Preliminary Evaluation of Aluminum Foil Compatibility with EVA and POE Encapsulants

Emerging photovoltaic (PV) technologies with inexpensive cell interconnect material will help to further reduce the manufacturing costs of solar cells. Aluminum foil has been explored as an inexpensive alternative material replacing silver and copper interconnect materials in the IBC (interdigitated back contact) cells or as moisture barrier in the backsheet. It is critical to assess the compatibility of the aluminum foil with dominant encapsulant types so the reliability of PV modules with aluminum interconnect is not compromised over decades of exposure in the field. In this work, through extended accelerated stress tests, we have evaluated the compatibility of aluminum foil with two encapsulant types, EVA (ethylene vinyl acetate) and POE (polyolefin elastomer). This aluminum/encapsulant compatibility evaluation was performed using both glass/glass and glass/backsheet constructions. The extended accelerated stress tests used in this work were UV (300 kWh/m2) and damp heat (1500 hours). Based on the after-stress optical and performance parameters of the mini-modules, it is demonstrated that the POE encapsulant is more compatible with aluminum foil compared to the EVA encapsulant irrespective of the substrate type, glass or backsheet.