The National Audit Office (NAO) has reported on the progress and future of the electricity transmission upgrades.

Upgrading the electricity transmission network will be necessary to support Clean Power 2030 and longer-term net-zero objectives. As recently reported here, the current system is wasting wind generation and costing billions as the grid has not yet caught up with the growth in renewable generation.

The NAO was critical of the slow action of Ofgem and of allowing renewable energy generation such as wind turbines, to be construct too far from main transmission lines. When the grid cannot carry enough electricity from where it is produced to where it is needed, the Neso intervenes to keep supply and demand in balance. This has normally meant paying wind farms to turn off and gas plants to turn on.

The NAO’s latest report says that these payments, known as constraint costs totalled £1.9bn in 2025-26, and could increase up to £7.8bn by 2030 without action.

“Value for money now depends on delivery. Failure to implement these necessary grid upgrades will hamper economic growth as well as increase consumer bills,” commented Gareth Davies, head of the NAO.

However, the NAO notes that delivering all the grid upgrades by 2030 will be “very challenging” with significant planning, supply chain and system access risks. Indeed, some of the projects are already forecast for delivery after 2030. This means some new generation is likely to connect before necessary grid upgrades are complete, potentially making the waste worse.

Whilst DESNZ, Ofgem and NESO have taken steps to accelerate approvals, the NAO believes that delays to grid upgrades risk even higher bills. The body estimates a £70bn upgrade as critical, but with the problem that such investment will increase short-term costs.

Ofgem estimates that this £70bn of investment would increase the network charges paid by consumers by £60 by 2030, but save them £30 overall compared to the increased constraint costs if projects are not accelerated. As such, the decision to invest is somewhat political.

If the upgrade is to be financed, then the question is where the costs should fall, and between concepts such as zonal pricing, ‘social tariffs’, bank taxes, general taxation and many more, the burden is unlikely to fall any time soon.

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