Ørsted Completes 600 MWh Iceni Battery Build at Hornsea 3 Site in Norfolk

The Iceni battery energy storage system near Norwich, Norfolk, has reached full construction completion, with Ørsted confirming that its first large-scale UK battery energy storage system is now built.

A project team assembled across four companies reaches its build milestone.

The facility takes its name from the Norfolk-based warrior tribe of the Roman era and sits alongside the onshore converter station for the Hornsea 3 Offshore Wind Farm. Once finished, the battery energy storage system is set to rank among the largest in Europe. The team behind it brings together specialists from Ørsted, Hitachi Energy, Knights Brown, and Tesla on a project the company describes as first-of-its-kind.

Bus-length Tesla units and output sized for 80,000 homes

A total of 170 megapacks have now been installed at the site. Each unit measures the length of a classic Routemaster London bus yet weighs as much as five of them. Together they will deliver 600 MWh of capacity with a 300 MW power rating, matching the daily power consumption of 80,000 UK homes.

Why the site layout is unlike a stand-alone project

The design of Iceni sets it apart from conventional storage builds. The site is split into two areas divided by the Hornsea 3 Onshore Converter station, with the two halves linked by 18 33kV cables, each stretching more than 600 meters. Sharing a grid connection point with Hornsea 3, rather than connecting independently to the National Grid, has added further technical complexity.

Testing begins as energization preparations advance.

Work on site has moved into the final stages of mechanical and electrical installation. The 33kV cross-site cables are currently being installed and terminated, while the first stage of commissioning and testing is already well underway. Preparations are also being made for energisation of the BESS Transformer.

Managers point to storage benefits and cross-company co-operation

Beatrice d'Eufemia, Project Manager for Iceni BESS at Ørsted, called the completion of construction on the company's first large-scale UK battery energy storage system a milestone moment for the company. She explained that the system will make the best use of renewable energy produced in the UK, as excess electricity can be stored when generation exceeds demand and then used when demand is greater, helping balance the grid and lower electricity costs for everyone.

Richard Swann, Construction Manager for Iceni BESS at Ørsted, said it was a real testament to the hard work, dedication and co-operation of the team from many different organisations that construction has been completed successfully. David Shillabeer, Head of Transmission & Distribution at Knights Brown, described reaching the milestone as a significant achievement for everyone involved.

He noted that delivering a battery energy storage system of this scale required close collaboration between Ørsted, Knights Brown and the many other organisations that contributed to its success.

Beyond the engineering, Shillabeer said the scheme has enabled investment in local people, skills development and the creation of opportunities across Norfolk and the wider region. He added that Knights Brown is proud to have played its part in an important project supporting the UK's transition to a more resilient, low-carbon energy system, while leaving a positive legacy for the communities in which it works.