Concentrating Photovoltaic Gets A Spotlight

There’s concentrated solar power (CSP), which involves using mirrors to focus sunlight on receivers to heat a fluid and, through several possible processes, make power. That’s not what we’re talking about with the Amonix 7700 concentrating photovoltaic (CPV) Solar Power Generator, which uses a remarkably efficient technology developed with help from the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL). The technology is so good, NREL said, that the cells can make electricity at a cost competitive with natural gas.

CPV uses concentrating optics to focus sunlight onto small cells. As the NREL explained it, “the 7700 uses acrylic Fresnel lenses to concentrate sunlight up to 500 times its usual intensity and direct it onto 7,560 tiny, highly efficient multi-junction PV cells.” In a laboratory setting, the cells have converted sunlight into usable electricity at a world-record 41.6 percent rate; in the real world the Amonix 7700 cells “are achieving 31 percent efficiency at the module level and 27 percent at the system level in the field, the highest ever achieved for an operating CPV concentrator.”

image via National Renewable Energy Lab

This heightened efficiency reduces both costs and land use, both important points in solar power’s competition with natural gas and other fossil fuels. According to the NREL, “The 7700 already has driven the price of electricity from solar down to the price of electricity from natural gas, according to the California Market Price Referent.” And Amonix said the 7700 can produce 1 megawatt of electricity in just five acres, “twice the amount of energy per acre than any other solar technology.”

NREL awarded Amonix $1.2 million in 2004. The company received another $15.6 from the U.S. Department of Energy in 2007, which it used to pry loose $18 million from investors and get manufacturing of the 7700 going at a Seal Beach, Calif., plant.

Pete Danko is a writer and editor based in Portland, Oregon. His work has appeared in Breaking Energy, National Geographic's Energy Blog, The New York Times, San Francisco Chronicle and elsewhere.