Electrical Characterization of Solar Array Panels by Absolute Electroluminescence Intensity

Abstract

Quality control in manufacturing solar array panels is important and requires detailed inspection. The conventional inspection method evaluates the current-voltage characteristics of the arrays, but those of the individual solar cells in the arrays cannot be obtained. This paper proposes a simple inspection method for evaluating individual solar cells in an array using electroluminescence (EL). This light emission phenomenon occurs when a forward current is injected into a solar cell. Current crack detection in solar cells has used images of relative EL intensity. However, this study focused on images of absolute EL intensity. This novel method was demonstrated using the solar array panel on the proto-flight model of JAXA‘s SLIM (Smart Lander for Investigation Moon) project before and after testing. The SLIM solar panel consists of arrays of InGaP/GaAs/InGaAs triple-junction solar cells. The validity of the new method was confirmed by comparing the array's electrical properties measured by the conventional method and the sum of the cell's electrical properties derived from the absolute EL intensity.