Ørsted said on 20 October 2026 that construction of its 300 MW, 600 MWh Iceni battery energy storage system near Norwich, Norfolk, is complete. It is the company’s first large-scale battery in the UK and sits beside the onshore converter station of the Hornsea 3 offshore wind farm.
What Ørsted reports
Ørsted says 170 Tesla Megapacks are installed and commissioning and testing are under way. The site is split in two by the Hornsea 3 converter station, and the two battery areas are linked by 18 cables at 33 kV, each longer than 600 metres. Hitachi, Knights Brown and Tesla worked with Ørsted on the build. Ørsted also describes the shared grid connection with Hornsea 3 as an added technical complexity compared with a standalone connection.
Complete, with work still listed
The same statement lists the final stages of mechanical and electrical installation, cross-site cable installation and termination still ongoing, and preparations to energise the battery transformer. Construction is described as complete while those steps remain open, so energisation and full commissioning are the dates that matter for grid service.
| Item | Figure | Basis |
|---|---|---|
| Power rating | 300 MW | Ørsted, March 2025 and October 2026 |
| Energy capacity | 600 MWh | Ørsted, March 2025 and October 2026 |
| Duration at full power | 2 hours | ENB calculation: 600 MWh divided by 300 MW |
| Megapacks installed | 170 | Ørsted, October 2026 |
| Average energy per Megapack | about 3.5 MWh | ENB calculation: 600 MWh divided by 170 |
| Cross-site cables | 18 at 33 kV, over 600 m each | Ørsted, October 2026 |
| Operational target | End of 2026 | Ørsted, March 2025 |
Ørsted equates 600 MWh to the daily electricity use of 80,000 UK homes, which is 7.5 kWh per home per day (ENB calculation). When the project broke ground in March 2025 the company said Iceni would be one of Europe’s largest battery systems and that sharing one connection between two generators could make better use of congested networks.
What to watch
The dated checks are the energisation of the battery transformer, completion of the cross-site cable terminations, and whether Iceni is operational by the end of 2026 as Ørsted targeted in March 2025. Context on UK battery revenue: UK battery daily price spread and the winter test.
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