On November 2, 2026, BW ESS announced that the first phase of its Hams Hall battery energy storage system in the West Midlands, UK, had entered commercial operation. Rated at 350 MW and 1,243 MWh, it is Europe's largest operating battery storage project by energy capacity, according to the announcement.

The project moved from energisation to commercial operation in 20 days. Its partners include Sungrow, Energy-IO and National Grid.

The distinction between the project's power and energy ratings matters: 350 MW describes its rated power, while 1,243 MWh describes its energy capacity. Dividing the latter by the former gives a nominal duration of approximately 3.6 hours at rated output, although actual operating duration will depend on how the system is used.

The 20-day interval highlights the transition from energisation to commercial operation, but it does not describe the project's full construction or commissioning timeline. Its longer-term significance will depend on operating performance and how the system is used over time.