A unique method has been developed to in-situ monitor the accelerated degradation in Cu(In, Ga)Se2 solar cells, in which a degradation setup uses humidity, high temperatures and illumination as loads. IV characteristics of the solar cells are collected during the degradation. Cu(In, Ga)Se2 solar cells and minimodules were degraded in the set-up and analyzed. We report on the formation of spots on the cell surface and indicate modifications in the i-ZnO/CdS region that result in changes in the external quantum efficiency. Furthermore, an increase in series resistance and a decrease current density was measured.