Large-Area Junction Damage in Potential-Induced Degradation of c-Si Solar Modules

We report a large area of millimeter-scale p-n junction damage caused by potential-induced degradation (PID) of lab-stressed crystalline-Si modules. Kelvin probe force microscopy results show electrical potential change across the junction, and a recovery was observed after heat treatment. Electron-beam induced current results support the large-area damage instead of local shunts and a much lower collected current for the affected junction area. Furthermore, secondaryion mass spectrometry indicates that the large-area damage correlates with sodium contamination. The consistent results shed new light on PID mechanisms to investigate that are essentially different than the widely reported local junction shunts.