Multiscale Modeling of Shingled Cell Photovoltaic Modules for Reliability Assessment of Electrically Conductive Adhesive Cell Interconnects

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New interconnect schemes that replace metallic solders with electrically conductive adhesives (ECA) are appearing in recent embodiments of crystalline silicon photovoltaic (PV) modules. Recently, potential ECA interconnect failure modes were identified and characterized, which included cohesive cracking and debonding of the adhesive joint. In this work, we elucidate on how and to what extent the driving force for ECA degradation develops in shingled cell modules. We have employed a multiscale modeling approach, using the finite-element method, to accurately predict the driving force for both accelerated stress testing conditions and on-sun exposure of PV modules. When we compare our driving force predictions for a generic PV module with the experimentally characterized fracture properties of a candidate ECA, we found that interconnect failure of only poor quality or otherwise damaged joints is likely to occur. Furthermore, we show how a 2-D submodel can efficiently predict limits for the debond driving forces without needing to employ the multiscale modeling approach.