Defects localization research in photovoltaic cells: Methods and devices

Abstract

The article presents a method to determine local defects in solar photovoltaic cells (PVC). It is based on the non-contact measurement of PVC area temperature distribution by a special thermovision system when applying forward and reverse voltage to the cell. Distribution of PVC surface temperature is determined by nonuniformity of current density (because of local defects) and reveals itself in the intensity of thermal radiation in the infrared spectrum (IR). The difference between the light detector signals when applying a forward or reverse voltage to PV cells and in the absence of applied voltage to the PVC is used to eliminate the effect of IR light patch, surface irregularities emissivity of solar cells, heterogeneity sensitivity light detector array. The hardware and software implementation techniques using the focal plane array of infrared 3–5 micron spectral range and 320 × 256 elements size are presented.