Non-destructive approach for severity investigation of shunts in crystalline silicon photovoltaic modules by combination of electroluminescence imaging and lock-in thermography

Abstract

The characterization of localized shunts in photovoltaic (PV) modules is of major concern due to its impact on the performance and reliability of the modules. Generally, lock-in thermography has been used as an effective non-destructive technique for the characterization of shunts in solar cells; however, it has limited applicability in PV modules. Electroluminescence (EL) imaging is another non-destructive technique for the investigation of shunts, which can be employed in both cells and modules in a much faster and inexpensive way. However, it suffers from a limitation in differentiating shunts from other defects. In this paper, a novel non-destructive approach is presented by combining both techniques, which systematically overcomes the limitations of an individual technique for the characterization of shunts in commercial crystalline silicon PV modules. The dark lock-in thermography technique has been utilized to locate shunts in cells and combined with different aspects of EL imaging applications for the spatial severity analysis of individual shunts. The proposed approach has been successfully employed to investigate the severity of different shunts in modules. This approach can be helpful in locating shunts on the basis of severity, which can be related to the performance, degradation and reliability of PV modules.