In-Situ Characterization of Potential-Induced Degradation in Crystalline Silicon Photovoltaic Modules Through Dark I–V Measurements

A temperature correction methodology for in-situ darkI-V(DIV) characterization of conventional p-type crystalline silicon photovoltaic (PV) modules undergoing potential-induced degradation (PID) is proposed. We observe that the DIV-derived module power temperature coefficient (γ_dark) varies as a function of the extent of PID. To investigate the relationship between γ_dark and DIV-derived module power (P_dark (T_s), measured in situ and at the stress temperature) two parameters are defined: change in the DIV-derived module temperature coefficient (Δγ_dark) and DIV-derived module power degradation at the PID stress temperature (ΔP_dark (T_s)). It is determined that there is a linear relationship between Δγ_dark and ΔP_dark (T_s). Based on this finding, we can easily determine the module γdark at various stages of PID by monitoring P_dark (T_s) in situ. We then further develop a mathematical model to translate P_dark (T_s) to that at 25 °C (Pdark (25 °C)), which is correlated with the module power measured at the standard testing conditions (PST C). Our experiments demonstrate that, for various degrees of PID, the temperature correction methodology offers a relative accuracy of ±3% for predicting PST C. Furthermore, it reduces the root-mean-square error (RMSE) by around 70%, compared with the PSTC estimation without the temperature correction.