Power and Energy Rating Considerations in Integration of Flow Battery with Solar PV and Residential Load

Abstract

Integration of renewable energy sources such as solar photovoltaic (PV) generation with variable power demand systems like residential electricity consumption requires the use of a high efficiency electrical energy system such as a battery. In the present study, such integration has been studied using vanadium redox flow battery (VRFB) as the energy storage system with specific focus on the sizing of the power and energy storage capacities of the system components. Experiments have been carried out with a seven-day simulated solar insolation and residential load characteristics using a 1 kW VRFB stack and variable amounts of electrolyte volume. Several scenarios have been simulated using power and energy scale factors. Battery response, in terms of its power, state of charge and efficiency, has been monitored in each run. Results show that the stack power rating should be based on peak charging characteristics while the volume of electrolyte should be based on the expected daily energy discharge through the battery. The PV source itself should be sized at about 25% more energy rating than the average daily load. The ability to design a VRFB with a high power-to-energy ratio makes it particularly attractive for PV-load integration.

Constant-Power Characterization of a 5 kW Vanadium Redox Flow Battery Stack

“…The OCV was found to vary nearly linearly with SoC over this SoC interval. Over this range of SoC overpotential is solely dependant on current density, which is consistent with the results shown by Parameswarappa et al [3] and J.Langer et al [9]. Since the cycling protocols were carried out over fixed stack voltage ranges and higher power operation required higher overpotentials, the operating SoC range was lower at high powers.…”

“…Geographical location, seasonal conditions, and time decide the power extraction from the solar energy resource. The seven-day PV profile presented by Parameswarappa et al [3] shows large variability in power during insolation time as well as in the cumulative energy extracted on a day-to-day basis. A utility-scale electrical power plant is best operated continuously at its design condition while continuing to supply electricity as per the consumer demand, and leveling the peaks in demand ("peak shaving") is a major concern for these plants.…”

“…The ESS has to charge during low demand hours and discharge for short times during peak hours. In contrast, in a solar PV system integrated with residential load [3], charging occurs relatively quickly, and discharge occurs over a long period. Thus, the ESS requires to operate at different powers depending on the absorption and demand of the power.…”

Versatility of sulfonated poly (vinylidene fluoride‐co‐hexafluoropropylene) membranes incorporated with sulfonated octaphenyl polyhedral oligomeric silsesquioxane for vanadium redox flow battery applications

“…The eco-friendliness, fast response, ambient temperature operation, and high competence of these batteries provide great potential for long-term applications. [6][7][8][9] Recently, great attention has been given to the development of appropriate VRFB components such as electrodes, membranes, electrolytes and so forth. Ion-exchange (IE) membrane is considered as a state-ofthe-art component in VRFB system that can allow proton migration and defend electrolyte crossover for circuit accomplishment.…”

“…Besides, completely independent between the energy associated with the electrolyte capacity (tank size) and the power related to the reactor size in VRFBs. The eco‐friendliness, fast response, ambient temperature operation, and high competence of these batteries provide great potential for long‐term applications 6–9 …”