The Office of Gas & Electricity Markets (Ofgem), the energy regulator for Great Britain, has granted initial approval, subject to consultation, to 80 energy projects delivering new powerlines and substations.
More than £15bn will ensure the continued safe operation of Great Britain's gas transmission and distribution networks, Ofgem said.
An initial £8.9bn investment is being committed to Britain's high-voltage electricity network, with a further £1.3bn ready to go, to power the biggest expansion of the electricity grid since the 1960s.
The draft settlement for RIIO-T3 (April 2026 to March 2031) is the first step in an estimated £80bn investment programme boosting electricity network capacity.
The investment in the grid, which will rise to around four times the current spending levels, will allow for 80 transmission projects and all associated works across Great Britain to be completed within five years.
These projects will upgrade more than 4400km of overhead lines and deliver 3,500km of new circuits, including investments offshore, doubling the total build in the last 10 years. It means up to 126 GW of clean power generation will be connected to the grid by 2030, if all goes to plan, alongside additional flexible storage and technologies.
Over the last six months, the energy regulator has studied the spending proposals from the electricity transmission owners, National Gas, and the gas distribution companies, to ensure they represent value for billpayers. Bids deemed to be not in the best interests of consumers have been turned down, Ofgem said. This scrutiny has resulted in potential reductions of more than £8bn, equivalent to around 26% of the initial proposals put forward.
The investment allowances include £4.2bn for National Grid, £3.1bn for Scottish & Southern Electricity Networks (SSEN) and £1.6bn for Scottish Power.
Ofgem chief executive Jonathan Brearley said: “Britain’s reliance on imported gas has left us at the mercy of volatile international gas prices which during the energy crisis would have caused bills to rise as high as £4,000 for an average household without government support. Even today the price cap can move up or down by hundreds of pounds with little we can do about it.

“This record investment will deliver a homegrown energy system that is better for Britain and better for customers. It will ensure the system has greater resilience against shocks from volatile gas prices we don’t control.
“These 80 projects are a long-term insurance policy against threats to Britain’s energy security and the instability of prices. By bringing online dozens of homegrown, renewable generation sites and modernising our energy system to the one we will need in the future we can boost growth and give ourselves more control over prices too.
“Doing nothing is not an option and will cost consumers more – this is critical national infrastructure. The sooner we build the network we need, and invest to strengthen our resilience, the lower the cost for bill payers will be in the future.
“However, this can’t be done at any price, which is why we have built in cost controls and negotiated a fair deal for both investors and consumers. And we won’t hesitate to intervene if network companies don’t deliver on time and on budget.”
Taken all together the net cost of these investments on bills amounts to around £24 a year, or less than 40p per week, by March 2031, although this does not take into account the overall benefits of reaching clean power that can reduce bills.
The draft determinations are now published for consultation with final decisions made by the end of 2025.
Some of the energy companies would have liked Ofgem to go further and approve more investment.
SSEN Transmission said: “Based on an initial assessment, Ofgem's draft determination does not go far enough to deliver the investible, financeable and ambitious framework required to unlock the unprecedented levels of investment needed to deliver lower and more stable bills.”
It said that Ofgem’s methodology “does not reflect the true, evidence-based costs that are required to develop, build and maintain a reliable electricity transmission network in the north of Scotland”.
Got a story? Email news@theconstructionindex.co.uk