- Each of the cell’s six junctions has been designed to capture light from a specific part of the solar spectrum
- Another variation of the same cell created efficiency record under one-sun illumination at 39.2 per cent
Scientists at the National Renewable Energy Laboratory (NREL) have created a solar cell that comes with an efficiency of nearly 50 per cent. This six-junction solar cell is holding the world record for the highest solar conversion efficiency at 47.1 per cent. said NREL. This was measured under concentrated illumination.
Another variation of the same cell created efficiency record under one-sun illumination at 39.2 per cent. John Geisz, a principal scientist in the high-efficiency crystalline photovoltaics group at NREL said that this device demonstrates the potential of multijunction solar cells.
Capture light from a specific part of the solar spectrum
In order to construct the device, NREL researchers used III-V materials. They have a wide range of light absorption properties. Each of the cell’s six junctions has been designed to capture light from a specific part of the solar spectrum.
This device contains about 140 total layers of various III-V materials to support the performance of these junctions. Still, it is three times narrower than a human hair. III-V solar cells are often used to power satellites due to this efficient nature and cost associated with making them.
Ryan France, co-author and a scientist in the III-V Multijunctions Group at NREL said, “On Earth, however, the six-junction solar cell is well-suited for use in concentrator photovoltaics. One way to reduce cost is to reduce the required area and you can do that by using a mirror to capture the light and focus the light down to a point. Then you can get away with a hundredth or even a thousandth of the material, compared to a flat-plate silicon cell. You use a lot less semiconductor material by concentrating the light. An additional advantage is that the efficiency goes up as you concentrate the light.