Almost 14 million smart and advanced smart meters were operating in British homes and businesses in the fourth quarter of 2018.
The latest figures from the Department of Business, Energy and Industrial Strategy (BEIS) show an 8 per cent increase from the previous quarter.
Yet compared to the same period last year, installation activity by large energy suppliers is down by 16 per cent.
As of 31 December there were a total of 12.65 million smart and advanced meters operating in domestic properties and 1.12 million in non-domestic properties.
During the quarter large suppliers made up the bulk of installations, with 1,105,400 domestic smart meters being installed – a 2 per cent decrease in domestic smart meter installations compared to the previous quarter.
Energy suppliers have an obligation to take “all reasonable steps” to install smart meters in all homes and small businesses by the end of 2020.
In response to the figures, Citizens Advice reiterated its call for the deadline to be extended to 2023.
Gillian Guy, chief executive of Citizens Advice, said: “It’s worrying that at this key moment, when the switch to second generation smart meters should be accelerating, installation rates overall are actually slowing down.
“Millions of people who have had a smart meter fitted may find it doesn’t work properly when they switch supplier, while millions more are not able to get a smart meter installed even if they want one.
“Customers on prepayment tariffs, in rural areas, and in large parts of the north of England and in Scotland, are in danger of being left behind.
“Smart meters will provide benefits for customers, but with the rollout beset by technical problems, the current timetable is unrealistic. There’s little chance that the 2020 deadline will be met, it should be extended to 2023.”
Natalie Hitchins, Which? head of home products and services, said: “The rollout of smart meters has been plagued with problems – our research found that for almost six in ten of those we surveyed who had switched energy supplier since they got smart meters, either their smart meter, their in-home display, or both stopped working.
“These latest figures show suppliers have a mountain to climb, given that only a quarter of meters are operating in smart mode.
“All parties involved should be focusing their resources on ensuring the rollout delivers on the promise to bring greater convenience and a more competitive energy market – not just hassle and soaring costs for customers, funded by their very own bills.”
A number of big six energy companies are still installing first-generation (SMETS1) smart meters, despite the deadline for such installations passing.
British Gas, SSE, Eon, Npower and EDF all say they will continue to install SMETS1 devices, even though the deadline for installations was 5 December 2018.
Interoperability has been a key concern throughout the rollout, with many first-generation devices being unable to work after a customer switches supplier.
SMETS1 devices are expected to have “full functionality” from May, according to the government official overseeing the smart meter rollout.
The Data Communications Company said a total of 500,000 second-generation (SMETS2) smart meter devices had been installed as of 8 March.