Computation of Coupling Parameters between Neighboring Panels in Photovoltaic Arrays

Lightning phenomena are rather common for Photo-Voltaic Arrays, as these systems are usually deployed in open areas. A numerical assessment of the effects due to either direct hits or indirect strikes is very useful to preventively investigate possible damages to the structures or to electronic circuits connecting the array to the power grid. A 3D FEM simulation would require huge amounts of computational power, due to different geometric scales present in the model, ranging from the millimeter size of some circuital component to the kilometer scale of the lightning channel. Therefore, lumped models have been proposed to compute the overvoltage and overcurrent developing during lightning strikes. Such models comprise both actual electronic components (e.g., the solid-state devices for power conditioning) and equivalent elements describing lightning to photovoltaic panels coupling, but also interactions between neighboring panels in the array. In this work, the computation of such inter-panel coupling parameters is described, making use of different methods, combining semi-analytical expressions for stray mutual inductances and approximate solutions for stray capacitances.