UK energy regulator Ofgem fined energy supplier British Gas 4.5 million pounds for failing to supply advanced meters to some large business customers by an April 2014 deadline, it said on Wednesday.
British Gas, owned by Centrica, will have to pay the money to the Carbon Trust, a global advisory focused on moving to a sustainable, low carbon economy.
Customers missed out on receiving better information about their energy consumption and the opportunity to control costs, the regulator said.
British Gas said it had installed around 42,000 advanced meters at businesses by the deadline, more than any other energy supplier, but some customers, including some who had recently joined, did not receive the meters.
A government plan to roll out advanced meters to businesses began in 2009 as part of a national project to modernise the energy sector.
(This version of the story corrects to read business customers, paragraph one.)
(Reporting by Nerijus Adomaitis in Oslo; editing by Jason Neely)