Electrical and Temperature Behavior of the Forward DC Resistance With Potential Induced Degradation of the Shunting Type in Crystalline Silicon Photovoltaic Cells and Modules

Abstract

Potential-induced degradation (PID) is an unsolved and major power degradation mechanism that affects photovoltaic (PV) cells, and the tendency to increase the operating voltage of PV systems will render it worse, affecting their reliability. A method, which can detect PID at an early stage, can alleviate reliability issues, safeguarding high energy output. The measurement of the forward dc resistance (FDCR) provides promising results for the early PID detection (<;2% power loss). The FDCR method is tested on single-cell and multi-cell PV modules and it is the pathway for the development of a detection method at the system level. This work examines the effect of PID degradation rate and temperature on the detection sensitivity (electrical behavior) of the FDCR method. Additionally, the effect of temperature (temperature behavior) on the FDCR as PID progresses is studied. The electrical behavior demonstrates that the detection sensitivity is robust to PID degradation rate and temperature and that the degradation rate is not related to the initial shunt resistance of the PV cell. The temperature behavior indicates that the temperature coefficient of the FDCR is initially negative and increases toward more positive values as PID progresses. Furthermore, the electrical variation of the FDCR with PID progression is much higher (74%) than the variation of the FDCR due to temperature (19%) and this favors PID detection.