September 13, 2009
New Silicon Solar Cell Design Cuts Costs
Yet another report about lowered costs for making photovoltaic solar cells.
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 most obvious target for a DC appliance is air conditioning. This is a very large user of power, and there is no technical reason why air conditioner units could not be manufactured with DC motors. To keep wiring reasonably light weight, voltages of 100 to 200 volts are going to be needed, either by wiring panel in series, or by some form of DC to DC converter. Since DC wiring is going to be separate from the household AC wiring, it would be easiest to apply DC to central air conditioning rather than a number of room air conditioners.
There is however a mis-match between when the most power is available (roughly noon), and when the bulk of the air conditioning load occurs (later afternoon and early evening). This is a problem in California and Arizona for the emerging solar power industry, which sees one of the advantages of solar thermal over PV power as its ability to store heat during the day, and generate power with the stored heat during the late afternoon-early evening peak of power use. For home use, the trick would be to integrate a cold storage unit in the air conditioner, chilling water at mid day when PV power is available, so that the chilled water can cool air when the direct PV power has waned in the afternoon.
the bulk of the air conditioning load occurs (later afternoon and early evening)
But why does the bulk of A/C load happen later than the solar insolation that heats up houses?
I suspect the main reason is that people come home from work later on and turn on the A/C. That means the home has been storing heat all day. Wouldn't the simple solution be to just leave the A/C on during the day? Or, if some houses take a while to heat up, so that A/C isn't needed until the middle afternoon, wouldn't the simple solution be to have an electronic thermostat with a lower temperature earlier in the day?
Sure, you waste a little power because a cooler house loses more heat (due to the greater temperature differential between inside and outside), but wouldn't that inefficiency be less important than the losses (and additional system costs) that you'd get by storing chilled water?
Reducing the cost of the PV cells, and thus solar panels is all well and good. Many applications will benefit.
But how much of a solar energy farms' cost is the cost of solar panels?
The cells could be free, but Solar will remain a supplemental and secondary power source, until such time, if ever, as 1) they have solved the problem of the sun's daily disappearances, and 2) the density of insolation at the earth's surface is increased by at least a couple of orders of magnitude.
The rapid progress with PV is going to cut into the advantages of solar concentration for utilities. I have thought thermal storage would prove the decisive advantage of concentrators, maybe not. Greater ability to track the sun is also a plus.
At the consumers end, distributed generation, the costs of PV will only go one way, downward. There is no reason to think inverters won't keep falling in price and rising in reliability. And not too long ago a design that integrated an inverter into each panel was announced. The advantage would be lower cost from automated production with the panel.
I don't sense merit in DC for air conditioning or heat pumps at home. But I think for large installations - such as a Wal-mart store - DC might be considered. I will defer to the numbers and if DC would be better that settles it for me.
First off, it continues to be hot outside in the evening. Second, people add TV, computing, cooking, and other activities when they come home from work.
I think using electricity to create ice during the morning and noon time makes a lot of sense during hot periods. Then during the cooler periods (e.g. March, April when there's lots of sunlight) use a heat pump to heat water or salt or perhaps lead.
Plus, when we have lots of electric vehicles we can use PV to charge them during the day. Though most of the cars are at employer parking lots most of the time during the day and the PV is at home. So PV doesn't map well to most car use cases.
I wonder what percentage of home electricity is used for heating and cooling.
@Fat Man: No source of electricity is a cost effective way to produce all electricity.
And as I said: "Solar will remain a supplemental and secondary power source"
Actually, air conditioning is a natural for AC. Induction motors are the simplest and most reliable things you can put inside a sealed refrigerant circuit, and that's what they need. On the other hand, variable speed is also good. This means feeding a 3-phase motor from a variable-frequency power supply, and if you're doing that you might as well start with DC.
I can see an inverter-based induction motor drive which has both AC and DC inputs and can invert to to 60 Hz on the line terminals if it has an excess.
Cheaper PV is a good thing. Cheap clean energy in general is a good thing. You can store it away as ice, or charge your electric car. Anything that makes PV cheaper than peak electric rates is going to spur adoption and accelerate the decline of the cost curve.
A power source that would power easily supply 20% of electricity demand if it was as cheap as gas. Which makes supplementary sounds just not right