Transformerless Photo Voltaic Inverter Topologies for Low Power Domestic Applications

Abstract

 In the last two decades there is significant growth in solar power due to the developments in photovoltaic (PV) and power semi conductor technologies. Traditionally aphotovoltaic system consists of either a line frequency transformer on ac side or a high frequency transformer on dc side to provide galvanic isolation between PV panels and grid. By removing transformer from PV system, the size of the system can be reduced significantly and efficiency can be improved. However, with the presence of parasitic capacitance between PV and ground, a variable common mode voltage appears in the system. This results in increase of leakage current and distortion in grid current. This paper presents a study on various inverter topologies that are used in harvesting the solar power. Further, a simulation study is carried out on a single phase H4 topology to assess the performance using bipolar and unipolar pulse width modulation (PWM) techniques. The simulation study is carried out in MATLAB SIMULINK and results are presented.