1‐MeV electron irradiation damage inn+‐pjunction InP solar cells has been studied as a function of irradiation temperature, in comparison with those in GaAs cells. Solar cell property degradation of InP solar cells due to electron irradiation has been found to strongly decrease with an increase in irradiation temperature while that in GaAs cells is independent of irradiation temperature up to 150 °C. These results are explained by thermal annealing phenomena of radiation‐induced defects in InP solar cells. The irradiation temperature dependence of radiation damage in InP cells has been analyzed based on annealing characteristics of radiation‐induced defects, determined by deep‐level transient spectroscopy measurement, in InP. ©1995 American Institute of Physics.