Direct measurement of moisture ingress in PV laminates

This work demonstrates a novel method for the measurement of moisture ingress into PV laminates, by the use of humidity indicator cards encapsulated within the structure. The humidity indicator cards change colour due to moisture exposure, which is quantified by processing images of the samples taken with a camera. To allow the variance of colour to be matched to specific levels of humidity, a detailed calibration was first performed. To achieve this, laminates with the structure [EVA-humidity indicator card-EVA-glass] were stabilised in an environmental chamber at 85ºC at increasing levels of relative humidity. The colour change of the humidity indicator cards corresponding to the relative humidity inside the chamber was then plotted on RGB colour space diagrams. The purpose of this work is the development of a measurement method for the moisture that accumulates at the front side of PV cells, for the experimental verification of simulations of the moisture ingress into PV modules and the better understanding of degradation modes related to corrosion.