New solar cells could even work at night

Dec. 20, 2010 at 7:02 PM
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IDAHO FALLS, Idaho, Dec. 20 (UPI) -- U.S. researchers say they've developed a new kind of solar cell that can generate energy even at night, promising a new form of renewable energy.

The key is their ability to harvest infrared radiation as well as visible light, Steven Novack at the U.S. Department of Energy's Idaho National Laboratory in Idaho Falls says.

Almost half of the available energy in the spectrum of solar radiation resides in the infrared band, and infrared is re-emitted as heat by the Earth's surface after the sun has gone down, meaning the cells can even capture some energy during the night, he says.

Novack estimates a complete system using the new cells would have an overall efficiency of 46 percent, whereas the most efficient current silicon solar cells top out at about 25 percent.

Also, currently solar cells can only produce their top output in a narrow range of conditions. For example, if the sun is in the wrong position, sunlight is reflected off a silicone solar cell instead of being absorbed to create energy.

The new cells can absorb radiation at a variety of angles, the researchers say.

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