EDF to optimise 1.2GWh battery project for BW ESS in England
Yusuf Latief
Posted on: 28 April 2026
It's the longest duration battery EDF has contracted to date and will be used to deliver flexibility to the UK's power system.
EDF and BW ESS have partnered on the first phase of the Hams Hall Battery Energy Storage System in England, a 350MW/1,243MWh grid-scale battery project and the longest duration battery EDF has contracted to date.
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 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 (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.
According to EDF, 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.
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Stuart Fenner, Wholesale Market Services Director at EDF, said by optimising the Hams Hall battery "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 of Revenue at BW ESS, said: “We’re very pleased to welcome EDF as our optimisation partner on the Hams Hall project.
“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.
The announcement comes as battery storage is increasingly seen as a cornerstone of the UK’s clean energy transition, described as such by consultancy firm Forvis Mazars, with around 6.1GW installed and several multiples in development.
At the same time, the economics of storage are becoming more complex. As highlighted in analysis on Energy Global, the market is shifting toward the consolidation of developers and platforms and the bundling of hardware and services for optimisation and multi-revenue strategies.
