Microgrids with integrated renewable resources are emerging as a solution for reducing the dependency on conventional fossil fuel and reducing emissions in distributed systems

Microgrids with integrated renewable resources are emerging as a solution for reducing the dependency on conventional fossil fuel and reducing emissions in distributed systems. The variability of renewable power sources requires quick response and highly efficient storage devices with larger power and energy density, which creates a challenge in developing renewable energy based microgrids in large scale. To obtain the optimal performance from an integrated renewable energy, round trip efficiency of the entire system must be characterized. Although many new energy storage technologies are reaching the consumer market, there is little field experience to support their adoption. Furthermore, most commercially available charging systems have been designed for lead acid batteries and when used with other energy storage technologies may adversely affect the round trip efficiency of the system. Thus the energy storage system may not reflect the manufacturers predicted performance. Therefore, in this project, we fully characterize the round trip efficiency of a photovoltaic system that uses a vanadium redox batter (VRB).The VRB energy storage system is an electrical energy storage system based on the vanadium-based redox regenerative fuel cell that converts chemical energy into electrical energy. The VRB differs from traditional battery storage in that the amount of energy it can store is independent of its power rating. The size of the stack determines the power rating whereas the amount of electrolyte determines the energy capacity. Thus the energy rating of the VRB can be changed by increasing or decreasing the amount of electrolyte in the storage tanks. Furthermore, the VRB can be stored for long periods of the tiome without charge degradation. In this project, a complete PV-VRB microgrid is characterized holistically.