Ofgem has given the provisional green light to an initial £24bn investment programme to enhance energy security while enabling the transmission of more clean energy from renewable sources.  

More than £15bn will ensure the continued operation of Great Britain’s gas transmission and distribution networks, making sure they deliver safe and secure supplies of gas to households and businesses across the UK. 

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 determination for the RIIO-T3 price control period (1 April 2026 to 31 March 2031) is the first step in an estimated £80bn investment programme boosting electricity network capacity, protecting UK households from the volatile international gas markets that caused the massive fluctuations in energy bills in recent years.  

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 right across the country to be completed within five years.

Ofgem says this will significantly increase the grid’s capacity, through new power lines, substations and other technologies, to handle the flow of electricity from new renewable sources.    

These projects, which are also vital for driving growth, will upgrade over 4,400km 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 alongside additional flexible storage and technologies, enough to power millions of households with clean, stable and secure energy.    

Over the last six months, the energy regulator has scrutinised spending proposals from the electricity transmission owners, National Gas and the gas distribution companies, to ensure they represent the best value for billpayers.

Strict emphasis has been put on delivery targets while pushing companies to be as efficient as possible, and where necessary, bids that we do not think are in the best interests of consumers have been turned down. This scrutiny has resulted in potential reductions of more than £8bn, equivalent to around 26% of the initial proposals put forward.     

Ofgem CEO, 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.”   

This investment covering upgrade and expansion of the electricity grid, maintenance and also gas depreciation in its entirety is estimated to increase network charges on bills by £104 by 2031. This includes £30 for the gas networks and £74 for the electricity grid. 

The draft determinations are now published for consultation with final decisions made by the end of 2025.    

However, some energy companies would have liked Ofgem to have gone further.

SSEN Transmission said 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 will consider Ofgem's draft in detail over the coming weeks and continue to work with the regulator, government and wider stakeholders.