We compared the degradation process in organic bulk heterojunction solar cells, upon exposure to a temperate (Belgium) and a sub-equatorial (Benin) climate. Differences in degradation of these devices have been attributed to humidity differences between the temperate and Beninese environments. Our analyses revealed, the decrease rate on 240 h of J(SC) is about 40% in Belgium and 45% in Benin, when the devices are exposed to light and to ambient air. The diffusion of H2O and O-2 species through the layers is more rapid when the temperature is high. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license