Modelling and Transient Analysis of the Photovoltaic Systems Under Direct and Indirect Lightning Strokes

Since the photovoltaic systems are installed in outdoor or rooftops, transient overvoltages caused by lightning surges is one of the important factors that could lead to disruption in performance or failure of photovoltaic systems and equipment. Therefore, accurately modeling and study of these transients is necessary in order to effectively protect the photovoltaic systems. So far, the conventional model of solar panels that is used for lightning studies is purely resistive in which the stray capacitors are not considered; however, owing to the nature of high frequency being of lightning stresses, the effect of stray capacitances in voltage and electric field distribution is important. In this paper, an improved model to simulate the solar panels under transient conditions caused by lightning surges has been introduced so that in addition to the resistive structure used in conventional models, the effect of stray capacitances is also considered. Actual test results confirm the accuracy of the proposed model compared with conventional models. In the following, by simulating the frequency-dependent model for the overall structure of a photovoltaic system in EMTP-RV environment, the overvoltages caused by direct and indirect lightning strokes to photovoltaic panels have been analyzed. A method for determining the appropriate minimum distance between the lightning rod and solar panels to avoid damage to panels, if the lightning rod is struck by the lightning surges, is also provided.