Hornsea 3 Transmission

By Ørsted’s Q3 2025 investor presentation, the Hornsea 3 project and associated 300 MW BESS had reached around 10% degree of completion, with onshore converter stations and cable routes progressing according to schedule and fabrication of the two offshore converter stations reported to be on schedule. This update confirms active manufacturing of the main HVDC converter platforms for the Hornsea 3 transmission system at supplier facilities.

Offshore construction on the Hornsea 3 transmission system effectively started in Q1 2025 when installation of the offshore export cables commenced along the Offshore Export Cable Corridor between the two offshore converter stations and the landfall at Weybourne Beach, Norfolk. The Safety Zone Application records that export cable installation began in Q1 2025 and is scheduled to continue through Q4 2026, forming the first major offshore construction activity for the project’s HVDC link.

Installation of the Hornsea 3 HVDC offshore export cables commenced in Q1 2025. Jan De Nul Group is carrying out seabed preparation, transport, installation and protection of approximately 350 km of 320 kV DC export cables and a platform interlink cable connecting the two offshore converter stations to the onshore converter station at Swardeston, Norfolk, via landfall at Weybourne Beach. The cable installation campaign uses Jan De Nul's vessels Isaac Newton and Connector for laying, with Simon Stevin for rock installation. The Safety Zone Application confirms export cable installation runs from Q1 2025 through Q4 2026. By November 2025, the project had reached approximately 10 percent completion.

Installation of Hornsea 3’s offshore export cables started in Q1 2025, initiating the laying of two HVDC circuits (four cables in total) running from the offshore converter stations through the Offshore Export Cable Corridor to landfall at Weybourne Beach, Norfolk. According to the Safety Zone Application and supporting project documents, these export cable works form a dedicated OEC installation campaign running from Q1 2025 to Q4 2026, undertaken under Ørsted’s contract with Jan De Nul Group for the HVDC export and platform interlink cables.

On 25 January 2024, Ørsted and Jan De Nul Group signed the offshore export cable installation contract for the Hornsea 3 offshore wind farm’s HVDC transmission system. Jan De Nul will carry out seabed preparation, transport, installation, and protection of approximately 350 km of HVDC export cables and a platform interlink cable connecting Hornsea 3 to the UK national electricity grid, with cable-laying vessels Isaac Newton and Connector and rock-installation vessel Simon Stevin deployed for the works planned between 2025 and 2027.

Orsted took final investment decision on Hornsea 3 Offshore Wind Farm on 20 December 2023. With a capacity of 2.9 GW, Hornsea 3 will be the world's single largest offshore wind farm, producing enough renewable electricity to power more than 3.3 million UK homes. Orsted had secured a Contract for Difference in allocation round 4 (July 2022) at an inflation-indexed strike price of GBP 37.35/MWh (2012 prices). All major contracts were in place at FID, including agreements with Siemens Gamesa (SG 14-236 DD turbines), NKT (HVDC export cables), Aibel and Hitachi (converter stations), Jan De Nul (cable installation), and SeAH Wind (monopile foundations at the new Teesside factory). Most capital expenditure was contracted ahead of recent inflationary pressures. Orsted will build the transmission assets and divest them to an OFTO post-commissioning under UK regulation.

NKT was awarded the supply contract for the high-voltage DC export cable system for the Hornsea 3 offshore wind farm on 31 March 2023. The contract, with an estimated value of approximately EUR 500 million (EUR 400 million at standard metal prices), covers design, manufacturing, jointing and termination of two 320 kV DC circuits with approximately 170 km offshore route length and 50 km onshore route length, plus four circuits of 1.5 km 400 kV AC onshore cable connecting the onshore substation to the National Grid. The cables will be manufactured at NKT's high-voltage factory in Karlskrona, Sweden. NKT previously delivered the cable system for Hornsea 2.

Ørsted awarded Hitachi Energy the HVDC Light transmission technology contract and Aibel the EPCI contract for two offshore converter platforms for Hornsea 3.

Development Consent Order (DCO) for the Hornsea Three Offshore Wind Farm, which comprises 197 wind turbine generators, two offshore converter stations (OCSs), inter-array cable networks and HVDC offshore export cables running in two circuits (four cables) from the array area to landfall at Weybourne Beach, Norfolk, was granted on 31 December 2020 and came into effect in February 2021, providing project-wide planning consent for these generation and transmission assets.

In Ørsted’s Q3 2025 investor presentation, the company states that for Hornsea 3 it plans, in the coming period, to complete the onshore export cable and install the offshore export cable, followed by energisation of the offshore converter station, initiating system testing and commissioning activities for the HVDC transmission link.

For the initial 1.6 GW configuration of Hornsea Three, a grid connection for this capacity had already been secured and was acquired by the project from SMartWind, indicating that a National Grid connection agreement for the project was in place before the capacity was later increased.

After determining that the Hornsea Three area could accommodate up to 2.4 GW, rendering the original 1.6 GW grid connection agreement invalid, the project began a process with National Grid to identify a new, suitable grid connection for the increased generation capacity.