Energy firms should be required to inform every customer what proportion of their bills will contribute to the supplier's profits, MPs have urged.
The cross-party Energy and Climate Change Committee called for householders to be given a detailed breakdown of where their gas and electricity bills go.
Under the proposal, annual statements to be provided by energy companies would include details of their operating costs, wholesale prices and profits.
The breakdown would also feature contributions to environmental levies, the costs of smart meters and investments.
The committee said the move would ensure customers were better informed and help improve competition in the widely-criticised energy market.
Conservative MP and committee chairman Tim Yeo said recent reports of wholesale price-fixing had reinforced the need for greater transparency.
"Trust in energy companies is at rock bottom and consumers don't have the right information to hand to make informed choices about where they get their energy," he said.
"Most consumers simply don't know how to interpret their energy bills and this puts them off attempting to switch suppliers. The Government should be doing all it can to increase competition in the energy market and must make it easier for new entrants to join the market."
There are concerns that many energy customers are paying more than they need to because of the bewildering array of tariffs available.
The Government recently announced plans to simplify the options and force energy companies to give their customers the cheapest deal available to them.