We monitor the short circuit current and the open circuit voltage of Si, GaAs and GaInP solar cells versus the fluence of 1 MeV electrons. From these data, we extract the fluence dependences of the lifetime and of the concentration of compensating centers. This allows to compare in detail the radiation hardness of cells made with these materials and to modelize their degradation under a given irradiation. (C) 2001 Elsevier Science B.V. All rights reserved.