UK Offshore Wind Grid Connections[Draft]

Three onshore Transmission Owners (TOs) provide the connection points: National Grid Electricity Transmission (NGET) for England & Wales, Scottish Power Transmission (SPT) for southern Scotland, and SSEN Transmission (SHET) for northern Scotland and the islands. OFTOs own the offshore assets; TOs own the onshore grid they connect to.

The Offshore Transmission Owner regime was established by the Energy Act 2004, which inserted section 6C into the Electricity Act 1989 enabling competitive tenders for offshore transmission licences. The Energy Act 2008 strengthened the property-transfer and tender machinery. Transmitting electricity at 132kV or above in UK territorial waters and the Renewable Energy Zone (REZ) requires a transmission licence. The regime enforces ownership unbundling— transmission must be separated from generation.

Since TR6 (2020), bids are evaluated 100% on price — the lowest TRS wins, provided the bidder passes the technical threshold. Up to 8 bidders are shortlisted at ITT (increased from 5 at TR6).

Before the OFTO regime, and for projects below the 132kV threshold, developers own and operate their own transmission assets.

Early and small offshore wind farms operating at voltages below 132kV (typically 33kV) do not require a transmission licence. The developer retains ownership of the export cable. Nine such projects remain operational, from North Hoyle (60 MW, 2003) to Kincardine (50 MW floating, 2021).

In August 2024, DESNZ enacted a licence class exemption allowing offshore wind farms to use 132kV array cabling without divesting it to an OFTO. This applies only to inter-turbine array cables connecting turbines to offshore substations — not export cables to shore.

No project has yet used the OFTO build model, where the OFTO (rather than the developer) constructs the transmission assets. Ofgem explored a late competition model for non-radial (coordinated) assets, but in December 2024 shifted to developing an early competition OFTO build model. In September 2025 Ofgem published a further call for input on the early-competition approach. Fewer non-radial projects than expected, with later connection dates (early-mid 2030s), reduced time pressure.

In England, offshore wind farms above 100 MW are classified as Nationally Significant Infrastructure Projects (NSIPs) under the Planning Act 2008 and require a Development Consent Order (DCO). In Wales, the NSIP threshold is 350 MW. The DCO can "deem" a marine licence within it, acting as a one-stop consent. In Scotland, offshore wind is consented under Section 36 of the Electricity Act 1989 plus a marine licence from the Marine Directorate. Northern Ireland has its own devolved consenting regime.

Three NPSs govern offshore wind and transmission consenting: EN-1 (overarching energy), EN-3 (renewable energy infrastructure), and EN-5 (electricity networks infrastructure). The 2024 suite was designated January 2024; updated 2025 revisions came into force 6 January 2026.

The UK is transitioning from radial point-to-point offshore connections to a coordinated offshore network. This shift is driven by cost savings, reduced environmental impact, and the need to connect 50+ GW of offshore wind.

Crown Estate Round 5 is the first UK leasing round launched with a pre-established grid connection strategy. NESO ringfenced 4.5 GW in the connections queue and designed the network: one HVDC connection into South Wales plus two HVAC connections. Three preferred bidders: Equinor (1.5 GW), Gwynt Glas/EDF+ESB (1.5 GW), and Ocean Winds (1.5 GW).

The OTNR East Anglia coordination initiative brings together multiple projects — Sea Link, Nautilus, North Falls, and Five Estuaries — to explore shared offshore and onshore infrastructure around the Suffolk coast, reducing community disruption and cable landfall proliferation.

OFTOs receive a guaranteed Tender Revenue Stream (TRS) funded by Transmission Network Use of System (TNUoS) charges, which are socialised across all system users. The regime is similar to availability-based PFI contracts — utility-like returns with protection from volume risk.

The declining cost of capital reflects the regime's maturity and growing investor confidence. Bidders increasingly use capital markets financing (project bonds, credit enhancement) with higher gearing and longer tenor.

Ofgem assesses whether developer spend was "economic and efficient". Some costs may be disallowed, meaning the developer can lose money on the OFTO transaction. Developers have raised concerns about this process, arguing that CfD auctions already incentivise cost efficiency.

Early TR1 projects (20-year licences) begin expiring from ~2029–2031. Most assets have longer economic lives than their initial licence period. Ofgem is consulting on options: direct award extension to incumbent OFTO, competitive re-tender, or decommissioning. A decommissioning reserve is funded through the TRS.

Received Royal Assent on 18 December 2025. Key offshore transmission provisions (some awaiting commencement orders):

The OTNR Pathfinder process identified early coordination opportunities. The SEP/DEP shared transmission (Sheringham Shoal Extension + Dudgeon Extension) is the first UK project with shared offshore transmission infrastructure. The East Anglia coordination initiative and ScotWind HND-designed transmission corridors follow the same principle.

The Energy Act 2023 created the legislative basis for Multi-Purpose Interconnector (MPI) licences. In November 2024, Ofgem approved two OHA pilot projects under this framework: LionLink (1.8 GW, Netherlands) and Nautilus (1.4 GW, Belgium). These combine interconnection with offshore wind transmission. Regulatory treatment: modified cap-and-floor for the cable element + RAB-based for the offshore converter platform. An enduring MPI/OHA regime is in development.

Ofgem confirmed the headline 98% availability target is retained for HVDC systems, re-sequenced the tender timetable for the GCC extension, and will consult further in 2026 on bidder incentive mechanisms and OFTO access and control (OMSA structure).

67 offshore wind transmission systems are catalogued in the companion research document. The table below summarises the technology evolution by generation.

The UK no longer participates in the EU Internal Energy Market. UK offshore wind projects are ineligible for PCI/PMI designation or associated benefits. NESO engages bilaterally with ENTSO-E for system planning coordination.

The UK is not a formal NSEC member (members: BE, DK, FR, DE, IE, LU, NL, NO, European Commission) but participates via an MoU signed December 2022. The 300 GW offshore wind by 2050 target was agreed at the Ostend North Sea Summit on 24 April 2023. The January 2026 Hamburg Summit reaffirmed this commitment. The Offshore TSO Collaboration (OTC) received a mandate from NSEC to develop concrete project proposals for 2030–2040.

The first ONDP (2024) identified the Northern Seas corridor as requiring approximately 274 GW of offshore wind capacity by 2040. UK hybrid projects (LionLink, Nautilus) are included in the analysis. ENTSO-E finds that hybrid interconnectors in the Northern Seas would be economically beneficial.

The Energy Act 2023 created the legislative basis for MPI licences as a new asset class. MPIs combine interconnection with offshore wind transmission. Ofgem's OHA pilot approvals for LionLink and Nautilus (November 2024) are the first regulatory implementation. An enduring framework is in development, with Ofgem preferring "implicit trading with offshore bidding zones" after consultation.

This page was fact-checked using automated verification (OpenAI gpt-5.4 with web search). Two iterations were run against the research document, with findings independently verified before corrections were applied.