A Single-Stage CCM Zeta Microinverter for Solar Photovoltaic AC Module

Low power inverter mounted on each photovoltaic (PV) panel, i.e., microinverter is gaining popularity due to the increased energy harvest. This paper proposes a novel single-stage zeta microinverter for PV applications. The proposed topology is based on zeta converter with high-frequency transformer isolation and a single low side switch on the primary side of transformer. The most distinctive feature of the proposed inverter is its ability to work in continuous conduction mode (CCM) over a wide load range, which results in high efficiency, reduced current stress, and components´ rating. All the secondary switches operate at line frequency, thus reducing switching losses significantly. A comprehensive study of the proposed microinverter, including steady-state analysis and design, has been reported. A 220-W microinverter was designed, developed, and tested in the laboratory. Experimental results are demonstrated to verify the CCM operation of the inverter and its performance over a wide load range.