Potential induced degradation (PID) is one of the significant reliability problems, observed commonly in all PV technologies, that can lead to catastrophic failures of solar modules due to a high voltage stress. For CIGS PV, PID caused performance loss is generally less observed than for x-Si PV , but it still occurred in the field. In order to contain the performance issues related to PID at system level, it is important to understand the degradation mechanisms behind this degradation type. We conduct an extensive post-mortem analysis on a commercial CIGS solar panel that failed to PID in an accelerated test (Bias application of -1000 V for 48 hours at damp heat conditions of 85 oC, 85% RH). Connected solar cells representing non-damaged and damaged areas of the module were obtained by coring. An in-depth comparison analysis between these samples was done via various laboratory based techniques including photoluminescence (PL) imaging, I-V measurements and secondary ion mass spectroscopy (SIMS) to identify the real degradation mechanisms as observed in full modules.