IN Brief:
- The Didcot project will provide 300MW of power and 600MWh of battery capacity.
- Eku Energy acquired the development from TBC Partners and expects construction to start in 2026.
- An underground cable will link the two-hour system to the upgraded Didcot transmission substation.
Eku Energy has acquired a planned 300MW/600MWh battery energy storage project at Didcot in Oxfordshire from TBC Partners. Construction is expected to begin later in 2026, with the two-hour system scheduled to connect to National Grid’s Didcot substation in 2028 through a new underground cable.
The acquisition moves Eku into control of a project with a defined transmission connection and a construction timetable, although procurement, financing, and final delivery work remain. At 300MW, the facility would rank among the larger batteries in the UK market. Its 600MWh energy capacity would allow full-power discharge for two hours before operating limits and conversion losses.
The battery will connect directly to the transmission system at Didcot. National Grid has been upgrading the substation with three new electrical equipment bays and three supergrid transformers, creating infrastructure capable of handling additional power flows. The project will connect south-west of the site, at a node associated with major historic generation and an increasingly complex mix of demand, renewable output, and network reinforcement.
TBC Partners developed the project before the sale. Eku will now take responsibility for progressing it through construction and operation, bringing experience from storage projects in the UK, Australia, Japan, and other markets. Acquisition of a development-stage asset can shorten the route to a portfolio-scale project, but it also transfers connection, planning, supply chain, and market risks to the buyer.
A large battery entering a changing market
The UK battery sector has expanded rapidly as renewable generation, price volatility, and balancing requirements have increased. Early projects could rely heavily on frequency-response revenues, but those markets became crowded as capacity grew. New assets increasingly require a broader revenue stack spanning wholesale trading, the Balancing Mechanism, reserve products, capacity market payments, and network services.
A two-hour duration gives Didcot enough energy to cover short evening peaks and respond to intraday price spreads, while retaining the fast response expected from lithium-ion systems. It is less suited to multi-day renewable shortfalls, which require longer-duration storage, demand management, interconnection, or dispatchable generation. The commercial model must match the plant’s physical capability rather than treating all storage megawatts as interchangeable.
The 2028 connection date provides a route to market but exposes the project to changes in balancing products, grid charges, and competitor capacity before operation begins. National Grid’s substation works reduce one infrastructure uncertainty, although detailed compliance studies, protection coordination, metering, and commissioning must still be completed. A fixed connection date also shapes equipment procurement because transformers and switchgear can carry long manufacturing lead times.
The underground cable will form part of the project’s high-voltage electrical system, linking the battery’s power conversion equipment and transformers to the transmission network. Cable rating, route, thermal performance, earthing, and protection design will influence both construction and long-term availability. Large battery projects are often described by container count, but the grid connection and balance of plant determine whether those containers can exchange power reliably.
Delivery discipline matters more than portfolio headlines
Eku has identified construction later this year, leaving a relatively compressed period for equipment contracting and mobilisation. Battery cells, inverters, transformers, switchgear, control systems, and fire-safety equipment must be specified as an integrated plant. Long lead times for high-voltage transformers and connection equipment can become critical-path items even when battery modules are readily available.
Operational strategy will also affect degradation. Frequent cycling can increase revenue but consume cell life, while holding reserve capacity may reduce energy throughput but create availability obligations. Optimisation software must balance immediate market prices against warranties, state-of-health forecasts, and the need to remain compliant with connection and capacity market requirements.
The project adds a substantial controllable asset to a part of the network already undergoing reinforcement. It can absorb excess electricity, reduce short-duration imbalances, and inject power rapidly when demand or system prices rise. Those functions will be valuable only if the plant is available at the required times and if market arrangements reward behaviour that supports the network rather than simply moving congestion between settlement periods.
The acquisition transfers a development package, not a completed asset. Eku must convert it into a commissioned 300MW plant by 2028 while the UK storage market becomes more competitive and technically demanding. Operating availability and response accuracy after energisation will determine the project’s value. Construction, commissioning, grid-code compliance, and cell-performance management remain ahead.