Thermo-mechanical stress modeling and experimental investigation on micro-cracks in tilling ribbon photovoltaic modules during lamination and mechanical load test

Photovoltaic (PV) module failures due to silicon cell cracking are gaining more and more attention. It is found that Ethylene Vinyl Acetate (EVA) is one of the most significant contributions to reduce failures resulting from the fracture of silicon solar cells. In this work a full understanding of the impact of lamination and external mechanical loads on the cracking of newly developed tilling ribbon (TR) mono-crystalline modules (encapsulated with a Zebra-EVA), and the direct impact of micro-cracks on the module power after mechanical load test, has been developed. Finite element modelling (FEM) is used to predict the temperature and stress distribution inside each layer and the surface deformation of the PV assembly in the encapsulation, as well as the accumulated stresses of the PV module under mechanical loads. Comparing to the conventional PV module, a TR module was found to have significantly enhanced efficiency by 1.5% with an increased power of more than 20 W. Compared to the conventional EVA layer, Zebra-EVA could reduce the probability of micro-cracks by 3.6% during lami-nation and effectively decrease the mechanical stress imposed on silicon cells when the module is exposed to external mechanical conditions, offering a lower cracking risks and less power losses, which agreed with the simulation results. It is shown that conversion efficiency of a PV module is improved through TR technique, while its lamination-induced cracking and the failure probability induced from mechanical loading can be efficiently reduced by utilizing Zebra-EVA encapsulate.