French utility EDF is working with energy storage developer BW ESS on the first phase of the Hams Hall battery energy storage system (BESS) in North Warwickshire.
Through its PowerShift platform, EDF will optimize the 350 MW/1,243 MWh BESS plant, under a ten-year floor agreement. This allows the battery to provide flexibility to the electricity grid by balancing supply and demand, supporting grid stability and promoting the integration of new renewable energy generation.
The project is currently under construction and is expected to be commercially operational in the fourth quarter of 2026, with a second phase expected to add 50MW/210MWh of capacity at a later date. Hams Hall is a key project in BW ESS’s British portfolio and is co-owned by energy investor AIP Management, which acquired a 49% stake in the project and other UK assets September 2025.
Once operational, the project will be the largest BW ESS capacity project in the world. the Bramley BESS project quadrupled (100 MW/331 MWh), the largest operational BESS plant in the United Kingdom at the time, according to the company.
Stuart Fenner, Director of Wholesale Market Services at EDF, said: “Hams Hall will be the longest battery life contracted by EDF to date (3.5 hours). By optimizing this through our PowerShift platform we can unlock the flexibility needed to support more renewable energy and help achieve EDF’s goal of electrifying Britain.”
The site benefits from proximity to major electricity charging centers and is connected to the nearby Hams Hill 400kV National Grid substation. This allows the project to reduce congestion risks while maximizing access to arbitration and balancing services.
This latest optimization partnership further expands EDF’s growing battery storage portfolio in the country, and comes a month after the utility secured a similar partnership with independent power producer Matrix Renewables. EOF will provide route-to-market (RTM) services and optimization for the 500 MW/1,000 MWh Eccles BESS project in Scotland, once it begins commercial operations in summer 2027.
