Nearly 4m energy smart meters in homes and businesses are faulty, government figures have shown, in a further blow to the “troubled” rollout of the technology. Data from the Department for Energy Security and Net Zero reported that, at the end of last year, 3.98m meters in Great Britain were not working properly. The department had initially reported that there were only 2.7m faulty meters in June 2023 but the figure for June has been revised up – to 4.31m – because of reporting errors from some suppliers. The latest data has raised concerns that customers may have been overcharged on their gas and electricity bills, and has prompted the government to write to the industry regulator, Ofgem, urging action against energy providers who are not supporting customers and meeting legal obligations. Smart meters are seen as an important part of the transition to net zero by allowing homeowners to more easily track their energy use and take steps to reduce consumption. They send real-time data on customer usage to suppliers remotely when in “smart mode”. However, when they are not connected properly, customers have to rely on estimated bills, which is resulting in some paying too much for their energy. A spokesperson for the industry body, Energy UK, said: “Technical problems can prevent some meters from operating in smart mode and while this can be for reasons outside their control, suppliers still have an obligation to replace them when this happens.” It added that the best way to avoid inaccurate bills through estimated readings was to send manual meter readings until their supplier is able to fix the issue. Last week Lord Callanan, minister for energy efficiency and green finance, wrote to Ofgem saying the number of faulty meters fell short of what the government expected to see, and urged the regulator to take action. He added that the level of underperformance of some operators showed that legal requirements put in place to ensure meters operated in smart mode were not being universally followed. Last year, the public accounts committee called on ministers to set out how they plan to convince the public to take up a smart meter more than a decade into the “troubled” rollout of the technology. About 60% of all domestic and business meters now smart. A Department for Energy Security and Net Zero spokesperson said: “The vast majority of smart meters are working correctly. “However, we are concerned that reporting errors by a minority of suppliers have uncovered more meters not operating in smart mode than previously thought.” Smart Energy GB, a government-backed non-profit set up to help with the smart meter transition, said there are now almost 35m smart meters in Great Britain “and the vast majority are operating as intended”. It added that there had been an overall improvement in the proportion of smart meters operating in smart mode since 2022, increasing from 87.3% at the end of 2022 to 88.6% at the end of 2023.