EDF has partnered with BW ESS on the first phase of the Hams Hall battery energy storage system (BESS) in North Warwickshire, UK, a 350MW 1,243MWh grid-scale project that will become the longest-duration battery contracted by EDF to date.
The Hams Hall Phase One installation, currently under construction on the northeastern edge of Birmingham, is designed to deliver up to 3.5 hours of storage. It is expected to enter commercial operation in Q4 2026. A second phase is planned to add a further 50MW, bringing total site capacity to 400MW / 1,424MWh.
Under a 10-year floor agreement, EDF will optimise the asset using its PowerShift platform, enabling the system to provide flexibility services including balancing supply and demand, supporting grid stability and integrating higher shares of renewable generation.
BW ESS’s largest project globally
Hams Hall is co-owned by BW ESS and AIP Management, and represents a major expansion of BW ESS’s UK portfolio. Once completed, it will be the company’s largest project globally – around four times the size of the 100MW 331MWh Bramley BESS, which was the UK’s largest at its commissioning in February 2025.
The site is connected via the nearby Hams Hall 400kV National Grid substation, providing access to key electricity demand centres and reducing network congestion risks while maximising participation in arbitrage and balancing markets.
Once operational, the system is expected to supply electricity equivalent to the needs of around 1.3 million homes during peak periods.
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 expanding battery storage portfolio, reflecting the growing role of long-duration BESS in supporting a more flexible and resilient UK electricity system as renewable generation increases.
Photo: Hams Hall Battery Energy Storage System (BESS) in North Warwickshire, UK, April 2026. © BW ESS
