Investigation of dominant degradation mode in field‐aged photovoltaic modules using novel differential current‐voltage analysis approach

摘要

Abstract Photovoltaic (PV) modules are susceptible to various types of defects and degradations (D&Ds) under field‐operating conditions, which affect their performance and reliability. These D&Ds have non‐uniform distribution in the PV modules, which makes it difficult to distinguish amongst multiple D&Ds using a single characterization technique. In the present work, a simple non‐destructive characterization approach called differential current‐voltage (DIV) analysis using current‐voltage (I‐V) measurements have been developed for investigation of the dominant degradation mode in the cells of modules, wherein consecutive cells have been partially shaded while measuring the I‐V curve of the modules. For this purpose, a batch of crystalline silicon PV modules operating under hot and humid climatic conditions for 20 years has been investigated. A correlation has been established between the trend of percentage change in modules' electrical parameters during DIV measurements and the dominant degradation mode present in the cell under investigation. The trend of change in short circuit current and voltage at maximum power point has been identified as key electrical parameters to identify the dominant degradation mode in the cell. To analyse the trends of DIV analysis, the effect of prominent degradation modes on the module parameters has been investigated using electrical simulations. The investigated PV modules have been cross‐characterized through microscopic inspection and electroluminescence imaging to identify various D&Ds present in the investigated modules. The results of cross‐characterization substantiate the findings of DIV analysis. The presented DIV approach can be used for the analysis of non‐uniform degradation in the PV plants under field‐operating conditions.