An analysis of the market showed the cheapest deal in July 2016 was Iresa's Flex 1 tariff, costing £734 per year.
Now, the best deal is Iresa's Flex 4 tariff, which costs £834 per year, found price comparison website uSwitch.
The big six energy suppliers have hiked their cheapest deals by an average of £135, or 16 per cent, since September, with E.ON's cheapest deal increasing the most. The price rose 26 per cent from a £760 per year tariff available in September 2016 to a £959 tariff today.
The average cost of standard variable tariffs at small and medium energy suppliers are also on the rise, climbing an average of nine per cent, or £87, since October.
The increasing cost of wholesale energy is to blame, uSwitch said. Last summer, prices started rising at their fastest rate in years.
Emma Bush, uSwitch.com energy expert, said energy bills are set to rise further in 2017.
"The cost of both standard and fixed deals continues to rise, and the respite provided by some suppliers’ price freezes will soon come to an end," Bush said.
Big six energy supplier's cheapest deals in September 2016 and January 2017
|Supplier||Cheapest Deal in September||Price||Cheapest Deal in January||Price||Difference (£)||Difference (per cent)|
|E.ON||E.ON Saver Fixed 1 year v1||£760||E.ON Saver Fixed 1 Year v5||£959||£199||26 per cent|
|npower||Online Fix September 2017||£801||Online Price Fix February 2018||£971||£170||21 per cent|
|EDF||Simply Fixed October 2017||£849||Blue+Price Protection Jan 18||£967||£118||14 per cent|
|SSE||SSE 1 Year Fixed v8||£782||SSE 1 Year Fixed v9||£970||£188||24 per cent|
|ScottishPower||Online Fixed Saver November 2017||£820||Online Fixed Saver March 2018||£952||£133||16 per cent|
|British Gas||All current British Gas plans||£1,044||All current British Gas plans||£1,044||£0||0 per cent|
|Average||£135||16 per cent|