Leakage Current Calculation for PV Inverter System Based on a Parasitic Capacitor Model

The occurrence of leakage current that can occur in photovoltaic (PV) system depends strongly on the value of parasitic capacitance between PV panel and the ground. However, traditional method to acquire that value is by experience estimation. This paper presents a novel 2-D parasitic edge capacitance model and a straightforward approach to accurately calculate the involved panel parasitic capacitance. The parasitic capacitances are divided into cell-to-frame capacitance C_cf, cell-to-rack capacitance C_cr, and cell-to-ground capacitance C_cg. Based upon that, a pi-shape circuit model is derived to predict the leakage current in the PV array. Theoretical calculation, MATLAB simulations, and experimental measurements finally verify the accuracy of the proposed methods. The approaches are very useful for the evaluation of leakage current in the PV system. It is demonstrated that the proposed approach combines the ease of applications and satisfying accurateness.