Finite element thermal stress analysis of a solar photovoltaic module

One of the principal causes of failure in photovoltaic (PV) modules is delamination at interfaces in a PV module formed by several layers of different materials. As delamination is driven by stress, it is important to determine the nature and magnitude of such stresses within a PV module. Such stresses can arise during the lamination of the PV module when layers of glass, ethyl-vinylacetate (EVA), solar cells, EVA and Tedlar backsheet are bonded together at about 150°C. When the PV module is cooled down to room temperature, residual stresses will be induced due to the mismatch in coefficient of thermal expansion (CTE). When the PV panel is subsequently exposed to sunlight, the temperature distribution redistributes the residual stress. In this paper, finite element analysis is conducted to determine the stresses induced in the PV module during lamination and subsequent exposure to sunlight. In the analysis of the illuminated PV module, optical parameters are considered to determine the heat dissipation on the areas exposed directly to sunlight. Heat losses by convection and radiation are also considered. The results show that the area around the corners of the glass cover experience high tensile principal stresses which may cause it to fracture. The peeling stresses at the interfaces in the PV laminate are found to increase from the center towards the edges. This trend suggests that delamination - if it occurs - will most likely start from the edges of the laminate.