A novel topology for solving the partial shading problem in photovoltaic power generation system

In centralized or string photovoltaic (PV) systems, PV modules must be connected in series in order to generate a sufficiently high voltage to avoid further amplification and to efficiently drive further converters. This always requires dozens of PV modules, however some of them maybe suffer from partial shadow caused by trees, clouds or other things. In this case, power generated from each PV module becomes unbalanced so that total output powers greatly decrease. Furthermore, hot-spot effect caused by partial shadow is likely to damage the PV cells and affect the security of PV system. In order to solve these problems, a novel topology of PV system composed of many series-connected PV modules with corresponding energy feedback circuits is proposed in this paper, a feedback circuit is independently utilized to feed the output energy of PV system to the corresponding circuit including shadowed PV module. The simulation and experimental results verify that the proposed topology can make each PV module operate on the maximum power point individually regardless of partial shadow. The energy feedback circuits do not operate without partial shadow, they have no power loss under this condition, therefore the circuit efficiency is improved.