The company that sells a battery’s power usually does not own it
Ask who owns a British battery and the public registers answer a different question. They name the company that sells its power. On 118 of the 182 batteries whose owner we can name, that company is an optimiser under contract, paid to trade an asset it holds no stake in. We have followed the control filings behind the operating fleet and can now name the owner of 6,636 MW of 8,000 MW, which is 83 per cent of everything running.
What the registers actually name
Elexon's balancing mechanism register names a lead party. That is the company allowed to sell the unit's power and answer for it. The capacity market register names a holder, and for a battery that is almost always a company created for the one site and named after it. Neither register has a field for the owner, and neither claims to.
Take the lead party as the owner and you credit Tesla, EDF, Habitat Energy and Arenko with dozens of sites that none of them own. Across the 182 batteries we can attribute, the trader and the owner are different houses on 118 and the same house on 64.
How the owner is decided
A control filing decides it. Companies House publishes, for every company, who holds more than a quarter of it and who can appoint and remove its directors. We follow that chain up from the project company until it stops, and we record where it stopped.
Shared addresses and shared directors are leads and nothing more. We were caught twice. Once by a set of directors who sat on dozens of unrelated boards, and once by a registered office that holds eight hundred and seventy five other companies. Every join on this site now prints the document it rests on, on the page, beside the answer.
The register also carries names that no longer exist. One operating battery is held on our data by a company that was renamed three years ago, and reading the old name would have put it with the wrong owner. A list of unknown owners is partly a list of renames.
Three grades, said plainly
Confirmed means a control filing, or the owner's own published statement, names the company. That covers 159 of the 182.
Probable means the evidence is strong and indirect. The same controlling party as a sister company, or a capacity market site of the same capacity a kilometre away. That covers 17.
Named means the register leaves the owner blank, the balancing code carries the owner's own initials, and a sibling unit at the same site is already settled. That covers 6.
Who owns the operating fleet
| Group | Batteries | Capacity |
|---|---|---|
| Gresham House Energy Storage Fund | 26 | 812 MW |
| Zenobe Energy | 21 | 766 MW |
| Copenhagen Infrastructure Partners (Alcemi develops) | 5 | 512 MW |
| Voltwise Power (Sandbrook Capital) | 10 | 446 MW |
| Statera Energy | 4 | 402 MW |
| Harmony Energy Income Trust (assets under Foresight Group) | 10 | 398 MW |
| TagEnergy | 7 | 324 MW |
| Pivot Power (EDF Renewables UK) | 6 | 307 MW |
| and 35 more groups, each with its own page | ||
Ownership sits across 43 groups. Several of them appear nowhere in the market registers under their own name, because they hold through a project company and sell through somebody else. Every group has its own page: which batteries, where, who sells for them, what they were paid, and the document behind each join. A battery that re-registered under a new code is counted once, under the code it runs on today.
What is still open
49 of the 231 batteries, 1,364 MW, carry no owner we can put a document behind. Some are project companies waiting on a single filing each. Some name nobody at all in either register, and the site itself has to be identified before the company can be. The count moves most weeks and this page is written from the data, so it moves with it.
The optimiser pages show which trader runs which fleet, which is the other half of the same question.