Comparative analysis of single-phase grid connected transformerless photovoltaic inverter topologies

Transformerless inverters have change the way to connect a photovoltaic (PV) system to the electrical grid, due to their excellent performance in the energy conversion process. Nowadays, there are many different topologies for this kind of systems, that most have three main characteristics; high efficiency, constant common mode voltage and small size. Moreover, the control implementation must be simple and the cost should be low. Due to the wide variety of topologies, in this paper, a comparative analysis of efficiency in the case of three main single-phase topologies for transformerless grid connection is performed. The analysis is focus in the common mode currents and in the efficiency. The efficiency analysis includes an analysis of power losses distribution in the semiconductors which provide information to perform a good thermal design of the converter.