Comparative assessment of leakage current in a photovoltaic grid connected single phase transformerless inverter system

Abstract

Innovation in PV technology and increase in production capacity is making PV panel installation cost less expensive than past. To utilize available solar power effectively, high efficient power electronics converters are required. In a transformerless inverter system, several benefits such as reduction in cost, size and weight as well as high efficiency can be achieved. However, problem of leakage current, DC current injection and other safety issues occur in a system without isolation transformer. The common mode voltage is influenced by the selection of power electronic topology and PWM switching technique. Through this paper, the authors are making an effort to suggest suitable transformerless inverter topology based on comparison of leakage current. The PV inverter system connected to grid, is simulated for different transformerless inverter topology. Leakage current obtained from simulation result is compared to the standard norms. The control method is applied such that high efficiency and unity power factor is maintained. In addition a simple control structure is studied for two stage conversion.