Fluence Energy Powers Up Massive UK Battery Site and Wins Deal to Double Its Capacity

Varco Energy (Varco), a pioneering UK-based battery storage asset owner and operator backed by the Adaptogen Capital Battery Storage Fund, and Fluence Energy UK Ltd. (Fluence), a subsidiary of Fluence Energy, Inc. (NASDAQ:FLNC), are pleased to announce Phase 1 of the Sizing John Battery Energy Storage System (BESS) has successfully entered full commercial operations.

The 57 MW / 137.5 MWh project is located within the Mersey Ring east of Liverpool, a region known for its acute grid constraints. In addition, Varco has launched Phase 2 of the project and selected Fluence to expand the site by an additional 85.5 MW / 201 MWh, to achieve a combined 142.5 MW / 348.5 MWh project.  On energisation of Phase 2, the Sizing John project will rank among the largest battery energy storage systems in the UK.

This milestone represents a major advancement in Varco's and Fluence's shared mission to accelerate the UK's energy transition by deploying innovative, utility-scale battery storage solutions in one of the nation's most constrained grid regions.

A Two-Stage, Innovative Approach to Grid Stability

The Sizing John project has been designed as a two-phase development to maximize both immediate and long-term impact. Phase 1 of the Sizing John BESS has a duration of 2.4 hours, which is one of the longest durations of any operational battery project in the UK. Its longer duration will help lower overall energy costs by addressing growing congestion in the region and reducing price volatility created by rising renewable generation.

Phase 1 is now fully operational, powered by Fluence's Gridstack solution, providing critical storage capacity to help balance local supply and demand and support renewable integration. Phase 2 has commenced construction with an expected commercial operation date in Q4 2026. Phase 2 will incorporate the Fluence-supplied next-generation Gridstack Pro 5000 with advanced grid-forming capabilities, providing critical support to the UK's grid by actively regulating voltage and frequency, providing essential regional grid stability.

Fluence has delivered and operates grid-forming projects worldwide, demonstrating the technology's role in supporting stable, renewable-based power systems. The importance of such technology has been underscored by recent events, such as the Iberian blackout, which highlighted the urgent need for assets that can independently support both grid voltage and frequency without relying on traditional synchronous generation.