Performance Comparison of Single-Phase Transformerless Grid-Connected PV Inverters

Transformerless inverter has been found as one of the economical solutions for grid-connected PV application because of its higher conversion efficiency, lower cost, smaller size, and light weight in comparison with those have a transformer. However, the problem of leakage current, DC current injection and other safety issues occur in a system without an isolation transformer. Standards featuring with ancillary services for the next generation PV systems have changed in some countries. The future PV systems have to provide a full range of services as what the conventional power plants do, e.g. Low Voltage Ride-Through (LVRT) under grid faults and grid support service. In this paper, several H-Bridge based transformerless grid-connected inverters have been compared to each other taking into account key factors of grid tied inverters such as leakage current and Common-Mode Voltage (CMV) in different modulations, reactive power injection, and LVRT capability.