Researchers at NASA Develop Concept for Obtaining High Energy-Conversion Efficiency in PV System

January 14, 1999 by Jeff Shepard

Researchers at NASA's Jet Propulsion Laboratory (JPL, Pasadena, CA) have developed a concept for obtaining high energy-conversion efficiency in a photovoltaic (PV)system. The process involves concentration and spectral dispersion of sunlight, and the use of several types of solar PV cells, each placed at its optimum location in the spectrum. The spectral dispersion can be accomplished through the use of mirrors or lenses combined with prisms, while the PV cells can be of the conventional single-junction type, which are less costly than advanced multijunction cells. The JPL researchers have conducted preliminary experiments to demonstrate the feasibility of the concept on several types of cells, using artificial sunlight and prisms that had not been optimized. Based on these preliminary experiments the researchers estimate that an optimized system of this type could perform with an energy-conversion efficiency approaching 50 percent. Multijunction solar cells yield efficiencies between 20 and 30 percent, while conventional solar cells yield efficiencies from 11 to 19 percent in white light.