Analysis of Accelerated Damp Heat Test for Degradation Analysis and Recovery Method of Photovoltaic Module

Conventional damp heat (DH) tests conducted at 85 °C and 85% relative humidity (RH) for module degradation cannot reproduce outdoor failures in a short time and it may take up to 4000 h to reproduce multienvironmental stress values. Therefore, an accelerated DH test for photovoltaic (PV) modules is proposed, in which temperatures up to 120 °C are applied to accelerate the degradation mechanism while keeping the humidity fixed at 85%RH and module performance and electroluminescence images are investigated. The environmental stress detected after 600 h at 120 °C/85%RH is comparable with the results of the DH test recorded at 85 °C/85%RH for ≈5000 h. Moreover, the power drop by replacing the backsheet/ethylenevinyl acetate (EVA) and backsheet/EVA/solar cell for one cell area in the PV module after 1000 h DH test at 85 °C and 85%RH is mitigated. After replacing the EVA and backsheet of one cell from the minimodule, a power recovery of 1.6% is achieved. By replacing the backsheet, EVA, and one solar cell from the minimodule, a power recovery of 1.9% is achieved. This analysis indicates that instead of replacing the complete module, it is possible to replace the damaged part of the module.