Protection of Photovoltaic Systems Against Direct Lightning Strokes

As the photovoltaic systems (PVs) are installed in open areas, lightning surges constitute a significant cause of PVs equipment failure. Therefore, the study of lightning-related overvoltages in PVs is vital, and guidelines for the protection must be investigated. This paper demonstrates the frequency-dependent modeling of PVs and determines the resulting overvoltages from direct lightning strokes in the EMTP environment. By analyzing the protection equipment including the lightning rods, surge protection devices (SPDs), the equipotential bonding system (EBS), and the integrated grounding system, the appropriate protection system against lightning overvoltages is proposed. The results show that by installation of SPDs, along with EBS and an integrated grounding system between solar panels and inverters, complete protection for inverters is achieved. In this mode, the energy stress experienced by SPDs is less than their energy handling capacity. As a result, the type of ground system implementation has a significant impact on the optimal performance of the SPDs. The paper also introduces a method based on rolling sphere theory and the Monte Carlo method for designing and placing lightning rods in PVs. The presented method is cost-effective compared to the conventional methods, as it determines the appropriate number and height of the lightning rods.