The impact of acetic acid corrosion on the front-side contacts and the finger electrodes of c-Si PV cells

Damp-heat stresses typically lead to corrosion related degradation for Ethylene-vinyl acetate (EVA) encapsulated PV modules. The degraded module appears as bright areas along the busbars in electroluminescence (EL) images. The most likely mechanism that causes these bright areas is corrosion at the silver contacts and the finger electrodes at the front surface of the cell, due to acetic acid accumulation. In this work, these mechanisms are investigated by immersion of half encapsulated cells into acetic acid solutions with different concentrations. Dark and light I-V curve measurements and electroluminescence images were conducted during the course of ageing to investigate the power degradation. The chemical changes in materials are identified by optical microscopy images and SEM-EDX analysis.