An overview of the measurement techniques and results of studies on the stability of copper indium gallium selenide (CIGS) solar cells and their individual layers in the presence of atmospheric species is presented: in these studies, solar cells, their molybdenum back contact, and their ZnO:Al front contact were exposed to liquid water purged with gases from the atmosphere, like carbon dioxide (), oxygen (), nitrogen (), and air. The samples were analyzed before, during, and after exposure in order to define their stability under these conditions. The complete CIGS solar cells as well as the ZnO:Al front contact degraded rapidly when exposed to combined with , while they were relatively stable in purged with or . This was caused by either degradation of the grain boundaries in the ZnO:Al film or by the dissolution of part of this film. Uncovered molybdenum films, on the other hand, oxidized rapidly in the presence of and , while they were more stable in the presence of with and/or .