Satellites get high-efficiency non-silicon solar cells

17 Jun 2002

The Photovoltaics Division of Emcore Corp has begun shipping InGaAs-based dual-junction solar cells, with efficiencies of more than 25%, for satellite applications. Emcore says that the cells far exceed the capabilities of silicon-based solar cells, which have a theoretical maximum efficiency of about 19% and degrade quite rapidly during orbit.

Emcore's cells are based on a dual-junction InGaP/GaAs compound semiconductor grown on a germanium substrate. The company reports a minimum average efficiency of 23% at air mass zero and 28 degrees centigrade. Emcore says that the solar cells achieved an efficiency ranking of 25.3%, based on customary satellite industry metrics, which is the highest in the world for large-area (27.5 cm²) dual-junction flight solar cells that are ready to ship.

The company says that solar cells are one of the most significant influences on the cost of satellites and the increased efficiency could lead to satellites becoming a viable alternative for transmitting voice and Internet traffic.

Emcore has also produced high-efficiency triple-junction cells with a minimum average efficiency of 26% at air mass zero in pilot tests. Preliminary radiation tests at NASA's Jet Propulsion Labs have shown enhanced radiation stability with a power degradation of only 8% for an equivalent life of 15 years in a geostationary orbit. The company plans to start in-flight production of triple-junction cells in summer 2000.