Energy companies have cast doubt over whether Government promises to ensure people are on the cheapest tariffs will actually mean lower bills for households.
Ministers yesterday announced proposals to require energy firms to provide just four tariffs for each fuel and to place all customers on the cheapest price available for their chosen tariff.
There are currently 410 tariffs on the market and 650 "dead" tariffs which existing customers were on, but which were not available to new customers, making it hard to shop around.
At the moment, consumers could save an average of £72 and a maximum of £158 if they switch to the best deal in the market on their payment method, and more if they switch and change payment method.
Under the proposals outlined yesterday, suppliers would be limited to four "core tariffs" per fuel, to end the proliferation of tariffs.
The tariffs would have to include one standard variable rate and one fixed term, fixed price tariff to ensure that those two rates, which account for 85% of customers, are clear, simple and easy to compare between suppliers.
The Government said it wanted all customers placed on the cheapest available price as quickly as possible and by summer 2014 at the latest.
EDF Energy, which supplies to around 700,000 households in the greater South West having absorbed SWEB, the former state-run electricity supplier for the region, almost a decade ago, said it is already "fully committed" to "simple and transparent tariffs" and is "determined to lead the way in rebuilding customer trust".
In a statement, an EDF spokesman said: "We have offered typical customers the lowest standard variable dual fuel prices of all major suppliers for 50 of the last 52 weeks.
"And this winter, our new standard prices will still be cheaper on average for typical customers than all other major suppliers which have announced price rises in recent months.
"EDF Energy will now examine the proposals in detail and looks forward to working with ministers during the consultation period."
E.ON said its customers could choose from no more than five tariffs, and it had made the rates simpler and more easily comparable.
Critics have warned that the proposals could see an end to cheap deals, stop consumers switching suppliers, reduce competition and push up bills in the long run.