Smart meters, which monitor energy use in real-time, will save households £7.3bn over the next two decades, the government said on Wednesday as it set out its strategy for the roll-out of the energy-saving technology.

The roll-out – the most comprehensive yet planned in any country – will require 53m smart meters to be installed in 30m homes and businesses, starting in 2014 and finishing in 2019. Households are likely to save £23 on their annual energy bills by 2020, the government has estimated, up from its previous estimate of £14 in savings.

But these figures were disputed by the consumer group Which? and by smart metering industry experts.

Jessica Driscoll, senior advocate at Which?, said: "It's too difficult to say that people will save a certain amount of money. The savings depend on people making changes to the way they use energy, and that is very hard to do. Smart meters are just one way of helping people make those changes."

She said Which? had not yet made an estimates of the cost or savings from the technology because there was not yet enough information to make a reliable estimate.

£23 eh? Why that's nearly enough to half-fill my car's tank with fuel.

An alternative view is smart meters are convenient spies in the home, letting the authorities learn more about what people get up to in the privacy of their own property.

An alternative view is smart meters are convenient spies in the home, letting the authorities learn more about what people get up to in the privacy of their own property.

Don't these smart meters use power? If they only use 1W each and we install 50 million of them, that's an extra 50MW to reduce electricity consumption.

Just sayin'

Charles Hendry, energy minister, said: "Smart meters will enable us to modernise the electricity system over the coming years and create the smart grids we will need to bring new low carbon energy sources online, and handle much higher demand for electricity as we progressively electrify transport and heating."

There's also no reason that gas can't be produced from "green" sources.

I heard that these smart meters allow National Grid/power companies to switch off appliances in your home remotely, to reduce demand. Can anyone verify?

Grow beans in big green house, get people to wander around and eat loads of them, collect the resulting outbursts somehow?

I heard that these smart meters allow National Grid/power companies to switch off appliances in your home remotely, to reduce demand. Can anyone verify?

Yes but only low priority items like fridges and freezers, possibly hot water tanks etc.