This paper reports the low-energy proton irradiation effects on GaAs/Ge solar cells for space use. The proton irradiation experiments were performed with a fluence of 1.2 x 10(13) cm(-2), energies ranging from 0.1 to 3.0 MeV. The results obtained demonstrate that the irradiation with a proton energy of 0.3 MeV gives rise to the most degradation rates of I-sc, V-oc and P-max of the solar cells with no coverglass, which is related to the proton irradiation-induced vacancies near the pn junction in GaAs/Ge cells. The degradation rates of I-sc V-oc and P-max of the solar cells with coverglass increase as the proton energy increases due to the cascade ions induced by collision processes. It is found that the coverglass has an obvious protection effect against the irradiation with the proton energy below 0.5 MeV. (c) 2005 Elsevier B.V. All rights reserved.