A 400 MW / 800 MWh battery on the Ayrshire coast reached financial close on 23 September and issued notice to proceed the same day, putting construction of one of Scotland's largest storage assets on a path to commercial operation in the third quarter of 2028. The developer is Revera Energy, a platform Carlyle launched in May 2025. The battery will be built by Sungrow. The revenue will be shaped by bp and Danske Commodities.
Read the counterparty list as a document rather than an announcement. It is a fairly precise description of what it now takes to finance a transmission-connected battery in Britain.
Hunterston sits in North Ayrshire, about 50 km south-west of Glasgow, immediately north of the B6 boundary that Revera describes as one of the most persistent power grid bottlenecks in the country. It is roughly a mile from the Hunterston A and B nuclear stations; Hunterston B stopped generating in 2022, and decommissioning at Hunterston A began in 1990. The site connects to SP Energy Networks' 400 kV transmission system, and construction of a private 400 kV substation is already under way.
That location defines the asset's job. Scotland generates more wind than it can move south, and the constraint between Scottish generation and English demand is a recurring cost to the system. A battery at the constraint does not only trade energy; it earns from relieving congested hours and from the stability services that retired nuclear and thermal plants used to provide. The commercial case is therefore partly a network case, which is what makes it financeable at this scale.
Revera reached final investment decision on Hunterston in June 2026. It is the platform's second UK transmission-connected battery to close this year: Windyhill, at 200 MW / 400 MWh in Glasgow, closed in February and is under construction with operations targeted for the fourth quarter of 2027. A third project, Kincardine in Fife at 400 MW / 800 MWh, is expected to start construction in the first quarter of 2027. Together the three represent 1 GW / 2 GWh and more than GBP 500 million of investment in Scotland, with Revera estimating around 550 direct construction jobs and 45 long-term operational roles. Scotland's First Minister John Swinney welcomed the investment publicly, calling the portfolio one of the largest battery storage builds anywhere in the UK.
| Counterparty | Role | What it does for the financing |
|---|---|---|
| Santander, Barclays, Commonwealth Bank of Australia, NatWest | Non-recourse senior debt | Sets the revenue certainty the structure must deliver |
| Sungrow | Battery supply and long-term service agreement | Hardware performance risk transferred to a supplier with a service obligation |
| OCU Group | Balance of plant contractor and long-term operations and maintenance | Covers the electrical and civil scope between the battery blocks and the network |
| bp | Long-term tolling structure, plus optimization | Converts merchant upside into a contracted payment |
| Danske Commodities | Long-term floor structure, plus trading and optimization | Puts a defined downside under the cash flow |
| Revera Energy | Construction oversight and long-term asset management | Keeps execution and asset management with the sponsor |
The structure splits the two halves of a merchant battery's revenue problem. A floor gives lenders visibility on the downside; a tolling arrangement sells the upside for a contracted payment. Danske Commodities will run an automated algorithmic book across wholesale and ancillary services behind the floor, and both trading houses sit in the dispatch chain alongside Revera's asset management.
The next phase of the portfolio shows where duration is going. Revera says it holds up to a further 400 MW / 1,600 MWh with approved planning consents, land rights, grid access under NESO's Gate 2 process and 15-year capacity market contracts, with construction proposed to start in the coming months. Hunterston and Windyhill are both two-hour systems at headline ratings; 400 MW paired with 1,600 MWh is four hours. A capacity market contract pays for availability, the floor protects the trading floor, and the tolling arrangement monetises the top — a longer battery can serve all three more comfortably than a two-hour unit, which is the commercial logic behind the shift.
Sungrow's package here is not simply an equipment sale. It pairs the battery system with a long-term service agreement, which is what a lender needs to see before accepting twenty years of performance risk on technology it cannot itself inspect. The balance-of-plant and long-term maintenance scope sits with OCU, a UK contractor, which keeps civil and electrical delivery, grid interface works and site operations in local hands while the storage technology comes from Asia. Interface risk between the two sits in the commissioning schedule: auxiliary power, protection settings, controls, communications and performance testing all have to be closed before the plant can operate as a single asset.
The comparison with the sector's other directional signal is worth noting. Chinese suppliers are now the default hardware choice for UK transmission-connected storage, at the same time as UK policy debate about critical infrastructure supply chains continues. What made that possible was not price alone but the service architecture around the sale.
All figures, including the 400 MW / 800 MWh capacity, the four-lender debt syndicate, the counterparty roles and the Q3 2028 operations date, are consistent across the developer's own release and at least three independent trade outlets. The exact battery system type and the financial terms of the debt, floor and tolling agreements have not been disclosed by any party and are not estimated here. The four-hour characterization of the next portfolio phase is derived from Revera's own stated 400 MW / 1,600 MWh figures.