A Review on H6 Transformerless PV Grid-Tied Inverters

Photovoltaic (PV) grid-tied inverters are essential for integrating solar energy into modern power grids. Transformerless topologies have become increasingly significant due to their superior efficiency, reduced cost, and compact size compared to traditional transformer-based inverters. Among these, the H6 topology has gained prominence for its ability to suppress common-mode (CM) leakage currents and maintain high efficiency. This paper reviews the principles, advantages, limitations, and applications of the H6 topology, with a comparative analysis against other transformerless inverter designs such as H5, HERIC, and NPC. Particular emphasis is placed on leakage current suppression, control strategies, and future research directions involving wide-bandgap devices and AI-based optimization. Reported efficiencies exceed 97%, making H6 inverters suitable for residential and commercial PV applications. This review highlights ongoing challenges in EMI, thermal management, and grid compliance, and provides insights into future developments in PV inverter technology.