£10m · Series A · Energy · London, UK
British long-duration energy storage company Certain Energy has closed a £10m Series A led by the British Business Bank, with Centrica, Ceres Power and Temasek Trust's Catalytic Capital for Climate and Health participating. The company, previously called RFC Power, said in its 26 August announcement that the funding will commercialise its manganese flow battery technology and prepare it for deployment.
The round is not simply a cash injection. Ceres' regulatory announcement says its contribution comprises £1m in cash and £1.5m of equity issued for engineering services. Ceres will retain roughly 37% of the company and receive a share of future product revenue. The British Business Bank separately confirmed a £3.5m investment, while the full syndicate backs a business moving from university-derived technology towards a grid-connected system.
The tanks carry the duration
Certain Energy's system stores and releases energy through a patented hydrogen-manganese chemistry. In a flow battery, energy capacity can be increased by enlarging the electrolyte tanks rather than redesigning the electrochemical stack. That gives the company a route to extend storage from hours into days while separating the cost of energy capacity from the power hardware.
The company reports system round-trip efficiency above 75%, a design life of more than 20 years and a target energy-storage cost below $20/kWh. Those are company targets and performance claims, not yet proof of commercial operation at grid scale. The Series A's central milestone is therefore a planned grid-connected MWh-class system in India, alongside an expanded UK research facility and a supply chain capable of delivering repeatable projects.
That programme matters because storage economics are not decided by chemistry alone. A grid customer needs evidence that a system can be manufactured consistently, installed, serviced and financed over a long operating life. Certain Energy says it will work with existing production facilities and supplier networks rather than build a dedicated gigafactory. If the India system validates performance outside the lab, that partner-led model could reduce the capital needed to scale; until then, commercial deployment remains the execution test.
A spinout becomes independent again
The business began as an Imperial College London spinout in 2017. Ceres acquired RFC Power's remaining share capital and intellectual property in September 2025, then used this financing to spin the company back out under the Certain Energy name. The result is an independent company with strategic investors across public capital, energy operations and engineering.
That ownership structure may provide more than funding: Ceres is contributing technical services, while Centrica brings a utility perspective. But the announced relationships are not customer orders. The next evidence to watch is whether the MWh demonstration and supply-chain work convert the battery's claimed cost and durability into replicable deployments.
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Climate hardware scales when trust becomes repeatable — Daniel Betts, Christian Hernandez Gallardo & Blue Frontier, hosted on EUVC · 8 October 2026. The article examines the same transition from technical proof to field evidence, repeatable manufacturing and buyer confidence.
