Modeling and testing the mechanical strength of solar cells

The strength and fracture behavior of solar cells govern the failure of cells in a photovoltaic module under thermal and mechanical loads. In this study, the testing and modeling of strength of silicon solar cells with aluminium metallization are presented. Therefore, the contribution of microstructure in solar cells was analyzed regarding stiffness and fracture behavior. With this knowledge, a simulation model was created to evaluate the influence of each layer to the stress field inside the silicon part of the solar cell. The model was used to evaluate 4-point bending experiments, which were performed to determine the strength of solar cells on front and backside and in two different directions, parallel and perpendicular to the busbars. It is shown that the strength and breakage depend strongly on the side and direction of loading. The lowest strength was detected for the backside being loaded with tensile stress parallel to the busbars.