Wholesale energy prices increased significantly from December 2007 as oil prices climbed steadily throughout every season eventually peaking at $147 barrel in July 2008 (Some 'experts' were predicting that oil would hit $200 dollars a barrel right at the end of the season). However, the impact of the "credit crunch" drove oil prices down to below $60/barrel towards the end of the year, less than half of their peak in July, and Gas and Electricity prices soon followed.
British Gas raised gas prices by 35% and electricity prices by 9% in 2008 just 6 months after a 16% increase - the only decrease we have seen so far since is a 10% reduction, although suppliers argue that in 2008 when prices started to rise they did not pass on the increases straight away.
Suppliers argue they may have 'brought' energy beforehand at higher prices. Most of the 'big 6' suppliers are vertically integrated and the majority of them have plenty of power generation to pay their supply businesses so they don't ought to buy from the marketplace regularly (although retail will argue they generally do).
While suppliers cannot adjust their prices each day for household / domestic supplies like they may and do for your commercial sector because of the numbers involved, they have got had plenty of opportunities over the last year to pass through on a lot of the falls.
What exactly is the betting that suppliers cut their prices with a token percentage after winter 09/10 when they have maximised their profits. Know more about Erdgas Vergleich Gewerblich