Investigation of Potential Induced Degradation for Various Module Manufacturers and Technologies

A steadily increasing system voltage in photovoltaic power plants has improved their performance in the last years. However, this also exposed the modules to higher electrical potentials (high voltage stress; HVS) which can cause Potential Induced Degradation (PID). In the solar industry it is well-known that PID can lower the power of large-scale installations significantly. Some module manufacturers have shown to have found a way to prevent their modules from suffering this power loss due to PID. In literature leakage currents due to low insulation resistance are often connected to occurring PID. We therefore performed a detailed investigation of 16 state of the art modules of 5 different technologies (mono-Si, poly-Si, CdTe, CIGS, a-Si) and manufacturers. I-V-characteristics, Electroluminescence (EL) images as well as insulation resistances have been measured after several time steps to quantify the degradation process of each module. Besides this comparison, special focus is laid on the investigation of the relative power loss under different illumination levels.