Unveiling the Potential of Electroluminescence Characteristics in Investigating Different Types of Defects and Degradations in c-Si PV Module

Abstract

Photovoltaic (PV) cells can be characterized using current-voltage (I-V) as well as electroluminescence (EL) characteristics. However, unlike I-V, the potential of EL characteristics has not been well discussed in the literature. In this work, the impact of different types of defects on the EL characteristics is studied, and the possible use of EL characteristics in the qualitative and quantitative investigation of defects is unveiled. Defective field-aged and new modules with artificially induced defects were taken for experimental study. EL current-intensity (I-ɸ) and EL voltage-intensity (V-ɸ) characteristics were studied for the cells suffering from major defects such as cracks, busbar interconnect failure, and PID-shunting. It is observed that I-ɸ characteristic is useful in the investigation of shunting defects, whereas V-ɸ characteristic is in diagnosing defect that increases series resistance. Bulk defects within a cell affect EL calibration constants and increase cell-to-cell mismatch within a module. The findings of this work would be useful for extracting valuable information from EL images regarding defects and degradations.