December 11, 2006
Boeing Spectrolab Achieves 40% Solar Cell Efficiency
Here's a big advance in solar photovoltaic technology:
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.
But you can predict that in about 20 years solar will be in widespread use. It is an extension of the trend line over the past 40 years and a reasoable estimate based on current advances in nano tech, etc. Not that we get a busrt of solar on July 2nd, 2024, but I'd expect "some" solar in the 2010s and "a lot" of solar in the 2020s.
"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."
Actually the news are even better: According to this article below, they are not using mirrors to concentrate light. Perhaps they used the word "concentrator" in a misleading manner, because it seems that they are merely using several stacked layers that capture the leftover light.
It is said in this article that they are hoping to build cells that generate energy "at a cost of 8-10 cents per kilowatt/hour, making solar electricity a more cost-competitive and integral part of the US energy mix." This sounds great, but note that there are also amortization costs for the users, in the sense that these cells might probably deteriorate within 5-10 years, and if this happens, then the investment may not be amortized by the generated energy.
The Devil is in the details. But in any case, this is good work...
Just asking but: How much of an improvement does this represent over current solar technology?
Improvements in efficiency are only interesting if they lead to greater improvements in cost. If a 4x improvement in efficiency is created by a 8x greater cost, it will not help the solar case.
You don't need to use mirrors.
A fresnel lens is easy to make and can be composed of plastic, which is good for mass production.
Solar photovoltaics aren't "inherently cleaner". Like most resources, they take energy and some petroleum to produce. The Energy Returned On Energy Invested (EROEI) for today's COTS photovoltaics are horrible. It takes 20 years to generate enough energy to match that which was needed to produce the cells.
Using a concentrator improves things. Getting better efficiency improves things. Note that the greater efficiency must not be outweighed by more energy intensive construction.
My understanding is that the general idea is to use reflection based concentration methods. There are some smaller installations already operational using dish reflectors with a high efficiency PV cell at the focus, and there is a 154MW project being kicked off by a company called Solar Systems in Australia with a large array of heliostats focused on power towers. Because the concentration factors being discussed are up to 500x suns, the high cost of the cells is offset by the small cell area. Keeping the cells cool under these conditions is an important consideration.
I will respond to various comments. The 40.7% efficient concentrator cell is a great development along the road to cost-effective solar. This requires a concentrator system using point focused sunlight and dual axis tracking. You should note this conversion efficiency is under “laboratory” and not field conditions and they are cooling the cells to maximize efficiency. One application for this cell is to use a 10” square acrylic Fresnel lens to refract sunlight at 700X concentration onto this one cm2 surface. Active cooling of the cell produces another profit center for thermal energy. One-sun panel systems are from 12% to 18% efficient while a hybrid PV/thermal concentrator system using this cell can utilize 60% to 70% of the sun’s energy. The energy used to produce this cell and lens is considerably less than the energy to produce a flat plate PV panel when comparing the same outputs. We all need to shift our focus to concentrating solar power because this is where we are making great progress in increasing the conversion efficiency of solar cells.
The Trouble is there are so manys to do better with this tech. Are we always going to be divided with these I mean get MIT guys to who know how to concentrate light with a pane of glass that does not have to pointed right at the sun then use that method of making hydrogen from with juice that you are not useing Then you got somthing all by your lonesome you don't buy anything, the economey goes down the tubes we still end in hell