The National Audit Office (NAO) has said that consumers face rising energy bills without urgent upgrades to the electricity grid, in a report published on 11 September 2026. The NAO found that the grid cannot carry enough electricity from where it is produced to where it is needed, forcing the National Energy System Operator (NESO) to keep supply and demand in balance by paying wind farms to turn off and gas plants to turn on1.
Those payments, known as constraint costs, are passed through to household bills. In the 2025-26 financial year they totalled around £1.9bn, and the NAO said this could increase to £7.8bn by 2030 without concerted action from NESO1. Ofgem estimates that £70bn of investment is required in the grid between 2025 and 2031, which is already expected to increase the network charges consumers pay by £60 by 2030. The report says acceleration would still save consumers £30 overall compared with the increased constraint costs if projects are not accelerated1.
NESO identified three projects in particular that needed to be accelerated to meet Clean Power 2030, and eight others where acceleration would also reduce constraint costs. The NAO said there has not been a "significant acceleration" in any of these projects so far1. Of the total 80 projects NESO identified as necessary in its 2024 Clean Power advice, 64 are ongoing, but most are at an early stage of development and are not expected to be connected by the dates NESO believes are optimal for keeping constraint costs down between now and 20301.
The report describes the upgrade timetable as "very challenging". The queue for grid connections grew tenfold in five years, reaching over 700GW, around four times Britain's projected need by 2030, and some green energy projects have to wait for up to a decade before they can be brought online1. NESO implemented changes to the approval process for connecting new facilities last year in a bid to curtail so-called zombie energy projects, which have typically been stalled for financial or regulatory reasons but hold a place in the queue ahead of projects that are ready to go1.
"While the Department for Energy Security and Net Zero, Ofgem and NESO have started to improve the way they work together, the planned upgrades of the electricity grid will test systems not designed for activity at this pace or scale."
Why it matters for households
Constraint costs are recovered through network charges, so the pace of grid reinforcement feeds directly into the standing and unit charges a household pays, regardless of how much electricity it uses. The NAO's figures set out the trade-off: higher network charges of about £60 by 2030 if the work proceeds, against constraint costs that could reach £7.8bn a year if it does not1.
For a home's energy independence, the constraint problem is a limit on what can be connected. A household that installs solar, battery storage or a heat pump depends on the wider network being able to absorb and move power; where the grid is congested, generators are paid to stop rather than deliver. The connection queue described in the report, at over 700GW against around four times Britain's projected need by 2030, is the mechanism by which new generation waits for access1. The national supply picture therefore shapes what is available to homes, and at what cost, before any decision is taken at the property.
The report does not set out what the three prioritised projects are, where they are located, or what they would cost individually. Those details have not been reported1.
What happens next
The NAO said value for money now depends on delivery, and that failure to implement the necessary grid upgrades will hamper economic growth as well as increase consumer bills1. No dated milestones for the three accelerated projects, or for the eight others, are given in the report as reported. National Grid will invest £1.2bn through its UK supply chain partners to deliver upgrades across 1,000km of overhead line routes1.