Results from the high efficiency solar panel experiment flown on CRRES

Results from the high efficiency solar panel experiment (HESP) flown on the Combined Release and Radiation Effects Satellite (CRRES) are presented. The on-orbit solar cell degradation is correlated with the proton and electron environments. Comparisons between GaAs/Ge and Si solar cells are presented, and results from three different annealing methods of like GaAs solar cells are compared. Solar cell degradation showed good correlation with changes in measured proton fluences. GaAs/Ge solar cells performed better than two different types of Si solar cells under equivalent coverglass shielding. A comparison of like GaAs/Ge solar cells under different quartz coverglass thicknesses showed that increasing the coverglass thickness from 6.5 mils to 12 mils resulted in a 12% increase (75% to 87%) in percentage of BOL (beginning-of-life) maximum power at the end of the mission. Increasing the quartz thickness from 12 mils to 30 mils resulted in only a 4% increase in percentage of BOL maximum power at the end of the mission at almost triple the weight penalty. Forward bias annealing outperformed both constant heating and pulsed heating biasing techniques for cells under 6 and 12 mils coverglass