EDF Energy’s UK profits fell 8.7% in the first half of this year.
It made £513 million in the first six months of 2015 compared to £560 million in the same period last year.
The company also lost 4% or 260,000 customer accounts compared to the end of June last year but claims to have sold more gas to householders due to colder weather.
The Big Six supplier said the reduction in operating profits is due to “a higher depreciation charge which is a direct result of the sizeable investments we have been making in our business”.
It has invested £3.7 billion in existing nuclear and coal-fired stations, the new Hinkley project and customer business.
EDF Energy said power generation from its nuclear stations was “broadly stable” at 30.3TWh in the first six months of 2015.
British Gas today announced its profits doubled in the first half of this year.