A modified MPPT algorithm with integrated active power control for PV-battery systems

Conventional operation strategy for photovoltaic (PV) system is to operate PV at maximum power point (MPP) for maximum energy harvest. However, this will cause problems in some scenarios. For PV-battery systems, when the batteries are nearly fully charged, operating PV at MPP will overcharge the battery, and decrease the lifespan of batteries. Besides, it has been reported that in some sunny days, surplus power generated by PVs can cause the turmoil of the distribution power network. To address this problem, this paper proposed a modified maximum power point tracking (MPPT) algorithm with integrated active PV output power control. The proposed algorithm has been experimentally verified in an off-grid PV-battery system. According to the Power-Voltage characteristic of PV, there are two possible operating points for reduced power output, thus, a comparison of two operation points is discussed.