Risk Analysis of the Lightning-Related Transients on Photovoltaic Systems: Application to a Solar Power Plant Without a Lightning Protection System

Since photovoltaic systems (PVs) are installed in the open environment, they are exposed to lightning strokes in which the resulting overvoltages can lead to the failure of sensitive equipment including inverters and solar panels. This paper presents a method to analyze the lightning-related overvoltages in PVs and calculate the failure rate of sensitive equipment. In the presented method an accurate modeling of different equipment to perform the risk analysis of lightning transients is proposed. To evaluate the proposed method, a real PV power plant is simulated in EMTP software and the overvoltages caused by lightning stroke are calculated. The results of the simulation show that frequency-dependent modeling of PVs and modeling of the inverters' heat sink has a significant effect on the estimation of overvoltages generated at different locations of the PV power plant. The paper also proposes a method to calculate the failure rate of different equipment of solar power plants, i.e., inverters and solar modules. By knowing the failure rate of the equipment, the reliability of the PVs can be evaluated more accurately and the implementation of a protection scheme for the lightning strokes can be achieved more economically.