Vanadium flow batteries store electrical energy in liquid electrolytes containing vanadium ions at different oxidation states. The electrolytes circulate through electrochemical cell stacks where charge transfer occurs during charging and discharging. Pumps, tanks, power conversion equipment and monitoring systems form part of a complete installation.
Why flow architecture changes the duration equation
Because much of the stored energy sits in external electrolyte reservoirs rather than inside the cell stack itself, changing storage duration can involve increasing electrolyte volume — a different engineering proposition from adding more cells or modules in a sealed battery format. In practice, that means power and energy can be sized somewhat separately, which is one reason flow systems attract attention for multi-hour duty cycles.
Lifetime throughput records electricity supplied across repeated cycles, not the energy capacity available in one discharge.
Endurium targets utility-scale and commercial duty
Invinity's Endurium family is designed for utility-scale and commercial applications where storage may be used repeatedly to absorb power and supply it later. Further cost reductions could depend on cell materials, repeatable stack manufacture, electrolyte handling, power electronics integration and more efficient assembly — though the company has not apportioned its proposed £10 million development allocation among these individual engineering activities.
An operational milestone, carefully read
A separate installed Invinity flow battery has delivered more than 1 GWh of cumulative energy throughput, an operational milestone disclosed in October 2026. That figure deserves precise interpretation. Lifetime throughput records electricity supplied across repeated cycles, not the energy capacity available in one discharge, and it does not establish a new sale or capital receipt.
The distinction matters commercially. Cumulative throughput is evidence of cycling endurance and electrolyte stability in the field — the attributes that underpin long-duration economics — but it is not a proxy for order intake, revenue, or the rated capacity of a single system. For developers evaluating flow technology against lithium-ion for daily cycling or longer-duration applications, the useful signals are degradation behaviour over thousands of cycles, round-trip efficiency, and the cost of stack replacement versus electrolyte top-up over the asset's life.
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