Evaluating Solar Cell Fracture as a Function of Module Mechanical Loading Conditions

Cell cracking presents a serious risk for the long term reliability of c-Si photovoltaic modules. Cracks may not initially result in performance loss, but over time performance may degrade as the module experiences stresses in the field such as temperature cycling and snow/wind loading. This performance loss is due to the formation of new cracks with front side loading, propagation of existing cracks, and the opening of existing cracks in which regions of the cell become more electrically isolated. This work utilizes a new tool, the LoadSpot, that allows for I-V performance characterization and electroluminescence imaging of PV modules while under mechanical load. We explore a variety of cell technologies to understand the magnitude of mechanical stress required to induce cell fracture, and assess the impact these cracks have on performance. In addition, we study the use of cyclic loading to open existing cracks. The tests used in this work have potential applications in product development, factory quality control, product evaluations, and optimization of mounting hardware and methods.