Britain’s electricity transmission network is struggling to keep pace with the growth of renewable generation, with delays to planned upgrades threatening to increase costs for consumers, according to a new National Audit Office (NAO) report.
The report, Upgrading the Electricity Transmission Network, published on 11 September, found that much of Britain’s transmission infrastructure dates from the 1950s to 1970s and was designed around a power system dominated by large fossil-fuel generators. The network is now facing constraints as generation patterns change and more renewable capacity is connected.
The NAO said more than 80 transmission projects have been identified as necessary to increase network capacity and reduce constraint costs. However, delivering all the required upgrades by 2030 will be “very challenging”, with planning, supply chain and system access risks still affecting some projects.
The audit office warned that some new generation is likely to connect before the associated grid upgrades are complete. Delays could increase both project and constraint costs and postpone the benefits of a cleaner electricity system.
RenewableUK welcomed the report. Its chief executive, Tara Singh, said wind power had reduced wholesale electricity prices by 31% in 2025 by displacing more expensive gas generation. The figure comes from analysis by the Energy and Climate Intelligence Unit cited by RenewableUK.
“The problem identified by the NAO is that Britain’s outdated grid can’t yet move all that cheaper, homegrown power around the country efficiently,” Singh said.
RenewableUK also highlighted the NAO’s estimate that a typical household could be £30 a year better off if network expansion is accelerated rather than continuing at the current pace.
Singh said: “Britain has built clean power – we now need to build the grid that gets it to consumers as fast as possible.”
The NAO said achieving value for money will depend on stronger oversight, transparent monitoring of progress and effective scrutiny of project costs.
