BW ESS Starts Commercial Operation at 1,243-MWh Hams Hall Battery

• BW ESS started commercial operation of Hams Hall phase one in England in October: 350 MW / 1,243 MWh.
• The company says the site is Europe's largest battery by MWh; it reached commercial operation 20 days after energisation.
• A second phase will lift the site to 400 MW / 1,424 MWh; BW ESS has not given a date.

BW ESS has started commercial operation of the first phase of its Hams Hall battery in North Warwickshire, England, bringing 350 MW / 1,243 MWh online, the company said on Nov. 2. The milestone came in October, 20 days after the site was energised.

The battery sits next to National Grid's 400-kV Hams Hall substation. BW ESS says it is now Europe's largest battery by storage capacity. Sungrow, Energy-IO, National Grid and the system operator NESO worked with BW ESS through commissioning and testing. Sungrow agreed in 2024 to supply 280 grid-forming PowerTitan 2.0 units, about 1.4 GWh in total.

The start-up follows the bank debt BW ESS secured in October from OCBC, Rabobank and Societe Generale. A 10-year floor and optimisation agreement with EDF underpins revenue. Under that deal EDF optimises the battery with its PowerShift flexibility platform, using it to balance supply and demand on the grid.

Hams Hall phase one in numbers

• 350 MW / 1,243 MWh now in commercial operation, out of a planned 400 MW / 1,424 MWh.
• 87% of the site's final storage capacity sits in phase one; phase two adds 50 MW and 181 MWh (list.solar calculation).
• 3.55 hours of discharge at full power from phase one (list.solar calculation).
• 20 days from energisation to commercial operation, according to BW ESS.
• 7%: phase one's 350 MW against the 4,956 MW of operational batteries listed in the government's July 2026 Renewable Energy Planning Database (list.solar calculation).
• 23–27 GW of batteries needed in Great Britain by 2030 under the Clean Power 2030 Action Plan, up from 4.5 GW at the end of 2024.

"The project was built and commissioned on budget and ahead of schedule," Chief Executive Erik Strømsø said in a statement.

BW ESS now runs more than 1.8 GWh of battery storage worldwide, up from more than 540 MWh when it announced the Hams Hall debt on Oct. 22. In the UK, Hams Hall joins its 331-MWh Bramley battery in Hampshire. Hams Hall belongs to the 2.6-GWh Ardenham portfolio that BW ESS co-owns with AIP Management.

BW ESS is also building 857 MWh at Berkswell in England. It has not given a date for Hams Hall's second phase.