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New Solar Cell Sets World Efficiency Record
asoduk writes to tell us that a new world record has been set for the most efficient photovoltaic device. Topping the scale at 40.8% efficiency, the new solar cell differs significantly from the previous record holder. "Instead of using a germanium wafer as the bottom junction of the device, the new design uses compositions of gallium indium phosphide and gallium indium arsenide to split the solar spectrum into three equal parts that are absorbed by each of the cell's three junctions for higher potential efficiencies. This is accomplished by growing the solar cell on a gallium arsenide wafer, flipping it over, then removing the wafer. The resulting device is extremely thin and light and represents a new class of solar cells with advantages in performance, design, operation and cost."
At 40%, you're talking about 400W when in direct sunlight. With eight hours of sunlight per day the average house needs less than four square metres. Now, of course, you aren't going to be using the most power at the times when these are generating, but it can definitely put a significant dent in your electricity bills.
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Was taking forever to load, so here's the article:
Scientists at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) have set a world record in solar cell efficiency with a photovoltaic device that converts 40.8 percent of the light that hits it into electricity. This is the highest confirmed efficiency of any photovoltaic device to date.
The inverted metamorphic triple-junction solar cell was designed, fabricated and independently measured at NREL. The 40.8 percent efficiency was measured under concentrated light of 326 suns. One sun is about the amount of light that typically hits Earth on a sunny day. The new cell is a natural candidate for the space satellite market and for terrestrial concentrated photovoltaic arrays, which use lenses or mirrors to focus sunlight onto the solar cells.
The new solar cell differs significantly from the previous record holder - also based on a NREL design. Instead of using a germanium wafer as the bottom junction of the device, the new design uses compositions of gallium indium phosphide and gallium indium arsenide to split the solar spectrum into three equal parts that are absorbed by each of the cell's three junctions for higher potential efficiencies. This is accomplished by growing the solar cell on a gallium arsenide wafer, flipping it over, then removing the wafer. The resulting device is extremely thin and light and represents a new class of solar cells with advantages in performance, design, operation and cost.
NREL's Mark Wanlass invented the original inverted cell, which recently won a R&D 100 award. His design was modified by a team led by John Geisz that further optimized the junction energies by making the middle junction metamorphic as well as the bottom junction. Metamorphic junctions are lattice mismatched - their atoms don't line up. The material properties of the mismatched semiconductors allows for greater potential conversion of sunlight.
NREL is the U.S. Department of Energy's primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for DOE by Midwest Research Institute and Battelle.
http://www.treehugger.com/files/2006/12/new_world_recor.php
TFA is slashdotted, but a little googling shows this happened two years ago.
How can I believe you when you tell me what I don't want to hear?
I think it depends on what you mean by "the market". There are plenty of places where, due to low average solar energy/square meter and cheap grid power, solar will be unexciting until the day when you can get spray-on 95% efficient solar cells in a can. On the other hand, if you are paying 5 or 10 thousand dollars/kg to launch satellites, cutting edge solar cells might well be cost effective even if they cost as much, per square centimeter, as top edge microprocessors. All other markets fall somewhere between those two.
The previous record holder was 40.7%
I'm not sure why this is here, this was a press release in Mid august.
"Complete" solar's ROI is 20 years, but solar hot water heaters here in Hawaii - where we get a lot of sun - with the federal solar tax credit - I'll make my money back in O N E year!
Horns are really just a broken halo.