Different methods for accelerated ageing have been performed on single-junction AlGaAs/GaAs cells with ARC. The storage in a 95/spl deg/C/100% humidity environment has been found to be the most appropriate test procedure. The factor of acceleration has been experimentally estimated. After definition of the ageing procedure, III-V single-junction solar cells with different structures have been examined. It was found, that the material of the window layer is the most critical parameter for durability. AlGaInP yields hard-wearing devices, while AlGaAs can cause problems.