U.S. Department of Energy

    Record Efficiencies Show Promise for Concentrating Solar Cells

    July 20, 2005

    Spectrolab, a Boeing company, announced in June that it has built a concentrating solar cell that converts 39 percent of the sunlight hitting it into electricity, a new world record. Concentrating solar power systems use lenses or mirrors to focus sunlight onto high-efficiency solar cells. Spectrolab, working under contract to DOE and DOE's National Renewable Energy Laboratory (NREL), achieved its record under sunlight concentrated by a factor of 236 (referred to as "236 suns"), using a "multijunction" solar cell. These solar cells consist of multiple layers of semiconductor materials, with each layer designed to capture different frequencies of sunlight, allowing the cell as a whole to convert a large part of the solar spectrum into electricity. Spectrolab's achievement bested its sponsor, NREL, which had announced a record efficiency of 37.9 percent under 10 suns during a conference in May.

    According to NREL, concentrator manufacturers such as Amonix, Inc. and electric utilities like Arizona's APS believe that solar concentrators could be competitive in the near future. A recent NREL press release quotes an APS executive, who said that when the industry starts producing 10 megawatts of solar concentrators per year, the economies of scale should drop the cost to about $3 per watt. We'll soon see if that's true, since Amonix and Guascor, a Spanish company, have teamed up to build a 10-megawatt-per-year assembly plant in Spain by year's end. See the NREL press release, and for more information about concentrating solar cells, see the DOE fact sheet "PV FAQs: What's new in concentrating PV?" (PDF 795 KB). Download Adobe Reader.