EDF and BW ESS, the 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 350MW / 1,243MWh 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 350MW of capacity, with a second phase adding 50MW to bring the total site capacity to 400MW / 1,424 MWh. Currently under construction on the northeastern fringe of Birmingham, the project is expected to reach commercial operation in Q4 2026.
Hams Hall forms a key part of BW ESS’s UK portfolio and is co-owned with energy and decarbonisation investor AIP Management. Upon completion it will become BW ESS’s largest capacity project globally; four times larger than Bramley BESS (100MW / 331MWh), 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 400kV 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 maximize 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.”
The project forms part of EDF’s growing battery storage portfolio, supporting the increasing role of grid-scale batteries in balancing the electricity system as wind and solar generation continue to expand across the UK.
