This article is more than 2 years old

This article is more than 2 years old

More than 1m extra first generation smart meters will be fitted in homes because the government has extended a deadline for their installation, despite the devices being criticised because they can “go dumb” when customers switch energy suppliers.

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Ministers set a target of the end of 2020 for every home to be offered one of the meters, which automate readings and display real-time energy use in pounds and pence.

So far 8.6m first generation, or SMETS1, meters have been installed. This year is meant to herald the first big push to roll out more advanced SMETS2 meters, which do not have the interoperability problems of the older ones.

But in a private letter to energy companies on Thursday, the government said systems designed to handle the newer meters were not ready, and so it was moving back a cutoff date for the older model by three months.

The reputation of smart metering could be harmed if problems with the meters were not ironed out, an energy official warned.

The extension moves the deadline from July to October and will lead to hundreds of thousands of people receiving the older devices, which can lose their ability to send readings after consumers switch supplier.

Smart meters were installed at an average rate of 363,000 per month for the first nine months of 2017, suggesting at least 1.08m extra will be installed as a result of the extension.

The actual figure is likely to be higher as the installation rate is accelerating. Bulb, the energy supplier, projects up to 1.7m SMETS1 will be fitted because of the rule change.

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The older meters’ interoperability problems are expected, but not guaranteed, to be fixed by October. The government announced in December that in some circumstances energy suppliers could be permitted to install the first generation meters for a further six months, meaning they could still be going into homes until spring 2019.

Hayden Wood, the co-founder of Bulb, which will use only SMETS2 models, said: “It’s disappointing that ministers are letting energy companies continue to install inferior, first generation smart meters for another three months.”

Neither the Department for Business, Energy and Industrial Strategy, nor Smart Energy GB, the body set up to promote smart meters, have been able to tell the Guardian how many SMETS2 meters have been installed.