Photovoltaic module with encapsulant system based on recyclable composite material

Abstract

An initial approach for a photovoltaic module with enhanced chemical recyclability and its recycling process is presented. The module encapsulant system consisted of a glass fiber reinforced composite material with cleavable epoxy matrix and a polymeric frontsheet as an additional protection for the composite. Using vacuum assisted resin infusion process, lab-size modules with monocrystalline back-contact cells were manufactured with the mentioned encapsulation. The performance stability under thermal cycling and ultraviolet exposure was acceptable, whereas in damp-heat conditions the electrical performance loss was slightly more pronounced. This was attributed to the effect of humidity in the cleavable groups of the resin, leading to an optically non-homogeneous composite material. Regarding the recyclability in mild acid conditions, the effect of process time, temperature and acetic acid concentration was analyzed. A suitable solvolysis window was defined leading to wafer, reinforcement and frontsheet separation and recovery. The study concluded that damp-heat stability should be optimized considering the features of the epoxy matrix in terms of a balance between durability in humid conditions and recyclability. Further, advancing in the recycling process would focus on parameter optimization and their influence in the nature and quality of recovered materials and components.