An incredible 52% of people are still with the energy provider they had four years ago - meaining they're almost certainly paying more than they need to for their gas and electricity.
Research from the Energy Switch Guarantee shows fewer than half the public has moved providers in that time.
Pamela Taylor, chair of the Energy Switch Guarantee, said there was "still has more work to do" to make sure people are happy when it comes to switching.
“Wholesale prices have fallen significantly in the last few months – which means there are now many good deals and potential savings on offer.
"My advice to consumers is not to rely on the price cap for a fair deal when they can switch supplier for a better one and potentially save hundreds of pounds."
Why people are staying put
The Energy Switch Guarantee - a voluntary industry initiative trying to make switching is hassle-free - found two people in five (39%) of those who haven’t moved were happy with their supplier’s service while almost as many (34%) were fine with what they were paying.
Will Kostoris, co-founder of Youtility , said: “The majority of consumers have not switched supplier in at least four years meaning many of these people will have been moved by their suppliers onto the standard variable rate – the most expensive tariff.
"This means they will be paying hundreds of pounds too much.”
Recent figures from automated switching service WeFlip show people on standard variable tariffs can save an average of £381 a year by moving suppliers.
Sally Jaques, head of energy at WeFlip , said “Standard Variable Tariffs are among the very worst energy deals on the market."
She added: “The only good news in all of this for everyone stuck on the price-cap-tracking SVTs, is that they are free to leave at any time. There are no exit penalties for SVT customers, just a big saving when they switch."
