INFLUENCE OF PHOTOVOLTAIC MODULE MOUNTING SYSTEMS ON THE THERMO-MECHANICAL STRESSES IN SOLAR CELLS BY FEM MODELLING

摘要

The mounting system of photovoltaic (PV) modules has a significant impact on the thermo-mechanical stress in PV modules. In this work the clamping of framed PV modules is compared to the clamping of unframed PV laminates by a simulation study using the finite element method (FEM). The FEM modelling allows to calculate the local stress distribution in the solar cells directly. We present results from a model of a standard glass-backsheet PV module with 3 mm glass under homogenous mechanical pressure load of up to 5400 Pa. The thermal stress from the lamination process is considered as a pre-study, similar to [1]. The frameless clamped PV laminate shows a significantly larger displacement of 147 mm than the framed PV module with 54 mm for 2400 Pa. In line with the findings of Kajari-Schroeder [2] we simulate an elliptic deflection distribution for the framed PV module, whereas the clamped PV laminate shows a wave-like shape. Consequently, the area of high tensile stresses in the silicon solar cells, with a maximum value of 142 MPa at 2400 Pa load, is narrowly located around the highest curvature at the center of the framed PV module. In case of the frameless clamped PV laminate we identify four areas of high tensile stresses with a higher maximum value of 218 MPa. The results show that the frame reduces the tensile stresses in the solar cells significantly compared to unframed laminates.