Potential-induced degradation of encapsulant-less p-type crystalline Si photovoltaic modules

We investigated the long-term durability of our newly developed encapsulant-less p-type crystalline silicon (c-Si) photovoltaic (PV) modules, with a base made of polycarbonate (PC), against potential-induced degradation (PID) in dry and damp-heat (DH) environments. Encapsulant-less modules were found to have high PID resistance compared to conventionally encapsulated c-Si PV modules in both PID conditions. We observed a slight PID for the encapsulant-less modules in which the cover glass was in contact with the solar cell. The slight PID can be suppressed by using a base with a deeper groove so that a sufficient gap between the cover glass and the cell is prepared. Yellow precipitates were formed in the encapsulant-less modules in the DH environment. This is probably due to the hydrolysis of the PC, and proper measures to prevent the precipitate formation should be applied for the industrialization of the encapsulant-less modules.