High Efficient Solar Energy Conversion Using Sepic Converter With String Current Diverter

Solar energy is the readily available and the cheapest form of energy. It is non-polluting and cheap of cost. Most of the proposed approaches thus far have relied on the use of series string of the DC-DC converter to create a high voltage string connected to the DC-AC inverter. However, under inhomogeneous irradiation, the power generated by each PV module and the output DC voltage of each boost become unbalanced so that the output currents of each DC-DC are balanced and equal to the string current. In this case, the boost converter cannot always deliver all the power from a mixture of shaded panels and those delivering full power. In this paper, a string current diverter is proposed to overcome this problem. One important feature of the proposed circuit is to decouple each converter from the rest of the string, making it insensitive to change in the string current. On the other hand, the string current diverter circuit is very easy to control and does not operate without inhomogeneous irradiation. Hence it is possible to obtain the maximum power from the PV module with the maximum power point tracking algorithm implemented on each DC-DC converter. The simulation and experimental results of the proposed topology are verified using MATLAB.