Characterization of Degradation under Standard Environmental Testing Methods for Crystalline Silicon Photovoltaic Modules

Standard environmental tests have been developed for photovoltaic (PV) modules to assess the reliability of their performance in a short period of time. These tests generate different modes of degradation by combination of environmental stresses. There is a need to differentiate between the standard tests on the basis of severity. This helps to understand the individual and combined degradation effect occurred due to temperature and humidity stress, which is the focus of the present study. In this work, standard tests viz. humidity freeze (HF), thermal cycling (TC) and damp heat test (DH) have been performed on different batches of multi-crystalline silicon PV modules. One batch of modules was subjected to combined tests wherein the three tests were performed in succession and the other batch was separately subjected to the individual tests. Spatial characterization techniques i.e. electroluminescence (EL) and dark lock-in-thermography (DLIT) imaging were used in tandem with illuminated current voltage (I-V) analysis for detection and quantification of degradation under the standard tests. The information obtained from the comparison between the different tests, on a scale of time and severity can be helpful for preliminary investigations performed on effects of the common environmental degradation factors like high temperature, high humidity and thermal ramping. The presented findings can further aid research and development on different aspects of reliability testing on PV module performance under environmental effects.