Direct Measurement of Moisture Ingress in PV Laminates

Abstract

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