Our plans to invest up to £12bn transforming Central and Southern Scotland’s electricity transmission network have been approved today (4 December 2025) by UK energy regulator, Ofgem, in its RIIO-T3 Final Determination, which runs from 2026 to 2031.
This is a record level of investment in a major rewiring programme, that will unlock capacity and economic growth, as well as reducing electricity bills and network constraints. These investments are expected to deliver a sustained economic benefit to UK GDP of around £2bn per year.
As Britain’s electricity demand increases, and is expected to double by 2050, the grid needs investment to ensure resilience and to better serve a modern, flexible, greener energy system.
To do this, we will now begin work to build 12 new major substations, upgrade 450km of existing circuits, reconduct 87km of overhead lines and replace 35km of underground cable between 2026 and 2031.
The investment also includes two new subsea electrical superhighways off the east coast of Scotland. The multi-billion-pound Eastern Green Link 1 and Eastern Green Link 4 subsea high voltage lines will have a joint capacity of 4GW and have the combined subsea cable length of 706km.
All this work will be undertaken by a highly skilled workforce. As the transmission owner in Central and Southern Scotland, we plan to double our workforce by recruiting 1,400 new roles directly and supporting a further 11,000 jobs across the country.
The investment is expected to cost around £12.07 per year on a customer’s bill, an increase of £6.47, but is expected to save far more than this in the long term.
The total transmission investment across the UK is estimated to reduce constraint costs – the costs to turn off generators when there is no way of transporting their electricity – by around £5bn per year, saving up to £167 per bill per year by 2030.
Nicola Connelly, CEO of SP Energy Networks, said:
“We welcome Ofgem’s final determination recognising the need for this historic investment in critical network
infrastructure. “Our record investment of almost £12bn will unlock capacity in the grid and bring economic growth across our area of central and southern Scotland and beyond. Whilst also bringing costs down for consumers by reducing network constraints.
“We are committed to ensuring consumers and network users get a fair deal. Making this crucial investment now will drive a positive impact on stabilising and lowering consumer energy bills in the longer term. And it will achieve the UK’s ambition to be a clean energy superpower, enhancing the security and resilience of our energy supplies.
“We will continue to engage with Ofgem to ensure a regulatory framework that incentivises the largest ever investment in the electricity grid and helps move the UK towards its climate targets.”
View our RIIO-T3 Business Plan
Register as a Stakeholder and select 'SP Transmission' as an interest to stay up to date.