WASHINGTON - The U.S. Department of Energy (DOE) announced that Spectrolab Inc. has developed a new concentrator solar cell with a sunlight-to-electricity conversion efficiency of 40.7 percent, a new world record in solar cell efficiency. The new cell uses a "multi-junction" structure, in which several layers each capture part of the sunlight passing through the cell. These layers allow the cell to capture more of the solar spectrum and convert it into electricity. The Spectrolab cell relies on an optical concentrator to focus sunlight onto the cell.
Researchers have been working toward the "40 percent barrier" for the past two decades. In the 1980s, multi-junction solar cells achieved about 16 percent efficiency, and DOE''s National Renewable Energy Laboratory broke the 30 percent barrier in 1994. Today, most satellites use these multi-junction solar cells, and Spectrolab, a subsidiary of the Boeing Company, recently produced its two millionth solar cell using multi-junction technology. The new Spectrolab cell, developed with DOE funding, could lead to more affordable solar power systems here on earth, costing as little as $3 per watt to install and producing electricity at a cost of 8-10 cents per kilowatt/hour.