Ørsted has completed construction of its first large-scale battery energy storage system (BESS) in the UK, a 300 MW project located near Norwich, Norfolk, alongside the onshore converter station for its Hornsea 3 Offshore Wind Farm. Commissioning and final electrical works are ongoing ahead of the system becoming operational.

The project, named Iceni after the ancient warrior tribe associated with Norfolk during the Roman era, comprises 170 battery units, known as Megapacks. According to Ørsted, the system will have an energy storage capacity of 600 MWh and a power rating of 300 MW, equivalent to the daily electricity consumption of 80,000 UK homes.

When completed, Iceni will be one of the largest battery energy storage systems in Europe, according to the company.

A complex grid connection shared with Hornsea 3

The project’s configuration presents specific engineering challenges. The battery installation is divided into two areas separated by the Hornsea 3 onshore converter station. The two sections are connected by 18 33 kV cables, each more than 600 metres long.

Ørsted also highlighted the additional technical complexity arising from sharing a grid connection point with Hornsea 3, compared with a standalone connection to the National Grid.

The project team brings together specialists from Ørsted, Hitachi Energy, Knights Brown and Tesla. According to the company, the project is in the final stages of mechanical and electrical installation, with the cross-site cables being installed and terminated. The first phase of commissioning and testing is also underway, while preparations are being made to energise the battery system’s transformer.

Storing surplus renewable electricity

Iceni is designed to store excess electricity when generation exceeds demand and release it when consumption rises. This can help balance the electricity grid and make greater use of renewable energy, according to Ørsted.

“It’s a milestone moment for Ørsted that construction is now complete on our first large-scale battery energy storage system in the UK,” said Beatrice d’Eufemia, project manager for Iceni BESS at Ørsted.

She added that storing surplus electricity and using it when demand is higher could help balance the grid and lower electricity costs.

Richard Swann, construction manager for Iceni BESS at Ørsted, described the successful completion of construction as a testament to the work and cooperation of the teams from the organisations involved.

David Shillabeer, head of transmission and distribution at Knights Brown, also highlighted the project’s regional contribution, including investment in local people, skills development and employment opportunities across Norfolk and the wider region.

He said the project would support the UK’s transition to a more resilient, low-carbon energy system while creating a positive legacy for local communities.