Investigation of moisture ingress and egress in polymer – Glass laminates for PV encapsulation

The combinations of different and time-varying environmental conditions affect PV modules operating outdoors, both instantaneously and by causing different types of long-term performance degradation and failure modes. Among the most crucial environmental stressors for long-term effects is moisture ingress. Moisture reacts with the back sheet, encapsulant and outer parts of the solar cells. If the encapsulant is the commonly-used ethylene vinyl acetate (EVA), moisture that has entered the laminate reacts with the VA content, producing acetic acid. This reacts with the contacts on the cells, causing corrosion and eventual negative impact on the electrical output. This work investigates the rates and patterns of moisture ingress into and egress from c-Si PV laminates as the external humidity changes, through both simulation and experiment.