CIGS degradation due to water ingress: post-mortem analysis of a field-exposed PV module

To bridge the two worlds of the lab and the field, we propose an approach based on coring, unpackaging and post-mortem analysis. We show how in-depth lab-based characterization techniques can be applied on field-deployed PV modules to study the real outdoor degradation mechanisms. In this case, we aim to make a step forward in the understanding of CIGS degradation due to water ingress. A local analysis of both electrical and material properties on a severely degraded commercial module was performed, allowing to trace back the occurring water-induced degradation mechanisms. The degradation mainly affected the TCO layer, through the formation of Zn-based hydroxides, and the Mo back contact layer, which oxidized up to its complete corrosion of the P3 scribes. This resulted in a deterioration of the electrical properties, especially in terms of Rs increase, Voc reduction and Jsc limitation, before ruining the performance entirely at a more advanced stage of degradation.