The price increase applies to the independent supplier’s standard variable tariff and will affect customers differently according to their energy use.
A spokesperson for the supplier said: “The cost of buying electricity has increased significantly in recent months. We’ve absorbed that rise for as long as we could, but are now having to increase the price of our variable tariff. We know this will come as a disappointment to our customers, and are sorry we can’t protect them from rising wholesale costs any longer.”
The supplier also warned that “many smaller suppliers” will have to make similar price changes.
GB Energy Supply will contact all customers on their variable tariff giving them 30 days’ notice and the opportunity to switch with no exit fees. It added: “As ever, we are committed to great service and great value so we’ll drop our prices as soon as we can.”
Uswitch energy expert Claire Osborne said: “This is an eye-wateringly large price hike for GB Energy’s standard variable rate customers, making this tariff almost as expensive as the average big six variable plan. The supplier has raised the price of this deal twice since July, meaning some customers will now be paying almost £300 a year more than they were just three months ago.
“Co-operative Energy was the first large supplier to increase variable prices in two years and, with GB Energy’s latest hike, we could see more providers follow suit. Rising wholesale prices are appearing to have a particular impact on medium and small suppliers, forcing many to also increase the cost of their cheapest deals.
“But there are still many competitive tariffs available on the market – for now at least – although they may not be around for long if wholesale prices continue rising. Consumers concerned about their energy bills going up, especially as we head towards winter, should shop around for fixed deals which provide protection against potential price rises.”
The increase follows green independent Ecotricity’s announcement this week that prices would increase by an average of 5.7 per cent for dual fuel customers, due to the cost of policy and rising costs from grid operators.