use. Now, if they can manage to do this cheaply it'll be a game changer. See below for reasons why this approach has big cost reduction potential.
They don't waste precious photons.
The silicon wire arrays created by Atwater and his colleagues are able to convert between 90 and 100 percent of the photons they absorb into electrons—in technical terms, the wires have a near-perfect internal quantum efficiency. "High absorption plus good conversion makes for a high-quality solar cell," says Atwater. "It's an important advance."
The key to the success of these solar cells is their silicon wires, each of which, says Atwater, "is independently a high-efficiency, high-quality solar cell." When brought together in an array, however, they're even more effective, because they interact to increase the cell's ability to absorb light.
Is a low price possible? They use far less silicon than in a conventional silicon PV cell. Plus, the flexibility of the material lends itself to lower cost manufacturing techniques.
Each wire measures between 30 and 100 microns in length and only 1 micron in diameter. "The entire thickness of the array is the length of the wire," notes Atwater. "But in terms of area or volume, just 2 percent of it is silicon, and 98 percent is polymer."
In other words, while these arrays have the thickness of a conventional crystalline solar cell, their volume is equivalent to that of a two-micron-thick film.
Since the silicon material is an expensive component of a conventional solar cell, a cell that requires just one-fiftieth of the amount of this semiconductor will be much cheaper to produce.
The composite nature of these solar cells, Atwater adds, means that they are also flexible. "Having these be complete flexible sheets of material ends up being important," he says, "because flexible thin films can be manufactured in a roll-to-roll process, an inherently lower-cost process than one that involves brittle wafers, like those used to make conventional solar cells."
Decent efficiency photovoltaic (PV) solar cells made from cheap copper, zinc, tin, and sulfur but rarer selenium. The efficiency is close to that of commercial thin film PV.
Researchers at IBM have increased the efficiency of a novel type of solar cell made largely from cheap and abundant materials by over 40 percent. According to an article published this week in the journal Advanced Materials, the new efficiency is 9.6 percent, up from the previous record of 6.7 percent for this type of solar cell, and near the level needed for commercial solar panels. The IBM solar cells also have the advantage of being made with an inexpensive ink-based process.
Even with selenium this type of cell has materials cost advantages over existing commercial thin films from First Solar made of cadmium and telluride. Also, this cell has advantages over the CIGS (copper indium gallium selenide) cells of the newer thin film manufacturers since indium and gallium cost more and CIGS also uses selenium.
But currently capital costs are more important than materials cost - at least among the thin film makers. The thin film makers are managing to find ways to cut their costs without switching to cheaper elements. Some CIGS PV makers expect to get their costs down to 50 cents per watt in 2010 versus current low cost leader First Solar's 85 cents a watt in 2009. Also, silicon polycrystal prices have fallen so far and have the potential to fall even farther so that silicon PV makers shouldn't be counted out of the race to lower costs..
Price declines in PV, bigger incentives by state and federal governments, and state requirements for more power from renewables are combining to cause a possible doubling in the amount of PV installed in the United States in 2010 as compared to 2009.
Researchers at Boston College have found evidence that a theory about how to double photovoltaic sunlight conversion efficiency might really work.
The results are a step toward solar cells that break conventional efficiency limits. Because of the way ordinary solar cells work, they can, in theory, convert at most about 35 percent of the energy in sunlight into electricity, wasting the rest as heat. Making use of hot electrons could result in efficiencies as high as 67 percent, says Matthew Beard, a senior scientist at the National Renewable Energy Laboratory in Golden, CO, who was not involved in the current work. Doubling the efficiency of solar cells could cut the cost of solar power in half.
First Solar, Solyndra, Nanosolar, and other contenders are already developing lots of ways to cut manufacturing costs. If the cost cutting trend continues PV will become cost effective for a larger number of potential buyers even without a big efficiency boost. But a doubing in efficiency would be on top of these manufacturing innovations.
Sandia National Laboratories scientists have developed tiny glitter-sized photovoltaic cells that could revolutionize the way solar energy is collected and used.
The tiny cells could turn a person into a walking solar battery charger if they were fastened to flexible substrates molded around unusual shapes, such as clothing.
Such cells could be placed on irregular building shapes, vehicle surfaces, and surfaces where conventional PV can't attach.
Sandia lead investigator Greg Nielson said the research team has identified more than 20 benefits of scale for its microphotovoltaic cells. These include new applications, improved performance, potential for reduced costs and higher efficiencies.
“Eventually units could be mass-produced and wrapped around unusual shapes for building-integrated solar, tents and maybe even clothing,” he said. This would make it possible for hunters, hikers or military personnel in the field to recharge batteries for phones, cameras and other electronic devices as they walk or rest.
The much lower use of silicon should cut costs since silicon is a major portion of the cost of silicon-based PV. This suggests these cells might be able to compete on cost versus the cheaper CdTe and CIGS thin film PV that is currently underselling silicon PV on price.
“So they use 100 times less silicon to generate the same amount of electricity,” said Okandan. “Since they are much smaller and have fewer mechanical deformations for a given environment than the conventional cells, they may also be more reliable over the long term.”
The conversion efficiency is pretty high - higher than the cheap thin films.
Offering a run for their money to conventional large wafers of crystalline silicon, electricity presently can be harvested from the Sandia-created cells with 14.9 percent efficiency. Off-the-shelf commercial modules range from 13 to 20 percent efficient.
New discoveries for making better solar cells keep getting announced by research labs while a growing assortment of PV makers compete with new approaches for cutting manufacturing and installation costs. Some day PV is going to become a cheap way to generate electricity.
30 years ago then California Governor Jerry Brown was called Governor Moon Beam in some quarters. The state's trying to live up to its reputation with state regulatory approval for the first satellite solar power installation which will beam energy down near Fresno.
California regulators went out of this world today and gave the go-ahead to a power-purchase agreement involving the nation’s first solar power plant in space.
Pacific Gas & Electric Co., the state’s largest utility, will proceed with a 15-year contract with Manhattan Beach start-up Solaren Corp., after receiving approval from the California Public Utilities Commission.
The project, which is expected to go live in 2016, will use solar cells from Solaren on orbiting satellites to convert energy from the sun into radio-frequency waves. The waves will be transmitted to a receiving station near Fresno and reverted back into electricity.
Satellite solar power in theory is a better use of photovoltaic solar cells for a couple of reasons. The satellites can get hit by the sun's radiation more hours of the day and sunlight in space is higher concentration than the sunlight that reaches down to the Earth's surface.
The problem of course is that space launch makes putting lots of PV satellites into orbit an expensive undertaking. Yet PG&E apparently thinks Solaren can pull off this project in a cost effective manner.
Anyone understand what has changed the economics of space solar power that makes it possible for Solaren to get a public utility and a utility regulator to take them seriously? Lighter weight PV? Higher conversion efficiency PV? Declines in costs of space launch? Other?
Using nanocrystal-based inks printed onto metal foil photovoltaics start-up Solexant claims it can get its costs under those of low cost leader First Solar.
Making the entire cell using a roll-to-roll process gives the company an advantage over other thin-film photovoltaic companies that print on glass, which is heavier and limited to smaller areas, says Solexant CEO Damoder Reddy. "The cost benefit is dramatic, allowing us to produce cells for 50 cents a watt," he says. First Solar, a thin-film company that uses vacuum deposition to print its cells onto glass, has manufacturing costs of 85 cents per watt. Nanosolar, another company making nanocrystal solar cells, uses a different semiconductor that requires chemical reactions to take place during printing, which increases the complexity and expense of the process. "We print a preformed semiconductor," which eliminates such steps, says Reddy.
Nanosolar is the solar cell maker to beat on costs. I am optimistic about continued big price declines for solar cells because a number of venture capital start-ups like Nanosolar, Solyndra, and Solexant are making credible claims for PV fabrication approaches that enable lower cost manufacturing.
I worry about the approach of Peak Oil (and the possibility that world oil production has already peaked). Because of Peak Oil we need to shift more energy usage to electricity. But our biggest problem isn't how to generate more electricity. We can build nukes and wind turbines. Even solar power is going to become competitive in some areas. Our biggest problem is how to make electricity more usable for transportation. We can electrify the rails to move freight without using oil and lay more rails. But we need better cheaper batteries. It is still not clear to me that batteries will improve fast enough to make the transition away from oil for personal transportation easy enough.
An article by David Wagman about big electric utilities embracing solar power discusses some of the trade-offs of photovoltaics (PV) versus concentrating solar power (CSP). Turns out PV versus CSP is about more than just average cost per kwh. PV can produce power under lower lighting conditions in areas closer to the poles and with more clouds. The article hits a lot of issues with utility-scale solar power. Worth a read.
PV can produce at least some electricity under less than ideal conditions, such as low sun angles and overcast skies. That characteristic is why utilities in places like Massachusetts, Michigan and New Jersey can become solar energy players alongside their brethren in the desert Southwest.
On the other hand, since PV instantly makes electricity when photons hit it the electric power outputted is noisier when clouds pass over. CSP, by contrast, involves heating liquids up to high temperatures in order to eventually generate steam. The temperature of the liquids does not drop rapidly when clouds pass over. So CSP is more dependable in response to passing clouds.
PV also offers the advantage of modularity and scalability. Utilities and large energy users can start relatively small and scale up as demand grows and as they become more comfortable with the technology. But scalability can have its drawbacks, too. For one thing, the larger the deployment the greater the likelihood that cloud cover will affect output.
For similar reasons CSP also can provide power in the evenings. The very hot flowing liquids can heat up molten salts in insulated containers as a way of storing the heat. Then in the evenings as the sun goes down CSP can still provide electric power. It is cheaper to store heat in molten salts than to store electricity in batteries.
Since CSP doesn't work in lower light climates this means that solar far has more growth potential for evening use in the American southwest and under areas with high insolation such as Australia and North Africa.
Researchers at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) released a new study on the installed costs of solar photovoltaic (PV) power systems in the U.S., showing that the average cost of these systems declined by more than 30 percent from 1998 to 2008. Within the last year of this period, costs fell by more than 4 percent.
The number of solar PV systems in the U.S. has been growing at a rapid rate in recent years, as governments at the national, state, and local levels have offered various incentives to expand the solar market. With this growth comes a greater need to track and understand trends in the installed cost of PV.
The 2008 decline was in module costs whereas the previous 10 years saw declines mostly in installation and other non-module costs.
According to the report, the most recent decline in costs is primarily the result of a decrease in PV module costs. "The reduction in installed costs from 2007 to 2008 marks an important departure from the trend of the preceding three years, during which costs remained flat as rapidly expanding U.S. and global PV markets put upward pressure on both module prices and non-module costs. This dynamic began to shift in 2008, as expanded manufacturing capacity in the solar industry, in combination with the global financial crisis, led to a decline in wholesale module prices," states the report, which was written by Wiser, Galen Barbose, Carla Peterman, and Naim Darghouth of Berkeley Lab's Environmental Energy Technologies Division.
During those 10 years of fairly flat PV module prices the manufacturing costs declined as economy of scale increased and companies like First Solar developed new PV fabrication methods. Thin films and other innovations promise large production cost drops in the next 10 years. Solyndra, Nanosolar, and other newer PV makers have developed other ways to cut PV costs and these innovative VC-funded start-ups are changing the economics of solar power. I expect unsubsidized solar to become cost competitive in especially sunny markets such as Southern California and Arizona.
Using thin film copper indium gallium diselenide (CIGS) coated onto roof tiles Dow is going into the business of selling solar photovoltaic tiles for roofs.
The Dow Chemical Company (NYSE: DOW) today unveiled its line of DOW™ POWERHOUSE™ Solar Shingle, revolutionary photovoltaic solar panels in the form of solar shingles that can be integrated into rooftops with standard asphalt shingle materials. The solar shingle systems are expected to be available in limited quantities by mid-2010 and projected to be more widely available in 2011, putting the power of solar electricity generation directly and conveniently in the hands of homeowners.
Groundbreaking technology from Dow Solar Solutions (DSS) integrates low-cost, thin-film CIGS photovoltaic cells into a proprietary roofing shingle design, which represents a multi-functional solar energy generating roofing product. The innovative product design reduces installation costs because the conventional roofing shingles and solar generating shingles are installed simultaneously by roofing contractors. DSS expects an enthusiastic response from roofing contractors since no specialized skills or knowledge of solar array installations are required.
PV tiles have some advantages over PV panels. The most obvious is that the panels are an additional step to install and with additional bracketing. When a house is first constructed or it needs a new roof laborers already install tiles. The incremental labor cost of installing PV tiles rather than conventional tiles is smaller than the cost of of installing PV panels.
The Dow shingles can be installed in about 10 hours, compared with 22 to 30 hours for traditional solar panels, reducing the installation costs that make up more than 50 percent of total system prices.
When you'll know solar PV has hit the mainstream: prefabricated housing will come with optional PV roofs. Seriously, house factories have lower labor costs because they can use much more automation. PV installation on pre-fab housing as shingles or other roofing material could be done at very low labor cost in a housing factory.
Global Solar Energy, the company which makes the PV material that Dow is using, has recently achieved 15.45% efficiency with their CIGS PV material. That's a substantial step up from the efficiency of the PV they are currently selling and close to the efficiency of silicon-based PV.
Global Solar Energy, Inc., the premier manufacturer of Copper Indium Gallium diSelenide (CIGS) thin film solar products, today announced that the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL), the nation’s primary laboratory for renewable energy and energy efficiency research and development, confirmed 15.45 percent total area efficiency for Global Solar’s production level CIGS material. Adding to this news, Global Solar announces a peak efficiency of 11.7 percent for production CIGS solar cell strings manufactured at its 35-megawatt German and 40-megawatt U.S. plants.
Global Solar Energy's 75 MW yearly production capacity is small potatoes. Nanosolar's new PV plant in Germany has a yearly production capacity of 640 MW. Solyndra just started construction on a new production facility with a planned yearly 500 MW production capacity. While Showa Shell Sekiyu K.K. has announced plans for a thin film PV plant with a 900 MW yearly production capacity. Yet Dow is forecasting billions of dollars per year in sales for their PV shingles. If the demand develops then either Global Solar will have to scale up in a hurry or Dow's going to need another partner.
A New York Times article reports on other PV roofing material makers. For the home market PV tile will probably become the preferred choice.
A California company is using silicon ink patterned on top of silicon wafers to boost the efficiency of solar cells. The Sunnyvale, CA, firm Innovalight says that the inkjet process is a cheaper route to more-efficient solar power. Using this process, the company has made cells with an efficiency of 18 percent.
The efficiency increase was from a starting efficiency 16.5-17% up to 18%. So this additional layer captures an additional 1% of the sunlight falling on the silicon PV cells. This by itself isn't going to close the cost gap between silicon PV and cheaper thin film PV from the likes of First Solar, Solyndra, and Nanosolar. But it is another reason why PV prices are going to stay down even as demand surges in China and the United States.
This report reminds me of how 1366 Technologies is also going to sell an efficiency-boosting technique to silicon PV makers. The existing manufacturers are now so big that new entrants develop technology to sell to them rather than directly going into manufacturing themselves. The scale of existing manufacturers make the barriers to entry too big for most innovators. There are exceptions to this such as Nanosolar which looks like it is coming out with manufacturing technology so revolutionary that they might be entering the market as the new low cost leader. Impressive achievement if so. Sure looks that way given their order book.
No reason for continued gloom about high solar power prices. The market is turning up lots of innovators. Costs are falling.
On Wednesday, Nanosolar pulled back the curtain on its thin-film photovoltaic cell technology — which it claims is more efficient and less expensive than that of industry leader First Solar — and announced that it has secured $4.1 billion in orders for its solar panels.
CEO Martin Roscheisen claims lower costs than cost leader First Solar. Great news if true.
Nanosolar has an unusual manufacturing approach using thin aluminum foil and a wet chemistry for depositing CIGS (Cadmium Indium Gallium Selenide) thin film on the foil as the foil moves rapidly. This continuous flow approach holds the prospect of much lower cost of manufacture. Their new plant in Germany can produce 640MW per year when operated 24x7.
Today Nanosolar demonstrated the completion of its European panel-assembly factory as part of an inauguration event attended by Germany's Minister of the Environment, the Governor of the State of Brandenburg, and a host of other leading public officials. Located in Luckenwalde near Berlin, the fully-automated factory processes Nanosolar cells into finished Nanosolar panels using innovative high-throughput manufacturing techniques and tooling developed by Nanosolar and its partners.
The panel factory is automated to sustain a production rate of one panel every ten seconds, or an annual capacity of 640MW when operated 24x7. Nanosolar also today announced that serial production in its San Jose, California, cell production factory commenced earlier this year.
That 640MW is probably in practice equivalent to about a quarter that amount on average - depending heavily on just where the panels are installed. I'm guessing roughly 10 such factories would produce the equivalent of a new nuclear power plant every year. If they can get their costs low enough then raising the capital for a big capacity build will be easy to do. They claim their process makes cost reduction much easier than competing approaches.
Electrically, it is the industry’s highest-current thin panel, by as much as a factor of six. It is also the industry’s first photovoltaic module certified by TUV for a system voltage of 1500V, or 50% higher than the previously highest certified. Together this enables utility-scale panel array lengths and results in a host of substantial cost savings during the deployment of solar power plants.
Our lab and production teams have managed to make more progress on efficiency than we had planned on in any of our business plans. Recall that we print CIGS onto inexpensive metal foil, that is, something that some have been skeptical can work while others have been wondering whether it can deliver efficient cells.
So we are pleased to announce that our low-cost printed-CIGS-on-metal-foil cell stack and process produces quite efficient cells: Earlier this year, NREL independently verified several of our cell foils to be as efficient as 16.4%.
In production efficiency is running at only 11%. If Nanosolar can get their production cell efficiency up to 16.4% that would cut substantially cut their costs.
PV costs are definitely on a downhill slope after several years of stagnant prices. Now we have two main competitors driving costs below $1 per watt. Good news. Will costs of supporting equipment such as grid tie inverters also drop? Or will the development of DC (direct current) appliances avoid the need for grid tie inverters for home PV installations?
Michael Graham Richard has some cool pictures of their manufacturing process.
Update: Be sure to read Chris Nelder's more detailed look at Nanosolar's cost advantages. They cut interconnect costs, reduce need for aluminun frames, and cut costs in other ways relating to installation. They might end up far cheaper than First Solar, the current cost leader. Solyndra has been lauded in the press as the potential big rival to First Solar. But if the claims about Nanosolar are true then Nanosolar might beat both of them. Sure looks like PV costs are headed for a big fall.
Improvements to conventional solar cell manufacturing that could significantly increase the efficiency of multicrystalline silicon cells and bring down the cost of solar power by about 20 percent have been announced by startup 1366 Technologies of Lexington, MA.
They claim they can boost light-to-electron conversion efficiency for a very small increase in manufacturing cost. This helps the silicon cells compete against the currently lower cost thin film cells made by First Solar.
Such cost reduction would make solar power more competitive with conventional sources of electricity. In sunny environments, this could bring the cost of solar down to about 15 or 16 cents per kilowatt hour, says Craig Lund, 1366 Technologies's director of business development. That's cheaper than some conventional sources of electricity, especially those used during times of peak electricity demand.
The company is going to sell manufacturing equipment to PV makers. So this tech will drive down costs of multiple suppliers. Also, the efficiency boost will increase the amount of power you can get from the same roof after.
The company’s ultimate business will be to make and sell texturing and metallization machines that solar cell manufacturers can incorporate into their existing assembly lines. “The big news for us is that we’re going into commercial production with equipment that delivers an 18-percent multicrystalline cell,” Lund says.
For years progress is lowering photovoltaic costs seemed slow to non-existent. But rapidly growing demand (mostly caused by government policies) was hiding progress in cutting costs. Many companies are working on practical innovations to lower costs and all this effort is beginning to show real results in the market place. I've become optimistic that solar power is going to become much cheaper.
What I'd like to know: can we expect grid tie inverter costs to fall as much as PV costs? Also, how practical is it to use some of the PV power directly in DC appliances? Will DC (as distinct from AC) appliances remain too rare for PV DC power bypass grid tie inverters and more cheaply power appliances?
The price per watt has now dropped to US$1.80 for polysilicon-based products, which is lower than the US$1.85 level The Information Network previously thought the industry would see at the end of 2009. By way of comparison, the average selling price in the third quarter of 2008 was US$4.05 per watt.
Whether we will see a continued rapid decline in prices remains to be seen. Currently I doubt any manufacturer aside from First Solar can make a profit below $1 per watt. Anyone have insights into the costs of China's biggest PV makers?
Also, anyone have insights into how much prices for residential PV installations are declining?
The decline in demand as a result of the recession combined with a big ramp up of manufacturing capability (it caused by the high energy prices that helped trigger the recession) created the glut. But China now is aiming to become the dominant maker of PV. Suntech Power of China is selling product in the US at a loss in order to gain market share.
Chinese companies have already played a leading role in pushing down the price of solar panels by almost half over the last year. Shi Zhengrong, the chief executive and founder of China’s biggest solar panel manufacturer, Suntech Power Holdings, said in an interview here that Suntech, to build market share, is selling solar panels on the American market for less than the cost of the materials, assembly and shipping.
...But even in the solar industry, many worry that Western companies may have fragile prospects when competing with Chinese companies that have cheap loans, electricity and labor, paying recent college graduates in engineering $7,000 a year.
But if Suntech Power is already selling at a loss at today's prices I fail to see how it can afford to sell at a half or a quarter of today's prices. I doubt manufacturing costs will drop that quickly.
DisplaySearch, a unit of research firm NPD Group that focuses on the display and solar markets, reports today that global solar cell manufacturing capacity is expected to grow 56% in 2009 to 17 gigawatts, with further growth at a 49% compounded rate to more than 42 GW in 2013.
The country may raise its solar-power capacity to 2,000 megawatts by 2011 and 20,000 megawatts by 2020, from 150 megawatts at the end of last year, Cui Rongqiang, head of the Shanghai Solar Energy Society, said by telephone today.
I do not come across articles on China's use of concentrating solar power (CSP). Yet at least in the United States CSP looks cheaper than PV. CSP also makes it much easier to shift production from afternoon into evening via heat storage in molten salts.
Renewable energy will account for 4 percent of the city’s total consumption by next year and 6 percent by 2020, the Beijing Municipal Development and Reform Commission said in a statement handed out to reporters at a briefing today.
The central government aims to meet 15% of its energy needs through renewable sources by 2020. Beijing hopes to triple its solar heater capacity by the same year, according to Greenpeace China.
Can Suntech or another Chinese PV maker catch up with First Solar on costs? Can PV catch up with CSP on costs? Anyone got insights on these questions?
Okay, this is really strange. But if you integrate concentrating solar power mirrors to the existing electric generating equipment of a coal electric plant the result is the cheapest way to generate electric power from the sun.
A project that will add solar power to a coal-fired power plant could reduce the amount of coal required to generate electricity and dramatically cut the cost of solar power.
Effectively this avoids lots of idle electric generator capital equipment at night.
"The thing that's attractive about this is you only have to buy the solar field portion of the plant, which is 50 to 60 percent of the cost of the plant," says Hank Price, director of technology at Abengoa Solar. That could effectively make solar-thermal power about 30 to 50 percent cheaper, according to various estimates. That would equate to a range of about six to 12 cents per kilowatt-hour, which is competitive with many conventional sources of electricity. "It's potentially the most cost-effective way to get significant solar power on the grid," he says.
There are obvious limits to this approach. Coal plants need to be in sunny areas and to have land available near them. Plus, there must be some physical distance limitation for how far the heated liquid can be transported to the coal plant. So the percentage of total electricity coming from concentrating solar at an existing coal plant is limited to 10-15% according to the article.
The price drops in PV were so long in coming a lot of commenters on past posts on solar cells expressed skepticism that solar would ever become cheap. But big production capacity expansions, technological advances (most notably by First Solar) that cut costs, and the recession have finally popped the high prices for PV. Over about the last 15 months photovoltaic panel prices have dropped 40%.
For manufacturers, the problem boils down to a sharp drop in panel prices amid increased supply and tighter demand. Panel prices have fallen by nearly 40 percent from their peak last spring, estimates Chris Whitman, the president of U.S. Solar Finance, which helps arrange bank financing for solar projects.
Overcapacity could lead to a shake-out in the industry. Some companies are shutting down manufacturing lines whose costs are too high.
After scaling up rapidly in response to strong demand during 2007 and early 2008, falling demand has seen the solar market hit by a glut of silicon, the raw material used in most panels, and solar panels themselves. As a result, silicon prices have dropped by as much as 40 per cent in the past year, while panel prices have fallen by about 20 per cent, making many older production lines unviable.
The party for buyers looks set to continue. Barclays Capital analyst Vishal Shah expects more big price drops in 2010.
“Given the overly optimistic demand outlook of most Chinese solar players and expectations of continued production ramps, we see additional downside risk to module pricing exiting 2009,” he adds. “More importantly, we expect 2010 module ASPs to decline by 25%-30%.”
These rapid price declines are a reason to wait before putting PV on your roof. Even if you live in Phoenix or Tucson Arizona you are better off waiting another year. The amount you'll have on electricity in a year if you install PV is less than you'll have by waiting for cheaper prices. Wait for the price drops to slow up before buying. You basically should wait until yearly price drops to become smaller than your yearly expected savings.
One analyst expects solar to become grid competitive by 2010. Perhaps that is true in the summer in SoCal because of the high cost (at least by American standards) of electricity.
In an Aug. 13 research note, UBS (UBS) analyst Robin Cheng said she expects photovoltaic electricity to be competitive with power from the grid by 2010 in those parts of Europe and the U.S. that get more regular sunshine, and by 2014 in regions that experience more cloud cover. "Until then, the industry is heavily dependent on government incentives," she writes.
Differences in local electric rates as well as differences in insolation (the amount of photons hitting the surface) are just two of the factors that determine whether solar power makes sense where you live. Here's a list of things to keep in mind when trying to decide on PV for your home roof:
What is most needed are many small refinements that drop the costs of existing manufacturing technologies. These refinements are best done by industry development teams.
The federal government is behind the times when it comes to making decisions about advancing the solar industry, according to several solar-industry experts. This has led, they argue, to a misplaced emphasis on research into futuristic new technologies, rather than support for scaling up existing ones. That was the prevailing opinion at a symposium last week put together by the National Academies in Washington, DC, on the topic of scaling up the solar industry.
My thinking has been moving along similar lines. 5 and 10 years ago I was a big advocate for more funding of academic research into photovoltaic materials. But as I watch First Solar drive down the cost of manufacturing to now below $1 per watt and dropping I get the sense that the field of battle has really shifted to factories and engineering teams who work on automating PV manufacturing. Companies like eSolar make me think the same thing about concentrating solar.
The meeting was attended by numerous experts from the photovoltaic industry and academia. And many complained that the emphasis on finding new technologies is misplaced. "This is such a fast-moving field," said Ken Zweibel, director of the Solar Institute at George Washington University. "To some degree, we're fighting the last war. We're answering the questions from 5, 10, 15 years ago in a world where things have really changed."
Solar is not a panacea, even if its price drops in half and then again in half. It has the obvious problem that the sun does not always shine. A world insolation map shows that on the worst day of the year insolation varies from one part of the world to another by multiples. Arizona's worst day gets several times more solar energy than Germany's worst day. This is especially problematic for Germany and other northern European countries (and some eastern parts of Canada and Maine) whose electric demand peak is in the winter. Arizona (and even more so Darwin Australia) gets a solar peak when electric demand peaks for air conditioning. So solar works well for air conditioning in some hot climates with sunny summer weather.
The ability of concentrating solar power (CSP) heat to be stored in molten salts for use several hours later makes concentrating solar's potential substantial as a way to supply solar power when the real summer demand peak occurs in late afternoon and early evening. Moderate sized CSP projects in Spain and Arizona are where CSP technologies are getting refined. Arizona is a perfect place for this sort of thing given the very hot summers with lots of air conditioning electric power demand and blue skies. But since these projects need government (meaning taxpayer) subsidies in Arizona they are a long way from making sense in Seattle or Berlin - much less Helsinki.
Yet another solar start-up with an interesting technology. Roll-to-roll manufacturing is one way to try to make PV production really cheap.
Xunlight, a startup in Toledo, Ohio, has developed a way to make large, flexible solar panels. It has developed a roll-to-roll manufacturing technique that forms thin-film amorphous silicon solar cells on thin sheets of stainless steel. Each solar module is about one meter wide and five and a half meters long.
Their conversion efficiency is currently only 8%. They expect to go into commercial production in 2010.
The odds are against each new solar photovoltaics start-up. Existing companies are going up big learning curves in boosting efficiency and lowering production cost. The production cost leader First Solar has a thin film process that achieves 10.7% efficiency. SunPower's higher cost polysilicon process is turning out silicon cells at 22% efficiency (though it seems commercially they are at 19.3%). Does Xunlight have a really big cost advantage in manufacturing? They'll need one.
Startup Enphase Energy of Petaluma, CA, is now making the first micro-inverters. These smaller inverters can be bolted to the racking under each solar panel, to convert DC power into AC for each panel individually. The company claims that the devices will increase a PV system's efficiency by 5 to 25 percent and decrease the cost of solar power.
The company also claims this inverter lowers costs of components. So lower costs and higher efficiency.
Skyline Solar, a startup that today announced its existence to the world, has developed a cheaper way to harvest energy from the sun. The company's solar panels concentrate sunlight onto a small area, reducing the amount of expensive semiconductor material needed to generate electricity.
Skyline Solar uses the parabolic trough approach used in solar thermal electric plants. They only concentrate the light by a factor of 10. Other companies pursuing photovoltaics (PV) with solar concentrators use much higher factors of light concentration and therefore have much bigger heat dissipation problems. The falling prices for PV reduces the advantage of using concentrators. The cheaper the PV the less point in using concentrators to reduce the amount of PV used.
Increases in PV efficiency help improve the economics of concentrating solar. If SunPower can improve their PV from 22% to 24% and beyond this will lower concentrating solar's costs because the same amount of mirrors will make more electricity. Higher efficiency PV fits well with concentrating solar. So concentrating solar with silicon-based high efficiency PV competes with thin film lower efficiency and lower cost PV.
An Israeli solar concentrator start up, Zenith Solar, is also claiming a cheaper way to do concentrated solar that uses both PV and thermal energy.
The technology, a system of rotating dishes made up of mirrors, is capable of harnessing up to 75 percent of incoming sunlight – roughly five times the capacity of traditional solar panels. In addition, using mirrors to reduce the number of photovoltaic cells needed, it makes the cost of solar energy roughly comparable to fossil fuels.
While this technology has been implemented elsewhere, Israeli start-up ZenithSolar – working in conjunction with Israel’s Ben-Gurion University – is a pioneer in combining it with a water-based cooling system that increases the photovoltaic cells’ efficiency and produces thermal energy to boot.
The value of that thermal energy depends on what you can do with it. Solar thermal's highest value comes in late winter and early spring when the days have gotten longer but the weather is still cold. The thermal energy can be used to heat buildings. But on a hot summer's day the hot water is only useful if it can boil and produce steam to generate electricity.
Do solar concentrators have a long range future? Or will declining PV prices make concentrators pointless?
The Q1 2009 conference call between photovoltaics maker SunPower's top executives and financial analysts covered the question of how fast solar panel prices are falling. Answer: pretty fast. While SunPower claims to have cut average selling prices by less than 10% so far this year the analysts point to competitors who've made bigger cuts and the CEO of SunPower admits they see another 20% of price cuts coming in the rest of 2009.
Nicholas Allen - Morgan Stanley
So you expect another 20% decline in pricing over the course of the year?
Yes. The way you should think of it from our perspective is that we are prepared for... or we've tested into our models up to 20% more price decline this year.
SunPower is probably the second strong player in the PV space after First Solar. This statement by its CEO is therefore very telling.
If you are thinking about putting solar panels in your house then wait. You can't possibly make or save enough money off those panels in the next 8 months to return you 20% of your costs.
The reference here to "poly pricing" is for polysilicon crystal which is a production input to silicon PV production (though not for thin film PV as made by First Solar). I've read other sources claiming that prices for poly have declined from a peak of $450 to $100 per kilogram.
Pavel Molchanov - Raymond James
Target for a 50% all-in cost reduction by 2012. Given that poly pricing had collapsed much faster than pretty much anyone would have expected, do you see any upside to that target?
Thanks Pavel for the question. Tom, I'll take this to keep us moving quickly. We also guided that two-thirds of that cost reduction which happened by 2010 or sooner. And yes, we are seeing some opportunity for that to accelerate.
So SunPower expects to cut their own production costs by a third by 2010 and more by 2012. This tells you where solar PV costs are going and how fast they are going there.
For the several years I've been writing posts about the prospects for solar panels a core of skeptical commenters have consistently reacted by claiming that PV costs have declined so little for so long that PV is never going to become viable. But look at the numbers above. The era of relative price stability in PV prices has ended. The era of rapid price declines is upon us. It is about time.
Now Solaren Corporation, a startup based in Manhattan Beach, CA, is trying to get the idea off the ground. It's working with the California utility Pacific Gas and Electric (PG&E), which intends to enter into a power-purchase agreement with the company. If the agreement is approved by regulators, starting in 2016, the utility will purchase 200 megawatts of power from Solaren at an undisclosed price--that is, if the startup can get a system into space and working by then. The company has already selected a site in California for the receiving station; it hasn't said exactly where, but it will be close to a PG&E substation and won't require long-distance transmission lines.
For transmitting the power down to Earth the article mentions both microwaves and lasers. Are lasers practical for this purpose? In that case wouldn't another photovoltaic array be needed on the surface to convert again to electricity? Granted, that array would receive a very focused beam of light. So the area needed would be much smaller.
Also, does anyone know the conversion efficiency for microwaves into electricity?
It is hard to judge the odds of this getting off the ground (both figuratively and literally) by 2016.
A company in Washington State claims that by using automotive industry suppliers to mass produce parts a solar concentrator and Stirling engine can achieve high efficiency and low cost electric power generation.
Infinia's founders showed him their design for a solar-powered Stirling engine, with the heat provided by what looked like a large, mirrored satellite dish. The other end was cooled by a car-radiator system. A mechanical drive kept the dish pointed at the sun throughout the day. At night it folded up like a flower to help retain heat (with a small biofuel tank as backup).
Using the Stirling as a generator, Infinia could convert 24% of the sunlight hitting the dish into electricity - a better conversion rate than most solar panels have. Sitton needed no further convincing. He went hunting for investors just as the solar market was heating up. Since 2005 he has secured $70 million in funding from venture firms such as Vulcan Capital, owned by Microsoft co-founder Paul Allen.
Can they make this compete with other solar technologies? Anyone have insights on this?
You know that nanotechnology is going to, like, revolutionize the future, right? We are all just sitting around waiting for the nanotech revolution to arrive. Nanocups will help cloak electric vehicles and of course feed their solar cells to keep them moving. At least that seems like the bottom line to me.
Researchers at Rice University have created a metamaterial that could light the way toward high-powered optics, ultra-efficient solar cells and even cloaking devices.
Naomi Halas, an award-winning pioneer in nanophotonics, and graduate student Nikolay Mirin created a material that collects light from any direction and emits it in a single direction. The material uses very tiny, cup-shaped particles called nanocups.
Solar thermal concentrators built with nanocups would be more efficient at capturing light.
Because nanocup ensembles can focus light in a specific direction no matter where the incident light is coming, they make pretty good candidates for, say, thermal solar power. A solar panel that doesn't have to track the sun yet focuses light into a beam that's always on target would save a lot of money on machinery.
Solar-generated power of all kinds would benefit, said Halas. "In solar cells, about 80 percent of the light passes right through the device. And there's a huge amount of interest in making cells as thin as possible for many reasons."
Halas said the thinner a cell gets, the more transparent it becomes. "So ways in which you can divert light into the active region of the device can be very useful. That's a direction that needs to be pursued," she said.
Since nanocups will focus light from any direction they could avoid the problem of lost concentrated solar efficiency due to diffuse light caused by airborne sulfur aerosols.
MIT mechanical engineering prof Emanuel Sachs thinks his solar photovoltaics (PV) start-up 1366 Technologies can bring down the costs of silicon polycrystal-based PV below the current cost of thin film PV. His company's goal is to bring the cost down even below coal electric in 3 years. 1366 Technologies is pursuing at least 4 technological improvements in order to beat coal electric.
1366 Technologies' first idea, called a "light-capturing ribbon," is to manufacture so-called interconnect wires with V-shaped grooves. Normally, light hits those interconnect wires, which are under the solar cell, and bounces straight out. By contrast, the grooved wires reflect light at an angle so that it can bounce onto a solar panel's glass covering and back down onto the cell. That "internal reflection" squeezes a bit more electricity from the incoming light without having to reinvent the production process.
The second idea is to redesign the wires that carry current on a solar panel to be smaller and less expensive. There are two other improvements on the drawing board, including one that uses reflective wires to trap more light onto cells, but the company is cagey on the exact details.
PV below the cost of coal electric would simultaneously lower the prices we pay for electricity, reduce conventional pollutants such as particulates and mercury, and also reduce greenhouse gas CO2 emissions.
I would like to see polysilicon PV beat the current low cost leader FirstSolar's Cadmium Telluride thin films. For a few reasons. First off, silicon-based PV achieves higher conversion efficiencies. Higher conversion efficiencies mean you can get more electric power out of the same rooftop area. This raises the potential energy output for electric power generation for homes and commercial buildings. Second, whether Tellurium (Te) production can scale up is uncertain. Third, silicon PV is probably easier to deal with in terms of disposal at the end of life (though I'm not certain on that point).
I still see any of the major PV technologies as such big net pluses that making any of them very cheaply will be a big win for all of us.
A cheap synthetic system that works better than plant photosynthesis for producing hydrocarbons from carbon dioxide, water, and sunlight might some day provide a great source of energy. Toward that end some Penn State researchers have advanced the state of the art for light-driven methane generation using titania nanotubes. I love to see this kind of advance.
Dual catalysts may be the key to efficiently turning carbon dioxide and water vapor into methane and other hydrocarbons using titania nanotubes and solar power, according to Penn State researchers.
Burning fossil fuels like oil, gas and coal release large amounts of carbon dioxide, a greenhouse gas, into the atmosphere. Rather than contribute to global climate change, producers could convert carbon dioxide to a wide variety of hydrocarbons, but this makes sense to do only when using solar energy.
"Recycling of carbon dioxide via conversion into a high energy-content fuel, suitable for use in the existing hydrocarbon-based energy infrastructure, is an attractive option, however the process is energy intense and useful only if a renewable energy source can be used for the purpose," the researchers note in a recent issue of Nano Letters.
Craig A. Grimes, professor of electrical engineering and his team used titanium dioxide nanotubes doped with nitrogen and coated with a thin layer of both copper and platinum to convert a mixture of carbon dioxide and water vapor to methane. Using outdoor, visible light, they reported a 20-times higher yield of methane than previously published attempts conducted in laboratory conditions using intense ultraviolet exposures.
This is still a laboratory-level advance. Industrial field use is still years away. But it is the sort of advance that could eventually provide a way to suck large amounts of carbon dioxide out of the atmosphere. Further enhancements to make longer chain hydrocarbons could yield synthetic hydrocarbon liquids for transportation.
One of the advantages of a synthetic replacement for photosynthesis is the ability to operate for a larger fraction of the year. March 21 and September 21 are halfway points between the shortest and longest days of the year. In the northern hemisphere March 21's photons drive far less photosynthesis than September 21's photons because plants are still in frozen state in the more northern areas (with a similar pattern in the southern hemisphere with swapped dates for spring and fall starts). The late winter and early spring photons could be harnessed sooner in a synthetic system that didn't require plant growth to create areas for capturing the photons. Also, a synthetic system could cover ground which currently can't support much plant life.
A synthetic system built to float far out to sea could absorb photons and do synthesis over area of the ocean that are too nutrient poor to support much microbial life. While such installations are too expensive today in the future nanoassemblers will drastically reduce the cost of construction of massive floating solar collecting synthetic hydrocarbon production ships.
Update: To clarify: Methane is a far more potent atmospheric warmer than carbon dioxide. So a synthetic methane synthesizer with a big leak in it would warm the planet. In fact, if one wanted to, say, prevent an ice age then synthetic methane producers with their output vented to the atmosphere would be one way to do it. On the other hand, if one's photochemical hydrocarbon synthesizer produced longer chain liquid hydrocarbons (gotta be longer than Hank Hill's propane in order to remain liquid) then the atmospheric warming risk would be eliminated. Since the longer chain hydrocarbons are far more desirable for transportation a method for generating them would be ideal.
While the bulk of concentrating solar now in use is for solar thermal steam electric power generation it is not the only use of concentrating solar. Highly concentrated light shined on photovoltaic (PV) materials greatly lowers the amount of PV needed. If the concentrator costs less than PV for the same area then concentrator plus PV can be a cheaper way to go. A Canadian company, Morgan Solar, claims to have a better way to concentrate sunlight for PV solar.
A couple of years ago, Nicolas's brother John Paul Morgan came up with the idea of a solid-state solar concentrator system: a flat, thin acrylic optic that traps light and guides it toward its center. Embedded in the center of Morgan Solar's concentrator is a secondary, round optic made of glass. With a flat bottom and convex, mirrored top, the optic receives the incoming barrage of light at a concentration of about 50 suns and amplifies it to nearly 1,000 suns before bending the light through a 90-degree angle.
Unlike other concentrators, the light doesn't leave the optic before striking a solar cell. Instead, a high-efficiency cell about the size of an infant's thumbnail is bonded directly to the center bottom of the glass optic, where it absorbs the downward-bent light. There's no air gap, and there's no chance of fragile components being knocked out of alignment.
They think they can compete with thin film solar on costs by 2011.
Some business and engineering decisions must still be made, but he expects that the company will be able to build its system for less than $1 per watt by 2011--"and with some vertical integration, considerably less." This would lead to a product close to 30 percent efficient at costs competitive with thin film.
FirstSolar is the market leader for low cost thin film photovoltaics. In Q1 2008 FirstSolar claimed a manufacturing cost of $1.14 per watt. They aren't sitting still. By 3Q 2008 they were claiming $1.08 per watt. Their cost will be even lower in 2 years time. Morgan Solar needs to come in under $1 per watt to compete.
Concentrating solar for PV is best used with higher priced PV that has higher conversion efficiencies. The higher cost for materials with higher conversion efficiency does not matter because the amount of PV used is very small. Concentrating solar's ability to compete might end up hinging on how much conversion efficiencies improve. A doubling of conversion efficiency would probably cut Morgan's cost in half. More than a doubling in PV conversion efficiency might be possible.
TEMPE, Ariz.--(BUSINESS WIRE)--Feb. 24, 2009-- First Solar, Inc. (Nasdaq: FSLR) today announced it reduced its manufacturing cost for solar modules in the fourth quarter to 98 cents per watt, breaking the $1 per watt price barrier.
“This achievement marks a milestone in the solar industry’s evolution toward providing truly sustainable energy solutions,” said Mike Ahearn, First Solar chief executive officer. “First Solar is proud to be leading the way toward clean, affordable solar electricity as a viable alternative to fossil fuels.”
First Solar has cut their cost by about 16% in less than a year. Impressive. Complaints that solar PV costs go down too slowly are starting to sound outdated.
The largest solar thermal plant in the world is now operational in Spain. (thanks "Fat Man" for the heads-up)
The salts—a mixture of sodium and potassium nitrate, otherwise used as fertilizers—allow enough of the sun's heat to be stored that the power plant can pump out electricity for nearly eight hours after the sun starts to set. "It's enough for 7.5 hours to produce energy with full capacity of 50 megawatts," says Sven Moormann, a spokesman for Solar Millennium, AG, the German solar company that developed the Andasol plant. "The hours of production are nearly double [those of a solar-thermal] power plant without storage and we have the possibility to plan our electricity production."
7.5 hours is long enough to provide peak electric power during the peak late afternoon and evening hours of a very hot summer day. The article says this is the first heat storage facility for a concentrated solar facility on this scale. So we need to wait and see how well it works in practice. The $380 million cost for a 50 MW facility sounds pretty pricey to me, especially since this isn't 50 MW of 24x7 power.
Maybe someone else can make better sense of this SciAm article than I can. They quote only a doubling in electricity cost for electricity from this method as compared to coal. How can solar thermal (i.e. concentrated solar) cost twice as much as coal regardless of whether molten salt storage is used?
All told, that means thermal energy storage at Andasol 1 or power plants like it costs roughly $50 per kilowatt-hour to install, according to NREL's Glatzmaier. But it doesn't add much to the cost of the resulting electricity because it allows the turbines to be generating for longer periods and those costs can be spread out over more hours of electricity production. Electricity from a solar-thermal power plant costs roughly 13 cents a kilowatt-hour, according to Glatzmaier, both with and without molten salt storage systems.
Coal electric with no conventional pollutant emissions would cost more. Add in the cost of carbon capture and then nuclear power becomes cheaper than coal. Concentrating solar isn't going to compete with coal all that much. Nuclear, geothermal, and (with limits) wind are the real competitors to coal because coal is a base load source of electric power. Solar isn't for base load.
That price is still nearly twice as much as electricity from a coal-fired power plant—the current cheapest generation option if environmental costs are not taken into account. But Arizona's APS and others can then use solar energy to meet the maximum electricity demand later in the day. "Our peak demand [for electricity] is later in the evening, once solar production is trailing off," Lockwood says. That's "the reason we went that direction and are so interested in storage technology."
This is the big reason why concentrating solar might have a big future regardless of what happens with photovoltaic prices. The heat generated by concentrating the light is a lot easier to store than electricity. Concentrating solar with salt storage can stretch across the peak demand hours - at least in the US where summer is peak demand time. In Britain peak electric demand is in winter when not a lot of sun shines. So solar power does not work well in Britain.
The 50MWe AndaSol plant is located in the community of Aldeire in the Marquesado valley in the Province of Granada, Southern Spain. Thanks to the high altitude (1,100 m) and the desert climate, the Marquesado Valley offers exceptionally high annual direct insolation of 2,200 kWh/m²yr. The 549’360m² parabolic trough solar field is built-up by 1,008 EUROTrough collectors, arranged in 168 parallel loops. It will occupy app. 200 hectares of land. It will generate live steam of 100 bar/371°C to the reheat steam turbine with a cycle efficiency of 38%, gross. With an annual direct normal radiation of 2,200 kWh/m² per year, the AndaSol plant will generate almost 182 million kWh per year of clean solar electricity in 100% solar operation. The plant will be built, owned and operated by the specific project company, Partner 1. Partner 1 will sell as renewable independent power producer the generated solar electricity to the utility under the standard renewable power purchase terms regulated by the Spanish Royal Decree 2818/98. Using solar beam radiation as it’s primary energy, the solar plant will avoid approximately 172,000 tons of CO2 annually in Southern Spain otherwise being emitted by coal and heavy fuel oil operated power plants in the region.
In a market that 182 million kwh might sell for, say, 10 cents per kwh. It would probably sell for less in the US where the average retail cost of electricity is about 11 cents per kwh. But let us assume a higher price in Europe. Okay, that would still only amount to $18.2 million per year. Seems like a small return on a few hundred million dollar investment plus operating costs and maintenance costs. But if this electricity is sold during peak hours maybe it sells for more than 10 cents per kwh? Does a political deal assure a higher price? If so, how much higher?
Let us consider the avoided CO2 emissions. If the 172,000 tons of avoided emissions were taxed at $30 per ton (which is one figure I've heard proposed for how much carbon emissions should be taxed) then the amount of avoided carbon taxes would be only $5.2 million per year. That doesn't improve profitability very much.
I am curious to know more about the real costs for concentrated solar plus molten salt storage. Anyone have better sources of information on this topic?
Berkeley, CA — A new study on the installed costs of solar photovoltaic (PV) power systems in the U.S. shows that the average cost of these systems declined significantly from 1998 to 2007, but remained relatively flat during the last two years of this period.
Researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) who conducted the study say that the overall decline in the installed cost of solar PV systems is mostly the result of decreases in nonmodule costs, such as the cost of labor, marketing, overhead, inverters, and the balance of systems.
The flat costs in 2006 and 2007 might be because of large government subsidies that drove up module costs.
The decline averaged 3.5% per year. I expect the 2009 decline to be much larger due to the contracting economy.
The study examined 37,000 grid-connected PV systems installed between 1998 and 2007 in 12 states. It found that average installed costs, in terms of real 2007 dollars per installed watt, declined from $10.50 per watt in 1998 to $7.60 per watt in 2007, equivalent to an average annual reduction of 30 cents per watt or 3.5 percent per year in real dollars.
The researchers found that the reduction in nonmodule costs was responsible for most of the overall decline in costs. According to the report, this trend, along with a reduction in the number of higher-cost “outlier” installations, suggests that state and local PV-deployment policies have achieved some success in fostering competition within the industry and in spurring improvements in the cost structure and efficiency of the delivery infrastructure for solar power.
The full 42 page report is downloadable as a PDF. The report says that total installed costs are lower in Japan and Germany. Germany has bigger government incentives for installations that probably created economies of scale in installation. Japan is cheapest with only 3/4ths US cost. Both module and non-module costs flattened in the 2005-2007 period.
These cost reductions, however, have not occurred steadily over time. From 1998-2005, average costs declined at a relatively rapid pace, with average annual reductions of $0.4/W, or 4.8% per year in real dollars. From 2005 through 2007, however, installed costs remained essentially flat. During this period, U.S. and global PV markets expanded significantly, creating shortages in the supply of silicon for PV module production and putting upward pressure on PV module prices. As documented in the next section, however, silicon shortages are not the sole cause for the cessation of price declines during 2005-2007, as average non-module costs also remained relatively flat over this period.
Non-module costs are almost half of total costs. So when we read about declines in PV module costs keep in mind even if module costs went to zero the total cost for residential solar PV would remain pretty high.
As shown, capacity-weighted average costs declined from $10.5/W in 1998 to $7.6/W in 2007, equivalent to an average annual reduction of $0.3/W, or 3.5%/yr in real dollars.Using this method, the decline in total average PV installed costs since 1998 appears to be primarily attributable to a drop in non-module costs, which fell from approximately $5.7/W in 1998 to $3.6/W in 2007, a reduction of $2.1/W (or 73% of the $2.9/W drop in total installed costs of this period). In comparison, module index prices dropped by only $0.8/W from 1998-2007, and increased somewhat from 2003-2007.13 As with the trend in total installed costs, however, average non-module costs remained relatively stable from 2005-2007.
The overall 3.5% yearly decline rate means progress has been slow. Will it continue to be slow. Or will we reach a critical mass where price declines become much more rapid?
Some Berkeley researchers believe that starting with cheaper raw materials is the road to much cheaper photovoltaics.
Berkeley -- Unconventional solar cell materials that are as abundant but much less costly than silicon and other semiconductors in use today could substantially reduce the cost of solar photovoltaics, according to a new study from the Energy and Resources Group and the Department of Chemistry at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory (LBNL).
These materials, some of which are highly abundant, could expand the potential for solar cells to become a globally significant source of low-carbon energy, the study authors said.
The analysis, which appeared online Feb. 13 in Environmental Science & Technology, examines the two most pressing challenges to large-scale deployment of solar photovoltaics as the world moves toward a carbon neutral future: cost per kilowatt hour and total resource abundance. The UC Berkeley study evaluated 23 promising semiconducting materials and discovered that 12 are abundant enough to meet or exceed annual worldwide energy demand. Of those 12, nine have a significant raw material cost reduction over traditional crystalline silicon, the most widely used photovoltaic material in mass production today.
Silicon crystals and some of the elements in photovoltaic thin films (e.g. the indium and gallium in CIGS - copper indium gallium selenide) are expensive and in limited supply. So how can they scale? By contrast, iron is a lot more plentiful and cheaper/
The team identified a large material extraction cost (cents/watt) gap between leading thin film materials and a number of unconventional solar cell candidates, including iron pyrite, copper sulfide and copper oxide. They showed that iron pyrite is several orders of magnitude better than any alternative on important metrics of both cost and abundance. In the report, the team referenced some recent advances in nanoscale science to argue that the modest efficiency losses of unconventional solar cell materials would be offset by the potential for scaling up while saving significantly on materials costs.
Will materials manipulated on the nanoscale be craftable into higher efficiency photovoltaics?
In a comprehensive report on the subject this morning, Collins Stewart solar analyst Dan Ries notes that spot market poly prices have fallen from a peak of about $450/kg in mid-2008 to the $130-$150/kg range more recently. That’s a pretty dramatic move - but the decline is far from over.
Ries contends that spot prices by mid-2009 will plunge to the $40-$60/kg level, due to a severe oversupply.
One analyst expects PV prices to drop so far that PV will start to compete with other methods of generating electricity.
The silver lining here is that in the long run, much lower prices for polysilicon are the most direct way to bring down solar electricity production costs low enough to compete with conventional utility scale power generation. With poly in the $40-$60/kg range, he says, module prices would drop to the $1.70-$2/watt range, and utility scale projects could produce power for 11 cents/watt. At that rate, he says, solar would be “reasonably competitive” with combined cycle natural gas facilities and wind turbines.
The world may be running out of oil. But it is not running out of energy. We can shift to solar, wind, and nuclear. We just need great batteries for the cars.
Analysts at HSBC forecast average selling prices for solar systems will drop by about a fifth in 2009 given oversupply and a tighter credit environment, but prices for cells and modules have so far fallen much faster than those for silicon and wafer.
If you are thinking about putting PV on your house now is not the time to do it. Wait a year and save big.
In the U.S. solar industry, the ripple effects of the crisis extend all the way to the panels that homeowners put on their roofs. The price of solar panels has fallen by 25 percent in six months, according to Rhone Resch, president of the Solar Energy Industries Association, who said he expected a further drop of 10 percent by midsummer.
For homeowners, however, the savings will not be as substantial, partly because panels account for only about 60 percent of total installation costs.
The largest series of solar installations in history, more than 1,300 megawatts, is planned for the desert outside Los Angeles, according to a new deal between the utility Southern California Edison and solar power plant maker, BrightSource.
The technology isn't the familiar photovoltaics — the direct conversion of sunlight into electricity — but solar thermal power, which concentrates the sun's rays to create steam in a boiler and spin a turbine.
The big solar and wind facility builds in California are driven by state government requirements on electric utility companies to get more electric power from renewables. This announcement tells me that the utilities see solar concentrators as still cheaper than PV.
The reality, according to Neal Dikeman, partner with VC firm Jane Capital Partners, is that only one or two thin-film projects have brought product to market in 30 years, and it's a US $100M-$200M dollar up-front investment "just to play the game and see if your product really works."
Silicon Valley investors have mistakenly bet on "really great teams" while the technology is still at a science experiment stage, he argues — investors are beginning to realize this, he thinks, and that the industry is sitting on the back end of about 5-10 years of US $100M bets. "We're going to see a bunch of write-offs coming up," he warns.
Dikeman argues that very few of the thin film PV start-ups have succeeded in getting a good thin film PV production process operating at large scale. So First Solar is really an outlier.
Dikeman expects the entrance of semiconductor equipment manufacturing suppliers such as Applied Materials and Oerlikon will help matters. If these companies can work out processes and equipment for doing thin films PV manufacturing then a lot more companies will be able to get into the business of thin film PV manufacturing.
Solar cells may generate clean green electricity but manufacturing them involves a witches brew of toxic chemicals that could harm the environment if millions of solar panels end up in landfills, according to a report issued Wednesday by the Silicon Valley Toxics Coalition.
First off, not all the chemicals used to make photovolatics (PV) are there in the PV at the end of the manufacturing process. But, yes, at the end of the life of PV there is a valid question of how to dispose of it. My guess is that some types of PV contain enough valuable metals that melting them down to separate out the metals will be worth it.
The California environmental group is calling for solar manufacturers to take back and recycle their panels at the end of their 20-to-25 year lifespan. “We feel it’s a very important time for the solar industry because it is getting ready to take off and before that happens it’s time to look at important issues around designing out some of the toxics,” Silicon Valley Toxics Coalition executive director Sheila Davis told Green Wombat. “The big issue is whether there is a transparent supply chain and whether solar companies monitor their supply chains.”
The solar PV industry is for recycling. But does anyone see an obvious problem with the idea that manufacturers will take back the PV at end of life?
The solar industry’s trade group says it embraces the report’s recommendations. “We completely support take-back and recycling,” says Monique Hanis, a spokeswoman for the Solar Energy Industries Association in Washington. “We’re in a fortunate position in that we’re still an emerging industry and have an opportunity now to establish standards and proactively set up processes before we end up with solar panels on every rooftop.”
Most of the PV manufacturers in business today won't exist 25 years from now. Some of the biggest suppliers a few decades hence will be companies that aren't even selling PV today. The take-back idea only works if the original seller exists to do the taking back. Otherwise original sellers are going to need to set aside cash in some kind of industry fund to pay for retrieval and disposal. But how to estimate the cost of doing that 25 years in advance or the rate of return of money set aside today for this purpose?
Regulations requiring utilities to use more renewable power provides an incentive for the construction of solar thermal electric power generation sites. Solar thermal has a cost advantage over silicon-based photovoltaics.
Costing about 18 cents a kilowatt-hour at present, solar thermal power is roughly 40% cheaper than that generated by the silicon-based panels that sit on the roofs of homes and businesses, according to a June report by Clean Edge Inc. and the Co-op American Foundation. Analysts say improved technology and economies of scale should help lower the cost of solar thermal to about 5 cents a kilowatt-hour by 2025. That would put it on par with coal, the cheap but carbon-spewing fuel that generates about half the nation's electricity.
Should we attach much credence to cost projections for solar thermal? Why expect that it can become that cheap? I see photovoltaics (PV) has having greater potential for cost reductions because PV is simpler in operation. So I expect PV will eventually cost less than solar thermal.
Currently, solar cells are difficult to handle, expensive to purchase and complicated to install. The hope is that consumers will one day be able to buy solar cells from their local hardware store and simply hang them like posters on a wall.
A new study by researchers at the UCLA Henry Samueli School of Engineering and Applied Science has shown that the dream is one step closer to reality. Reporting in the Nov. 26 edition of the Journal of the American Chemical Society, Yang Yang, a professor of materials science and engineering, and colleagues describe the design and synthesis of a new polymer, or plastic, for use in solar cells that has significantly greater sunlight absorption and conversion capabilities than previous polymers.
The research team found that substituting a silicon atom for carbon atom in the backbone of the polymer markedly improved the material's photovoltaic properties.
Yang's lab has reached 5.6% efficiency. Yang thinks 10% efficiency is achievable with plastic photovoltaics.
The new polymer created by Yang's team reached 5.1 percent efficiency in the published study but has in a few months improved to 5.6 percent in the lab. Yang and his team have proven that the photovoltaic material they use on their solar cells is one of the most efficient based on a single-layer, low-band-gap polymer.
While the efficiency is low the use of plastics can deliver a couple of benefits. First off, low cost is a possibility. Second, the light weight and flexibility creates the possibility of installation in locations which could not support heavier weight photovoltaics. For example, long lightweight PV sheets could be hung on the sides of buildings.
The biggest potential downside of a plastic is degradation in response to prolonged light exposure. The product would need to be extremely cheap to make frequent replacement economical.
CAMBRIDGE, Mass. — New ways of squeezing out greater efficiency from solar photovoltaic cells are emerging from computer simulations and lab tests conducted by a team of physicists and engineers at MIT.
Using computer modeling and a variety of advanced chip-manufacturing techniques, they have applied an antireflection coating to the front, and a novel combination of multi-layered reflective coatings and a tightly spaced array of lines — called a diffraction grating — to the backs of ultrathin silicon films to boost the cells' output by as much as 50 percent.
The carefully designed layers deposited on the back of the cell cause the light to bounce around longer inside the thin silicon layer, giving it time to deposit its energy and produce an electric current. Without these coatings, light would just be reflected back out into the surrounding air, said Peter Bermel, a postdoctoral researcher in MIT's physics department who has been working on the project.
But what was the absolute efficiency of conversion? Is the 50% an increase over ultrathin silicon film PV efficiency and not over conventional thicker silicon PV?
The thinnest of this design cuts the cost of expensive silicon crystal.
And the potential for savings is great, because the high-quality silicon crystal substrates used in conventional solar cells represent about half the cost, and the thin films in this version use only about 1 percent as much silicon, Bermel said.
This project, along with other research work going on now in solar cells, has the potential to get costs down "so that it becomes competitive with grid electricity," Bermel said. While no single project is likely to achieve that goal, he said, this work is "the kind of science that needs to be explored in order to achieve that."
I am increasingly optimistic that the cost of PV is going to plummet. Now if only technological advances for lightweight batteries suitable for cars could cause similar cost reductions for electric cars we'd gain a major piece of the puzzle needed for migration away from fossil fuels.
Swiss and Chinese researchers lifted the conversion efficiency of a bendable and thin type of solar cell.
Researchers in China and Switzerland are reporting the highest efficiency ever for a promising new genre of solar cells, which many scientists think offer the best hope for making the sun a mainstay source of energy in the future. The photovoltaic cells, called dye-sensitized solar cells or Grätzel cells, could expand the use of solar energy for homes, businesses, and other practical applications, the scientists say. Their study is scheduled for the November 13 issue of ACS’ The Journal of Physical Chemistry C, a weekly publication.
The research, conducted by Peng Wang and colleagues — who include Michael Grätzel, inventor of the first dye-sensitized solar cell — involves photovoltaic cells composed of titanium dioxide and powerful light-harvesting dyes. Grätzel cells are less expensive than standard silicon-based solar cells and can be made into flexible sheets or coatings. Although promising, Grätzel cells until now have had serious drawbacks. They have not been efficient enough at converting light into electricity. And their performance dropped after relatively short exposures to sunlight.
In the new study, researchers describe lab tests of solar cells made with a new type of ruthenium-based dye that helps boost the light-harvesting ability. The new cells showed efficiencies as high as 10 percent, a record for this type of solar cell. The new cells also showed greater stability at high temperatures than previous formulas, retaining more than 90 percent of their initial output after 1,000 hours in full sunlight.
These cells offer two potential advantages: First off, they should be lower cost due to expected ease in manufacturing. Second, both their flexibility and their light weight will allow installation in places which otherwise would not support the presence of solar cells. For example, cars could have them on their roofs without a big weight penalty. Also, side walls and other vertical surfaces could be covered with lightweight solar cells whereas much heavier weight silicon photovoltaics would weigh too much for easy installation. Skyscrapers might some day get covered with Grätzel solar cell sheeting.
While they achieved 10% efficiency they only achieved 9.1% efficiency using materials that can be incorporated into a plastic.
The new dye absorbs light far better than the conventional dye. Because the dye absorbs light so well, it's possible to cut the thickness of the active material in the solar cell in half, which makes it easier for electrons to escape the solar cell and reach an external circuit. That, in turn, increases efficiency, in this case to 9.1 percent.
The researchers also paired the new dye with a nonvolatile solvent-based electrolyte. It's not quite as stable as an ionic liquid, and it can't be used with plastic. But it allowed slightly higher efficiencies--up to 10 percent.
With advances happening that cut costs for such a large variety of solar photovoltaic materials I am optimistic about the future of solar energy. PV electric power will come down in cost so far that it will compete with grid power during the day first in high sunlight areas such as the US southwest and gradually in lower and lower light areas. This will slow and eventually stop and reverse the growth of coal burning for electric power. It will also cut natural gas consumption and save it for more valuable space heating and fertilizer production.
Our biggest future energy problem continues to be for transportation. While the world recession has cut oil demand and oil prices the eventual resumption of economic growth will push oil prices back up again and the peak in world oil production is not many years away. I'm still not clear on whether advances in battery technology will happen soon enough to make the transition away from liquid fuels.
Tired of waiting for solar photovoltaics costs to finally drop? Looks like the wait is almost up. Average Selling Prices (ASPs) of solar photovoltaic modules are expected to decline 20% in 2009 and 25% in 2010.
After subsidies, Plan B for module makers is to sell products at a discount to keep inventory moving. It helps that manufacturing costs continue to decline about 10% each year, thanks to design improvements and benefits of scale. But it seems a little coincidental that most solar companies happened to predict the ASP for their products will decline at the exact same rate.
Analysts from Deutsche Bank (nyse: DB - news - people ), UBS (nyse: UBS - news - people ), Hapoalim Securities and Goldman Sachs all reached a different consensus, namely that ASPs will need to decline closer to 20% in 2009 to absorb excess inventory, and as much as 25% the following year.
Commerzbank said the impact of tougher financing conditions would affect returns seven times more than would module prices. It puts next year's financing needs for global photovoltaic projects at 33 billion euros, of which 20 billion would need debt financing.
But all indications pointed to a near halt in debt financing for large-scale solar power parks outside Germany, Commerzbank added, which would last until at least the second quarter of 2009.
The credit crunch will also cause delays and cancellations of new solar photovoltaic manufacturing plants. That will tend to boost prices by reducing future supply.
First Solar and some of the PV manufacturers are claiming costs much lower than current prices. As production capacity expands the prices should drop down closer to manufacturing costs.
Researchers at Rensselaer Polytechnic Institute have discovered and demonstrated a new method for overcoming two major hurdles facing solar energy. By developing a new antireflective coating that boosts the amount of sunlight captured by solar panels and allows those panels to absorb the entire solar spectrum from nearly any angle, the research team has moved academia and industry closer to realizing high-efficiency, cost-effective solar power.
“To get maximum efficiency when converting solar power into electricity, you want a solar panel that can absorb nearly every single photon of light, regardless of the sun’s position in the sky,” said Shawn-Yu Lin, professor of physics at Rensselaer and a member of the university’s Future Chips Constellation, who led the research project. “Our new antireflective coating makes this possible.”
Note that these numbers do not indicate the percentage of the light that gets converted into electricity. But solar cells that absorb more photons will probably increase their electric power output roughly proportionate to the amount of additional light absorbed. I say roughly because the light that would otherwise get reflected away might be at frequencies that do not convert well to electrons.
An untreated silicon solar cell only absorbs 67.4 percent of sunlight shone upon it — meaning that nearly one-third of that sunlight is reflected away and thus unharvestable. From an economic and efficiency perspective, this unharvested light is wasted potential and a major barrier hampering the proliferation and widespread adoption of solar power. After a silicon surface was treated with Lin’s new nanoengineered reflective coating, however, the material absorbed 96.21 percent of sunlight shone upon it — meaning that only 3.79 percent of the sunlight was reflected and unharvested. This huge gain in absorption was consistent across the entire spectrum of sunlight, from UV to visible light and infrared, and moves solar power a significant step forward toward economic viability.
Increased absorption combined with solar concentrators could greatly reduce the amount of PV material needed per amount of electricity produced. This will work in favor of more expensive high conversion efficiency PV materials. So the cheaper thin film PV will effectively face more competition from the more expensive and more efficient silicon-based PV.
Researchers led by John Rogers, a professor of materials science and engineering at the University of Illinois in Urbana-Champagne, used a combination of etching and transfer printing to create arrays of silicon cells that are one-tenth the thickness of conventional cells. They demonstrated multiple possible designs for solar panels incorporating the microcells, including dense arrays flexible enough to bend around a pencil. "You could roll them up like a carpet, transport them in a van, and unfurl them onto a rooftop," Rogers says.
The thinness ought to lower costs as compared to conventional silicon photovoltaics (PV).
"We can make it thin enough that we can put it on plastic to make a rollable system. You can make it gray in the form of a film that could be added to architectural glass," said John Rogers of the University of Illinois at Urbana-Champaign, who led the research.
"It opens up spaces on the fronts of buildings as opportunities for solar energy," Rogers said in a telephone interview.
After waiting for decades for PV to become cost efficient and flexible to use I think the 2010s will be when PV finally takes off on a massive scale and becomes ubiquitous.
Not everyone sees solar power as environmentally compatible.What is waste land to one person is a pristine ecosystem to another person.
Solar companies proposing large power plants in the Mojave Desert are facing opposition from conservationists. They say a rush to build solar here threatens to tear up large tracts of desert habitat and open space.
But where do the defenders of an unmolested Mojave come down on the question of nuclear power? It has the smallest footprint of any of the fossil fuels replacements.
The squabble is likely to intensify now that Congress this week moved forward on a long-term extension of the solar tax credit. Two other proposed bills would fast-track solar power projects looking to build on federal lands. State mandates on utilities to provide more renewable energy has created an enormous market for solar, an energy that requires two things the Mojave has in spades – acreage and sunshine. But the desert’s defenders argue that solar panels should be located on city rooftops rather than pristine lands.
One reason we are seeing more large scale solar power projects around Southern California is a state mandate for utilities to get more of their power from renewable sources of energy. This favors large scale solar power over rooftop solar. The rooftop solar also runs into zoning restrictions aimed at beautifying towns. I know people who've had trouble getting approval to put photovoltaics on their roof for example.
I expect the local rooftop zoning restrictions to lessen as prices fall and a larger fraction of homeowners (and voters) want to put PV on their own roofs. But opposition to covering deserts with PV might grow rather than shrink. If PV ever starts paying more per acre than crops (and can it?) then PV won't hit such obstacles in farm country where land has long been thought of as a productive resource.
Some analysts were predicting a double digit decline in PV prices in 2009. But initial indications are for a smaller price decline.
On Aug. 20, Zhengrong Shi, chief executive of Suntech Power Holdings, (STP) said early prices for 2009 are flat to 5% down compared with 2008. Suntech is one of the world's 10 largest solar module makers.
That same week Andrew Klump, Trina Solar's (TSL) vice president of business development, said on the quarterly conference call that the company sees price declines of just 3% to 5% in 2009.
The credit crunch and the question of US solar tax credit extension both are big question marks on 2009 PV demand.
University of Calgary climate change scientist David Keith and his team are working to efficiently capture the greenhouse gas carbon dioxide directly from the air, using near-commercial technology.
In research conducted at the U of C, Keith and a team of researchers showed it is possible to reduce carbon dioxide (CO2) – the main greenhouse gas that contributes to global warming – using a relatively simple machine that can capture the trace amount of CO2 present in the air at any place on the planet.
...Keith and his team showed they could capture CO2 directly from the air with less than 100 kilowatt-hours of electricity per tonne of carbon dioxide. Their custom-built tower was able to capture the equivalent of about 20 tonnes per year of CO2 on a single square metre of scrubbing material – the average amount of emissions that one person produces each year in the North American-wide economy.
That 100 kwh per removed tonne of CO2 would be pretty good in terms of energy cost. If the electricity cost only 10 cents per kwh then the cost per tonne would be only $10. Some proposed carbon tax regimes are at $30 per tonne and up. This could be done with photovoltaics once PV becomes cheap enough. The fact that the sun doesn't shine all the time won't matter. Just run the process when the power is available. No need for transmission lines or even expensive circuitry to convert the electricity into AC power. Though materials costs and piping the CO2 somewhere might add substantial costs.
"This means that if you used electricity from a coal-fired power plant, for every unit of electricity you used to operate the capture machine, you'd be capturing 10 times as much CO2 as the power plant emitted making that much electricity," Keith says.
The U of C team has devised a new way to apply a chemical process derived from the pulp and paper industry cut the energy cost of air capture in half, and has filed two provisional patents on their end-to-end air capture system.
The technology is still in its early stage, Keith stresses. "It now looks like we could capture CO2 from the air with an energy demand comparable to that needed for CO2 capture from conventional power plants, although costs will certainly be higher and there are many pitfalls along the path to commercialization."
What I'd like to see: Use sunlight to drive an artificial photosynthesis process that will fix hydrogen from water to CO2 from the atmosphere. The output would be hydrocarbons usable to power cars and for other purposes. All this will come with time.
Update: See the comment by Bruce Dunn. Looks like the energy for the initial CO2 capture is a small fraction of the total amount of energy needed for this method. So this looks like a bad idea.
Move over cheap but lower efficiency thin film photovoltaic cells. A company called Suniva claims a cheaper way to make photovoltaic cells with high conversion efficiency.
A cheap new way to attach mirrors to silicon yields very efficient solar cells that don't cost much to manufacture. The technique could lead to solar panels that produce electricity for the average price of electricity in the United States.
Suniva, a startup based in Atlanta, has made solar cells that convert about 20 percent of the energy in the sunlight that falls on them into electricity. That's up from 17 percent for its previous solar cells and close to the efficiency of the best solar cells on the market. But unlike other high-efficiency silicon solar cells, says Ajeet Rohatgi, the company's founder and chief technology officer, Suniva's are made using low-cost methods. One such method is screen printing, a relatively cheap process much like the silk-screen process used to print T-shirts.
The company thinks it can achieve a further cost reduction by using thinner wafers while still maintaining a high conversion efficiency. But that goal lies in the future. If they can achieve it then they expect their solar cells to become competitive with some of the much cheaper existing non-solar ways to generate electricity.
SALT LAKE CITY – University of Utah engineers devised a new way to slice thin wafers of the chemical element germanium for use in the most efficient type of solar power cells. They say the new method should lower the cost of such cells by reducing the waste and breakage of the brittle semiconductor.
The expensive solar cells now are used mainly on spacecraft, but with the improved wafer-slicing method, "the idea is to make germanium-based, high-efficiency solar cells for uses where cost now is a factor," particularly for solar power on Earth, says Eberhard "Ebbe" Bamberg, an assistant professor of mechanical engineering. "You want to do it on your roof.
Higher efficiency of germanium PV will allow a roof to collect a larger fraction of all power used in a home. But cost is a problem because germanium is so expensive.
Germanium serves as the bottom layer of the most efficient existing type of solar cell, but is used primarily on NASA, military and commercial satellites because of the high expense – raw germanium costs about $680 per pound. Four-inch-wide wafers used in solar cells cost $80 to $100 each, and the new cutting method may reduce the cost by more than 10 percent, says Grant Fines, chief technology officer for germanium wafer-maker Sylarus Technologies in St. George, Utah.
On orbital satellites and other space applications where weight is such a huge cost the higher cost of germanium solar cells is justified by their higher efficiency.
Silicon-based solar cells on Earth have maximum efficiency of 20 percent, Fines says. In space, germanium solar cells typically convert 28 percent of sunlight into electricity, but on Earth where solar concentrators are used, they can convert more than 40 percent of sunlight into electricity, and their efficiency theoretically exceeds 50 percent, he adds.
The ability to slice these wafers thinner will both cut production costs and reduce weight which is so critical for space applications.
The idea of building solar photovoltaic shingles has been dreamed about for a long time. Installation of the roof would amount to installation of the PV with little added effort. But attempts to achieve commercial success in this endeavor haven't succeeded commercially so far. Now a couple of companies have teamed up to sell thin film photovoltaic shingles.
In an effort to promote the adoption of solar technology, United Solar Ovonic of Auburn Hills, MI, has teamed with a major roofing company to create a metal roof system that generates electricity from sunlight. The partnership offers seven different prefabricated systems, ranging in capacity from 3 to 120 kilowatts. Tests show that the solar roof panels are rugged and can withstand winds in excess of 160 miles per hour.
The article does not mention cost as compared to other approaches. But in theory this approach ought to be able to hit lower price points since it reduces materials needs and simplifies installation.
They claim the pay-back can be as low as 10 years. That's probably in California which has both high electric power prices and lots of sun. In Washington state with cheap hydro power and a whole lot less sun the economics are probably pretty abysmal.
Centria designs and assembles the solar roof systems using United Solar's adhesive thin films, which can simply be peeled off of their backings and stuck to the roofing materials. The company then distributes the final product through small metal-roofing manufacturers that do the installations for building owners and architects. EnergyPeak comes with a 20-year warranty and, depending on the state in which the solar roof is installed, could pay for itself in less than 10 years, Centria says.
The trend in solar has been toward large PV and concentrating solar power facilities out in deserts. Home PV doesn't capture economies of scale that the big facilities can achieve. But some day PV shingles will become cheap enough that they'll become standard on most new housing construction.
Technology Review takes a look at the work of MIT researcher Marc Baldo whose team has developed a way to use glass sheets to concentrate light onto the edge of the glass. This can focusing light from a larger area onto a smaller (and therefore cheaper) amount of photovoltaics material.
Unlike the mirrors and lenses in conventional solar concentrators, Baldo's glass sheets act as waveguides, channeling light in the same way that fiber-optic cables transmit optical signals over long distances. The dyes coating the surfaces of the glass absorb sunlight; different dyes can be used to absorb different wavelengths of light. Then the dyes reëmit the light into the glass, which channels it to the edges. Solar-cell strips attached to the edges absorb the light and generate electricity. The larger the surface of the glass compared with the thickness of the edges, the more the light is concentrated and, to a point, the less the power costs.
Baldo, an associate professor of electrical engineering, published his findings recently in Science. On their basis, he projects that his solar concentrators could be made big enough for the electricity they help generate to compete with electricity from fossil fuels. Indeed, says Baldo, panels equipped with the concentrators "could be the cheapest solar technology."
An earlier announcement about this research from July reports this technology might hit the market in as little as 3 years.
The researchers coated glass panels with layers of two or more light-capturing dyes. The dyes absorbed incoming light and then re-emitted the energy into the glass, which served as a conduit to channel the light to solar cells along the panels' edges. The dyes can vary from bright colors to chemicals that are mostly transparent to visible light.
Because the edges of the glass panels are so thin, far less semiconductor material is needed to collect the light energy and convert that energy into electricity.
"Solar cells generate at least ten times more power when attached to the concentrator," added Baldo.
Because the starting materials are affordable, relatively easy to scale up beyond a laboratory setting, and easy to retrofit to existing solar panels, the researchers believe the technology could find its way to the marketplace within three years.
Mapel, Currie and Goffri are starting a company, Covalent Solar, to develop and commercialize the new technology. Earlier this year Covalent Solar won two prizes in the MIT $100K Entrepreneurship Competition. The company placed first in the Energy category ($20,000) and won the Audience Judging Award ($10,000), voted on by all who attended the awards.
A cheap way to turn light into electricity will not immediately solve our problem with dwindling oil reserves. But add in advances to cut the costs of lithium batteries for cars and the transition away from fossil fuels will become much easier.
In fact, there’s a land rush at the federal Bureau of Land Management. As of July, the BLM reported more than 125 applications to build solar power on about 1 million acres of desert, up from just a handful of proposals a few years ago.
“We think there’s a good market there,” says Travis Bradford, an expert at the Prometheus Institute, a Boston-based solar-energy market research firm. His firm sees 12,000 megawatts (12 gigawatts) of solar thermal installed by 2020 and maybe 20 times that in coming decades.
That 12 gigawatts is probably equivalent to less than 6 gigawatts of solar. In fact, if it is based on peak power at noon then is average power even 4 gigawatts? That'd amount to less than 3 new nuclear power plants. This is the problem with solar power. The big scale-up doesn't become substantial for years to come.
Concentrated solar's estimated cost is similar to that of natural gas electric. But natural gas electric is available when you want it. So solar has to be cheaper in order to compete with natural gas without subsidy. Also, natural gas electric is more expensive than coal, wind, and nuclear electric. When solar falls down far enough to compete with the latter three sources that's when it becomes very interesting.
Concentrating solar technology produces electricity for about 17 cents per kilowatt hour (kWh), Mehos estimates. But subsidies remain critical to solar thermal development in both the US and Spain, two global hotbeds of CSP development. With the federal investment tax credit, or ITC, costs drop to about 15 cents per kWh – low enough to compete with natural gas.
A key feature of solar thermal is its potential to use heat-storage technology to generate power after the sun sets. Nevada Solar One is considering adding a molten-salt or similar system to allow it to supply power for several hours after sundown.
With such storage systems, solar thermal becomes even more attractive to utilities, experts say. Arizona Public Service is contracting with Abengoa to build a 280-megawatt solar thermal plant near Phoenix that will cost more than $1 billion and have molten-salt heat storage.
Storage means additional costs. But since concentrating solar produces heat before it produces electricity that heat creates the potential for storing the heat as a way to generate electricity after the sun goes down. That gives concentrating solar an advantage over photovoltaics (PV).
While concentrating solar is currently cheaper than photovoltaics I expect that will not always be the case. The company First Solar looks set to bring solar photovoltaics costs well below current concentrating solar electric costs.
But if you want the off-peak market, you’ll have to price your cells at about US $1 per watt. That price is called grid parity, and it’s the holy grail of the photovoltaic industry. At least 80 firms around the world, from Austin to Osaka, are in the chase.
Surprisingly, at the moment no company is closer to that grail than a little start-up called First Solar, which until very recently had been known only to specialists. It’s located in Tempe, Ariz., and analysts agree that it will very likely meet typical grid-parity prices in developed countries in just two to four years. It’s got a multibillion-dollar order book, it’s selling all the cells it can make, it’s adding production capacity as fast as it can, and its stock price has rocketed from $25 to more than $250 in just 18 months.
If First Solar alone can make 1 gigawatt of PV in 2010 and PV growth rates continue near 2008's level then PV installations probably will leave concentrating solar in the dust.
Right now, First Solar depends mainly on a government-subsidized program in Germany, where it has contracts worth more than $6 billion through 2012. Other markets with the same type of subsidies (known as feed-in tariffs, which spread the cost of alternative energy among all customers) include France, Italy, Spain, South Korea, and Ontario, Canada. To fill these orders, the company is undergoing a massive expansion of its manufacturing facilities that should boost annual production capacity to just over 1 gigawatt by 2009. This capacity could supply one-sixth of that year’s estimated global solar-cell business, which is currently growing at 50 percent per year.
Maybe concentrating solar's big competitive long term advantage against PV is the ability to produce heat energy for storage. What do you think? Does concentrating solar have a big future?
MIT researchers have developed a better catalyst for using electricity to split water into oxygen and hydrogen. Later the hydrogen can be burned to produce heat and electricity.
CAMBRIDGE, Mass. -- In a revolutionary leap that could transform solar power from a marginal, boutique alternative into a mainstream energy source, MIT researchers have overcome a major barrier to large-scale solar power: storing energy for use when the sun doesn't shine.
I think the rhetoric here is a little overblown. More obstacles remain. We still need better ways to store hydrogen. Granted, it is easier to store hydrogen in a stationary tank than in a tank in a car since the stationary tank is less constrained by weight or size or need to handle jolts and vibration. So I would like to hear more about the economics of stationary hydrogen storage. Plus, we need cheap and reliable fuel cells for burning the hydrogen to make electricity in the night.
Until now, solar power has been a daytime-only energy source, because storing extra solar energy for later use is prohibitively expensive and grossly inefficient. With today's announcement, MIT researchers have hit upon a simple, inexpensive, highly efficient process for storing solar energy.
Requiring nothing but abundant, non-toxic natural materials, this discovery could unlock the most potent, carbon-free energy source of all: the sun. "This is the nirvana of what we've been talking about for years," said MIT's Daniel Nocera, the Henry Dreyfus Professor of Energy at MIT and senior author of a paper describing the work in the July 31 issue of Science. "Solar power has always been a limited, far-off solution. Now we can seriously think about solar power as unlimited and soon."
Inspired by the photosynthesis performed by plants, Nocera and Matthew Kanan, a postdoctoral fellow in Nocera's lab, have developed an unprecedented process that will allow the sun's energy to be used to split water into hydrogen and oxygen gases. Later, the oxygen and hydrogen may be recombined inside a fuel cell, creating carbon-free electricity to power your house or your electric car, day or night.
But what efficiency can we expect? 50% efficiency doubles the cost. 25% efficiency quadruples the cost. The ultimate efficiency of this process is not mentioned in the articles I can find about this research. Efficiency losses in generation of hydrogen, storage, and in the burning of hydrogen to make electricity all boost the cost of the ultimately desired night time electric power.
The key component in Nocera and Kanan's new process is a new catalyst that produces oxygen gas from water; another catalyst produces valuable hydrogen gas. The new catalyst consists of cobalt metal, phosphate and an electrode, placed in water. When electricity — whether from a photovoltaic cell, a wind turbine or any other source — runs through the electrode, the cobalt and phosphate form a thin film on the electrode, and oxygen gas is produced.
Combined with another catalyst, such as platinum, that can produce hydrogen gas from water, the system can duplicate the water splitting reaction that occurs during photosynthesis.
Current costs of photovoltaics mean there's not enough photovoltaic generation capacity to make storage worthwhile. So we also need much cheaper photovoltaics. But that looks like it is in the pipeline if the claims of First Solar about their photovoltaics production costs are correct.
This does not provide an immediate solution. But the remaining engineering work all looks very solvable.
There's also still much engineering work to be done before Nocera's catalyst is incorporated into commercial devices. It will, for example, be necessary to improve the rate at which his catalyst produces oxygen. Nocera and others are confident that the engineering can be done quickly because the catalyst is easy to make, allowing a lot of researchers to start working with it without delay. "The beauty of this system is, it's so simple that many people can immediately jump on it and make it better," says Thomas Moore, a professor of chemistry and biochemistry at Arizona State University.
Thanks to Jill and Brock for the heads up.
Here's yet another prognosticator saying finally solar photovoltaics prices might go down after a few years of plateauing prices.
Worldwide production capacity for silicon and thin film panels will jump from 3.14 gigawatts in 2007 to 12.36 gigawatts in 2010, Travis Bradford, president of the Prometheus Institute, said at a Greentech Media conference this week.
Suppose all that capacity got used because, say, oil available for export starts to seriously decline as the Export Land Model predicts (and really go read that). People desperate for energy start trying to shift lots of uses of oil toward electric powered devices. Well, solar panel demand might skyrocket.
But Mr. Bradford foresees a big cut in PV prices.
Prices for traditional silicon-based solar panels will fall from $3.66 per watt in 2007 to $2.14 per watt in 2010, he forecasted, while the average price of thin-film panels is expected to drop from $2.96 per watt in 2007 to $1.81 per watt in 2010.
Part of the reason for the anticipated drop is that Bradford expects the amount of silicon for the solar industry to quadruple from 30,070 tons in 2007 to 125,302 tons in 2012.
Hawaii will benefit in a big way. Almost all of its electricity comes from burning oil. In the comments of a a previous post I did on the expected decline in photovoltaics prices a fellow named Scott says he's paying 36.6 cents per kilowatt-hour (kwh). That's over 3 times the US national average rate for electricity which in 2007 was 10.64 cents per kwh.
I see a curious effect of cheap solar: It will make air conditioning relatively cheaper than heating. During the summer we have lots of sunlight to drive solar cells to make electricity to run air conditioners. During the winter we lack the sunlight to make things warm. So rising oil prices combined with declining PV costs will cause migrations toward the equator.
Previously I became aware of the potential for paintable titanium nanotubes to make cheap solar photovoltaics from watching a slide show by CalTech researcher Nathan Lewis. So news from the University of Queensland about a cheap way to make titanium oxide crystals suitable for painting and the prospects for cheap photovoltaics strikes me as potentially important information.
Professor Max Lu, from UQ's Australian Institute for Bioengineering and Nanotechnology (AIBN), said they were one step closer to the holy grail of cost-effective solar energy with their discovery.
“We have grown the world's first titanium oxide single crystals with large amounts of reactive surfaces, something that was predicted as almost impossible,” Professor Lu said.
“Highly active surfaces in such crystals allow high reactivity and efficiency in devices used for solar energy conversion and hydrogen production.
“Titania nano-crystals are promising materials for cost-effective solar cells, hydrogen production from splitting water, and solar decontamination of pollutants.
“The beauty of our technique is that it is very simple and cheap to make such materials at mild conditions.
“Now that the research has elucidated the conditions required, the method is like cooking in an oven and the crystals can be applied like paints.”
Let us hope that Professor Lu meets with further successes in his research endeavors.
Neodymics inventor Jeff Radtke brings to my attention a claim that there are Moore's Law-like effects happening with photovoltaics prices that will make PV competitive by 2015.
In recent years, global PV production has been increasing at a rate of 50 percent per year, so that accumulated global capacity doubles about every 18 months. The PV Moore’s law states that with every doubling of capacity, PV costs come down by 20 percent. In 2004, installing PV cost about $7 per watt, compared to $1/W for wind, which at that time was beginning to stand on its own feet commercially, Last, year, as recently noted in this blog, average global solar costs had come down to between $4 and $5 per watt, right in line with the PV Moore’s law. Extrapolate those gains out six or seven years, and PV costs will be below $2/W, making photovolatics competitive with 2004 wind.
You can find more details on this argument here. But note that in 2004, 2005, and 2006 PV prices rose in the graph at that link. This is consistent with what I've seen with other sources of PV prices. Government incentives have driven up PV demand so quickly that prices have not fallen. Therefore the cost trend in recent years is hidden by high demand. We need to wait for supply to catch up to demand in order to find out how much costs have dropped in recent years. For example, the US government's Energy Information Administration shows substantial increases in PV module prices from 2005 to 2006.
Rapidly rising demand is likely hiding the effects of production cost declines. So we should see a big cut in PV prices once production capacity starts to catch up with demand. In places with especially high electric costs such and lots of insolation (e.g. SoCal, Italy, Hawaii, Japan) grid parity will come years sooner.
A recent financial report by PV maker Solarfun provides a small window into PV pricing. Solarfun reports PV prices in the first quarter 2008 were higher than in 2007. This is not a sign of declining costs.
. In the recent quarter, Solarfun’s net PV module shipments were 40.3 megawatts at $4.07 per watt, compared to shipments of 6.5 megawatts at $3.77 per watt last year.
Selling prices were particularly strong in Spain and Germany, and the company benefited from a strong euro in the quarter. Solarfun reported that 46.0% of its revenues were generated from Spain, followed by 36.0% in Germany. France accounted for 8.0%, Italy for 6.0% and Switzerland for 4%.
You can find reports about imminent $1/watt PV manufacturing costs. But with prices still running 4 times as high I feel like I'm still waiting for Godot.
A start-up company, Sunrgi, with a photovoltaics design based around focusing lenses and heat radiators claims that within 12 to 15 months they can get radically cheaper photovoltaics into mass production.
A new patents pending solar energy system will soon make it possible to produce electricity at a wholesale cost of 5 cents per kWh (kilowatt hour). This price is competitive with the wholesale cost of producing electricity using fossil fuels and a fraction of the current cost of solar energy.
XCPV (Xtreme Concentrated Photovoltaics), a system that concentrates the equivalent of more than 1,600 times the sun’s energy onto the world’s most efficient solar cells, was announced today by Sunrgi, a solar energy system designer and developer, at the National Energy Marketers Association’s 11th Annual Global Energy Forum in Washington, DC. The technology will enable power companies, businesses, and residents to produce electricity from solar energy at a lower cost than ever before.
“Solar Power at 5 cents per kWh would be a world-changing breakthrough,” said Craig Goodman, president, National Energy Marketers Association. “It would make solar generation of electricity as affordable as generation from coal, natural gas or other non-renewable sources, without requiring a subsidy.”
“In a little more than a year we were able to develop and successfully test XCPV,” said Robert S. (Bob) Block, co-founder and Sunrgi principal. “We expect the Sunrgi system to become available for both on- and off-grid power applications, worldwide, in twelve to fifteen months.”
What differentiates Sunrgi’s XCPV system from any other solar energy system includes: a proprietary, integrated low profile technology for concentrating sunlight; a proprietary technology and methodology for cooling solar cells; a low cost, modular system optimized for mass-production; less land area or “roof top” requirements than typical solar energy systems; a technology roadmap for continuous improvement; low-cost field installation; and, a custom-designed system for easy operation and maintenance.
Their device concentrates the sunlight by a factor of 1600. This allows them to use far less photovoltaic material. But it also requires excellent heat removal from the spots where the light gets concentrated. Since they use such small amounts of photovoltaics they can use highly efficient photovoltaics. So they plan to use Spectrolab (part of Boeing) PV material that is 37.5% efficient. They also track the sun during the day and so get less drop-off in power output in morning and afternoon.
Can they pull this off? Your guess is as good as mine.
Government policies spurred a rapidly rising demand for photovoltaics and these policies caused a rise in market prices. But an article in Technology Review reports some photovoltaics industry analysts are predicting a large drop in PV costs owing to rapidly growing capacity for making silicon crystals. The end of polysilicon shortages could cause PV costs to drop in half.
"It takes about two or three years to add capacity," says Travis Bradford, an industry analyst for the Prometheus Institute. The shortage has been severe enough to drive up silicon prices to more than 10 times normal levels, to $450 a kilogram, adds Ted Sullivan, an analyst at Lux Research.
The added silicon production capacity is now starting to begin operations. While only 15,000 tons of silicon were available for use in solar cells in 2005, by 2010, this number could grow to 123,000 tons, Sullivan says. And that will allow existing and planned production of solar panels to ramp up, increasing supply. "What that means, practically, is that [solar] module prices are going to come down pretty dramatically in the next two or three years," Bradford says.
Last week I linked to a PV stock analyst claiming a big drop in polysilicon costs is coming real soon now. But I'm still left wondering: How far above market prices is the manufacturing cost of polysilicon?
The rise in PV prices in the last several years might finally reverse itself. We can hope so. We need price relief from rising oil and natural gas prices. That price relief can only come in the form of cheaper substitutes.
Update: Japanese PV maker Sharp claims a new thin film PV plant will create PV cells for half the current costs.
In 2007, Sharp started operations at its Toyama plant in Japan for the manufacture of silicon for solar cells and more recently, in February 2008, it announced a collaboration with a production equipment company to develop equipment for manufacturing thin-film solar cells, giving the company a foothold in everything from raw materials to devices across a range of technologies, including polycrystalline and thin-film. In 2005, Sharp began mass production of tandem thin-film solar cells, for instance.
Sharp adds that the end of the 2009 financial year (March 2010) will see the start of operations at its new thin-film solar cell plant in Sakai City, Osaka prefecture in Japan, which will have an annual capacity of about 1 GW, the cost of generating solar power will be about half current levels in 2010. This, says Sharp, will be equivalent to around ¥23/kWh (US¢22/kWh), which is close to the current cost of domestic electricity.
The solar PV market has gotten so big with so many players and technological approaches that substantial price declines seem likely just due to the number of competing teams.
NEW ORLEANS, April 7, 2008 — Despite oil prices that hover around $100 a barrel, it may take at least 10 or more years of intensive research and development to reduce the cost of solar energy to levels competitive with petroleum, according to an authority on the topic.
“Solar can potentially provide all the electricity and fuel we need to power the planet,” Harry Gray, Ph.D., scheduled to speak here today at the 235th national meeting of the American Chemical Society (ACS). His presentation, “Powering the Planet with Solar Energy,” is part of a special symposium arranged by Bruce Bursten, Ph.D., president of the ACS, the world’s largest scientific society celebrating the 10th anniversary of the Beckman Scholars Program.
Gray sees a big benefit from using sunlight to split water for hydrogen as a fuel.
“The Holy Grail of solar research is to use sunlight efficiently and directly to “split” water into its elemental constituents – hydrogen and oxygen – and then use the hydrogen as a clean fuel,” Gray said.
Gray is the Arnold O. Beckman Professor of Chemistry and Founding Director of the Beckman Institute at the California Institute of Technology. He is the principal investigator in an NSF funded Phase I Chemical Bonding Center (CBC) – a Caltech/MIT collaboration – and a principal investigator at the Caltech Center for Sustainable Energy Research (CCSER).
Gray sees solar as costing about 35 to 50 cents per kwh and competitive solar at least 10 years away.
The single biggest challenge, Gray said, is reducing costs so that a large-scale shift away from coal, natural gas and other non-renewable sources of electricity makes economic sense. Gray estimated the average cost of photovoltaic energy at 35 to 50 cents per kilowatt-hour. By comparison, other sources are considerably less expensive, with coal and natural gas hovering around 5-6 cents per kilowatt-hour.
Because of its other advantages – being clean and renewable, for instance – solar energy need not match the cost of conventional energy sources, Gray indicated. The breakthrough for solar energy probably will come when scientists reduce the costs of photovoltaic energy to about 10 cents per kilowatt-hour, he added. “Once it reaches that level, large numbers of consumers will start to buy in, driving the per-kilowatt price down even further. I believe we are at least ten years away from photovoltaics being competitive with more traditional forms of energy.”
Solar energy won't become cost competitive everywhere at the same time. In areas with higher electricity costs and greater amounts of sunlight (e.g. southern California) solar becomes cost competitive sooner at a much higher price for the solar panels than it does in, say, British Columbia or Sweden.
Can an expert predict reliably that solar won't become cost competitive for 10 years? Or can lots of start-ups with lots of venture capital surprise the academics?
In recent years prices for solar panels haven't dropped at all. Growing demand, driven by tax credits and other government interventions, has kept prices up even as production capacity has soared. In spite of its northern geographic location and relatively low light levels government incentives have turned Germany into the biggest source of demand for photovoltaics. When government-caused demand growth flattens out will solar photovoltaics prices plummet?
An MIT researcher has found a way to significantly improve the efficiently of an important type of silicon solar cells while keeping costs about the same. The technology is being commercialized by a startup in Lexington, MA, called 1366 Technologies, which today announced its first round of funding. Venture capitalists invested $12.4 million in the company.
1366 Technologies claims that it improves the efficiency--a measure of the electricity generated from a given amount of light--of multicrystalline silicon solar cells by 27 percent compared with conventional ones.
The company expects other improvements to combine to get it to its $1/watt goal by 2012.
MIT Professor, 1366 founder and CTO, Ely Sachs, noted that 1366 Technologies will be combining innovations in silicon cell architecture with manufacturing process improvements to bring multi-crystalline silicon solar cells to cost parity with coal-based electricity.
Sachs added, "The science is understood, the raw materials are abundant and the products work. All that is left to do is innovate in manufacturing and scale up volume production, and that's just what we intend to do." The company has just taken space in Lexington to build its pilot solar cell manufacturing facility.
1366 Technologies' roadmap includes a new cell architecture that uses innovative, low-cost fabrication methods to increase the efficiency of multi-crystalline solar cells. This architecture, developed at MIT, improves surface texture and metallization to enhance silicon solar cell efficiency by 25% (from 15 - 19%) while lowering costs.
And what will happen if 1366’s claims pan out, and silicon-based solar cells really drop below $1 per watt within the next few years? If the costs for those cells, solar PV, drop more rapidly than expected, thin-film solar based on other materials could face more challenges than expected. However, companies that make thin-film cells like First Solar (NASDAQ: FSLR) and Nanosolar (coverage here) are working on their own process improvements, and it’s difficult to tell when breakthroughs will come.
As of this writing First Solar (FSLR) has a market capitalization of almost $18 billion. So the markets think First Solar could be the winner. So will 1366 score an upset? Photovoltaics makers can raise the capital needed if they can just come up with plausible technologies for lowering photovoltaics costs.
A pair of articles from MIT's Technology Review report on prospects of lower solar photovoltaics manufacturing costs. First, Solaria is developing cheaper ways to make cheaper silicon-crystal based photovoltaic using thinner cells and lower cost fabrication techniques.
Solaria, a startup based in Fremont, CA, intends to cut the cost of solar panels by decreasing the amount of expensive material required. It has recently started shipping its first panels to select customers. This spring the company will begin production of solar panels at a factory built to produce 25 megawatts of solar panels per year.
Current high costs for the type of silicon used in photovoltaics have significantly driven up the price of conventional solar panels. Solaria's cells generate about 90% of a conventional solar panel's power, while using half as much silicon, says Kevin Gibson, Solaria's CTO.
The eventual expected cost reduction is only 10 to 30 percent.
Gibson says Solaria's first products will be economical enough to compete with panels produced by much larger companies, and that successive product generations will cost between 10 and 30 percent less than their competitors.
We need a much larger drop in photovoltaics cost. But 30% would be very substantial.
An approach using titanium oxide nanocrystals and organic dyes has the potential for much larger price reductions.
Cheap and easy-to-make dye-sensitized solar cells are still in the early stages of commercial production. Meanwhile, their inventor, Michael Gratzel, is working on more advanced versions of them. In a paper published in the online edition of Angewandte Chemie, Gratzel, a chemistry professor at the École Polytechnique Fédérale de Lausanne in Switzerland, presents a version of dye-sensitized cells that could be more robust and even cheaper to make than current versions.
Dyes made out of organic material could be very cheap.
New dyes are also being investigated. In commercial cells, the dyes are made of the precious metal ruthenium. But researchers have recently started to consider organic molecules as an alternative. "Organic dyes will become important because they can be cheaply made," Gratzel says. In the long run, they might also be more abundant than ruthenium.
Costs of new nuclear and coal power plant construction have skyrocketed. So the price point that solar has to get down to in order to compete has risen. Competitive photovoltaics probably require at least a two thirds price cut to below $1/Watt capacity. When will that happen? Your guess is as good as mine.
A new solar thermal electric power installation in Boulder City Nevada uses arrays of mirrors to concentrate sun light to drive electric power generation. The cost of electricity for this plant is estimated at 15-20 cents per kilowatt-hour (kwh).
Many states, including California, are imposing mandates for renewable energy. All of that is reviving interest in solar thermal plants.
The power they produce is still relatively expensive. Industry experts say the plant here produces power at a cost per kilowatt- hour of 15 to 20 cents. With a little more experience and some economies of scale, that could fall to about 10 cents, according to a recent report by Emerging Energy Research, a consulting firm in Cambridge, Mass. Newly built coal-fired plants are expected to produce power at about 7 cents per kilowatt-hour or more if carbon is taxed.
That is at least double what cheaper sources of electricity cost in the United States. Can the costs really go down substantially with a bigger market?
While solar thermal still costs more than wind power predictable daylight hours and the ability to store the heat allows solar thermal to provide a more reliable power source.
According to the U.S. Department of Energy, wind power costs about 8 cents per kilowatt, while solar thermal power costs 13 to 17 cents. But power from wind farms fluctuates with every gust and lull; solar thermal plants, on the other hand, capture solar energy as heat, which is much easier to store than electricity. Utilities can dispatch this stored solar energy when they need it--whether or not the sun happens to be shining.
Solar thermal doesn't have to be able to provide electric power 24 hours per day to be useful. If its cost could drop in half then solar thermal would greatly reduce the use of coal and natural gas and allow limited fossil fuels to last longer and pollute less..
Acciona's plant, which began operation last year, produces 64 megawatts of electricity for the utility company Nevada Power, enough to light up 14,000 homes. The company's Spanish competitor Abengoa just announced a plan to build a 280-megawatt solar thermal plant outside Phoenix, which would be the largest such project in the world.
All you need is a lot of sun, a lot of space and a lot of mirrors — and NS1 has all of the above. 182,000 parabolic mirrors are spread over 400 acres of flat desert, creating a glistening sea of glass visible from miles away.
That's 35 homes worth of electric power per acre of land. Mind you, this is an area of the United States that gets above average amounts of sunlight. But this result suggests that use of solar thermal to power all homes would not use an inordinate amount of land - at least not in countries with lower population densities.
Solar thermal looks cheaper than solar photovoltaics and the heat from solar thermal can be stored to stretch into evening hours. But solar photovoltaics might have better prospects for lower cost reductions and it lends itself more easily to decentralized use and smaller installations on homes and other buildings.
ALBUQUERQUE, N.M. —On a perfect New Mexico winter day — with the sky almost 10 percent brighter than usual — Sandia National Laboratories and Stirling Energy Systems (SES) set a new solar-to-grid system conversion efficiency record by achieving a 31.25 percent net efficiency rate. The old 1984 record of 29.4 percent was toppled Jan. 31 on SES’s “Serial #3” solar dish Stirling system at Sandia’s National Solar Thermal Test Facility.
The conversion efficiency is calculated by measuring the net energy delivered to the grid and dividing it by the solar energy hitting the dish mirrors. Auxiliary loads, such as water pumps, computers and tracking motors, are accounted for in the net power measurement.
“Gaining two whole points of conversion efficiency in this type of system is phenomenal,” says Bruce Osborn, SES president and CEO. “This is a significant advancement that takes our dish engine systems well beyond the capacities of any other solar dish collectors and one step closer to commercializing an affordable system.”
Phenomenal? If it took them 24 years to gain 2% of efficiency and it is still more expensive than coal electric or nuclear (and that's probably the case) then I'm not so excited.
Improved optics helped to achieve this record.
Andraka says the first and probably most important advancement was improved optics. The Stirling dishes are made with a low iron glass with a silver backing that make them highly reflective —focusing as much as 94 percent of the incident sunlight to the engine package, where prior efforts reflected about 91 percent. The mirror facets, patented by Sandia and Paneltec Corp. of Lafayette, Colo., are highly accurate and have minimal imperfections in shape.
Note, however, that they also benefited from a cold day. This suggests that in sustained operation the real efficiency would be lower.
The temperature, which hovered around freezing, allowed the cold portion of the engine to operate at about 23 degrees C, and the brightness means more energy was produced while most parasitic loads and losses are constant.
Still, they've moved the state of the art closer to commercial feasibility. But will nanomaterial photovoltaics blow right past stirling engines for lower cost solar power? Or can the solar concentrator approach fall substantially in cost too?
Nanoptek, a startup based in Maynard, MA, has developed a new way to make hydrogen from water using solar energy. The company says that its process is cheap enough to compete with the cheapest approaches used now, which strip hydrogen from natural gas, and it has the further advantage of releasing no carbon dioxide.
Nanoptek, which has been developing the new technology in part with grants from NASA and the Department of Energy (DOE), recently completed its first venture-capital round, raising $4.7 million that it will use to install its first pilot plant. The technology uses titania, a cheap and abundant material, to capture energy from sunlight. The absorbed energy releases electrons, which split water to make hydrogen. Other researchers have used titania to split water in the past, but Nanoptek researchers found a way to modify titania to absorb more sunlight, which makes the process much cheaper and more efficient, says John Guerra, the company's founder and CEO.
Suppose this Nanoptek approach really works and eventually can be used to make hydrogen cheaply. What to do with it? Hydrogen is still difficult to transport and store. But hydrogen attached to carbon is very useful in both gas and liquid forms. The problem then becomes where to get the carbon? Ethanol seems a good candidate. It contains a partially oxidized carbon that'd be more useful if its oygen got replaced with a hydrogen. That would lead to ethane and eventually ethylene. The ethylene has many industrial chemical uses.
The hydrogen could also be used with the exhaust of an coal electric power plant to combine with the carbon in the carbon dioxide to again make reduced carbon in gaseous or liquid form. A hydrocarbon with longer carbon chains would be ideal since it would be liquid at room temperature and hence useful for powering cars and trucks. So a light-driven process for splitting water would be most useful combined with a process to reduce carbon into liquid hydrocarbon molecules.
Researchers at Idaho National Laboratory, along with partners at Microcontinuum Inc. (Cambridge, MA) and Patrick Pinhero of the University of Missouri, are developing a novel way to collect energy from the sun with a technology that could potentially cost pennies a yard, be imprinted on flexible materials and still draw energy after the sun has set.
The new approach, which garnered two 2007 Nano50 awards, uses a special manufacturing process to stamp tiny square spirals of conducting metal onto a sheet of plastic. Each interlocking spiral "nanoantenna" is as wide as 1/25 the diameter of a human hair.
Because of their size, the nanoantennas absorb energy in the infrared part of the spectrum, just outside the range of what is visible to the eye. The sun radiates a lot of infrared energy, some of which is soaked up by the earth and later released as radiation for hours after sunset. Nanoantennas can take in energy from both sunlight and the earth's heat, with higher efficiency than conventional solar cells.
"I think these antennas really have the potential to replace traditional solar panels," says physicist Steven Novack, who spoke about the technology in November at the National Nano Engineering Conference in Boston.
Plastic is orders of magnitude cheaper than the polysilicon crystal used in the expensive photovoltaics of today.
They think they can achieve a very high efficiency of energy conversion.
Commercial solar panels usually transform less that 20 percent of the usable energy that strikes them into electricity. Each cell is made of silicon and doped with exotic elements to boost its efficiency. "The supply of processed silicon is lagging, and they only get more expensive," Novack says. He hopes solar nanoantennas will be a more efficient and sustainable alternative.
The team estimates individual nanoantennas can absorb close to 80 percent of the available energy.
An order of magnitude drop in the cost of photovoltaics would make energy storage our biggest problem. The sun does not always shine. But when it does cheap photovoltaics would make photovoltaic electricity the cheapest source of power.
Super cheap solar electric would make more industries seasonal. For example, put the cost of electricity below 1 cent per kilowatt-hour in Arizona from the first day of spring through summer and it might make sense to do a full year's Aluminum smelting in 6 months in Arizona. Or maybe do all the smelting in 4 months.
Nitrogen fertilizer production could become seasonal as well. Use cheap electric power to fix hydrogen to nitrogen during the spring before crops get planted. Keep making fertilizer during the summer for use the next year. Other chemical feedstock synthesis could similarly be done when the power is very cheap.
Skyrocketing demand has kept up the prices for solar photovoltaics for several years running. However, the Earth Policy Institute expects rising production capacity to finally cause a big decline in photovoltaics cost in the next few years.
The average price for a PV module, excluding installation and other system costs, has dropped from almost $100 per watt in 1975 to less than $4 per watt at the end of 2006. (See data.) With expanding polysilicon supplies, average PV prices are projected to drop to $2 per watt in 2010. For thin-film PV alone, production costs are expected to reach $1 per watt in 2010, at which point solar PV will become competitive with coal-fired electricity. With concerns about rising oil prices and climate change spawning political momentum for renewable energy, solar electricity is poised to take a prominent position in the global energy economy.
Regarding competitiveness with coal: There are the not so minor details of where and when. Certainly photovoltaics become cost competitive in Arizona before Colorado and in Colorado before Alberta or England. So in the more northern climes and in cloudier areas the prices of photovoltaics will have to drop much further before becoming competitive. Also, photovoltaics will compete on June 21 in the northern hemisphere years before they compete on March 21, let alone December 21. Plus, we need really cheap electric power storage before day time photovoltaic energy will help us much during the night time. So keep in mind all the caveats and short-comings of solar power when you read rosy scenarios about solar energy.
The company which many observers think has the best chance to cause this big cost decrease is Nanosolar. CEO Martin Roscheisen says Nanosolar can get their production costs below $1 per watt.
- the world’s first printed thin-film solar cell in a commercial panel product;
- the world’s first thin-film solar cell with a low-cost back-contact capability;
- the world’s lowest-cost solar panel – which we believe will make us the first solar manufacturer capable of profitably selling solar panels at as little as $.99/Watt;
- the world’s highest-current thin-film solar panel – delivering five times the current of any other thin-film panel on the market today and thus simplifying system deployment;
- an intensely systems-optimized product with the lowest balance-of-system cost of any thin-film panel – due to innovations in design we have included.
The printed thin film process with which Nanosolar has just started commercial production looks like the ticket. They avoid the costs of the thick polysilicon crystals and supposedly can produce at fast speed using a printing technology.
The San Jose-based Nanosolar developed a proprietary ink that is based on “nanoparticles” of a material called copper indium gallium selenide (CIGR), which can be printed on metal foil, which is cheaper and 20 times more conductive than stainless steel.
Other companies that also specialise in 'thin-film solar' technology also use CIGRs, but require a vacuum chamber to disperse the particles. Nanosolar says its method of printing is cheaper and more effective. It can literally produce huge rolls of the product that are metres wide and up to kilometers long.
But Nanosolar is already sold out into 2009. If their process turns them a big profit during this time they obviously can and will ramp up. So how quickly will they ramp up? Will they run into troubles running their manufacturing process continuously?
A company in Japan has developed a novel way of making solar cells that cuts production costs by as much as 50 percent. The photovoltaic (PV) cells are made up of arrays of thousands of tiny silicon spheres surrounded by hexagonal reflectors.
The key advantage of the system is that it reduces the total amount of silicon required, says Mikio Murozono, president of Clean Venture 21 (CV21), based in Kyoto, Japan. "We use one-fifth of the raw silicon material compared with traditional PV cells," he says.
I am optimistic about cheaper photovoltaics for two reasons. First, it is a solvable problem. Second, many more teams in academia, government, and industry are trying to solve it.
A halving of photovoltaic prices would make photovoltaics competitive in much of the US southwest. So if this company achieves its goal photovoltaics sales will take off.
CV21 started production of its cells in October; the first of its 10-kilowatt modules go on sale this month. While these modules will initially cost about the same as the traditional variety, the price is set to drop by 30 percent in 2008, as production increases in May from 1,000 cells a day to 60,000 cells a day, says Murozono. The ultimate goal is to make them 50 percent cheaper than existing cells by 2010, he says.
Some people believe that once we pass the peak in world oil production we are at risk of deindustrialization. I don't see it. Sure some parts of the world are going to be very hard hit. Some oil emirates and less advanced countries are at risk. For fully industrialized countries I expect some deep recessions and a period of stagnant or declining living standards. But I do not think that the industrialized countries are at risk for total collapse. We have too many sharp scientists and technologists and too many ways to solve the problem of dwindling reserves of liquid hydrocarbons.
Our current high oil prices and this period of a world oil production plateau are actually fortunate for our prospects in a post-peak world. The higher prices are providing incentives for the development of substitutes. The post peak decline hasn't come on so suddenly that we lack time to adjust. People who want to feel total doom and gloom about the future should look elsewhere. Energy shortages aren't going to bring down industrial civilization.
Among the American states California has the strongest incentives for installing photovoltaics .
In its Northern California service territory, PG&E charges tiered rates for electricity, between 11.4 cents and 36.4 cents a kilowatt-hour, depending on usage. (A kilowatt-hour equals the energy needed to run a 100-watt bulb for 10 hours.) Utility spokesman John Tremayne says the average PG&E customer pays about 15 cents a kilowatt-hour, including surcharges and fees.
Solar power generated with photovoltaic panels, meanwhile, will run a homeowner about 18 to 19 cents a kilowatt-hour, assuming a cost of $24,000 to install a system that produces 4,300 kilowatt-hours of electricity, over 30 years, according to Barry Cinnamon, president and chief executive of Akeena Solar Inc., a solar-power installer based in Los Gatos, Calif.
Some customers have managed to cut their installation costs to as little as $15,000 after state rebates and a $2,000 federal tax credit, which, over a 30-year period, would produce power for about 10 to 14 cents a kilowatt-hour, according to Mr. Cinnamon, who says PG&E rates in his area are around 36 cents a kilowatt-hour, after surcharges and fees.
Half of the growth in solar power in the US until 2015 is expected to come in California. The article emphasizes state government incentives as an explanation for this. But California also has electricity costs that are, at the time of this writing about 37% above the national average. So solar doesn't have to become as cheap in California as it does in really cheap electricity states (below 8 cents per kwh) like Washington, North Dakota, Idaho, or Kentucky. Also, southern California has less clouds and more sunshine than most US states (Arizona notably excepted). So the same solar panels produce a lot more electricity in San Diego than they do in Milwaukee or Bangor or Seattle.
I think it hard to project solar installation growth out to 2015 for a reason that seems obvious from the excerpt above: Solar power's cost is not enormously above existing utility power. A reduction in solar's cost by a half or two thirds would make solar pretty competitive in Arizona and southern California. By 2015 Solar's cost could conceivably fall to a point where it becomes competitive in the most sunny areas.
Once the choice only of idealists who put the environment before economics, production of solar panels will double both next year and in 2009, according to U.S. investment bank Jefferies Group Inc, driven by government support especially in Germany and Japan.
A high ranking engineer at General Electric says in some parts of the United States photovoltaics will become cost competitive by 2015.
"At that point you can expect pretty much unbounded growth," General Electric Co's Chief Engineer Jim Lyons told the Jefferies conference in London on Thursday, referring to price parity in sunny parts of the United States by around 2015.
"The solar industry will eventually be bigger than wind."
Solar energy will become bigger than wind for a few reasons. First off, there is more energy outside in the form of photon torpedoes (sorry, couldn't resist) than in the form of air flowing. Wind is just one side effect of heating caused by those photons showering down on the planet. Second, while photovoltaic materials are currently rather expensive they have much greater potential to become dirt cheap than wind towers do. Third, photovoltaic installations hit fewer obstacles. Your neighbors are less likely to mind photovoltaics on your roof (especially when future photovoltaic materials are made to look like roof tiles) than they are a tower sticking up out of our yard 100 feet and making noise as the wind spins the blades.
Researchers at Harvard University have made solar cells that are a small fraction of the width of a human hair. The cells, each made from a single nanowire just 300 nanometers wide, could be useful for powering tiny sensors or robots for environmental monitoring or military applications. What's more, the basic design of the solar cells could be useful in large-scale power production, potentially lowering the cost of generating electricity from the sun.
We do not face a general energy shortage. We face a liquid fuels shortage. Solar is going to join wind and nuclear as non-fossil fuels sources of electricity that could replace most of the fossil fuels now used to generate electricity.
Given cheap, dependable, and high energy density batteries we could shift most transportation to electricity and most electric generation to non-fossil fuels energy sources. That is the path we need to follow to the post Peak Oil era.
Engineer-Poet explains we will have huge amounts of energy available once photovoltaics become cheap.
Annual energy consumption of the USA is about 98000 kWh of primary energy per capita. A square meter in the middle of Kansas receives about 1550 kWh of solar energy per year, so an American's consumption represents about 63 square meters of Kansas. 300 million Americans would need about 7300 square miles out of the 81,815 square miles of the state. Even if you reduced efficiency to 10%, you wouldn't need the entire state. We probably have enough area under roofs and roads to do the job already, no further development required.
We have PV made of silicon (27% of Earth's crust) and PV made of organics (representing carbon, possibly reclaimed from the atmosphere) on the way. Carbon nanowires are already better conductors than copper. Technology inevitably pushes to the limits of science (just compare the 14-inch Winchester disk drives of 3 decades ago to the one in the iPod). The science we have today is enough to supply an American level of comfort to billions, albeit using renewables rather than fossil fuels.
E-P thinks he knows a way to extract silicon for photovoltaics at a much lower cost. Not sure he's right about that. But I agree with him that it is a solvable problem.
Our problem is not a general energy shortage. What we are hitting is a liquid energy shortage. The development of technologies to allow electricity to substitute more for liquid fuels will allow us to move past the liquid fossil fuels era and enjoy rising living standards. But we might go through a painful transition before the batteries and other elements of our more electrified society come together.
Photovoltaic cells, most of which are made from silicon, have exploded in use around the country over the past five years as once-prohibitive costs for home use of the technology have declined. Between 2002 and 2006, the number of new photovoltaic systems installed in U.S. homes nearly tripled to 7,446 from 2,805, according to the Interstate Renewable Energy Council in Latham, N.Y. Industry officials say that such installations are expected to top 11,000 this year.
To put this in perspective the United States has about 70 million single family detached housing units. The yearly installation rate would have to go up by a factor of over 6000 to reach 1% of the existing single family home housing units per year (more for attached townhouses, apartment buildings, and other housing structures).
Sun Run's contract--called a purchased power agreement--won't eliminate the initial cost of getting solar electricity. But it will reduce by about 60 percent the pain of shelling out anywhere from $20,000 to $35,000 for solar panels, according to the company.
Akeena Solar's Andalay panel is supposed to cut installation time from four hours to 30 minutes. It's also meant to be more attractive and look like a skylight.
Sharp Solar, the largest solar panel maker in the world, has started to promote a pre-fab solar system to the U.S. market.
Ultimately what we need are photovoltaic shingles or tiles so that putting a new roof on a house installs photovoltaic materials. That would make most of photovoltaic installation cost just part of the existing cost of roofing installs.
Increasing demand for solar power,engineered by governments, has kept solar prices stable over the last 12 months. Prices have stayed close to $5-6/watt.
In 2005, silicon solar cell production was measured at 1.7 Gigawatts (GW) globally. That number is expected to grow to 10 GW by 2010. At the same time the electronic sector is growing at a five percent annual rate.
Another source shows solar module prices have risen about 11 percent in the last 3 years. That's a little higher than the overall rate of inflation. So we are not on a downward trend in solar photovoltaic prices. Government-engineered increase in demand (especially in Germany which accounts for half of all photovoltaic demand
Most of the decline in photovoltaics prices occurred before 1987. But this latest surge in demand for solar, especially in Germany, is driving a big increase in manufacturing capacity. Costs should drop once production capacity catches up with government-caused increases in demand.
If a photovoltaics manufacturer achieves a really big breakthrough in costs we should see a much more rapid increase in manufacturing capacity and a big drop in prices.
Using concentrating parabolic reflectors and a thermal storage system Palo Alto California company Ausra claims to have a workable way for solar power to supply electricity 24 hours per day.
Ausra claims to have solved the storage problem without using molten salts or other expensive means of conserving heat. In fact, the company estimates that the price of its electricity will drop to roughly 8¢ per kilowatt hour if it can store heat for 16 hours. "Thermal storage is generally considered to be quite a bit cheaper than electrical storage," says Nate Blair, a senior analyst at NREL. "There isn't a lot of power generation combined with storage systems that can take advantage of that. [Concentrated solar power] has a leg up on storage in the grid or flow batteries or even ultracapacitors."
The system will employ pressure and a steam accumulator to accomplish the trick. "You allow some of the steam to recondense," O'Donnell explains. "It flashes back to steam when you reduce the pressure just by opening the valve to the turbine."
Such long-term steam storage, however, is unproved. "Steam storage is currently feasible at small levels, for example, one hour or so," NREL's Mehos notes. "Due to large volumes and high pressures involved with steam storage, scaling up steam storage to baseload applications is very high risk."
Water boils at different temperatures at different atmospheric pressures. At high altitudes with thinner air and less atmospheric pressure water boils at lower temperatures. But put water under a sufficiently intense pressure and it will not boil into vapor. The idea is to store the water under high pressure so that it won't convert to steam and then release some of the water into a lower pressure area at night to allow the water to convert into high pressure steam and power turbines to generate electricity.
I don't know whether they can make it work. But this is an interesting approach. Store the energy as hot water rather than as hydrogen or electrochemically in a battery. Can they make this approach work? The storage container has to meet cost, pressure, and longevity goals. What sort of storage material could do this? Steel? Is insulation needed?
FORT COLLINS - Today, Colorado State University is taking another big step toward making Colorado a leader in sustainable energy production. Already internationally known for research in the development of clean energy solutions including alternative fuels, clean engines and intelligent power grids, Colorado State announced its innovative method for manufacturing low-cost, high-efficiency solar panels is nearing mass production - bringing hundreds of jobs to the region and potentially providing light and power for billions in the underdeveloped world.
In a new 200-megawatt factory, expected to employ up to 500 people, AVA Solar Inc. will start production by the end of next year on the pioneering, patented technology developed by mechanical engineering Professor W.S. Sampath at Colorado State. Based on the average household usage, 200 megawatts will power 40,000 U.S. homes.
Produced at less than $1 per watt, the panels will dramatically reduce the cost of generating solar electricity and could power homes and businesses around the globe with clean energy for roughly the same cost as traditionally generated electricity.
With installation the $2 per watt expected cost is still much lower than current photovoltaics.
The cost to the consumer could be as low as $2 per watt, about half the current cost of solar panels, and competitive with cost of power from the electrical grid in many parts of the world. In addition, this solar technology need not be tied to a grid, so it can be affordably installed and operated in nearly any location.
They say their manufacturing process will be highly efficient.
-Simple manufacturing process - fully automated and continuous production with no batch processing yielding high throughputs or production rates;
They also claim their process uses far less semiconductor material than crystalline silicon panels.
-Inexpensive, efficient raw materials - because they convert solar energy into electricity more efficiently, cadmium telluride solar panels require 100 times less semiconductor material than high-cost crystalline silicon panels.
The era of cheap solar photovoltaics is no longer a distant prospect.
Powered by $77 million in new investment, startup Heliovolt, based in Austin, TX, will build a factory next year for mass-producing a new type of solar cell that could, in much of the United States, make solar electricity as cheap as electricity from the grid. The company will be scaling up a new manufacturing technique that could produce high-performance thin-film solar cells more reliably than other methods.
Heliovolt is one of several startups developing a type of thin-film solar cell that converts light into electricity with a micrometers-thick layer of a copper-indium-gallium selenide (CIGS) semiconductor. Thin-film solar cells are attractive because they could produce electricity cheaper than conventional silicon solar cells.
Read the details in the linked MIT Technology Review article.
We have a problem with a looming fossil fuels shortage, especially for liquid fuel. But we do not face a general energy shortage or peak energy production problem. If necessary (or if we just get disgusted enough by conventional pollution) nuclear power could displace coal for electric power generation. Wind electric costs are going to go down and wind's role will grow. Also, one or more of an assortment of venture capital photovoltaics start-ups will bring low cost solar to the masses. With all the fine minds chasing this challenge I'll be surprised if photovoltaics aren't cost competitive for the American southwest within 5 to 7 years and for more temperate climates within 10 to 15 years.
A typical solar cell generates only one electron per photon of incoming sunlight. Some exotic materials are thought to produce multiple electrons per photon, but for the first time, the same effect has been seen in silicon. Researchers at the National Renewable Energy Laboratory (NREL), in Golden, CO, showed that silicon nanocrystals can produce two or three electrons per photon of high-energy sunlight. The effect, they say, could lead to a new type of solar cell that is both cheap and more than twice as efficient as today's typical photovoltaics.
This approach might achieve 40% efficiency of conversion. That's more than double what you'll find on the market today. (someone correct me if they know about commercial photovoltaic cells above 20% conversion efficiency)
By generating multiple electrons from high-energy photons, solar cells made of silicon nanocrystals could theoretically convert more than 40 percent of the energy in light into electrical power, says Arthur Nozik, a senior research fellow at NREL.
These researchers think silicon nanocrystals will be cheaper to make than multijunction photovoltaics that have achieved even higher efficiency. Given the multitude of approaches for achieving higher efficiency and lower costs our chances of getting cheaper photovoltaics seem high.
Cheap solar will some day make noon time the cheapest time to buy electricity. But will stationary battery storage ever become cheap enough to allow solar to compete for baseload demand?
Update: Another report finds silicon nanoparticles improve solar cell efficiency.
CHAMPAIGN, Ill. — Placing a film of silicon nanoparticles onto a silicon solar cell can boost power, reduce heat and prolong the cell’s life, researchers now report.
“Integrating a high-quality film of silicon nanoparticles 1 nanometer in size directly onto silicon solar cells improves power performance by 60 percent in the ultraviolet range of the spectrum,” said Munir Nayfeh, a physicist at the University of Illinois and corresponding author of a paper accepted for publication in Applied Physics Letters.
A 10 percent improvement in the visible range of the spectrum can be achieved by using nanoparticles 2.85 nanometers in size, said Nayfeh, who also is a researcher at the university’s Beckman Institute.
In conventional solar cells, ultraviolet light is either filtered out or absorbed by the silicon and converted into potentially damaging heat, not electricity. In previous work, however, Nayfeh showed that ultraviolet light could efficiently couple to correctly sized nanoparticles and produce electricity. That work was reported in the August 2004 issue of the journal Photonics Technology Letters.
5:14 p.m., July 23, 2007-- Using a novel technology that adds multiple innovations to a very high-performance crystalline silicon solar cell platform, a consortium led by the University of Delaware has achieved a record-breaking combined solar cell efficiency of 42.8 percent from sunlight at standard terrestrial conditions.
That number is a significant advance from the current record of 40.7 percent announced in December and demonstrates an important milestone on the path to the 50 percent efficiency goal set by the Defense Advanced Research Projects Agency (DARPA). In November 2005, the UD-led consortium received approximately $13 million in funding for the initial phases of the DARPA Very High Efficiency Solar Cell (VHESC) program to develop affordable portable solar cell battery chargers.
Combined with the demonstrated efficiency performance of the very high efficiency solar cells' spectral splitting optics, which is more than 93 percent, these recent results put the pieces in place for a solar cell module with a net efficiency 30 percent greater than any previous module efficiency and twice the efficiency of state-of-the-art silicon solar cell modules.
What I want to know: Are these materials inherently more or less expensive to manufacture for unit area than existing silicon photovoltaics? Do these materials lend themselves to greater cost reductions?
Big money is going to go into creation of a manufacturing prototype.
As a result of the consortium's technical performance, DARPA is initiating the next phase of the program by funding the newly formed DuPont-University of Delaware VHESC Consortium to transition the lab-scale work to an engineering and manufacturing prototype model. This three-year effort could be worth as much as $100 million, including industry cost-share.
The professors leading this effort are aiming for 50% efficiency.
The ground-breaking research was led by Allen Barnett, principal investigator and UD professor of electrical and computer engineering, and Christiana Honsberg, co-principal investigator and associate professor of electrical and computer engineering. The two direct the University's High Performance Solar Power Program and will continue working to achieve 50 percent efficiency, a benchmark that when reached would mean a doubling of the efficiency of terrestrial solar cells based around a silicon platform within a 50-month span.
Some are skeptical over whether solar electric energy will ever amount to much after decades of failing to become cost competitive. But my view is that many breakthroughs took decades to achieve. The fact that researchers have been searching for cheaper photovoltaic materials for decades isn't an argument against the feasibility of this quest. Rather, the number of first class minds pursuing this quest strongly suggests the ultimate goal of cheap and high efficiency photovoltaics is achievable.
Researchers at New Jersey Institute of Technology (NJIT) have developed an inexpensive solar cell that can be painted or printed on flexible plastic sheets. “The process is simple,” said lead researcher and author Somenath Mitra, PhD, professor and acting chair of NJIT’s Department of Chemistry and Environmental Sciences. “Someday homeowners will even be able to print sheets of these solar cells with inexpensive home-based inkjet printers. Consumers can then slap the finished product on a wall, roof or billboard to create their own power stations.”
“Fullerene single wall carbon nanotube complex for polymer bulk heterojunction photovoltaic cells,” featured as the June 21, 2007 cover story of the Journal of Materials Chemistry published by the Royal Society of Chemistry, details the process. The Society, based at Oxford University, is the British equivalent of the American Chemical Society.
These solar cells are built out of carbon nanotubes and carbon fullerenes.
The solar cell developed at NJIT uses a carbon nanotubes complex, which by the way, is a molecular configuration of carbon in a cylindrical shape. The name is derived from the tube’s miniscule size. Scientists estimate nanotubes to be 50,000 times smaller than a human hair. Nevertheless, just one nanotube can conduct current better than any conventional electrical wire. “Actually, nanotubes are significantly better conductors than copper,” Mitra added.
Mitra and his research team took the carbon nanotubes and combined them with tiny carbon Buckyballs (known as fullerenes) to form snake-like structures. Buckyballs trap electrons, although they can’t make electrons flow. Add sunlight to excite the polymers, and the buckyballs will grab the electrons. Nanotubes, behaving like copper wires, will then be able to make the electrons or current flow.
Does Mitra argue this approach is cheap because it is cheap already? Or does his approach depend on the eventual development of much cheaper ways to produce nanotubes or buckyballs? Does anyone know what the state of the play is for creation of carbon nanomaterials on an industrial scale?
If this stuff becomes cheap enough then it would not matter that the carbon bonds gradually break down due to UV light hitting them. One could just repaint surfaces every 7 or 10 years. Note that car and house paint can last that long and longer.
Cheap photovoltaics will make mid day electricity much cheaper than late afternoon and evening electricity. We need dynamic electric pricing in order to use photovoltaic electricity efficiently. We have plenty of ways to shift our demand around in a 24 period or even between seasons in some cases. Cheap photovoltaics might lead electric intensive industries such as aluminum to shift the bulk of their processing to spring and summer and into areas such as Arizona which have the most sunlight.
Using plastics to harvest the energy of the sun just got a significant boost in efficiency thanks to a discovery made at the Center for Polymers and Organic Solids at the University of California, Santa Barbara.
Nobel laureate Alan Heeger, professor of physics at UC Santa Barbara, worked with Kwanghee Lee of Korea and a team of other scientists to create a new "tandem" organic solar cell with increased efficiency. The discovery, explained in the July 13 issue of the journal Science, marks a step forward in materials science.
Tandem cells are comprised of two multilayered parts that work together to gather a wider range of the spectrum of solar radiation -- at both shorter and longer wavelengths. "The result is six and a half percent efficiency," said Heeger. "This is the highest level achieved for solar cells made from organic materials. I am confident that we can make additional improvements that will yield efficiencies sufficiently high for commercial products." He expects this technology to be on the market in about three years.
Heeger co-founded Konarka Technologies a few years ago to commercialize his solar cells research. The press release isn't specific on this point but Konarka might be the company to watch on the subject of commercializing the technology.
If Heeger's team can substantially raise the conversion efficiency and also cheaply manufacture solar cells with this design then solar photovoltaics could finally take off. Solar initially will cut into peak demand. But solar could also provide energy for transportation once cheap high capacity batteries for cars become available.
MIT's Technology Review reports on progress in raising solar photovoltaic cell efficiency.
The cell, which employs new "metamorphic" materials, is designed for photovoltaic systems that use lenses and mirrors to concentrate the sun's rays onto small, high-efficiency solar cells, thereby requiring far less semiconductor material than conventional solar panels. Last month Spectrolab published in the journal Applied Physics Letters the first details on its record-setting cell, initially disclosed in December, which converts 40.7 percent of incoming light into electricity at 240-fold solar concentration--a healthy 1.4 percent increase over the company's previous world-record cell. Other groups are developing promising cells based on the new type of materials, including researchers at the Department of Energy's National Renewable Energy Laboratory (NREL), in Golden, CO. The NREL researchers will soon publish results in the same journal showing that their NREL's designs are tracking Spectrolab's, improving from 37.9 percent efficiency in early 2005 to 38.9 percent efficiency today.
The Boeing subsidiary Spectrolab is keeping ahead of NREL. Are private sector workers more motivated or better funded? How about a hefty X Prize for the first group to exceed 50%, 51%, and so on?
Combine higher efficiency with solar concentrators for lower cost. Cheap solar power anyone?
Such high output may be just the beginning. Raed Sherif, director of concentrator products at Spectrolab, says there is every reason to believe that these metamorphic solar cells will top 45 percent and perhaps even 50 percent efficiency. Sherif says those efficiencies, combined with the vast reduction in materials made possible by 1,000-fold concentrators, could rapidly reduce the cost of producing solar power. "Concentrated photovoltaics are a relatively late entry in the field, but it will catch up very quickly in terms of cost," he predicts. (See "Solar Power at Half the Cost.")
Cheap solar power would favor a shift to electric cars. Combine cheap solar power with cheap, high capacity, and safe car batteries and market forces alone would make our environment much cleaner. We'd get cleaner air. But we'd also get cleaner water as the use of oil (leaks of which run off in rain) gradually dropped.
Cheap solar power would also lower costs and therefore accelerate economic growth and raise living standards. Cheap solar power with high conversion efficiency would use probably two orders of magnitude less land to produce the same amount of energy as biomass produces. So cheap solar power would reduce the demand for land for biomass energy. That would reduce habitat loss, especially in tropical lands such as Brazil, Malaysia, and Indonesia.
The rising price of oil and the expectation that oil production won't rise as fast as demand has powerfully concentrated many minds to look for alternative cheaper sources of energy. Cheap solar power is an achievable goal and I expect we will see it achieved by the 2020s at the latest.
Kevin Bullis of MIT's Technology Review reports on a new solar photovoltaic technology developed by Pasadena California start-up Soliant Energy which lowers the cost of photovoltaic power by use of a compact roof-mountable solar concentrator design.
Soliant has designed a solar concentrator that tracks the sun throughout the day but is lighter and not pole-mounted. The system fits in a rectangular frame and is mounted to the roof with the same hardware that's used for conventional flat solar panels. Yet the devices will likely cost half as much as a conventional solar panel, says Hines. A second-generation design, which concentrates light more and uses better photovoltaics, could cost a quarter as much. He says that a more advanced design should be ready by 2010.
The Soliant design combines both lenses and mirrors to create a more compact system. Each module is made of rows of aluminum troughs, each about the width and depth of a gutter. These troughs are mounted inside a rectangular frame and can tilt in unison from side to side to follow the sun.
Existing solar concentrators are too large and complicated to mount on residential roofs.
Due to my expectation that we'll see truly disruptive technologies come to market, I've long been skeptical of 50 and 100 year projections of carbon dioxide emissions from fossil fuels consumption. There's no way we are going to get out 30 years from where we are now without the development of a variety of technologies that make solar photovoltaics, wind, batteries, nuclear, and other non-polluting power sources much cheaper.
This report above provides an example of how we can expect disruptive technologies to come out of entrepreneurial start-ups. The higher the price of oil gets the more energy technology innovation we are going to witness.
We could speed up the rate of innovation by taxing fossil fuels or by government funding of more energy research. I prefer the latter approach over the former because I think it would require less cash shifted through government hands. Better a $10 billion a year research budget than several hundreds of billions per year of green taxes.
The ability to use solar power to generate liquid carbon-based fuels has the potential to generate energy for transportation much more efficiently than biomass, without biomass's water limitation, and with a much smaller land footprint. With all that in mind, some UCSD researchers have used solar power to partially reduce carbon dioxide.
Chemists have shown that it is possible to use solar energy, paired with the right catalyst, to convert carbon dioxide into a raw material for making a wide range of products, including plastics and gasoline.
Researchers at the University of California, San Diego (UCSD), recently demonstrated that light absorbed and converted into electricity by a silicon electrode can help drive a reaction that converts carbon dioxide into carbon monoxide and oxygen. Carbon monoxide is a valuable commodity chemical that is widely used to make plastics and other products, says Clifford Kubiak, professor of chemistry at UCSD. It is also a key ingredient in a process for making synthetic fuels, including syngas (a mixture largely of carbon monoxide and hydrogen), methanol, and gasoline.
A method to attach hydrogens to the carbon, totally displacing the oxygen, would produce hydrocarbons. Hook them up into long enough chains and the hydrocarbons become liquid at room temperature. Then you can put it in a gas tank and cruise.
A cheap method to use of solar power to create chemical feedstocks and liquid fuels would solve one of solar's biggest problems: the sun does not always shine. We could use nuclear power as baseload electric power. Then use solar power to create liquid fuels. That could entirely break our dependence on fossil fuels.
Given a sufficiently advanced and cheap enough battery technology we could use solar or nuclear power to charge batteries for transportation. But batteries are not the only potential way to use solar power for transportation. Solar power could run chemical processes to produce liquid fuels too.
If we could produce all our liquid hydrocarbon fuels from carbon dioxide extracted from the atmosphere then burning of liquid hydrocarbons would no longer increase atmospheric carbon dioxide. Instead we'd have an artificial carbon cycle in parallel with the natural carbon cycle.
ST. LOUIS, Dec. 06, 2006 -- Boeing [NYSE: BA] today announced that Spectrolab, Inc., a wholly-owned subsidiary, has achieved a new world record in terrestrial concentrator solar cell efficiency. Using concentrated sunlight, Spectrolab demonstrated the ability of a photovoltaic cell to convert 40.7 percent of the sun's energy into electricity. The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) in Golden, Colo., verified the milestone.
Note the use of the term "concentrator". Sounds like they are focusing light down from larger to smaller areas. So does the photovoltaic cell achieve 40% efficiency even with more intense concentrated light? Sounds like it.
"This solar cell performance is the highest efficiency level any photovoltaic device has ever achieved," said Dr. David Lillington, president of Spectrolab. "The terrestrial cell we have developed uses the same technology base as our space-based cells. So, once qualified, they can be manufactured in very high volumes with minimal impact to production flow."
High efficiency multijunction cells have a significant advantage over conventional silicon cells in concentrator systems because fewer solar cells are required to achieve the same power output. This technology will continue to dramatically reduce the cost of generating electricity from solar energy as well as the cost of materials used in high-power space satellites and terrestrial applications.
They think they can increase the conversion efficiency even higher.
"These results are particularly encouraging since they were achieved using a new class of metamorphic semiconductor materials, allowing much greater freedom in multijunction cell design for optimal conversion of the solar spectrum," said Dr. Richard R. King, principal investigator of the high efficiency solar cell research and development effort. "The excellent performance of these materials hints at still higher efficiency in future solar cells."
So how far will this drive down the cost of photovoltaic electricity?
Projections made on the future use of various source of energy are guesses. Go out enough years and unpredictable technological breakthroughs make all future projections wrong. Maybe battery breakthroughs will make electric cars practical for most uses. Maybe photovoltaic breakthroughs will halt the growth of coal for electric power. Or maybe nuclear power will replace coal as the whole world becomes too concerned by the growth in carbon dioxide emissions. Then again, maybe methods to capture all pollutants and equester carbon dioxide from burning coal will get so cheap that coal will become the cheapest way to get clean energy.
The problem with technologies that make fossil fuels cleaner is that they almost always cost more than not using such technologies. We are more assured of a cleaner environment if innately cleaner energy technologies become cheaper.
MIT's Technology Review has an interesting report on how MIT graduate student Matthew Orosz, while on a Peace Corps trip to Lesotho in southern Africa, saw Africans using a parabolic reflector to bake bread. Building on this idea Orosz came up with a way to use common parts to make a solar electric generator that is cheaper than photovoltaics.
The basic design of Orosz's solar generator system is simple: a parabolic trough (taking up 15 square meters in this case) focuses light on a pipe containing motor oil. The oil circulates through a heat exchanger, turning a refrigerant into steam, which drives a turbine that, in turn, drives a generator.
The refrigerant is then cooled in two stages. The first stage recovers heat to make hot water or, in one design, to power an absorption process chiller, like the propane-powered refrigerators in RVs. The solar-generated heat would replace or augment the propane flame used in these devices. The second stage cools the refrigerant further, which improves the efficiency of the system, Orosz says. This stage will probably use cool groundwater pumped to the surface using power from the generator. The water can then be stored in a reservoir for drinking water.
Since the parts are mass produced for automobiles they are half the cost of photovoltaics for generating electricity.
As a result, the complete system for generating one kilowatt of electricity and 10 kilowatts of heat, including a battery for storing the power generated, can be built for a couple thousand dollars, Orosz says, which is less than half the cost of one kilowatt of photovoltaic panels.
But does that cost estimate include maintenance costs and replacement parts? I'd expect a much higher mean time between failure for photovoltaics. Though when this gadget fails people with fairly common auto mechanic skills would be able to fix most of it and they'd be able to get many of the parts from an auto parts store.
There's a downside to the mass-produced parts: It is unlikely that many of these parts could be made much cheaper. The design is not as amenable to cost reduction as photovoltaics. Eventually photovoltaics will drop in cost below the cost of this system. Still, it is a pretty neat idea today.
Some questions: How much heat and electricity would this device generate in winter? Would the cold air prevent it from working? Also, can the heat do anything useful in the summer? Solar hot water comes to mind.
Another question: How noisy is it?
Ewing, NJ | 4 January 2006 -- Global Photonic Energy Corporation (GPEC), developer of organic photovoltaic (OPVtm) technology for ultra-low cost high power solar cells, announced that the company's research partners at Princeton University and the University of Southern California (USC) have achieved a new record in an organic solar cell that is responsive to light in the near infrared (NIR) range of the solar spectrum. NIR radiation is invisible to the human eye.
Many so-called "night vision" devices operate by sensing infrared light which is emitted by warm objects and makes up a substantial portion of all energy reaching the earth from the sun. Under only NIR radiation, the Princeton solar cell would appear to be generating power in the dark -- as the human eye is only sensitive to visible light.
This latest achievement is the highest level of conversion performance yet achieved for an organic solar cell in the IR portion of the solar spectrum. The Company's researchers detail this latest achievement in the December 2 issue of Applied Physics Letters.
The Global thirst for energy is continually expanding. Renewable energy sources have experienced rapid growth in recent years as costs have improved. Global solar cell production has grown over 20% annually for the last 20 years, reaching sales of $6 billion in 2004. This strong growth has resulted in a world-wide shortage of semiconductor silicon driving 2005 solar cell prices higher. Cost is a critical factor in the continued expansion of the solar cell industry. Currently, solar-generated power is four to six times more expensive to consumers than coal-generated power.
Silicon crystals are too expensive as a starting material for making photovoltaics cells. The development of organic photovoltaic materials holds the potential for much cheaper photovoltaics. These Princeton and USC researchers (see below) are not only pursuing organically based photovoltaics but they are also pursuing the development of much higher efficiency photovoltaics. The odds are developing a way to double or triple the conversion efficiency of organic photovoltaics will not increase costs per square meter of materials anywhere near as much. So cost per unit of energy produced will drop.
Recent efforts have focused on the use of "organic" materials. Organic semiconductors contain the ubiquitous element carbon and are capable of achieving ultra-low cost solar power generation that is competitive with traditional fossil fuel sources. Organic materials have the potential to achieve ultra-low cost production costs and high power output. The materials are ultra-thin and flexible and can be applied to large, curved or spherical surfaces. Because the layers are so thin, transparent solar cells can be applied to windows creating power-generating glass that retains its basic functionality.
GPEC sponsors research by Professor Stephen R. Forrest at Princeton and Professor Mark E. Thompson at USC. Professor Forrest's research team has focused on organic "small-molecule" devices that are assembled literally a molecule at a time in highly efficient nanostructures. These devices have layers and/or structural elements that can be extremely small -- at only 0.5 billionth of a meter thick and can be applied to low-cost, flexible plastic surfaces.
These scientists want to boost absorption of photons near the infrared frequency range because that is where much of the energy in sunlight is found.
One challenge for organic solar cells has been the efficient capture and conversion of sunlight. Sunlight consists of photons (particles of light) that are delivered across a spectrum that includes invisible ultraviolet (UV) light, the visible spectrum of colors -- violet, indigo, blue, green, yellow, orange and red -- and the invisible infrared or IR spectrum. The amount of incoming photons across the UV, visible and IR spectrums is about 4%, 51% and 45%, respectively. The photons absorbed by a solar cell directly impacts the power output. To achieve high power output, solar devices must take advantage of as much of the solar spectrum as possible. Typical organic solar cells absorb only a fraction of the visible portion of the solar spectrum. In fact, the best organic solar cells absorb and convert only about 1/3 of the total available light utilizing primarily the visible portion of the spectrum.
"This latest device demonstrates that significant power can be harvested from the IR and near-IR portion of the solar spectrum.", said Dr. Stephen R. Forrest. "In fact, this novel approach has the potential to double the power output of organic solar devices with power harvested from the near-IR and IR portion of the solar spectrum. With this approach we are well on our way to power levels exceeding 100 watts per meter", Forrest concluded.
Imagine organic photovoltaics coating windows especially in hot climates. Instead of letting in the infrared frequencies the photovoltaics convert those photons to useful electricity. So instead of heating a building and thereby increasing the demand for air conditioning the photovoltaic coating could keep out heat and turn it into electricity that would power air conditioners.
In the longer run imagine nanomaterials-based photovoltaic coatings that could adjust how much electricity they let into a room or into a car depending on whether a human was in the room or car. When a human was present the material could become transparent to allow ing lighting or provide the ability to look outside. House and car windows could be turned dark or transparent by dynamically changing nanostructures. When no one was in a car or house room the windows could become dark and that would mean the nanocoatings were absorbing the light that hit them and turning them into electric to charge batteries (which of course will be made from some nanomaterials as well). So on a hot summer day your car's seats wouldn't get as hot. Also, the inside trim wouldn't degrade as rapidly due to sun damage.
GPEC is funded by electric power industry venture capitalists Kuhns Brothers.
LOS ALAMOS, N.M., January 4, 2006 -- Los Alamos National Laboratory scientists have discovered that a phenomenon called carrier multiplication, in which semiconductor nanocrystals respond to photons by producing multiple electrons, is applicable to a broader array of materials that previously thought. The discovery increases the potential for the use of nanoscrystals as solar cell materials to produce higher electrical outputs than current solar cells.
In papers published recently in the journals Nature Physics and Applied Physics Letters, the scientists demonstrate that carrier multiplication is not unique to lead selenide nanocrystals, but also occurs with very high efficiency in nanocrystals of other compositions, such as cadmium selenide. In addition, these new results shed light on the mechanism for carrier multiplication, which likely occurs via the instantaneous photoexcitation of multiple electrons. Such a process has never been observed in macroscopic materials and it explicitly relies on the unique physics of the nanoscale size regime.
According to Richard Schaller, a Los Alamos scientist on the team, "Our research of carrier multiplication in previous years was really focused on analyzing the response of lead selenide nanocrystals to very short laser pulses. We discovered that the absorption of a single photon could produce two or even three excited electrons. We knew, somewhat instinctively, that carrier multiplication was probably not confined to lead selenide, but we needed to pursue the question."
Lead project scientist Victor Klimov explains, "Carrier multiplication actually relies upon very strong interactions between electrons squeezed within the tiny volume of a nanoscale semiconductor particle. That is why it is the particle size, not its composition that mostly determines the efficiency of the effect. In nanosize crystals, strong electron-electron interactions make a high-energy electron unstable. This electron only exists in its so-called 'virtual state' for an instant before rapidly transforming into a more stable state comprising two or more electrons."
Sooner or later some scientists are going to discover high efficiency photovoltaic materials that can be made very cheaply. This sort of research should get more funding. The benefits will be enormous when they come. Why not get the benefits sooner?
Also see my previous post on the work of Schaller and Klimov from May 2005: "Quantum Dots May Boost Photovoltaic Efficiency To 65%".
In research published today in Nature Materials magazine, UCLA engineering professor Yang Yang, postdoctoral researcher Gang Li and graduate student Vishal Shrotriya showcase their work on an innovative new plastic (or polymer) solar cell they hope eventually can be produced at a mere 10 percent to 20 percent of the current cost of traditional cells, making the technology more widely available.
"Solar energy is a clean alternative energy source. It's clear, given the current energy crisis, that we need to embrace new sources of renewable energy that are good for our planet. I believe very strongly in using technology to provide affordable options that all consumers can put into practice," Yang said.
The use of purified silicon currently prevents photovoltaics from reaching cost competitiveness. Another approach being pursued is the development of plants for making less purified silicon. But the plastics approach bypasses the problem altogether.
The price for quality traditional solar modules typically is around three to four times more expensive than fossil fuel. While prices have dropped since the early 1980s, the solar module itself still represents nearly half of the total installed cost of a traditional solar energy system.
Currently, nearly 90 percent of solar cells in the world are made from a refined, highly purified form of silicon -- the same material used in manufacturing integrated circuits and computer chips. High demand from the computer industry has sharply reduced the availability of quality silicon, resulting in prohibitively high costs that rule out solar energy as an option for the average consumer.
Made of a single layer of plastic sandwiched between two conductive electrodes, UCLA's solar cell is easy to mass-produce and costs much less to make -- roughly one-third of the cost of traditional silicon solar technology. The polymers used in its construction are commercially available in such large quantities that Yang hopes cost-conscious consumers worldwide will quickly adopt the technology.
Independent tests on the UCLA solar cell already have received high marks. The nation's only authoritative certification organization for solar technology, the National Renewable Energy Laboratory (NREL), located in Golden, Colo., has helped the UCLA team ensure the accuracy of their efficiency numbers. The efficiency of the cell is the percentage of energy the solar cell gathers from the total amount of energy, or sunshine, that actually hits it.
The conversion efficiency they have achieved is not yet high enough. But they think they can achieve a 3 or 4 times increase in conversion efficiency to make it competitive.
According to Yang, the 4.4 percent efficiency achieved by UCLA is the highest number yet published for plastic solar cells.
"As in any research, achieving precise efficiency benchmarks is a critical step," Yang said. "Particularly in this kind of research, where reported efficiency numbers can vary so widely, we're grateful to the NREL for assisting us in confirming the accuracy of our work."
Given the strides the team already has made with the technology, Yang calculates he will be able to double the efficiency percentage in a very short period of time. The target for polymer solar cell performance is ultimately about 15 percent to 20 percent efficiency, with a 15–20 year lifespan. Large-sized silicon modules with the same lifespan typically have a 14 percent to 18 percent efficiency rating.
Plastic decays in sunlight. So I'm not surprised by the projected 15 to 20 year lifespan. Other approaches as replacements for silicon could potentially last longer.
This development is not yet ready for market.
The plastic solar cell is still a few years away from being available to consumers, but the UCLA team is working diligently to get it to market.
"We hope that ultimately solar energy can be extensively used in the commercial sector as well as the private sector. Imagine solar cells installed in cars to absorb solar energy to replace the traditional use of diesel and gas. People will vie to park their cars on the top level of parking garages so their cars can be charged under sunlight. Using the same principle, cell phones can also be charged by solar energy," Yang said. "There are such a wide variety of applications."
Photovoltaics will become cost competitive some day. But it is very hard to guess when. The fact that talented groups of researchers (including some start-ups with funding from major venture capitalists) are working on approaches that avoid the high cost of silicon crystals makes me optimistic that a breakthrough will come within 10 years. We also still face the battery problem for how to store it for night use and also for transportation.
Golden, Colo. — Solar concentrators using highly efficient photovoltaic solar cells will reduce the cost of electricity from sunlight to competitive levels soon, attendees were told at a recent international conference on the subject. Herb Hayden of Arizona Public Service (APS) and Robert McConnell and Martha Symko-Davies of the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) organized the conference held May 1-5 in Scottsdale, Ariz.
"Concentrating solar electric power is on the cusp of delivering on its promise of low-cost, reliable, solar-generated electricity at a cost that is competitive with mainstream electric generation systems," said Vahan Garboushian, president of Amonix, Inc. of Torrance, Calif. "With the advent of multijunction solar cells, PV concentrator power generation at $3 per watt is imminent in the coming few years," he added.
We have seen steady progress in photovoltaic concentrator technology. We are working with advanced multijunction PV cells that are approaching 38% efficiency, and even higher is possible over time. Our goal is to install PV concentrator systems at $3 per watt, which can happen soon at production rates of 10 megawatts per year. Once that happens, higher volumes are readily achieved," Hayden, Solar Program Coordinator at APS, said.
Growth in the photovoltaic (PV) concentrator business was reflected in the conference attendance, three times that of the 2003 version. This rapid growth was attributed to recent PV concentrator installations and sales forecasts along with excitement created by new solar cell efficiencies approaching 40%. At the conference, NREL announced a new record efficiency of 37.9 percent at 10 suns, a measure of concentrated sunlight. Soon thereafter Boeing-Spectrolab, under contract to NREL and the Department of Energy, surpassed the NREL record with 39.0 percent at 236 suns announced at the European photovoltaic conference in Barcelona, Spain. The efficiency of a solar cell is the percentage of the sun's energy the device converts to electricity.
Photovoltaic (PV) concentrator units are much different than the flat photovoltaic modules sold around the world; almost 1,200 megawatts of flat PV modules were sold last year. PV concentrators come in larger module sizes, typically 20 kilowatts to 35 kilowatts each, they track the sun during the day and they are more suitable for large utility installations.
Those 1,2000 megawatts of flat PV modules sold last year are equivalent to 1 nuclear power plant running only part of the day. So maybe they equal a third or a quarter of a nuclear power plant. However, see the following article where one person is quoted estimating 14,000 megawatts of PV sold in the last year in the world.
Note the concentrator installations are more complex because they have mechanical components to keep the photovoltaics pointed at the sun. This is probably not practical for home roof photovoltaics due to materials, installation, and maintenance costs. Then will large commercial photovoltaics electric power generator facilities become cost effective before residential solar power?
Update: The San Francisco Chronicle has an article about growing venture capital funding of photovoltaics start-ups. Venture capital start-ups are pursuing flexible and cheap plastic photovoltaics.
Nanosys and Nanosolar in Palo Alto -- along with Konarka in Lowell, Mass. -- say their research will result in thin rolls of highly efficient light-collecting plastics spread across rooftops or built into building materials.
These rolls, the companies say, will be able to provide energy for prices as low as the electricity currently provided by utilities, which averages $1 per watt.
Note that the $3 per watt hope from the first article is 3 times the $1 watt figure to compete against utilities.
The Sand Hill Road venture capitalists are interested in photovoltaic materials that require far less capital equipment to produce.
"Silicon is very capital-intensive. You don't need a clean room for plastic power where capital costs are one-tenth of silicon," said Raj Atluru, managing director at the venture capitalist firm of Draper Fisher Jurvetson in Menlo Park, a major investor in Konarka.
Cheap solar power is inevitable. But when?
Golden, Colo. — Researchers at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) have shown that nanotechnology may greatly increase the amount of electricity produced by solar cells.
In a paper published in a May issue of the American Chemical Society's Nano Letters journal, an NREL team found that tiny "nanocrystals," also known as "quantum dots," produce as many as three electrons from one high energy photon of sunlight. When today's photovoltaic solar cells absorb a photon of sunlight, the energy gets converted to at most one electron, and the rest is lost as heat.
The research demonstrates the potential for solar, or photovoltaic, cells that reduce wasteful heat and maximize the amount of the sun's energy that is converted to electricity—a key step toward making solar energy more cost-competitive with conventional power sources.
The NREL research team, led by Arthur Nozik, included Randy Ellingson, Matt Beard, Justin Johnson, Pingrong Yu, and Olga Micic, and worked in collaboration with theorists Alexander Efros and Andrew Shabaev of the Naval Research Laboratory (NRL) in Washington, D.C.
The findings are further confirmation of pioneering work by Nozik, who in 2000 predicted that quantum dots could increase the efficiency of solar cells, through a process now termed "multiple exciton generation," or "MEG". Last year, Richard Schaller and Victor Klimov of Los Alamos National Laboratory in New Mexico were the first to demonstrate the electron multiplication phenomenon predicted by Nozik, using quantum dots made from lead selenide.
They say the existing solar cells go as high as 33% efficiency of conversion. But production solar cells installed on roofs are typically much lower efficiency than that. So if this new approach could be manufactured cheaply it would be at least 3 times higher in efficiency than existing manufactured solar cells.
"We have shown that solar cells based on quantum dots theoretically could convert more than 65 percent of the sun's energy into electricity, approximately doubling the efficiency of solar cells," Nozik said. The best cells today convert about 33 percent of the sun's energy into electricity.
The NREL and NRL researchers' paper also describes a new theoretical foundation for the multiple exciton generation process that is based on certain unique aspects of quantum theory.
The recent work demonstrates MEG in quantum dots of a second semiconductor material, lead sulfide.
The NREL/NRL work not only shows higher overall efficiency for multiple exciton generation,
it also establishes that the process occurs with lower photon energies, meaning it could make use of an even greater portion of the sun's light spectrum.
I am just guessing but this approach might be cheap to manufacture. Lead and sulfur are cheap. Selenium is also used (see below). Is selenium expensive?
Note above the reference to work by Richard Schaller and Victor Klimov that provided experimental evidence that led to this work. See my post from April 26, 2004 "Nanocrystal Photovoltaics May Achieve 60% Conversion Efficiency" for more on Schaller and Klimov's work.
We report ultra-efficient multiple exciton generation (MEG) for single photon absorption in colloidal PbSe and PbS quantum dots (QDs). We employ transient absorption spectroscopy and present measurement data acquired for both intraband as well as interband probe energies. Quantum yields of 300% indicate the creation, on average, of three excitons per absorbed photon for PbSe QDs at photon energies that are four times the QD energy gap.
Thanks to Dave Gobel for the tip.
Scientists in Japan have made the first device that can convert solar energy into electricity and then store the resulting electric charge. The "photocapacitor" designed by Tsutomu Miyasaka and Takurou Murakami at Toin University in Yokohama could be used to power mobile phones and other hand-held devices (Appl. Phys. Lett. 85 3932).
The cells can be arranged in series to produce 12 volts. (same article here)
The cells can also be connected to form larger, more powerful cells. Conventional capacitors that are charged using electricity can produce a voltage that is no greater than the input, or charging voltage, of one of the cells in a connected series. In contrast, the photocapacitor, like conventional batteries, can produce voltage equivalent to the collective input of photocapacitors connected in series. The researchers' prototype produces 0.7 volts. Connecting 18 cells would yield 12 volts, which is the output of a car battery, said Miyasaka.
The thickness of the photocapacitor depends on the thickness of the electrodes, and could be made narrower than one millimeter, said Miyasaka.
The scientists expect to make these cells practical to use within just 2 years. They are working on making the cells into a flexible plastic material.
If this stuff turns out to be cheap to make then imagine applying it as a coating to a hybrid car to allow car batteries to recharge while parked.
Peccell Technologies, Inc. (Peccell), a developer of a film-type dye-sensitized solar cells (DSC), has achieved a high voltage of over 4V - equivalent to that of a lithium ion battery - under illumination. The electrode of the DSC is made of titanium oxide paste, which is based on fine particles of titanium oxide supplied by Shoa Denko KK (SDK). The paste is applicable to both film-type DSCs for portable applications and conventional glass-substrate DSCs.
Peccell, based in Yokohama City and led by Prof. Tsutomu Miyasaka, Department of Biomedical Engineering, Faculty of Engineering, Toin University of Yokohama, was established in March 2004 for the development of DSC-related technologies.
At least one startup may beat Siemens to that goal. Konarka is now gearing up to manufacture its novel photovoltaic film, which it expects to start selling next year. Unlike Siemens’s, Konarka’s films don’t use buckyballs, instead relying on tiny semiconducting particles of titanium dioxide coated with light-absorbing dyes, bathed in an electrolyte, and embedded in plastic film. But like Siemens’s solar cells, Konarka’s can be easily and cheaply made.
The article also covers an interesting approach by a company called Nanosolar.
Down the road, researchers hope to boost nano solar cells’ power output and make them even easier to deploy, eventually spraying them directly onto almost any surface. Palo Alto, CA-based startup Nanosolar, which has raised $5 million in venture capital, is working on making this idea practical. The company is exploiting the latest techniques for automatically assembling nanomaterials into precisely ordered architectures—all with a higher degree of control than ever before possible.
Nanosolar’s approach is disarmingly simple. Researchers spray a cocktail of alcohol, surfactants (substances like those used in detergents), and titanium compounds on a metal foil. As the alcohol evaporates, the surfactant molecules bunch together into elongated tubes, erecting a molecular scaffold around which the titanium compounds gather and fuse. In just 30 seconds a block of titanium oxide bored through with holes just a few nanometers wide rises from the foil. Fill the holes with a conductive polymer, add electrodes, cover the whole block with a transparent plastic, and you have a highly efficient solar cell.
The ability to spray paint a surface with photovoltaics would allow sides and roofs of buildings, signs, billboards, water towers, bridges, and numerous other structures to be turned into solar collectors. In the United States human structures already cover an area equal to the size of Ohio and that is more than enough area to provide enough power for current level of usage if photovoltaics could be made that could cover all the human-built structures.
An article on Konarka Technologies explains how Konarka's approach allows photovoltaics to be made at lower temperates than current processes require.
The problem? Until now, PVCs have been made by heating the titanium crystals to 450 degrees Celsius and then coating them with a light-sensitive dye – a process known as “sintering.” That process was too expensive to make them a practical source of power. Tripathy and his researchers perfected a “cold-sintering” method that achieves the same result at temperatures of 150 degrees or lower.
Those cooler temperatures are critical to new uses for PVCs. When forged at higher temperatures, PVC material can only be coated onto glass, which makes for expensive, delicate product applications. Cold-sintering allows the PVC material to be coated onto plastics; in essence, a product’s outer shell becomes its power source.
And at those cooler temperatures, they can churn out large numbers of photovoltaic cells quickly and cheaply. The Konarka cell does not generate any more electricity than other power cells, or do so more efficiently. Its appeal is that the cell can be manufactured far more cheaply, so Konarka can churn out a large supply and, the company hopes, put them into all sorts of devices.
The ideal process would not require the use of any elevation of temperatures when the photovoltaics are applied. So if Nanosolar's process can be perfected it would open up a greater potential by allowing easier conversion of existing surfaces into photovoltaic collectors. Though the approach being pursued by Nanosys to incorporate photovoltaics into plastics to make roofing tiles would certainly work for new structures and when installing the inevitable new roofs when old roofs wear out.
Update: Nobel Prize winner Richard Smalley has an opinion piece on Small Times arguing for a big research effort to develop new cleaner and cheaper energy technologies to end our reliance on oil.
Imagine by 2050 that every house, business and building has its own local electrical energy storage device, an uninterruptible power supply capable of handling the needs of the owner for 24 hours.
Today using lead-acid storage batteries, such a unit for a house to store 100-kilowatt hours of electrical energy would take up a small room and cost more than $10,000.
Through advances in nanotechnology, it may be possible to shrink an equivalent unit to the size of a washer and drop the cost to $1,000. Among the approaches being developed today are nanotubes, nanowires and nanocomposites for batteries....
America should take the lead. We should launch a bold New Energy Research Program. Just a nickel from every gallon of gasoline, diesel, fuel oil, and jet fuel would generate $10 billion a year. That would be enough to transform the physical sciences and engineering in this country.
You can read some Congressional testimony by Smalley advocating a big energy research effort at the bottom of this previous post on energy policy. I think that Smalley is right that solar photovoltaics, batteries, fuel cells, and all sorts of other energy technologies are all solvable problems. With enough research and development the problems holding back the development of these approaches can all be solved. This is not a question of if but rather one of when. The technologies can be made to work and to be much cheaper than oil, natural gas, and coal. If we tried harder we could make those technologies become cost effective much sooner.
Right now, the efficiency rate--the amount of sunlight that gets turned into electricity--ranges from 3 percent to nearly 12 percent for various nanoparticles in different lab experiments. That could grow to 20 percent, said Michael McGehee, an assistant professor at Stanford in materials science and engineering. McGehee currently is conducting research on organic photovoltaic nanoparticles.
"It costs $300 per square meter now for crystalline solar cells. We think we can get this down to $30 a square meter," he said. Michael McGehee, an assistant professor at Stanford in materials science and engineering
That article has some good quotes by venture capitalists who see energy tech as a generally hot area for investment. The growth of venture capital involvement is reason for much more optimism about photovoltaics and other promising energy technologies. If various claims that the Saudis are exaggerating the size of their oil reserves turn out to be correct then we are going to be in need of these new energy technologies sooner that most think.
Marc Baldo and a collaborator at MIT have taken spinach chloroplast proteins and worked them into a photovoltaic solar cell that generates electricity.
Baldo's team isolated a variety of photosynthetic proteins from spinach and sandwiched them between two layers of conducting material. When light was shone on to the tiny cell, an electrical current was generated. Their discovery is reported in Nano Letters1.
Plant chloroplasts normally capture photons to excite electrons to drive photosynthesis. The machinery is there in chloroplasts to cause electron flow in the presence of light. If that machinery could be massaged into a form that would create lasting photovoltaic cells then it holds the potential of providing a way to make cheap photovoltaics. This idea has been around for a while and back in the late 1970s there was a short burst of funding for plant biochemists to work on chloroplast electrochemistry. The advocates of one proposed approach claim chlorophyll-photovoltaic cell may be able to convert 72% of sunlight to electricity.
As well, in a chlorophyll-photovoltaic cell (nicknamed the “chlorovoltaic cell,” or “CVC”) it will be useful to employ multiple layers of synthetic chlorophyll, each specializing in absorbing certain wavelengths of light. For instance, layers of chlorophyll-a and chlorophyll-b (both synthesized from plants) will specialize in blue-violet-red and orange-blue wavelengths respectively. New layers can be engineered using developed technologies such that they are able to absorb the energy from ultraviolet, yellow-green, and infrared light. With each layer parallel to one another, incident light will be used to its maximum capability.
My take on chlorophyll-photovoltaic cells is that they will be feasible some day but it is hard to say when. Their potential advantage over more conventional biomass approaches to energy is that they would not need to be tended to the way plants in fields or in vats must be. Their potential advantage over more conventional silicon photovoltaic cells is that they may some day be much cheaper to make. But one question that arises is whether the proteins in the chloroplasts can be treated to be made stable for long periods of time.
WASHINGTON - If all the highways, streets, buildings, parking lots and other solid structures in the 48 contiguous United States were pieced together like a giant jigsaw puzzle, they would almost cover the state of Ohio. That is the result of a study by Christopher Elvidge of the National Oceanic and Atmospheric Administration's National Geophysical Data Center in Boulder, Colorado, who along with colleagues from several universities and agencies produced the first national map and inventory of impervious surface areas (ISA) in the United States.
As calculated by the researchers, the total impervious surface area of the 48 states and District of Columbia is approximately 112,610 square kilometers [43,480 square miles], and, for comparison, the total area of the state of Ohio is 116,534 square kilometers [44,994 square miles].
The new map is important, because impervious surface areas affect the environment The qualities of impervious materials that make them ideal for construction also create urban heat islands, by reducing heat transfer from Earth's surface to the atmosphere. The replacement of heavily vegetated areas by ISA reduces sequestration of carbon, which plants absorb from the atmosphere, Elvidge says in the 15 June issue of Eos, published by the American Geophysical Union. Both of these effects can play a role in climate change.
In watersheds, impervious surface areas alter the shape of stream channels, raise the water temperature, and sweep urban debris and pollutants into aquatic environments. These effects are measurable once ten percent of a watershed's surface area is covered by ISA, Elvidge writes. The consequences of increased ISA include fewer fish and fewer species of fish and aquatic insects, as well as a general degradation of wetlands and river valleys. The impervious surface area of the contiguous United States is already slightly larger than that of its wetlands, which is 98,460 square kilometers [38,020 square miles].
Some argue that the use of photovoltaics as a power source will require the covering of too much surface area. Well, lets start with that area, 112,610 square kilometers [43,480 square miles], which is currently covered by human structures and look at what we would need to get enough power to use photovoltaics as our sole power source.
To put those numbers in perspective recall a previous post where I reported on a calculation by Dr. David Goodstein, Vice Provost and Professor of Physics and Applied Physics at Caltech about the surface area needed to be covered by 10% efficient photovoltaics to provide enough energy for the whole world at current consumption rates.
Solar energy will be an important component, an important part of the solution. If you want to gather enough solar energy to replace the fossil fuel that we’re burning today—and remember we’re going to need more fossil fuel in the future- using current technology, then you would have to cover something like 220,000 square kilometers with solar cells. That’s far more than all the rooftops in the country. It would be a piece of land about 300 miles on a side, which is big but not unthinkable.
Dr. Goodstein was kind enough to provide me with some of the basic facts that went into those figures. The energy that would be collected by 300 by 300 mile area is for the whole world and he's assuming a current world total fossil fuel burn of 10 TW (ten trillion watts). He's also assuming a 10% conversion efficiency for the photovoltaics.
We would need an area not quite twice the size of Ohio to get enough power for the entire human race at current rates of energy consumption. Of course, energy consumption is growing and so the area needed is going to grow. But the 10% conversion efficiency assumption is rather low. Groups at Lawrence Berkeley and Los Alamos National Laboratories are pursuing two different methods for boosting photovoltaic conversion efficiency to over 50%. The development of very high conversion efficiency photovoltaics is a matter of when not if. So the surface area that needed for collecting energy for photovoltaic electric power for the whole world is likely to be less than two Ohios.
A related interesting question is just how much of the surface areas covered by human structures will be available to be converted to solar power collectors? That depends on what types of materials can be made to be photovoltaics. If we could discover photovoltaic materials strong enough to use as road covering then roads could be made into energy collectors. While the development of such materials may be a more distant prospect there are lots of other areas covered by human activities aside from the obvious rooftoops that could be covered by solar collectors. Take, for example, train tracks. All the train weight comes down on the rails, not on most of the surface of the railroad ties or the gaps between the railroad ties. So one could imagine railroad track lengths turned into solar power collectors.
There are other ways that road and parking lot surfaces could be made more usable for photovoltaics. One obvious way would be to develop devices for moving cars to parking spaces in ways that allowed most of the surface area not be untouched by car tires. Then less a less strong photovoltaic material could cover all the areas aside from the tracks that the car moving devices used and where the car tires would be placed in parking spaces.
One obvious point about parking lots: If a parking lot is covered and the top is not itself a parking lot then the roof of the parking lot could be covered with photovoltaics. Though I'm not optimistic about the economics of covering Walmart parking lots with roofs to convert them into solar collectors. Still, advances in the development of cheaper materials might make this economically justifiable at some point in the future.
One esthetic problem with high conversion efficiency photovoltaics is that they will likely be dark in color since they will capture most of the photons that hit them. So roofs and sidings of houses covered with layered nanotube photovoltaics would be dark. Most people would probably find that acceptable for roofs but perhaps less so for sidings. One solution might be the development of less efficient photovoltaics that absorb only some colors of light. Such selective frequency absorbing photovoltaics will then allow houses to be different colors. This is not as far-fetched as it sounds. A physicist at Virginia Polytechnic Institute (sorry, no cite, this is from a couple year old memory) has argued that by controlling the spacing between nanotubes it is possible to control what light frequencies they aborb. To take this even further imagine nanotubes that are repositionable. One could perhaps send a pulsed current through them to order them to change their spacing to change their color. This might even provide a way to absorb more photons to provide more electricity during peak periods.
The lesson I'd like you to take away from this post is pretty simple: There is enough surface area already being used by humans that if we just use that surface area for photovoltaics we can get enough power for the human race's needs for many years to come.
Victor I. Klimov and Richard Schaller of the Los Alamos National Laboratory have shown that quantum dot nanocrystals will be able to absorb light for conversion to electricity at a much higher rate of efficiency than existing photovoltaic materials.
In ordinary photovoltaic cells, lots of sunlight goes to waste as it heats up the cell. New results suggest that solar cells made from nanocrystals can trade this wasteful heating for an electricity-generating boost.
Theoretical calculations indicate that nanocrystal-based solar cells could convert 60 percent of sunlight into electricity, say Richard D. Schaller and Victor I. Klimov of Los Alamos (N.M.) National Laboratory. The best solar cells today operate at an efficiency of about 32 percent.
Schaller and Klimov describe their results, the first observations of a long-sought cue ball effect in nanometer-scale crystals, in an upcoming Physical Review Letters.
A group at Lawrence Berkeley National Laboratory is pursuing a different approach that can convert over 50 percent of sunlight to electricity and Wladek Walukiewicz of that group claims that it will take 3 years to investigate whether their own approach will be practical to use for production of solar cells. For more on that approach see my previous post Material Discovered For Full Spectrum Photovoltaic Cell.
The problem of how to cheaply convert sunlight to useful electric power is eventually going to be solved. It would be worth it to spend more on research in this area to make the needed breakthroughs happen sooner. The same holds true for battery technology and fuel cell technology.
Over a typical 20-year life span of a solar cell, a single produced watt should cost as little as $0.20, compared with the current $4.
The article does not provide a prediction of when this price reduction will take place. Also, the article quotes a cost per watt for conventional existing electric power of $0.40 per watt and so the projected future price of photovoltaics will be half the price of existing sources of electricity. However, it is not clear how those costs were calculated. Do they include the costs of, for instance, storing solar power in batteries to have electricity to use when the sun goes down? My guess is that those costs are not included.
Photovoltaics without sufficient energy storage capacity will not reduce the peak electric generation capacity needed by electric utilities but will reduce average demand. So the result will be that a portion of the expected savings will be offset by higher prices charged by electric utilities that can't amortize their physical plant over as many generated kilowatt hours of electricity. What is needed is not just cheaper photovoltaics but also cheaper batteries or other means of electric power storage. Toward that end, advances in nanotechnology may eventually yield materials that combine batteries and solar cells in a single integrated sheet.
A September 30, 2003 press release from STMicroelectronics that is about their photovoltaic solar cell research efforts does not provide cost projections and sounds more qualified in terms of what they expect to achieve. The press release outlines 2 approaches they are pursuing to try to drive down the cost of photovoltaics.
Semiconductor-based solar cells have the highest efficiency (defined as the electrical energy produced for a given input of solar energy) but there is little that can be done to either increase the efficiency or reduce the manufacturing cost. ST is therefore pursuing alternative approaches in which the aim is to produce solar cells that may have lower efficiencies (e.g. 10% instead of 15-20%) but are much cheaper to manufacture.
"Although there is much support around the world for the principle of generating electricity from solar power, existing solar cell technologies are too expensive to be used on an industrial scale. The ability to produce low cost, high efficiency solar cells would dramatically change the picture and revolutionize the field of solar energy generation, allowing it to compete more effectively with fossil fuel sources," says Dr. Salvo Coffa, who heads the ST research group that is developing the new solar cell technology.
The ST team is following two approaches. One of these, invented in 1990 by Professor Michael Graetzel of the Swiss Federal Institute of Technology, uses a similar principle to photosynthesis. In a conventional solar cell, a single material such as silicon performs all three of the essential functions, which are absorbing sunlight (converting photons into electrons and holes), withstanding the electric field needed to separate electrons and holes, and conducting the free carriers (electrons and holes) to the collecting contacts of the cell. To perform these three tasks simultaneously with high efficiency, the semiconductor material must be of very high purity, which is the main reason why silicon-based solar cells are too costly to compete with conventional means of producing electric power.
In contrast, the Graetzel cell, known as the Dye-Sensitized Solar Cell (DSSC), mimics the mechanism that plants use to convert sunlight into energy, where each function is performed by different substances. The DSSC cell uses an organic dye (photosensitizer) to absorb the light and create electron-hole pairs, a nanoporous (high surface area) metal oxide layer to transport the electrons, and a hole-transporting material, which is typically a liquid electrolyte.
"One of the most exciting avenues we are exploring is the replacement of the liquid electrolytes that are mostly used today for the hole-transport function by conductive polymers. This could lead to further reductions in cost per Watt, which is the key to making solar energy commercially viable," says Coffa.
The ST team is also developing low cost solar cells using a full organic approach, in which a mixture of electron-acceptor and electron-donor organic materials is sandwiched between two electrodes. The nanostructure of this blend is crucial for the cell performance because the electron-donor and electron-acceptor materials have to be in an intimate contact at distances below 10 nm. ST plans to use Fullerene (C60) as the electron-acceptor material and an organic copper compound as the electron-donor.
STMicroelectronics isn't the only company pursuing Graetzel cell development. Venture capital funded Konarka Technologies, based in Lowell, Massachusetts, is also pursuing development of the TiO2 Graetzel cell with non-liquid electrolyte.
According to Paul Wormser, president and COO, the cells will be manufactured at room atmospheric pressure and below 150°C on flexible plastic substrates, using a non-liquid electrolyte.
Another venture capital funded company, Nanosolar, is pursuing a nanotechnological approach to produce flexible plastic photovoltaics.
NanoSolar asserts that it has solved some of the thorniest problems inherent in working with organic materials. The company, applying technology licensed from Sandia National Labs, says it has brought an architectural approach to the process, using self-assembling nano-structures that should substantially improve the energy efficiency of its solar cells.
With venture capital funded start-ups and established firms pursuing the development of photovoltaics that have the potential to be much cheaper to produce than silicon semiconductors a large reduction in the cost of photovoltaics seems a likely outcome.
Princeton University researchers have developed techniques that may finally make organic photovoltaics cheaper than existing silicon-based photovoltaic solar cells.
PRINCETON, N.J. -- Princeton electrical engineers have invented a technique for making solar cells that, when combined with other recent advances, could yield a highly economical source of energy.
The results, reported in the Sept. 11 issue of Nature, move scientists closer to making a new class of solar cells that are not as efficient as conventional ones, but could be vastly less expensive and more versatile. Solar cells, or photovoltaics, convert light to electricity and are used to power many devices, from calculators to satellites.
The new photovoltaics are made from "organic" materials, which consist of small carbon-containing molecules, as opposed to the conventional inorganic, silicon-based materials. The materials are ultra-thin and flexible and could be applied to large surfaces.
Organic solar cells could be manufactured in a process something like printing or spraying the materials onto a roll of plastic, said Peter Peumans, a graduate student in the lab of electrical engineering professor Stephen Forrest. "In the end, you would have a sheet of solar cells that you just unroll and put on a roof," he said.
Peumans and Forrest cowrote the paper in collaboration with Soichi Uchida, a researcher visiting Princeton from Nippon Oil Co.
The cells also could be made in different colors, making them attractive architectural elements, Peumans said. Or they could be transparent so they could be applied to windows. The cells would serve as tinting, letting half the light through and using the other half to generate power, he said.
Because of these qualities, researchers have pursued organic photovoltaic films for many years, but have been plagued with problems of efficiency, said Forrest. The first organic solar cell, developed in 1986, was 1 percent efficient -- that is, it converted only 1 percent of the available light energy into electrical energy. "And that number stood for about 15 years," said Forrest.
Forrest and colleagues recently broke that barrier by changing the organic compounds used to make their solar cells, yielding devices with efficiencies of more than 3 percent. The most recent advance reported in Nature involves a new method for forming the organic film, which increased the efficiency by 50 percent.
Researchers in Forrest's lab are now planning to combine the new materials and techniques. Doing so could yield at least 5 percent efficiency, which would make the technology attractive to commercial manufacturers. With further commercial development, organic solar devices would be viable in the marketplace with 5 to 10 percent efficiency, the researchers estimated. "We think we have pathway for using this and other tricks to get to 10 percent reasonably quickly," Forrest said.
By comparison, conventional silicon chip-based solar cells are about 24 percent efficient. "Organic solar cells will be cheaper to make, so in the end the cost of a watt of electricity will be lower than that of conventional materials," said Peumans.
The technique the researchers discovered also opens new areas of materials science that could be applied to other types of technology, the researchers said. Solar cells are made of two types of materials sandwiched together, one that gives up electrons and another that attracts them, allowing a flow of electricity. The Princeton researchers figured out how to make those two materials mesh together like interlocking fingers so there is more opportunity for the electrons to transfer.
The key to this advance was to apply a metal cap to the film of material as it is being made. The cap allowed the surface of the material to stay smooth and uniform while the internal microstructure changed and meshed together, which was an unexpected result, said Forrest. The researchers then developed a mathematical model to explain the behavior, which will likely prove useful in creating other micromaterials, Forrest said.
"We've shown a very new and general process for reorganizing the morphology of materials and that was really unanticipated," Forrest said.
The research was supported by grants from the Air Force Office of Scientific Research, the National Renewable Energy Laboratory and the Global Photonic Energy Corp.
Some day advances in fabrication techniques will so lower the cost of making photovoltaic solar cells that they will become cost-effective to generate a substantial portion of our electric power. The big question is when will this happen?
There are many approaches being pursued by various research groups searching for cheaper ways to make photovoltatic solar energy cells for the generation of electricity. One reason that photovoltaics are expensive is that it is expensive to make the highly purified silicon semiconductor material that most existing photovoltaic cells use. Eric McFarland at UC Santa Barbara is pursuing the development of a two layer approach that allows the use of a less pure and therefore much cheaper titanium dioxide semiconductor
The researchers' prototype suggests that the devices would be much less expensive to manufacture than today's solar cells and can be improved to be nearly as efficient. "It's enormously cheaper... more than a factor of 10," said Eric McFarland, a professor of chemical engineering at the University of California at Santa Barbara.
The titanium dioxide serves only as the lower layer charge carrier while a dye serves as a light absorbing layer.
To overcome this problem, McFarland and Jing have developed a multi-layer device that separates the light-absorption and charge-carrier transport processes.
The efficiency of this new type of photovoltaic is low at this stage in development. But McFarland thinks he can raise the effciency and a design that allows the use of much cheaper materials is a great way to make photovoltaics cost competitive.
Electrons excited in the dye shoot through the gold and are collected in the titanium dioxide. Missing electrons in the dye are replaced from the metal. Because the semiconductor does not have to absorb light itself, inexpensive semiconductors will do the job.
The flexible Spheral Solar Power photovoltaic panels will be usable in house construction and will give buildings a blue denim look.
Buildings of the future could be "clothed" in a flexible, power-generating material that looks like denim. The Canadian company developing the material says it can be draped over just about any shape - greatly expanding the number of places where solar power can be generated.
One big advantage that Spheral Solar has with their process is that they can use a lower grade of silicon. They also use less silicon.
There are no rare materials utilized in the manufacturing of Spheral Solar™ products. Silicon supply has already become a problem for wafer-based technologies that all use the same semiconductor silicon waste stream. Silicon wafer based technologies utilize 18-24 tons of silicon per megawatt of solar cells produced. SSP is expected to utilize 9 tons per megawatt. As a result of the continuous improvement plan already underway, SSP silicon utilization could improve to below 2 tons per megawatt. Because of its inherently low gram/watt consumption of silicon and its ability to utilize many grades of silicon, silicon supply is not a major concern for Spheral Solar™ technology.
See this previous post for more on Spheral Solar.
Also see this brief interesting history of how of Spherical Solar Power came to be. What is amazing is how Texas Instruments and Ontario Hydro failed to push to develop this promising technology for many years.
"We fully expect Spheral Solar(TM) Technology to revolutionize the solar energy industry for two reasons," said Klaus Woerner, ATS President and Chief Executive Officer. "First, the SST unique design only requires a fraction of the raw materials - particularly the silicon - used in traditional multicrystalline solar cells to produce the same amount of energy. Based on technical design enhancements made over the past year to SST, we have achieved a sunlight-to-energy conversion ratio that is competitive with conventional multicrystalline solar cells. Therefore, we expect to generate energy at far less cost per watt. In effect, we're talking about a new era for solar energy, where our technology can stand on its own in the marketplace, as a viable energy alternative."
"Second", added Mr. Woerner "SST is lightweight, pliable and break resistance, which means it can be formed into a variety of shapes and sizes to develop innovative new products that can be seamlessly and attractively integrated into consumer products and even the most complex building designs. Spheral Solar(TM) Technology will allow ATS to lead the world to more quickly.
On the web site of ATS's subsidiary Spheral Solar the company claims its technology will be cost competitive with fossil-fuel based electricity in some regions:
A significant breakthrough in renewable energy, Spheral Solar Power cells produce electricity at considerably lower cost than conventional solar technology, and on a cost-par with fossil-fuel based electricity in many regions of the world. Once commercially available, Spheral Solar™ cells will make solar power feasible for a vast array of new applications and markets, changing the dynamics of the photovoltaic industry, forever.
Their solar cells can bend to fit over structures: (update: no page still exists with this content)
Spheral Solar™ cells are strong. Unlike traditional, rigid solar cells which are highly fragile, a Spheral Solar™ cell is bendable and virtually unbreakable. Traditional solar cells usually consist of thin silicon wafers, bonded to a glass substrate. Not only are they fragile, but their weight and rigidity seriously limit where they can be applied. SSP’s patented design places minute silicon spheres into a special aluminum sheet. The resulting sheet is very strong and can be formed and applied to virtually any curved or flat surface, creating tremendous opportunities for new attractive products for the generation of solar power.
In order to forecast when photovoltaics will become competitive with fossil fuels as an energy source its important to look at historical prices for photovoltaics. I'm going to make posts about renewable energy cost trends as I find the data.
The US Department of Energy is the major funder of US photovoltaics research. In this paper from January 2001 Status and Recent Progress in Photovoltaic Manufacturing in the USA there is data on recent cost trends in photovoltaics from 1992 to 1999:
Module Manufacturing Costs and Capacities PV module costs are usually given in "dollars per watt," with the watt value defined in terms of the module power rating under specific conditions. Figure 1 shows total manufacturing capacity versus average direct costs for modules manufactured by participants in the PVMaT Project. The plot is based on 1999 data from 12 industrial participants, each of which has active production lines. The "average module manufacturing cost" is a weighted average based on the manufacturing capacity of each of these participants. As seen for the 12 manufacturers, PV manufacturing capacity has increased by more than a factor of seven since 1992, from 13.6 to 99.3 megawatts. Additionally, the weighted-average cost for manufacturing PV modules has been reduced by 36%, from $4.23 to $2.73 per peak watt. Projections through 2005 indicate a steady decline, to an average module manufacturing cost of $1.16 per peak watt at just over 865 megawatts of capacity.
Note that the reference to capacity is for manufacturing capacity for making photovoltaic cells. It is not installed capacity of photovoltaic cells. The decline in price from 1992 to the projected price for 2005 is less than a factor of 3. The decline in the price of photovoltaics was much more rapid in its earlier years. Says Greenpeace:
From 1972 to 1992, photovoltaic module costs have dropped one hundred fold.
Also, see the Figure 7.3 here for historical cost trends thru 1994. Cost decline appears to have slowed in percentage terms per year. Note that in figure 7.4 they show the potential for a more rapid decline in photovoltaics costs if thin film photovoltaics turn out to be workable. They comment:
Even sharper module cost reductions can be expected in the case of thin film PV cells, irrespective of the basic semiconductor employed (amorphous silicon, CdTe, CIS, or others). First, this is due to the use of a much smaller amount of semiconductor material and to much lower energy consumption rates. Secondly, thin-film manufacturing techniques (direct deposition) allow the direct manufacturing of 1,000 cm2 integrated solar modules (i.e. a-St) and are particularly well suited for mass production.
You can go here for a report on current capacity of each type of renewable energy source. Click on the Standard Report button for "Operating Capacity (kW) by Technology and Fuel". Note that while hydro (ie hydroelectric dams) provide the largest source of renewable the ranking after that are biomass, geothermal, wind, thermal, and then photovoltaic. Photovoltaic is almost 4 orders of magnitude less than biomass as an energy source and hydro is over 4 times greater an energy source than biomass. Photovoltaics have a long way to go.
To put that into larger perspective, total US generating capacity in 2000 was 825 GW of peak capacity. US photovoltaics capacity was only 75 MW which is less than one hundredth of one percent of the total. The US DOE National Center for Photovoltaics projects:
Our expectation for industry growth is 25% per year — a level that should be achievable according to recent market data.² At this level of growth, domestic PV capacity will approach 10% of U.S. peak generation by 2030.
Unless the rate of advance in thin film photovoltaics is accelerated we face rather distant prospects for use of photovoltaics as a way to reduce our dependence on Middle Eastern oil.