EDF and BW ESS, a global energy storage developer, owner, and operator, have partnered on the first phase of the Hams Hall battery energy storage system (BESS) in North Warwickshire, a 350 MW/1243 MWh grid scale battery project and the longest duration battery EDF has contracted to date. The project will help support a more flexible and resilient UK electricity system as renewable generation continues to grow.
Under the terms of a 10-year floor agreement, EDF will optimise the project using its PowerShift platform, enabling the battery to deliver flexibility to the electricity system by balancing supply and demand, supporting grid stability, and helping integrate increasing volumes of renewable generation.
The project will initially deliver 350 MW of capacity, with a second phase adding 50 MW to bring the total site capacity to 400 MW/1424 MWh. Currently under construction on the northeastern fringe of Birmingham, the project is expected to reach commercial operation in 4Q26.
Hams Hall forms a key part of BW ESS’s UK portfolio and is co-owned with leading energy and decarbonisation investor AIP Management. Upon completion, it will become BW ESS’s largest capacity project globally; four times larger than Bramley BESS (100 MW/331 MWh), which was the UK’s largest at the time of its inauguration in February 2025.
Once operational, the batteries will be capable of supporting the electricity needs of around 1.3 million homes for up to 3.5 hours, providing a significant boost to UK energy security and system flexibility. The site benefits from proximity to major electricity load centres and is connected at the nearby Hams Hall 400 kV National Grid substation, reducing congestion risks while maximising access to arbitrage and balancing services.
Stuart Fenner, Wholesale Market Services Director at EDF, said: “Hams Hall will be the longest duration battery EDF has contracted to date. By optimising it through our PowerShift platform, we can unlock the flexibility needed to support more renewable power and help deliver EDF’s purpose of electrifying Britain.”
Kilian Leykam, Executive Director, Revenue, BW ESS, added: “We’re very pleased to welcome EDF as our optimisation partner on the Hams Hall project. This collaboration enables a revenue structure designed to maximise the commercial potential of this strategically important UK asset. By combining BW ESS’s experience in developing and operating utility scale battery storage projects with EDF’s optimisation expertise, we will ensure that Hams Hall delivers exceptional value while fulfilling its role as a key flexibility asset in the UK electricity system.”
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