Power companies SSE and EDF are appealing against Ofgem’s decision not to refund money they believed they were overcharged for using the national transmission system.

SSE said it had been overcharged by 25% based on a European Union directive.

EDF added that Ofgem’s decision “risks creating uncertainty in the electricity market” if it is not reversed.

The energy firms are bringing their case to the Competition & Markets Authority (CMA).

‘£120m cost to consumers’

Ofgem responded: “Electricity consumers will be disappointed to learn that SSE and EDF have chosen to appeal our decision to reject proposals for a rebate of network charges that is likely to cost consumers up to £120 million and lead to increasing payments to larger generators in the longer term.

“Ofgem’s decision is a sensible interpretation of European Union regulations and is in the interests of consumers.

“We will robustly defend our decision at the CMA.”

> See SSE's statement