Performance assessment of field deployed multi-crystalline PV modules in Nordic conditions

This paper presents an investigation of data monitoring quality and evaluation of performance degradation of four different multi-crystalline silicon (mc-Si) photovoltaic (PV) modules installed in the higher latitude conditions in southern Norway. Degradation of each module has been investigated in terms of degradation of short-circuit current (ISC), open-circuit voltage (VOC), fill factor (FF) and maximum power (PMPP). The analysis for the period of monitoring data from 2014 to 2018 show no considerable module degradation compared to the standard degradation rate of all parameters. The statistical analysis of ISC shows an average degradation of 0.17% for all modules. Spectral corrections were applied to ISC and PMPP, in addition to temperature and irradiance corrections. Among the parameters, FF and ISC show slight degradation based on the yearly average method. Infrared images were used for validation of findings, but due to the unavailability of images from the initial installation period, the image results are inconclusive. Performance ratio plots based on corrected ISC values show very stable performances over the five-year period. The results suggest that PV modules in cold conditions may undergo lower degradation compared to typical degradation rates experienced in other regions.