Power supplier SSE’s 9% price rise for gas and electricity comes into effect today.
Affecting around 8.4 million customers, the average household energy bill will rise from £1,235 to £1,354.
Last week two ‘Big Six’ suppliers, British Gas and npower, also announced price rises for gas and electricity bills.
According to a price comparison site, around 75% of households went without heating at some point last winter to prevent higher energy bills.
Ann Robinson, Director of Consumer Policy as uSwitch.com said: "This price hike couldn’t come at a worse time… A price hike ahead of winter can only make this situation worse. Many will be worried about their energy bills this winter."
But she said the good news is there is exactly £300 difference between the cheapest and most expensive energy tariff on the market and is urging consumers to take advantage of it and switch suppliers.
She adds: "There are also some very competitive fixed price plans that offer protection from price hikes for the next two winters and which don’t have any exit penalties. The important thing is that households act today before these deals disappear and before their heavy winter bills kick-in."