Almost four million UK households are in debt to their energy provider, owing an average of £128 per home, according to a uSwitch survey.
Despite the mild winter, 14% of the households which owe money have seen their debt increase by £5 on last year, following a series of price hikes, the energy comparison company said.
The average household energy bill is now £1,265 a year, £53 more than a year ago and £793 or 168% higher than in 2004.
A third of those in debt owe more than they did a year ago while 9% owe less, the survey found.
Ann Robinson, uSwitch director of consumer policy, said: "The average household energy bill is £53 a year dearer than a year ago. For many consumers, the only thing that has kept this particular wolf from the door is the fact that this winter has been exceptionally mild."
More top news
Simon Cowell admitted he was "so embarrassed" after his shirt burst open during an X Factor audition.
Following the promise of further powers for Scotland, David Cameron is now talking about a new deal for the other home nations.
The Suitsy: Man creates business suit onesie