This study involved analyzing the reliability of two types of III-V solar cells: (1) III-V solar cells grown on new and recycled gallium arsenide (GaAs) substrates and (2) the III-V solar cells transferred onto an electroplated nickel (Ni) substrate as III-V thin-film solar cells by using a cross-shaped pattern epitaxial lift-off (CPELO) process. The III-V solar cells were grown on new and recycled GaAs substrates to evaluate the reliability of the substrate. The recycled GaAs substrate was fabricated by using the CPELO process. The performance of the solar cells grown on the recycled GaAs substrate was affected by the uneven surface morphology of the recycled GaAs substrate, which caused the propagation of these dislocations into the subsequently grown active layer of the solar cell. The III-V solar cells were transferred onto an electroplated Ni substrate, which was also fabricated by using CPELO technology. The degradation of the III-V thin-film solar cell after conducting a thermal shock test could have been caused by microcracks or microvoids in the active layer or interface of the heterojunction, which resulted in the reduction of the external quantum efficiency response and the increase of recombination loss.