Fixed-priced deals offer certainty for a set period but, if prices drop, people could find themselves stuck at a higher price.
The forecaster Cornwall Insight, which tracks the energy market, has suggested prices could increase again slightly in January, due to rising wholesale costs paid by suppliers.
It says the typical home could pay £1,762 a year.
Given prices are rising, Ofgem says people should consider fixed deals as an option.
However, it says they should seek independent advice and consider what is most important for them – the lowest price or the security of a fixed deal.
Price comparison site Uswitch says the market for fixes is the best in recent years.
Some deals allow you to fix for a year, some for longer.
Uswitch warns customers should check whether fixed deals have exit fees before signing up and ensure they fully understand the terms of the contract.
Because the price cap changes every three months, it is difficult to know with any certainty whether a fixed tariff is a good deal. The longer the fixed term, the greater the uncertainty.
