Integration of Vanadium Redox Battery with PV systems: Modeling and operational characteristics

Large-scale photovoltaic (PV) installations have experienced an unprecedented growth in the last few years, mainly due to renewable energy generation targets, government incentives, reduced installation costs and continuous advancement of the PV technologies. However, this growth brings new technical challenges to the electricity grid. For instance, the inherent intermittency of PV power has given rise to a number of approaches to compensate for the variability in its output. A possible solution could be the integration of battery energy storage with the PV power plants. The Vanadium Redox Battery (VRB) is one of the batteries having the potential to increase the supply reliability of large-scale PV power plants. This paper proposes the grid integration of a PV system using the VRB energy storage. The VRB was designed to smooth the fluctuating PV power, thus being able to deliver constant power to the electricity grid within a 5 minutes time frame (Australian Energy Market trading interval). An equivalent electrical model of a 26kW PV system including a 5kW, 1.25kWh VRB was implemented in MATLAB/Simulink/PLECS environment to analyze the operational performance of the proposed PV system.