High Efficiency PV fed Home Inverter with Grid Interfacing Capability

This paper presents a residential photovoltaic (PV) system with maximum power point tracking (MPPT) and grid interfacing ability. A multi-level boost converter (MBC), a battery bank and a half bridge inverter have been used to perform the function. A PV panel rated for 250 W, 29 V, 8.6 A is boosted to 72 V by the MBC. As the battery bank is connected at the output of the MBC, the output voltage is clamped at the battery voltage and is constant irrespective of irradiation. The power exchange between the PV array, battery bank, load and the grid has been suitably managed by the closed loop controller. Hence, reliable power has been delivered to the load. Variation in PV power is not reflected in the load voltage or dc bus voltage; instead changes occur only in the MBC output current. This leads to the elimination of voltage sensor for MPPT. The proposed system thus uses only the dc link current data for obtaining MPPT unlike the traditional systems that uses both voltage and current. The half bridge inverter is used to deliver the generated power from PV panel to the grid and load. The complete scheme rated for 250 W has been modeled using MATLAB/ SIMULINK and the results are compared in open loop and closed loop modes. The results gave a close agreement proving the efficacy of the system.