Most solar panels convert less than 20 percent of the energy in the sunlight that falls on them into electricity. A new $2.4 million project funded by the U.S. Advanced Research Projects Agency for Energy aims to greatly increase the amount of sunlight that becomes electricity. Its goal is a conversion efficiency of more than 50 percent, which would more than double the amount of power generated by a solar panel of a given size. This would cut the number of solar panels needed in half and potentially make solar power more competitive with fossil fuels.
In the new research effort, Harry Atwater, a professor of applied physics and materials science at Caltech, plans to use precisely structured materials to sort sunlight into eight to 10 different colors and direct those to solar cells with semiconductors that are matched perfectly to each color. As a result, more of the solar spectrum will be absorbed, and the energy contained in each slice of the spectrum will be converted mostly to electricity, rather than heat.