Modeling and Experimental Investigations of Thermo-Mechanical Stress Induced Micro-Cracks in Different Crystalline Silicon Photovoltaic Modules

Photovoltaic (PV) module failures due to silicon cell cracking are gaining more and more attention. In this work a full understanding of the impact of lamination and external mechanical loads on the micro-cracking of newly developed mono-crystalline PV modules, and the direct impact of micro-cracks on the module power after mechanical load test, has been developed. Comparing to the conventional PV module, a newly developed module using tilling ribbon (TR) and half cell (HC) technique was found to have significantly enhanced efficiency by 1.5% with an increased power of more than 20 W. In addition, a Zebra-EVA structure was tailored as the matched encapsulation layer in TR module for decreasing the cracking. Compared to the conventional EVA layer, Zebra-EVA could reduce micro-cracks ratio by 3.6% during lamination, which agreed with the simulation results using finite element method (FEM) by coupling the thermal and mechanical fields in a PV module. It also can be seen that Zebra-EVA could effectively decrease the strain stress imposed on silicon cells when the module is exposed to external mechanical conditions, offering the relative lower cracking risks and less power losses after mechanical load test. It is believed that conversion efficiency of PV module could be improved through combining new techniques TR and HC, while its mechanical load reliability can be enhanced by optimizing encapsulate structure as Zebra-EVA.