Ground currents in a photovoltaic power plant: Theoretical approach and experimental tests

Arrays of photovoltaic (PV) modules, mounted on metallic structures, always create stray capacitances between active conductors and ground. Thus, leakage currents flowing in these ground capacitances are formed. If the number of PV modules array is high, these currents can reach some amperes. Noticeable leakage currents can cause several problems related to the proper operation of electrical installation and appliances and to the safety of people. In this work, the problem of the ground currents in PV arrays is firstly studied from a theoretical point of view. Suitable equivalent circuits are presented. Then, the set-up and the results of a field measurement for the estimation of the leakage currents in an operating PV power plant are reported.