Lithium-Ion vs. Vanadium Batteries: a hybrid system can level the cost of energy
British scientists at the University of Sheffield have recently conducted a study comparing the performance of Lithium-Ion Batteries (LIBs) with that of Vanadium-Flux Batteries (VFBs).

The experiment focused on a commercial building in Southern California, more specifically a grocery store, open 7 days a week from 6 a.m. to 11 p.m., with a total electricity demand of 1583 MWh in 2012.
During the summer, this single-story building recorded significant peak loads, impacting on the photovoltaic array installed on the roof.
The researchers’ experiment used a mixed approach, that first assessed the performance of a photovoltaic system associated with only Lithium-Ion Batteries (LIB), then they used only Vanadium Redox Batteries (VFB), and finally implemented a hybrid VFB-LIB system.
The building targeted in the research has an area of 4543 m², and being composed on only one floor, its roof has the same area.
In the researchers' assumption, the total area of the photovoltaic panels is 70% the roof size, so they multiplied the area of the photovoltaic array by an assumed 20% efficiency, estimating a photovoltaic rating of 636 kW.
In addition, the panel slope was set at 10° and the panel azimuth at 0°, and the impact of the horizon was considered as negligible.
After applying several algorithms to calculate degradation variables, including rainfall flowrate, the researchers drew their conclusions.
Both LIB and VFB batteries, as well as their hybridization in a large-scale photovoltaic array, could have levelled out the cost of energy, bringing it to less than 0.22 USD/kWh, while still ensuring a self-sufficiency ratio (SSR) of 0.95.
"Between 0.8 and 0.95 SSR, the optimal duration of both systems ranges from 6 to 7.5 hours," the researchers said.
Using both technologies in a hybrid system, like the one suggested by the research, it should be possible to alternate power generation by preferentially covering the daily cycle with Vanadium Flux Batteries (VFBs). On higher-net-load days, when the outdoor temperature is lower and the supermarket's energy demand is high, the cycle can be covered by Lithium-Ion Batteries (LIBs).
The researchers conclude that, given the overlap between LIB and VFB technologies, it is also important to assess the cost of electricity connected with Lithium-Ion Batteries, whose trend is presently upward.
For this reason, it would be preferable to increase the use of VFB batteries for prolonged periods of low energy demand, shifting to LIB batteries when higher peak loads are reached.
The researchers published their findings in the paper: "The economics of firm solar power from Li-ion and vanadium flow batteries in California," recently published by SpringerLink, one of the most prestigious scientific publishers.