A PERFORMANCE COMPARISON OF HIGH-EFFICIENCY TRANSFORMER-LESS PV INVERTERS

In order to improve the efficiency and reduce the cost of photovoltaic (PV) systems, the use of transformer-less inverters is an alternative of increasing interest. However this topology needs to be studied in detail, as the absence of a galvanic isolation between the grid and the PV array leads to some problems, such as DC current injection and leakage currents. Transformer-less inverters shall comply with leakage current and power quality limits and reactive power handling capability, which are requested by national grid codes. These stringent requirements have triggered a race among PV inverters producers and among researchers to find the best possible PV inverter. This paper aims at benchmarking some recently published or patented topologies with the most successful industrial products and it offers a complete trends scenario and a critical comparison. The performances are evaluated in terms of efficiency, common mode voltage, leakage current, power quality, reactive power handling capability, size of the grid filter and power converter rating.