Varco and Fluence Unveil 142.5 MW Battery Energy Storage System to Support UK Grid
United Kingdom-based energy storage project developer and owner Varco Energy and the UK subsidiary of battery manufacturer Fluence Energy have put the first phase of the Sizing John Battery Energy Storage System into commercial operation near Liverpool.
The 57 MW / 137.5 MWh Sizing John project is located within the Mersey Ring east of Liverpool, a region known for its acute grid constraints. Varco is operating Phase I and has also launched Phase 2 of the project and selected Fluence to expand the site by an additional 85.5 MW / 201 MWh, to eventually achieve a combined 142.5 MW / 348.5 MWh project.
U.S.-based Fluence Energy, which started as a spinoff joint venture of Siemens and AES, has begun deploying its battery cubes and technologies globallly, including to Ukraine in the past year.
“Bringing Sizing John Phase 1 to operation and announcing Phase 2 is a testament to Varco’s commitment to innovation and grid resilience,” said Richard Whitmore, Director, Varco Energy, in a statement. “The addition of grid-forming capabilities will set a new standard for regional grid support, especially in the wake of the recent Iberian Peninsula blackout.”
Phase 1 of the Sizing John BESS will have a duration of 2.4 hours, which will help lower overall energy costs by addressing growing congestion in the region and reducing price volatility created by rising renewable generation. The first phase is powered by Fluence’s Gridstack battery solution.
Phase 2 has commenced construction with an expected commercial operation date in Q4 2026. Phase 2 will include the Fluence-supplied Gridstack Pro 5000 with advanced grid-forming capabilities for support to the UK’s grid by regulating voltage and frequency and providing essential regional grid stability.
The achievement marks the second Varco project to start operations after Native River BESS commenced full commercial operations in April 2025. Over the next 18 months, Varco expects to energize 250 MW of battery storage assets in the UK.