Grid tie inverter control for rooftop photovoltaic system

This paper presents a simulation of grid-connected photovoltaic (PV) system under fast atmospheric variations. With varying irradiation and temperature condition the maximum power point tracking (MPPT) controller is presented. This MPPT controller allows an optimum extraction of energy from the PV module. A single-phase phase-locked loop (PLL) is introduced for the grid interfacing system which enables the PV inverter to get synchronizes with the utility grid. Also a current controller is proposed to fulfill two requirements in grid connected system that are, (i) during overload condition or incase of unfavorable atmospheric conditions the load requirements should be shared by both PV inverter and the utility grid and (ii) during light load condition the excess energy generated from the PV inverter should be feed to the utility grid.