Materials Challenge for Shingled Cells Interconnection

This paper discusses some challenges that need to be tackled when designing a photovoltaic module using a shingled cells structure. We derive a simple analytical model to determine the conditions needed to avoid interconnection joint failure. It is found that interconnection materials with a low ratio of shear modulus G over shear strength τsh.str. is preferred for good interconnection joints reliability. As a result, solder joints appear inappropriate for the application, while electrically conductive adhesives (ECA) with low G/ τsh.str can better fulfill the requirements. An interconnection approach is also proposed which makes use of a combination of adjacent ECA and a non-conductive adhesive materials in a shingled configuration to help achieve string robustness and reliability.