We report experimental data on light soaking of a-Si: H solar cells as well as the role played by the temperature on the metastable light-induced defect growth. We studied the temperature and intensity dependence on the photoconductivity, μτ product and density of states at the Fermi level (g(Ef)) and we found that the rate of defect growth on the i-layer depends on the quality of the material and on the annealing temperature, resulting from an equilibrium between light-induced and light-annealed defects. The photoresponse of the devices is mainly ruled by its microstructure, and depends on the fraction of hydrogen bounded on internal surfaces. Results suggest a correlation between the decrease of μτ product for electron and the increase of the fraction of hydrogen bonded on internal surfaces, suggesting structural changes during the degradation process. Data show, also, that the thermal annealing effect is worthless up to 70°C because of light-induced defect-generation being the dominant process in recombination mechanisms.