A public spending watchdog said the smart meter rollout across Britain will cost every home £215 over the next 15 years but will only save consumers 3% annually on the average energy bill by 2030.
Consumers would save an average of 2% on the average bill of £1,328 until 2020, rising to £43 a year or 3% by 2030, the Government estimated.
The Commons public accounts select committee said the department for energy estimated the cost of the rollout would be £10.6 billion and households would contribute this through their energy bills.
The savings made by consumers were conditional on customers becoming more "savvy" and cutting their energy use, the committee warned.
It also said some aspects of the programme could be out of date by the time the meters are rolled out, saying consumers could receive the information on their smart phones but still have to pay for the "redundant" in-home displays.
The mass roll-out will start late next year and suppliers are obliged to take all reasonable steps to have them in households by the end of 2020.
The energy watchdog has urged customers who believe they may have money left in their former accounts to "come forward and make a claim."
Customers who think they haven't left a forwarding address or a final meter reading when they moved or switched should contact their old supplier.
The web site myenergycredit.com will help you do this.
Inevitably, there will be some former customers who will not be found and so the major suppliers are announcing what will happen to credit balances from now on.
In future, after two years, the credit balance will be used to help vulnerable customers - and suppliers will make it very clear what is happening.
The Big Six energy suppliers have launched a campaign to reunite former customers with money left in their accounts.
The MyEnergyCredit campaign will encourage customers who have switched suppliers or moved home without leaving a forwarding address to get in touch with their old company if they think they have left money behind.
Energy UK said £153 million in unclaimed credit had accumulated over the last six years, with the average balance at around £50.
The trade association said that from now on, after two years any unclaimed credit would be put towards funds to help the fuel poor and vulnerable, which would amount to at least £65 million over five years.
The Conservatives have accused Labour of bringing Britain's economy to its knees, after it announced proposals to revoke energy companies' licences helping protect the interests of the public. A Conservative Party spokesman said:
Labour left our country with a broken energy market and huge taxes on bills - meaning the number of people in fuel poverty nearly doubled in Labour's last five years.
We've been taking action to put this right. We've taken £50 off the average bill by rolling back green levies. We're carrying out a full, independent inquiry to fix the broken market we inherited. And we're forcing energy companies to simplify bills so people can be sure they are getting the best deal.
A new energy regulator would be charged with producing an annual scorecard for energy suppliers, reporting on the company's performance and identifying any possible areas of concern, Labour has announced.
Shadow energy and climate change secretary Caroline Flint said: "The public have a right to be treated fairly by energy companies. Where firms fail to meet these standards, there must be tough and decisive action. Too often energy companies seem to view the regulator's fines as a cost of doing business - not as a warning to get their act together.
"Of course consumers must be compensated - but if energy companies persist in mistreating their customers they must know their licence could be on the line."
A Labour government would give a new energy regulator the power to revoke energy companies' licences to help protect the interests of the public, the party announced today.
Shadow energy and climate change secretary Caroline Flint accused the Government of presiding over a "broken energy market" and said Labour would hand a tough new regulator the capability to cancel energy companies' licences where there were repeated instances of the most "serious and deliberate breaches of their licence conditions which harm the interests of consumers".
Figures obtained under the Freedom of Information Act, she claimed, showed energy companies had continued to "mistreat their customers" and face another 16 probes into mis-selling, poor customer service and other bad practice, despite Ofgem issuing 30 fines, totalling more than £87 million since 2001.
A treasurer at a village hall, which holds events for good causes, told ITV News energy companies should take responsibility on reducing power bills for registered charities.
Val Belton told ITV News: "I think it should be down to the energy companies to raise this question with you particularly when the bill is for Burpham Village Hall - they may think 'maybe that's a registered charity, I'll clarify whether they are'."
An ITV News investigation has shown that many charities are being over charged on their electricity bills.
We asked HMRC how charities can get a refund and whether they accept some charities are missing out on reduced energy bills. Here are their responses:
Does HMRC accept that many charities which are entitled to reduced VAT are missing out?
No, HMRC believes that the vast majority who are entitled to receive the reduced rate of VAT and CCL exemption. With millions of supplies made by fuel and power companies, it is not possible for HMRC to determine that every supply is taxed correctly. Ultimately though, the responsibility lies with the individual charity.
How does a charity get a refund for overcharged VAT?
If a charity believes it has been charged the wrong rate of VAT on a supply of fuel and power, or that it has been charged CCL, it should contact its supplier and request a refund.
Organisations need to tell energy suppliers they are registered as a charity so the correct tax rates can be applied, Energy UK told ITV News.
The advice comes after an investigation by ITV News showed many charities are overpaying on their energy bills.
When charities register with the Charities Commission it is vital they are told all the benefits to which they are entitled and how to apply.
It is not always obvious from the name that an organisation may be registered as a charity and suppliers can only know if they are told.
Charities should get in touch with their supplier so the appropriate tax rates can be applied. Suppliers want to help where they can and take their responsibility to their customers seriously but are unable to do so if they don’t have all the facts.
Under current HMRC rules companies cannot pay back more than four years of VAT.