The Office of Gas and Electricity Markets (Ofgem) told E.On that it must pay £7m for failing to adequately supply its business customers with advanced electricity meters.
In 2009 the UK government gave energy suppliers five years to provide its business customers with smart meters, which are more efficient at monitoring electricity and gas consumption.
Ofgem found that the energy company did not meet its target to supply smart meters to 20,000 of its business electricity customers by an April 2014 deadline. The company only provided the meters to 13,000 customers.
E.On agreed to pay the Carbon Trust £7m for what the energy regulator called an “unacceptable” failure.
The energy giant has a year to meet new interim targets or it could face a further £7m redress.
Anthony Pygram, Ofgem senior partner with responsibility for enforcement, said: “It is unacceptable that E.ON failed to roll out advanced meters to these business customers on time.
“Customers have lost out on receiving better information about their energy consumption and the opportunity to control costs. Unless E.ON improves their poor record, they will have to pay out even more and may face a sales ban.
“The rollout of advanced meters has the potential to transform the energy market. We expect all suppliers to learn the lessons from this ahead of the domestic smart-meter rollout, in particular the need to start the process in good time and ensure senior managers are committed to delivering on time.”
According to the BBC, a spokesman for E.On said: “Installing advanced meters to tens of thousands of business customers across the country was always going to be a significant challenge and one that threw up a variety of hurdles for suppliers to overcome.
“That said, we cannot, and will not, overlook the fact that we did not do enough in time to meet the deadline and in that regard failed to provide the efficient service our business customers demand and deserve.”