Ofgem said data shows that while the price rises announced this autumn by the energy companies have averaged 9.1%, wholesale prices have risen by just 1.7% - adding just £10 to the average household bill of £600.
The energy regulator said that its estimates for the wholesale price were based on how a representative supplier would typically buy energy, using forward purchases of gas and power at 12, 18, or 24 months ahead, to smooth out volatility in prices.
These buying strategies vary between suppliers, meaning each sees different overall changes to wholesale energy costs.
But the industry regulator said that looking ahead to this winter, the price paid for energy by suppliers was rising sharply compared to last winter, with gas up 8% and electricity up 13%.
The so-called big six energy companies were forced to explain to Parliament why bills are increasing so much this winter.
As the 'Big Six' energy firms prepare to face MPs over rising prices, here are a few facts on what makes up your energy bill.
The UK spends below average per kilowatt of energy in comparison to other EU countries.