But now energy analysts expect this to rise by as much as £100 within weeks when Ofgem revises the cap, wiping out all the savings households have made so far.
The price cap is revised every six months to take factors including wholesale costs into account, with the first revision scheduled for February 7.
Industry sources told the Daily Telegraph that when designing the cap, Ofgem was under “huge pressure” to come up with a number that was “politically acceptable” when it first came in.
This is despite the fact that its methodology was likely to wipe out the savings shortly afterwards.
Speaking at a conference two weeks ago Dermot Nolan, chief executive at Ofgem, said: “While I cannot say today exactly what it will be, wholesale costs have risen significantly over the last year. As a result, it is likely that we will announce an increase – and potentially a significant one – in the level of the cap.