Evaluation of multijunction solar cell performance in radiation environments

This report contains the results of the first systematic radiation study of five types of production multijunction solar cells. Cells optimized for beginning of life (BOL) efficiency were developed and obtained under the Air Force Manufacturing Technology (ManTech) program. These included GaInP₂/GaAs two junction cells from Spectrolab, and GaInP₂/GaAs/Ge three junction cells from both Spectrolab and TECSTAR. Additional two junction cells optimized for end of life (EOL) efficiency were obtained from Spectrolab. Radiation test data on EOL-optimized three junction cells were provided by Spectrolab. For all cell types I-V characteristics were obtained as a function of radiation fluence using electrons (0.6, 1.0, and 1.6 MeV) and protons (0.05, 0.1, 0.2, 0.4, 1.0, 5.0, and 10 MeV). From these data, omnidirectional damage coefficients were calculated, assuming infinite backshielding and eight different coverglass thicknesses