Under the schemes, suppliers who do not source the required proportion of electricity from renewable sources have to pay into a buy-out fund administered by Ofgem. The amount of payments outstanding into the buy-out fund for 2017-2018 at 31 August was £102.9 million. Ofgem said a shortfall of £58.6m remains.

The regulator also investigating Coventry-based Economy Energy over the same non-payment issue and has given notice that it requires two other non-compliant suppliers – URE Energy and Eversmart – to deliver all outstanding payments by 31 March 2019.