بررسی شبیه سازی فرایند تخریب ماژول های فتوولتائیک Simulation study on the degradation process of photovoltaic modules

1. Introduction Photovoltaic (PV) module is considered as the most reliable component in a PV system, and its life time is expected to be more than 20 years. Degradation, however, decreases the PV power delivery capacity over time [1]. A thorough understanding of PV module degradation is required to make better use of PV module during its life time. Studies on PV degradation often investigate the degradation modes, mechanisms, and degradation rates. The reported degradation modes include cell cracks, hot spots, glass soiling, ethylene vinyl acetate (EVA) browning, delamination, coating oxidation, etc., for crystalline silicon PV modules operated over 20 years in Italy [2]. These degradation models were also observed in PV modules of other technologies and exposed to various climates. In [3], Malvoni et al. studied the long-term performance loss of a 960 kWp PV system in the Mediterranean climate and concluded that the PV system demonstrated good performance compared to other plants located in the same climate. Kichou et al. [4] investigated the degradation modes and degradation rates of thin-film PV modules exposed to relatively dry and sunny climate in Spain. Bouraiou et al. [5] investigated the impacts of high temperature and the other climatic factors in the Saharan environment on the performance of PV modules installed in the desert region in south of Algeria. Chandel et al. [6] presented the performance degradation of mono-crystallinesilicon PV generator after 28 years of exposure at a western Himalayan in India, and the main defects observed in PV modules were encapsulant discoloration, delamination, oxidation of front grid fingers, and glass breakages. In [7], Jordan et al. concluded that hot spot was the most important degradation mode for crystalline modules installed in the last 10 years while the glass breakage and absorber corrosion dominated the degradation models for thin-film PV technologies. It was also concluded that PV modules exposed to hot and humid climates show considerably higher degradations modes than those in desert and moderate climates. These degradation modes decrease the light approaching the semiconductor junction and worsen the internal electrical properties of PV modules leading to the loss in power production. In [8], the long-term performance degradation rates of 12 PV systems with different technologies including monocrystalline silicon, multicrystalline silicon, amorphous silicon (a-Si), cadmium telluride (CdTe), copper indium gallium diselenide (CIGS) were investigated and the degradation rates varied significantly among these technologies. In [9], nearly 2000 degradation rates were reviewed showing a median annual performance degradation rate of 0.5% and that location and PV technology were most influential factors determining degradation rate. Accelerated tests and outdoor tests which are time-consuming and require substantial efforts are the most frequently applied approaches to study degradation of PV modules.