The U.S. Department of Energy (DOE) announced that with DOE funding, a concentrator solar cell produced by Boeing-Spectrolab has achieved a world-record conversion efficiency of 40.7%, establishing a new milestone in sunlight-to-electricity performance.
This breakthrough may lead to systems with an installation cost of only $3 per watt, producing electricity at a cost of 8-10 cents per kilowatt/hour.
Almost all of today’s solar cell modules do not concentrate sunlight but use only what the sun produces naturally, what researchers call “one sun insolation,” which achieves an efficiency of 12-18%. However, by using an optical concentrator, sunlight intensity can be increased, squeezing more electricity out of a single solar cell.
The 40.7% cell was developed using a multi-junction solar cell. It achieves a higher efficiency by capturing more of the solar spectrum. In a multi-junction cell, individual cells are made of layers, where each layer captures part of the sunlight passing through the cell. This allows the cell to get more energy from the sun’s light.
For the past two decades researchers have tried to break the 40% efficient barrier on solar cell devices. In the early 1980s, DOE began researching what are known as “multi-junction gallium arsenide-based solar cell devices,” multi-layered solar cells which converted about 16% of the sun’s available energy into electricity. In 1994, DOE’s National Renewable Energy laboratory broke the 30% barrier, which attracted interest from the space industry. Most satellites today use these multi-junction cells.
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