MPPT battery charge controller for PV hybrid systems

Abstract

Interest in solar energy has grown significantly in recent years. Various topics are pursued to extend the performance of PV modules and the theoretical understanding of photovoltaics has been the subject of many researches. In hybrid solar energy systems, batteries are used as energy storage. Photovoltaic arrays provide energy during steady operating conditions, while batteries are used as energy sources during transient operating conditions (backup sources). This project report presents the design of a battery charging circuit that improves maximum power point (MPP) under variable solar irradiance and constant temperature at 25 °C through a smart MPPT (maximum power point tracking) algorithm. The boost converter output voltage drives an optimal PI-controlled Bi- directional DC/DC converter to behave like a battery charger circuit under uncertain atmospheric conditions (night, shade). The purpose of this study is to operate MPP-designed photovoltaic systems under different environmental conditions to achieve superior efficiency and minimize overall system cost and obtain the appropriate voltage and current for efficient battery charging, therefore reducing battery losses and improving life cycle. A prototype 100 kW photovoltaic array was designed, and a boost MPPT controlled PV system with a battery energy storage using a bi-directional DC/DC converter is simulated and studied in the MATLAB/Simulink environment.