IN Brief:
- Hunterston has reached financial close and received notice to proceed following its June final investment decision.
- Santander, Barclays, Commonwealth Bank of Australia and NatWest are providing non-recourse senior debt.
- Sungrow will supply the 400MW/800MWh battery system, with OCU Group delivering the balance of plant.
Revera Energy has reached financial close and issued notice to proceed on the 400MW/800MWh Hunterston battery energy storage system in North Ayrshire, moving the project into construction.
The Carlyle-backed developer is targeting commercial operation during the third quarter of 2028. Hunterston follows the final investment decision announced in June and becomes Revera’s second UK transmission connected battery project to reach financial close during 2026.
Santander, Barclays, Commonwealth Bank of Australia and NatWest are providing non-recourse senior debt. Sungrow will supply the battery storage system and provide long term servicing, while OCU Group has been appointed balance of plant contractor and long term operations and maintenance provider.
Part of the project’s commercial structure has also been fixed ahead of construction. BP will provide a long term tolling arrangement and Danske Commodities a long term floor structure, with both companies providing trading and optimisation services.
The latest step moves Hunterston materially beyond the final investment decision reached in June. FID established the developer’s commitment to proceed; financial close completes the senior debt package, while notice to proceed releases the project into execution with the principal equipment, construction and commercial counterparties identified.
Hunterston will connect to SP Energy Networks’ 400kV transmission system on Scotland’s west coast, close to the former Hunterston nuclear stations and north of the B6 transmission boundary. The location puts the battery within a part of the network that carries substantial renewable output from Scotland towards demand further south.
At 400MW and 800MWh, the battery provides approximately two hours of discharge at maximum rated power. That configuration supports short-duration energy shifting, balancing and ancillary services while retaining the high power capability needed to respond rapidly to changes in system conditions.
The plant extends well beyond the battery enclosures. A transmission connected installation of this size requires high voltage transformers, switchgear, protection, metering, auxiliary supplies, controls, communications and a private substation capable of interfacing safely with the 400kV network.
The control architecture also has to coordinate state of charge with trading instructions and network requirements. Battery blocks may be dispatched according to market prices, contracted services or grid conditions, but the combined site must continue to respect its connection limits and protection settings throughout those operating modes.
Sungrow’s package covers the storage system, while OCU’s balance of plant role spans the infrastructure required to connect that equipment to the network. The division creates engineering interfaces around auxiliary power, communications, protection settings, controls and performance testing that have to be closed before commissioning.
The revenue structure is similarly distributed. Batteries can earn income through wholesale trading, balancing, ancillary services, capacity arrangements and other flexibility markets, but those revenue streams change as competition and system requirements develop.
Tolling and floor structures can provide greater revenue visibility than a wholly merchant operating model. That can support debt financing by limiting some exposure to market volatility while leaving the project operator and optimisation providers able to capture additional value within the contractual structure.
Revera says Hunterston forms part of a UK portfolio of up to 1GW and 2.8GWh. Its 200MW/400MWh Windyhill project is already under construction and is expected to enter commercial operation in the fourth quarter of 2027, while up to another 400MW/1.6GWh of consented storage has grid access and capacity market contracts.
The additional pipeline points towards longer storage duration. Hunterston and Windyhill are both two-hour systems at their headline ratings, whereas 400MW paired with 1.6GWh would provide four hours at maximum output. Longer duration allows a plant to shift more energy between periods but increases capital requirements and changes the revenue profile needed to support the asset.
Large battery projects can appear modular because substantial parts of the system arrive as factory assembled equipment. The site programme remains a major electrical and civil undertaking, with foundations, drainage, fire systems, cabling, transformers, switchgear, communications and staged energisation all required before the battery blocks can operate as one plant.
Financial close puts Hunterston firmly into that delivery phase. Its battery supplier, balance of plant contractor, lenders and commercial optimisers are now established, leaving equipment delivery, grid works and commissioning to determine whether the Q3 2028 operating target can be maintained.
The next evidence of progress will come from construction rather than another investment milestone. Hunterston has moved from an approved project into a financed transmission connected asset with notice to proceed issued and the principal delivery interfaces assigned.
