A current based approach for hotspot detection in photovoltaic strings

Abstract

Generally, photovoltaic (PV) panels are affected by variety of internal and external faults. Hotspot is regarded as an internal and permanent fault that is highly destructive in solar panels. In this study, a novel approach based on PV output current trajectory is proposed for hotspot detection in PV strings. The hotspot detection criterion consists of two parts. First, the Teager-Kaiser energy operator technique is applied for current change detection. Then, a novel hotspot detection index based on the cumulative rate slope calculation of PV current is applied. The proposed index has the advantage to distinguish between hotspot condition and other faults only by utilization of current measurement. The thermal behavior and the current trajectory are evaluated during hotspot condition. It is shown that the current characteristic of the cell during hotspot condition has a unique behavior, which is also justified by mathematical analysis. Different shading scenarios are considered in this study. However, the proposed approach can easily detect the one which cause hotspot condition and distinguish it from other type of scenarios. Therefore, the proposed approach can detect hotspot fault before the solar cell destruction. MATLAB simulations are applied in order to confirm the effectiveness of the proposed approach.