Most grid batteries in Britain get their own connection to the transmission network. Iceni doesn’t. Ørsted’s 300 MW/600 MWh battery energy storage system sits beside the onshore converter station for its Hornsea 3 offshore wind farm near Norwich, Norfolk, and plugs into the grid through the wind farm’s connection point. Ørsted said on Oct. 21, 2026, that construction is complete.
It’s Ørsted’s first large-scale battery in the UK, and the company says 600 MWh is about what 80,000 UK homes use in a day.
Project Scope
Knights Brown built the project. Tesla supplied 170 Megapack units, and Hitachi Energy is on the project team. Each Megapack is about as long as a Routemaster bus and weighs about as much as five of them, which says something about the crane and haul planning on a rural Norfolk site.
The layout is the unusual part. The battery yard is split into two areas on either side of the Hornsea 3 converter station, tied together by 18 cross-site 33 kV cables, each more than 600 m long. Ørsted says sharing the wind farm’s grid connection added technical complexity compared with a stand-alone hookup to National Grid.
Ørsted held its golden-shovel ceremony in March 2025. With civils done, crews are finishing the mechanical and electrical fit-out and terminating the 33 kV cables. First-stage commissioning and testing is underway, and the team is getting ready to energise the BESS transformer. Ørsted hasn’t given a date for commercial operation.
Why It Matters
Co-locating storage with offshore wind behind one connection is one of the cheaper ways to get more out of a grid queue that’s measured in years. If the battery can soak up output when the wind farm would otherwise be curtailed and sell it into evening peaks, the same connection carries more useful energy. That’s the theory. Iceni will be one of the first places to test it at this scale, and the controls problem of two generators sharing one export limit is harder than it sounds.
Ownership is cleaner than it might look. When Ørsted sold a 50% stake in the 2.9 GW Hornsea 3 project, it kept the battery out of the deal, so Iceni stays fully on Ørsted’s books.
For Knights Brown, which runs a dedicated transmission and distribution business, it’s a sizable job in a fast-growing work type. Britain’s battery pipeline is long. Projects that share connections with existing generation could jump ahead of it, and this is the template others will study.
Project Team & Details
| Developer | Ørsted |
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| Owner / Client | Ørsted |
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| General Contractor | Knights Brown |
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| Major Subcontractors | Tesla (Battery Megapack Supply)
Hitachi Energy (Project Partner, Role Not Specified) |
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| Status | Under Construction |
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| Funding Source | Private |
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