Seagreen Phase 1 OFTO
OperationalOffshore GridGB1,075 MW220 kV84 km2022
Basic information
9 fieldsAlso Known As
Seagreen Phase 1 OFTO · Seagreen Offshore Electricity Transmission (OFTO) Phase 1 · Seagreen Phase 1 OFTO Project Limited · Seagreen 1 OFTO · Seagreen 1 Offshore Transmission Assets · TR9 Seagreen OFTO
Status
operational
Capacity
1,075 MW
Project Company
Type
offshore grid
Transmission Model
Developer Build & Transfer
Expected Life
24 years
Website
Supply Chain (4)
Project Timeline (29)
10 Mar 2025Stake Transaction
On 10 March 2025, the joint venture between SSE Renewables, TotalEnergies and PTTEP that developed the Seagreen Phase 1 offshore wind farm signed an agreement with a consortium of Equitix and Kyuden Group to sell the project’s offshore transmission assets. Under this sale, the Equitix–Kyuden consortium, operating as Seagreen Phase 1 OFTO, will own, operate and maintain the transmission system—including three approximately 64 km offshore export cables, around 20 km of onshore cables, and the offshore and onshore substations—for 24 years under a transmission licence granted by Ofgem.
Equitix Investment Management Limited, Kyuden International Corporation and Kyuden T&D Global CO., Inc. Consortium acquired from Joint venture between SSE Renewables, TotalEnergies and PTTEP
16 Jan 2025Regulatory Other
Ofgem published the "Offshore Transmission: Draft Cost Assessment for the Seagreen Wind Energy Limited Offshore Windfarm Transmission Assets", providing a draft assessment of the costs and technical scope of the Seagreen transmission system—including three 64 km 220 kV subsea export cables, onshore cable circuits, and the Tealing onshore substation connection—prior to finalising the transfer value for the Seagreen Phase 1 OFTO.
~Dec 2023Construction Other
By 20 December 2023, Seagreen Wind Energy Limited confirmed that the final length of rock protection installed over the Seagreen export cables was 44.3 km, consistent with the approximate maximum set out in the Offshore Transmission Asset Cable Plan, indicating completion of export cable and associated protection installation and prompting Marine Directorate–LOT to request a marine licence variation to align the licence parameters with the as‑built transmission assets.
5 Mar 2024Other Permit Submitted
Authority: Marine Scotland · Licence: Marine Licence variation application to amend export cable rock protection extent for Seagreen export cables
On 5 March 2024, Seagreen Wind Energy Limited submitted a Marine Licence variation application, following a request from the Marine Directorate Licensing Operations Team (MD-LOT), to amend the licensed parameters for rock protection on the export cables after confirming that 44.3 km of rock protection had been installed, so that the licence accurately reflects the as-built Seagreen export cable protection used by the future Seagreen Phase 1 OFTO.
29 Nov 2023Other Permit Awarded
Licence: Variation of Marine Licence for Seagreen Offshore Transmission Asset reducing authorised offshore substations from five to two
On 29 November 2023, the existing Marine Licence for the Seagreen Offshore Transmission Asset was varied so that the number of offshore substation platforms (OSPs) authorised under the licence was reduced from five to two, aligning the licensed offshore transmission infrastructure with the as-built Seagreen Phase 1 configuration and parallel Seagreen 1A arrangements.
Oct 2023System Testing
The Crown Estate's UK Offshore Wind Report 2023 notes that the Seagreen Phase 1 project "completed commissioning works in October 2023, with all 114 turbines successfully installed and generating." Ofgem's 2024 Ex-Post Cost Review for the Seagreen Offshore Wind Farm Transmission Assets also states that construction of the Transmission Assets is complete and the Wind Farm is fully operational, with full export capacity due to be achieved in October 2023. Together, these confirm that commissioning and system testing of the Seagreen Phase 1 OFTO were completed by October 2023.
Oct 2023Commercial Operations Full Power
By October 2023 the Seagreen Phase 1 transmission system was fully operational, continuously transmitting power from the 1,075 MW Seagreen 1 offshore wind farm through three approximately 64 km offshore export cables and a further 20 km of onshore cables to the onshore substation in Angus for delivery into the Scottish grid.
13 Jan 2023Regulatory Other
Grant Thornton, on behalf of Ofgem, completed and dated the "Seagreen Offshore Wind Farm Transmission Assets – Ex-Ante Cost Review", analysing the economic and efficient costs of the Seagreen transmission assets delivered by Petrofac and Nexans to inform Ofgem’s determination of the transfer value and revenue for the future Seagreen Phase 1 OFTO.
2022Grid Offer Accepted
Authority: National Grid · Licence: Bilateral grid connection agreement (NETSO connection)
By 2022, the Seagreen Phase 1 transmission link (Qualifying Project for the Seagreen Phase 1 OFTO) had entered into a bilateral grid connection agreement with National Grid Electricity System Operator Limited (NGESO), in its capacity as the NETSO, satisfying Ofgem’s requirement for an agreed grid connection for the project’s offshore transmission assets.
26 Sept 2022Procurement Notice
Ofgem’s Tender Round 9 documentation for Seagreen Phase 1 OFTO sets the Seagreen Phase 1 Invitation to Tender (ITT) bid submission deadline as 26 September 2022.