Evaluation based on performance and failure of PV system in 10 years field-aged 1 MW PV power plant

Abstract

PV (Photovoltaic) power systems have been rapidly installed and spreading worldwide in recent years. And there is a belief that the PV power plant will operate stably for more than 25 years. However, the PV modules have an unexpected failure. In this paper, we diagnosed a 10-year-old power plant using drone with infra-red (IR) camera, current-voltage (I-V) and electroluminescence (EL) measurement. The approximately 1 MW plant, consisting of two different PV modules, 200 W and 220 W, showed various failure modes. 59% PV modules failure caused an output loss, and an inverter with a serious loss is expected to degrade more than its annual degradation rate in PV strings above 40%. As a result, the power loss was quantitatively estimated to hot spot, bypass diode failure and degradation rate, and the capacity of the current PV system was evaluated at 88.3% and 93.2%.