US lab births flexy, stingy solar cells
99 per cent less silicon
A team of US research scientists have made a startling breakthrough in solar-cell development, creating flexible wire-based cell substrates that use just one per cent of the silicon needed for brittle and comparatively heavy conventional cells.
Solar cells made from this material would not only be less expensive than current photovoltaics, but due to their low weight and bendable structure the could be used in a wide variety of applications. Solar curtains, anyone?
The new technique is described in a paper nimbly entitled "Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications" published in Nature Materials by a team of researches from the California Institute of Technology in Pasadena.
The trick in this new method is to bundle one-micrometer-thick silicon wires and embed the resulting array vertically in a flexible polymer. Thus bundled, the paper claims, the array could capture and transmit up to 96 per cent of light in peak conditions while requiring only one per cent of the silicon needed by conventional cells.
What's more, the wire arrays would have work over "over a broad range of incidence angles," thus capturing light efficiently with less need to be reoriented.
The researchers achieved their best results when coating the ends of the wires with an anti-reflective material, and predict that solar cells built using this technique would achieve efficiencies of around 17 per cent. Today's commercial-grade solar cells are in the 10 to 15 per cent range.
That 17 per cent figure, if achieved, would be impressive for such a flexible, materials-stingy technology. ®
It's been a good few days for solar technology. Just last week, IBM researched announced a new low-cost photovoltaic compound. Perhaps the folks in Armonk and the Pasadena boffins should hold a conference call.
10 year syndrome
In the late 70's when silicon was new and expensive, and electricity hand crafted by miners but still very cheap a solar panel (or windmill) took 10 years to pay for itself. You could by 4000 transistors for $100!
Now I can get 20,000,000,000 transistors for $100 (from pc world!), silicon is still made from sand and cheap as chips, and a electricity is so expensive the miners (if they were still here) could be carried to work by bankers and still make it cheaper, I find that a solar panel (or windmill) will take 10 years to pay for itself.
Every step forwards for green technology is nullified by business interests.
Cost of silicon
The cost of silicon, particularly semiconductor silicon has nothing to do with the cost of sand. The cost is almost completely processing (the same way you can't buy a car for the same cost of iron oxide dug out of the ground!)
The cost of transistors has gone down mainly because they are made more efficiently now and tend to use a hell of a lot less processed semiconductor grade silicon per transistor (think 16 square microns in 1975 for 4000 series CMOS to 0.001024 square microns today). If you wanted, you could buy a solar panel using 15625 times less area now for a lot less money, but you won't get much out of it :)
The fact that the cost of electricity has gone up in the last 30 years, is also reflected in the cost of the processed semiconductor grade silicon. The cost of solar power will not reduce significantly until it doesn't require huge quantities of specially processed silicon.
Darwin to Adelaide Solar Car Race Event 2011
Would make for an interesting ultra light weight exterior construction material for the annual Darwin to Adelaide Solar Car Race in 2011 and an excellent competition advantage at the same time .