The aim of this paper is to predict the degradation induced by proton and electron irradiations on the parameters (short-circuit current, open-circuit voltage and maximum power) of solar cells versus fluence, by a direct calculation now that the characteristics of the recombination centers induced by the irradiation have been determined. The calculation is performed for any energy of the irradiating particle and for any thicknesses and doping levels in the base and emitter. This approach allows also deducing the degradation of multijunction cells. The validity of this method is illustrated for the case of GaAs cells of different origins. (c) 2005 Elsevier B.V. All rights reserved.