Fracture Probability, Crack Patterns, and Crack Widths of Multicrystalline Silicon Solar Cells in PV Modules During Mechanical Loading

We experimentally analyze the position and opening behavior of cracks in multicrystalline silicon solar cells laminated in standard-sized frameless modules during mechanical loading in a 4-line-bending setup. The results of the experiment are reproduced by simulations for a standard module. These simulations open the opportunity to simulate also complex load situations. Cell interconnect ribbons have big influence to which critically extended module can be bended until a crack appears. Modules with cell interconnect ribbons that are parallel to the bending axis can be bended four times less until cell cracking than modules with cell interconnect ribbons oriented perpendicular to the bending axis and two times less compared with a module without cell interconnect ribbons. Small edge cracks parallel to the bending axis and cross cracks at the busbar decrease the critical bending in the module by a factor of four compared to small edge cracks perpendicular to the bending axis and crack-free cells. The presence of the backsheet decreases the crack width during mechanical loading by 30% compared to a module without a backsheet. In the standard module, the crack width of a single crack is 3.4 μm at loads comparable to the IEC 61215 5400 Pa test.