SSEN Transmission, the trading name of Scottish Hydro Electric Transmission plc, is the electricity transmission subsidiary of SSE plc and operates as the licensed Transmission Owner for the north of Scotland. Headquartered in Perth with offices in Aberdeen, Inverness and Glasgow, it owns, maintains and invests in the high‑voltage 132kV, 220kV, 275kV and 400kV network across more than a quarter of the UK’s land mass, including some of its most challenging terrain. Its network comprises underground and subsea cables, overhead lines on wooden poles and steel towers, and large substations, and currently includes around 148 grid substations, 5,070 km of circuits, 161 km of HVDC circuit and 11,656 transmission towers and structures. Following a minority stake sale completed in November 2022, SSEN Transmission is owned 75% by SSE plc and 25% by Ontario Teachers’ Pension Plan Board.
The company’s core role is to provide a safe and reliable supply of electricity by transporting power from generators, particularly wind, hydro and marine assets in the north of Scotland, to demand centres across Great Britain and by enabling new generation, storage and demand projects to connect to the transmission system. Its network already connects over 9 GW of renewable generation and exports around two‑thirds of the power produced in its area southwards, positioning it as a key enabler of UK and Scottish net‑zero and clean‑power ambitions. SSEN Transmission plans to invest tens of billions of pounds this decade in major onshore and offshore reinforcements, including Pathway to 2030 and Beyond 2030 projects such as Western Isles and Orkney HVDC links, Skye Reinforcement and multiple 2 GW Eastern Green Link subsea interconnectors jointly developed with National Grid. These programmes expand 400 kV infrastructure, HVDC capacity and new substations to connect large volumes of ScotWind and other offshore wind, strengthen security of supply for remote communities and unlock additional low‑carbon capacity.
As a natural monopoly it is economically regulated by Ofgem, which sets allowed revenues through the RIIO‑T price control and Accelerated Strategic Transmission Investment framework. SSEN Transmission emphasises innovation and digitalisation, using Network Innovation Allowance projects, advanced phasor‑based monitoring, HVDC R&D collaborations and a growing in‑house digital and operational technology function to build a more resilient, cyber‑secure and AI‑ready grid. The business works through long‑term framework partnerships with supply‑chain companies for substations, HVDC systems and subsea cables, and supports community benefit funds and housing and social‑value initiatives in host regions as its large investment programme scales. Between 2019 and 2025 the wider organisation expanded from around 470 to roughly 2,500 employees to deliver a rapidly growing asset base and its network for net zero.
