Simple method of PV cells balancing for maximum power harvesting in partially shaded environment

The energy, generated by photovoltaic (PV) module consisting of serially connected PV cells is considerably reduced when a unit is shadowed or has a defect. This problem can be remedied by bypassing the weak units by an active circuitry, such as power converter, connected in parallel to the PV units. This way the power converter balances the power between the PV units. This study evaluates the effectiveness of the unity-gain voltage balancing method to the PV strings comprised of PV cells. The results of this study show that the unity-gain voltage balancing strategy is highly effective when applied to cell-level since no significant voltage differences exist between the MPP voltages of the cells in the string. For steady state operation, the power loss due to the equalization was below 3% even for a high difference in temperature and insolation.