Factors Influencing Standard PID Test and Anti-PID Performance of Ga-Doped PERC Mono-Facial Photovoltaic Modules

Abstract

The potential-induced degradation (PID) performance is of high significance for photovoltaic (PV) modules. In accordance with the IEC 61215-2: 2021 standard, we analyzed the factors that affect the measurement of PID performance, including the effects of a light soak of the p-type gallium (Ga)-doped silicon mono-facial PV modules, the resistivity of the water used for humidification of the environmental chamber, and the relative humidity of the chamber. We also examined the change of the modules’ anti-PID performance under the erosion by NaCl solution and by higher humidity combined with NaCl solution. The results show that a light soak pre-treatment before the PID test of the module leads to a difference of 0.02% in average power loss. The influence of humidifying water with different resistivities used in the environmental chamber on the PID test is negligible. An increase in humidity substantially reduces the anti-PID performance of the module. When the EVA film thickness was reduced from 0.65 mm to 0.55 mm, the power loss increased from 2.25% to 3.96% after the PID test. In addition, NaCl on the backsheet of the module could accelerate the PID effect under applied electric field conditions, resulting in the formation of localized darkening area observed under electroluminescence (EL) image. Finally, after the PID test in the presence of higher humidity and NaCl solution, the average power loss of the modules amounted to 10.80%, while it was 1.29% for the modules after the standard PID test. Therefore, it is vital to improve the anti-PID performance of mono-facial PV modules in a high relative humidity and salt-mist environment.