# BW ESS starts Hams Hall, Europe's largest battery by capacity at 1,243 MWh

- Published: 2026-11-04 06:11 UTC
- Section: Power & Energy › Energy
- Tags: BW ESS Hams Hall, battery energy storage system, BESS UK, largest battery Europe, 1243 MWh, grid storage, National Grid
- URL: https://realtech.media/news/rt-d955f1e6584b00e5eee61a12_bw_ess_starts/

**The first phase of the West Midlands project brings 350 MW / 1,243 MWh online, reaching commercial operation 20 days after energisation.**

![Rows of containerised battery storage units at a grid battery station.](https://sgzwpqqelzmajkcubgkl.supabase.co/storage/v1/object/public/rt-media/2026/11/a7eb739d25d56a31.jpg)
*Illustrative photo of a grid-scale battery storage station; Hams Hall is not pictured.*

## Key points

- Phase one of Hams Hall brings 350 MW / 1,243 MWh into commercial operation.
- BW ESS says it is the largest battery in Europe by MWh.
- Commercial operation came 20 days after energisation.
- Phase two will raise the total to 400 MW / 1,424 MWh.

BW ESS has started commercial operations at the first phase of its Hams Hall battery energy storage system in North Warwickshire, England, adding 350 MW / 1,243 MWh to the grid [1][2]. The company announced the milestone in London on November 2 and says it makes Hams Hall the largest battery in Europe by storage capacity in MWh [2][3].

## Hams Hall battery: phases and numbers

Phase one reached commercial operation just 20 days after energisation and was built "on budget and ahead of schedule", according to chief executive Erik Strømsø [2]. The site connects to the nearby Hams Hall 400 kV National Grid substation [2].

| Parameter | Phase 1 | After phase 2 |
|---|---|---|
| Power | 350 MW | 400 MW |
| Storage | 1,243 MWh | 1,424 MWh |
| Duration | about 3.5 h | about 3.5 h |

BW ESS says the full 400 MW / 1,424 MWh system will be able to support around 1.3 million homes for up to 3.5 hours [2]. Sungrow, Energy-IO, National Grid and the system operator NESO worked with the company on commissioning, testing and preparation for operation [2].

## How the project is financed

Revenue is underpinned by a 10-year floor agreement with EDF, which guarantees a minimum income while the battery trades in the market [2]. In October BW ESS secured debt financing for the full 400 MW / 1,424 MWh project from OCBC, Rabobank and Societe Generale [2]. Hams Hall joins the 331 MWh Bramley battery in Hampshire in the company's UK portfolio, and it is part of the 2.6 GWh Ardenham portfolio co-owned with AIP Management [2][3].

Long-duration batteries of this size let the grid store surplus wind and solar output and release it during evening peaks, reducing curtailment of renewables.

## Our outlook

Phase two should lift Hams Hall to 1,424 MWh, and multi-hour projects of this size are becoming standard in Britain. The pace of grid connections, not battery supply, remains the main limit.

## Sources

1. [BW ESS news](https://bw-ess.com/news)
2. [Energy-pedia](https://www.energy-pedia.com/news/united-kingdom/bw-ess-announces-commercial-operations-of-hams-hall-battery-energy-storage-system-205918)
3. [Renewable Energy Magazine](https://www.renewableenergymagazine.com/storage/bw-ess-announces-commercial-operations-of-hams-20261102)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-d955f1e6584b00e5eee61a12_bw_ess_starts/