As the smart scheme rolls out, energy companies will be visiting every home in Britain over the next eight years to install the digital smart meters. The devices will allow people to see cost of gas and electricity, and exactly how much energy they are using, as well as putting an end to frustrating estimated bills.
British Gas and E.ON have already started installing smart meters and there are expected to be at least three million in customers' homes by 2014.
But experts are warning that firms could view the installation stage as chance to get into people's homes and sell them eco products - such as solar panels, new boilers or insulation.
Consumers could even be offered loans to pay for more expensive items in order to bump up the firms' profits. Adam Scorer, director at Consumer Focus, says: "This is a particular concern given the poor track record of suppliers on doorstep sales."
So far none of the 'big six' suppliers (British Gas, SSE, Scottish Power, EDF Energy, Eon and Npower) have signed up to the pledge, but a number of smaller players have - including Co-operative Energy, Ecotricity, First Utility, Good Energy, Ovo, Spark Energy, and Utility Warehouse.
Christine McGourty, director at Energy UK, which represents the major suppliers, says: 'The energy industry is working with consumer groups, the Government and others to develop a new code of practice for the installation of smart meters to ensure the process goes smoothly and protects customers' interests.'