National Audit Office says failure to implement £70bn modernisation would also hold back economic growth

• The ‘great grid upgrade’ is off track – ministers should spell out the risks for bills

Consumers will pay higher energy bills unless the UK government speeds up work on a vast programme of upgrades to the electricity grid to enable the switch to renewables, the public spending watchdog has warned.

The National Audit Office (NAO) said that without faster action the extra costs associated with managing the ageing power network, which are ultimately passed on to the public, could reach £7.8bn a year by 2030.