The National Audit Office (NAO) has begun an investigation into the £11 billion smart meter rollout.

The study will examine the economic case for the programme and whether the government is on track to meet the target of offering the meters to all households and small businesses in Great Britain by 2020.

It will also consider whether the government is doing the best it can to realise the intended long-terms benefits of the meters, estimated to be worth £16.7 billion.

The latest quarterly figures published by the Department for Business, Energy and Industrial Strategy (BEIS) in November show 8.6 million smart meters have now been installed out of an expected total of 53 million.

Delays to the launch of the central IT system provided by the Data Communications Company means suppliers are only just beginning to install second-generation SMETS2 meters, which offer multiple advantages over their less sophisticated SMETS1 forebears, most importantly interoperability.

During a debate on the government’s Smart Meters Bill in October 2017, business and energy secretary Greg Clark told the House of Commons a software update was being developed to enable the interoperability to SMETS1 meters. Energy minister Richard Harrington later added the conversion of SMETS 1 meters would commence within a year.

The bill was introduced to extend the government’s powers to direct the rollout by five years until 2025.

The NAO’s latest investigation is a follow up to two previous studies on the rollout published by the spending watchdog in 2011 and 2014. The report is expected to be released during the summer of 2018.

A spokesperson for BEIS, said: “Smart meters are a vital upgrade to bring our energy infrastructure into the 21st century. More than 8.6 million smart meters have already been successfully installed. These are already helping consumers to better understand their energy use and will take £300 million off domestic energy bills in 2020 alone.

“We will work closely with the NAO to help review the progress of this important programme.”