Many consumers were missing out on significant savings because they believed switching was a "hassle" and that all energy suppliers were the same, according to the Energy Advice Line.
Julian Morgan, managing director of the business electricity comparison, switching and advice service said new OFGEM research showed a two-year rise in the number of people who felt it was not worthwhile changing supplier.
The findings were contained in OFGEM's latest Consumer Engagement report.
"While it is good to see that the incidence of switching has stabilized, ending its year-on-year decline, negative perceptions about switching are still a cause for concern," Mr Morgan said.
"The report shows that among those who never switch supplier, the proportion who believe it is not worth the effort has risen significantly.
"This is a troubling misconception, as these consumers are missing out on significant savings for very little effort.
"Those who believe that switching is a 'hassle' has risen by 8 percentage points since 2012, and those who believe there's too little difference between suppliers to make it worthwhile, has risen by 10 percentage points.
"Both of these perceptions are unfounded and is costing consumers money."
The report found that consumers who had never switched supplier believed they needed to save a minimum of £158 on average to be encouraged to do so.
But Mr Morgan said savings of that order were entirely possible, depending on consumers' circumstances. He added that even among the Big Six suppliers, there was often considerable variation between deals.
"I urge consumers who doubt whether it is worthwhile switching to contact us and we can tell them within minutes how much, if anything they will save," Mr Morgan said.
"Chances are, if they have never switched, the savings could be significant and well above the figure of £158 which many say would make it worth the trouble.
"They will also discover that switching is not a hassle at all. Reputable and independent services like the Energy Advice Line do all the legwork.
"Once we have found the cheapest available option and a consumer decides to switch, there is virtually nothing else for them to do. We take complete control of the switching process, which is actually very quick and simple.
"We believe OFGEM still needs to make further efforts to educate the public about the benefits of switching - that it not only makes sound financial sense, but is actually very simple."
The Energy Advice Line actively campaigns for reform of the UK's energy market so that businesses and domestic energy consumers get a fairer deal and cheaper prices from the major suppliers.
It also offers a free and independent price comparison and switching service that enables consumers to shop the market for the cheapest energy deals with the click of a mouse. For further information visit Energy Advice Line