Voltage-based hot-spot detection method for photovoltaic string using a projector

Abstract

This paper proposes a voltage-based hot-spot detection method for photovoltaic (PV) string using the projector. Hot-spots form in solar cells at defects causing a high carrier recombination rate, it appears as a high reverse leakage current of p-n junctions when solar cells are partially shadowed. Using this characteristic, authors previously developed a voltage-based hot-spot detection method to quickly identify and characterize the severity of a module hot-spot. However, previous experimental results were shown for just one module. In this paper, experiments are done on plural modules in the string. From the result, this method works effectively for PV string. Correlations among illuminance, load resistance, hot-spot temperature, and risk factor are also discussed.