Fitting Procedure for PV Panel Measured Current-Voltage Characteristics

Current-voltage curve measurements are a potential tool for efficient monitoring and diagnosis of photovoltaic (PV) panels and systems. To determine indicators of aging, degradation and other such phenomena of PV panels, an attractive option is to fit an electrical model of the PV panels to measured data in order to detect changes. However, raw measurement data usually contains measurement noise and other factors that can distort the analysis. The fitting process is challenging for instance, by the fact that the measurement points are unevenly distributed on the current-voltage curve, being mainly clustered on the open-circuit region. This unintentional weight can distort the fit. To address these issues, the present paper introduces a procedure for fitting an electrical model of the PV panels to the measured current-voltage curves so as to alleviate the above problems. The proposed approach is a prerequisite for a reliable diagnosis of the PV system status.