The UK’s revised price cap on variable and default tariffs have come into effect. The price cap, originally announced in February has increased pricing by £117 to £1,254.
Pre-paid customers can expect a £106 to £1,242 a year for the same six-month “summer price cap” period.
The level will be reviewed during later in the year.
The rise has prompted many to look at alternatives to standard variable tariffs (SVTs).
Natalie Hitchins, head of home products and services at UK consumer watchdog Which? said: “Many people who hoped the price cap would bring an end to unwelcome price increases will be left reeling after price hike Monday adds more than one billion pounds to their energy bills.
“If you are one of the millions of energy customers stuck on a rip-off standard variable or default tariff, our advice is simple – switch as soon as possible.
“There has been a recent rise in the number of cheap deals on the market – so you could choose better customer service while potentially saving more than £300 a year.”
Stephen Murray, an energy expert at MoneySuperMarket, said: “This price rise might sound like an April fool, but unfortunately it’s no laughing matter.
“With the clocks going forward and summer on the way, you might not think now is the time to tackle your energy bill, but it really is.
“If you switch today to a competitive tariff with a big six or emerging provider, you could ignore all the noise from the regulator and see your annual bills come down by £250 or more.”
Lilly Green, head of research at auto-switching service Look After My Bills, said 17 energy companies are raising prices.
“The price cap has become an excuse for a price rise. Suppliers big and small are raising prices as high as they can,” said Green.
“No less than 17 energy companies are raising prices including all of the big six.
“A big six supplier has never raised prices by this much in one go. There’s no doubt many more suppliers will follow.
“The price cap was designed as a buffer for customers against expensive bills. Sadly, the big suppliers aim for the absolute maximum level, meaning you end up paying more than you need to.”