Reliability Evaluation of Solar PV System Incorporating Insolation-Dependent Failure Rates

Abstract

This paper presents an improved method for reliability evaluation of a grid-connected photovoltaic (PV) system, where special consideration is given to the effects of variable solar insolation. Along with the negative impacts on reliability due to variable generation, the presence of variable solar insolation affects the power loss and junction temperature of power electronic components, which in turn impacts their failure rate. In this paper, a power loss model for PV power electronic components is developed to account for the aforementioned effect, which is integrated into the reliability model based on discrete convolution. The analytical reliability model is developed using a three-dimensional outage model that accounts for outage states due to array failure, string failure, and solar insolation change. The outage model is used to construct a PV capacity outage probability and frequency table (COPAFT), which along with conventional generation COPAFT, is convolved with the load levels. The efficacy of the proposed method is demonstrated on the modified IEEE RTS-79 system.