The LCF – the overarching funding mechanism used to pay for renewable subsidies through small additions to electricity bills – is currently expected to exceed its £7.6bn ($9.3bn) cap and cost £8.7bn in 2020-2021.

The NAO report, Controlling the consumer-funded costs of energy policies: The Levy Control Framework, found that the now defunct DECC had taken too long to discover that it was on course to exceed the LCF cap.

“One