Solar array trades between very high-efficiency multi-junction and Si space solar cells

This paper describes a trade study between state-of-the-art, commercially-available very high-efficiency III-V multi-junction solar cells and advanced high-efficiency silicon cells at the bare cell and panel levels. The solar cell technologies in this comparison will be high-efficiency rad-hard 3-mil Si, dual-junction InGaP/GaAs (on Ge), and triple-junction InGaP/GaAs/Ge, with the beginning-of-life (BOL) efficiencies of 17%, 23%, and 26%, respectively. Two different 'typical orbits are considered: geosyncronous (GEO) and low-Earth (LEO) orbits. It is assumed that the end-of-life (EOL) conditions for GEO and LEO are equivalent to degradation due to 1-MeV electrons at 5E14 and 1E15 e/cm/sup 2/, respectively. Parameters critical to conventional rigid solar arrays such as specific power/mass (W/Kg), specific mass/area (Kg/m/sup 2/), specific power/area (W/m/sup 2/), and normalized end-of-life (EOL) $/W are compared for these cell technologies.