Spectrolab, Inc. has announced that they have developed a way to nearly
double the efficiency of solar cells. They've done it by
creating semiconductor Dagwood sandwiches, with over 20 layers.
The basic idea is to have different layers that respond to
different wavelengths of light. This way, a greater amount of
the total light energy is captured.
The technology requires the use of a lens, or some other means of
concentrating the light. That may limit its applicability
somewhat. Still it appearto be a major advance. It
could be the one thing we needed to make solar power competitive with
existing, lower-cost sources of energy.
It occurs to me that the rapid pace of development in this area could
actually pose a problem. Who is gong to want to invest in a
massive project now, when there is a chance that next year's technology
will render it obsolete?
I don't really thing that will be a problem. It certainly has
not slowed the development of computing technology. Plus,
there is such a high demand for energy, that even a plant that is less
than optimum, will still be producing something for which there is a
market.
The story is at Scientific American
href="http://www.sciam.com/article.cfm?chanID=sa003&articleID=643C3D30-E7F2-99DF-3108C4CB8A197667">here.
Even if the pace of development does cause some hesitancy in the minds
of investors, it would be a good problem to have, as problems
go.
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Does anyone know why the efficiency rises as intensity increases? The reported test used 240 times normal sunlight intensity, which means the concentrator has to be pretty high quality. And of course the chip has to be kept cool. Nevertheless, they quote potential cost/watt with a timespan of a bit more than a year. Could be interesting.
The prospects of rapidly advancing tech clearly limit customers, as well as investors. I've put of the large screen high def TV thing so far, arguing they will only get better and cheaper. The same could apply for a solar system. Lets say I'm about to spend $10 on a PV system that paysback in 12years. If I wait two years, and get a system
with a payback time of eight years -I reach a profit two years ealier by waiting. In any case the effect doesn't seem to be that strong, current PV manuafcturing is limited by materials availability. Wind turbine manufacturers are also experiencing problems with materials availability. So right now the market growth of both areas seems to be controlled by the improvement of manufacturing infrastructure, rather than demand.
I'm not sure there is increased efficiency with increased intensity, but use of lenses reduces the problem of materials shortages. There is no shortage of lenses. Or if you are talking cost efficiency, impure silicon (glass) is cheaper than pure silicon.
Also, gallium arsenide solar cells are more efficient than silicon ones, and can be operated at higher temperatures, but are more expensive and difficult to manufacture.