Characterisation of c-Si modules after 20 years of outdoor exposure on an electric vehicle

Characterisation of 4 crystalline silicon photovoltaic modules mounted on an electric vehicle and exposed outdoor for more than 20 years was performed. Heavy soiling was apparent and manual cleaning led to an average increase of Pmax of 14%, due mainly to an increase in Isc. One of the modules presented a severe damage with a FF below 37% and a decrease in the Pmax around -55%. An annual degradation rate of -0.24% for the module on the bonnet (different manufacturer than the other modules) and between - 0.84 to -2.75% for the other modules was obtained, being slight greater than other reported values for crystalline silicon bared modules. The visual inspection showed modules heavily soiled and different defects, such as finger interruptions, discoloration, delamination and broken cells were apparent. Electroluminescence and IR imaging enabled the identification of modules with defects of the cells that can cause high cell temperatures during module operation, potentially leading to damages and a relation between the soiling parts and the relative EL intensity was found.