Stress Analysis of Silicon Wafer-Based Photovoltaic Modules Under IEC 61215 Mechanical Load Test

Snow loading poses a significant problem to the integrity of photovoltaic (PV) modules. The weight of accumulated snow exerted on the PV modules can cause breakage of the glass cover and cells. The mechanical load test in IEC 61215 is designed to test the reliability of PV modules subjected to 2400 Pa, and subsequently to 5400 Pa of uniform load, in the revised standard. In this paper, finite element analysis is conducted to study the stresses in PV modules with non-tempered float glass, subjected to conditions in the mechanical load test. In this analysis, residual stresses that are induced during the module lamination process are taken into account in order to give an accurate representation of the existing stresses in the module. These residual stresses arise when the temperature of the PV laminate is lowered from the lamination temperature (typically 145 °C) to room temperature, due to the differences in coefficient of thermal expansion (CTE) of the constituent PV laminate materials. The results show that in the glass cover of the PV module, the region around the point where the aluminium frame of the module is secured experiences a high tensile principal stress, which may cause the glass to fracture. The solar cells experience tensile stresses, but this is not crucial as the values do not approach the failure stress of the silicon cells.