Opportunities in photovoltaics for space power generation

Photovoltaics provide virtually all power generation for space systems, and the majority of these, in recent years, are multijunction solar cells comprised of III-V materials. Multijunction solar cells are designed for optimal efficiency under the space AM0 (Air Mass Zero) solar spectrum and to operate with high reliability under hostile environmental conditions. State of practice crystalline multijunction solar cells are primarily triple junction (GaInP₂/GaAs/Ge) grown on Ge single crystal wafers. Development efforts are focused on increasing the efficiency of these cells beyond 30%. For next-generation spacecraft, space compatible thin-film solar cells are being developed. Nanotechnology and novel materials hold promise for extending cell performance beyond these technologies. Opportunities for space-qualified solar cells extend from commercial and government satellites, where power demands continue to grow, to power generation systems on the high altitude airships being developed in several nations.