Solar cell hits efficiency record

A world-record conversion efficiency of 40.7% was achieved by a concentrator solar cell produced by Boeing-Spectrolab with Department of Energy funding, the company and DOE announced last week. The solar cell is a multijunction device that captures a broader range of energy wavelengths than do most devices. It also uses an optical concentrator to focus and receive more of the sun's intensity, DOE notes. In 1994, DOE exceeded 30% efficiency, a record then, but this is the first time a solar device has broken the 40% barrier, the department says. By comparison, most solar cells capturing a single energy band of sunlight have an efficiency of 12-18%. Spectrolab, a Boeing subsidiary, manufactures solar cells for several types of mostly space-based applications and, for instance, provided the solar power systems for the Mars rovers. This latest breakthrough, DOE says, may lead to systems with an installation cost of only $3.00 per W, and it holds out the possibility of producing electricity for 8 to 10 cents per kWh, making solar electricity much more cost competitive.