EDF Energy’s 8.4% price increase for electricity kicks in today.
It follows a reduction in variable gas prices by 5.2% last month, knocking £29 a year from the average bill.
That means the Big Six supplier’s dual fuel customers on standard variable tariffs will pay 1.2% more a year.
That will take the average annual energy bill to £1,082.
The energy supplier said the price rise is due to rising electricity costs for some time.
A number of other energy firms, including npower, ScottishPower, Co-operative Energy and First Utility, have also increase prices.
According to Ofgem, consumers could save as much as £261 a year without having to move to a different supplier.
It reavealed around 7.7 million gas and electricity switches took place in 2016.