Analysis and diagnosis of hot spot failure in c-Si PV module

Abstract

The hot spot types in crystalline silicon photovoltaic(c-Si PV) module can be divided into the followings: series resistance type, cell reverse biased type, bypass diode over-current type and direct-current (DC) arc type. The most common type was cell reverse biased type (hot spot as we know). By collecting all kinds of failed PV module (PID, aging, glass fragmentation, short circuit of bypass diode, and back sheet cracking) in practical power station, the characteristic parameter of cell reverse biased hot spot was determined after comparative analysis of IV curve. Based on this characteristic parameter, a set of diagnostic procedure was designed. Then we tested the procedure on the power optimizer, the diagnostic accuracy of hot spot was 95% and the recall rate was 96%. In order to reduce the temperature of hot spot, we added aluminum fins on the back of PV module, and the temperature of hot spot was lowered maximum by 19.3°C compared with conventional module, which indicated that the aluminium fins have a certain cooling effect.