A low cost single-phase grid-connected photovoltaic system with reduced complexity

This paper presents a grid-connected photovoltaic (PV) system using the classical DC-DC buck converter, which is responsible for stepping down the resulting voltage from several series-connected panels. Besides, the buck converter provides sinusoidal current injected into the utility grid, which is possible by using hysteresis modulation. A CSI inverter employing thyristors is cascaded with the DC-DC stage so that AC voltage results. The inverter output voltage level is adjusted by using a low frequency transformer, which also provides galvanic isolation. Low cost, simplicity, and reduced harmonic content of the injected current are direct advantages of the proposed system, which is designed and analyzed by simulation. An experimental prototype is also implemented, as relevant results are presented and discussed.