The Impact of Cold Temperature Exposure in Mechanical Durability Testing of PV Modules

Existing mechanical durability testing sequences typically perform mechanical loading prior to environmental exposures such as thermal cycling or humidity freeze. Recent work has shown that the fracture strength of silicon solar cells can reduce after exposure to temperatures below -20 degrees C. In an effort to better evaluate modules with respect to cell crack durability, we explore the use of a single thermal cycle prior to mechanical loading. Modules were exposed to a static front-side load before and after exposure to a single thermal cycle and were characterized with current-voltage measurements and electroluminescence imaging. The results show a significant increase in the number of cell cracks that are generated at a given load after a single cold exposure. We explore how this can be used to further optimize the qualification test sequence for mechanical durability.