Companies outside the asset owner’s group sell power for 68 per cent of Britain’s operating battery capacity, according to analysis by Vitreous Labs. Public registers identify the registered seller, but leave investors to establish who owns the trading business.
Britain’s four largest registered battery sellers account for 2,472 MW of operating capacity. None owns the batteries it trades.
EDF Energy Customers Limited, Habitat Energy Limited, Tesla Motors Limited and Alcemi Storage Developments 4 lead a market in which asset ownership and power trading are largely separate businesses.
Across the 6,849 MW of operating battery capacity with a named seller, Vitreous Labs classifies 4,635 MW, or 68 per cent, as sold by a company outside the owner’s group. The remaining 2,214 MW, or 32 per cent, is sold within the ownership group.
The 68 per cent figure includes a small amount of capacity whose ownership has yet to be established. It is therefore the upper of two defensible estimates.
Elexon’s public records identify the company registered to sell each battery’s power. Establishing whether that seller belongs to the asset owner, and who controls the seller itself, requires a separate examination of corporate filings.
Who trades Britain’s batteries?
The operating fleet has 55 registered selling companies, of which 30 sell power for at least two batteries. The ten largest by registered capacity are:
| Registered seller | Batteries | Capacity, MW | Within owner’s group, MW | Outside owner’s group, MW |
| EDF Energy Customers Ltd. | 26 | 858 | 0 | 858 |
| Habitat Energy Ltd. | 21 | 561 | 0 | 561 |
| Tesla Motors Ltd. | 15 | 541 | 0 | 541 |
| Alcemi Storage Developments 4 | 5 | 512 | 0 | 512 |
| Zenobe Kilmarnock South Ltd. | 6 | 313 | 313 | 0 |
| Pivoted Power LLP | 6 | 311 | 261 | 50 |
| Thurrock Storage Ltd. | 3 | 300 | 300 | 0 |
| Octopus Energy Trading Ltd. | 8 | 298 | 0 | 298 |
| Arenko Cleantech Ltd. | 8 | 288 | 0 | 288 |
| BP Gas Marketing Ltd. | 5 | 259 | 0 | 259 |
The table brings together different business models. Most of the larger sellers are optimisers appointed to trade batteries for other owners. Some are companies associated with an individual site, selling power from units within their own group.
Alcemi requires a further distinction. It develops and operates the batteries for which it is the registered seller, while Copenhagen Infrastructure Partners owns the assets. It is classified here as outside the ownership group, although that relationship differs from a conventional appointment of an independent optimiser.
Who owns the trading desk?
Habitat Energy illustrates why the ownership of a seller can matter as much as its registered name.
The company sells power for 561 MW across 21 batteries without owning any of them, making it the fleet’s second-largest registered seller. Gresham House Energy Storage Fund accounts for 64 per cent of that capacity.
Habitat is owned by Quinbrook Infrastructure Partners. Quinbrook announced the acquisition on 30 November 2021. Habitat Energy Limited’s control filing records a new holding company taking a shareholding of at least 75 per cent on the same date.
Quinbrook also invests in generation. Its portfolio includes Cleve Hill and Uskmouth, both of which appear in NESO’s storage connection register. The parent of Britain’s second-largest battery seller therefore has development interests in the same connection queue as batteries traded by its subsidiary.
There is no suggestion of wrongdoing in these arrangements. Trading assets on behalf of other owners is an established part of the battery market, as is combining development and trading businesses within one group.
The difficulty is tracing those relationships. The energy registers identify the seller but do not explain its corporate ownership. A fund appointing an optimiser, a lender assessing a route-to-market agreement or a developer selecting a counterparty must look elsewhere to establish who controls the business.
What the figures can and cannot show
This analysis uses current seller registrations. Where a trading contract changed hands during the year, all the associated capacity is attributed to the seller registered today. The figures describe the current allocation of capacity, rather than each company’s trading activity over the year.
Battery ownership is drawn from Companies House control filings and capacity market agreement holders. That work is incomplete. Capacity with an unidentified owner is classified as outside the seller’s group, which raises the reported third-party share.
Group relationships also require interpretation. A seller’s legal name may bear little resemblance to that of its ultimate owner.
The classifications were revised as recently as 10 September 2026. Gore Street Energy Trading, Pivoted Power, UK Power Reserve and two other sellers had previously been recorded as third parties because their names differed from those of their owners. They are now classified as in-house, with supporting documentation recorded for each decision. ScottishPower Renewables remains unresolved.
These distinctions matter when reading the headline. The analysis measures whether the registered seller sits within the asset owner’s group. It does not imply that every company outside that group has the same commercial relationship with the owner.
Methodology
Operating capacity and registered sellers are taken from Elexon’s balancing mechanism unit reference and settlement data. Ownership is established battery by battery using Companies House persons with significant control filings and capacity market agreement holders, with the supporting document recorded against each asset.
Only current registrations are counted. A battery that has re-registered under a new code therefore appears once.
Companies House reports control in bands, with the highest defined as 75 per cent or more. No holding in this analysis is consequently described as 100 per cent owned.
All figures are generated from the underlying dataset whenever the site is built. The calculations and supporting records are published alongside the findings at Vitreous Labs.
Vitreous Labs examines NESO’s connection registers twice a week, reporting on contracted capacity, projects at risk of failure and capacity returning to the market. It maintains a public corrections register. This work uses National Energy SO Open Data under the NESO Open Data Licence v1.0, Companies House and capacity market data under the Open Government Licence, and balancing mechanism data from Elexon.
