A new approach to damage prediction for solar cells exposed to different radiations

Accurate prediction of solar cell performance in a space radiation environment is essential for selecting the appropriate cell technology for a given mission. A methodology for carrying out such assessments based on experimentally determined cell degradation as a function of electron and proton fluence has been applied successfully for many years. The necessary data to apply this methodology to novel cell types is usually not available, however, and it is imperative to be able to extract the maximum possible information from limited data. In this paper a new approach is outlined based on damage correlation using “displacement damage dose” which is derived from the product of the calculated nonionizing energy loss and the fluence. For electron damage it is found necessary in some cases to define a quantity “1 MeV electron equivalent dose” from which 1 MeV electron equivalent fluence can be calculated. With this new approach to damage correlation, it is possible to make accurate predictions of the expected degradation of solar cell performance in complex space radiation environments based on measurements made with only one proton energy and two electron energies, or with one proton and electron energy, and Co⁶⁰ gammas. The power of the method is demonstrated using reported data for GaAs and Si cells