ScottishPower today revealed core earnings at its UK energy supply and thermal generation business plunged in the first half of the year.
The firm, which is owned by Spanish company Iberdrola, said earnings before interest, tax, depreciation and amortisation (Ebitda) fell 76 per cent to £48.8m from £205.9m due to warmer weather.
Domestic power sales in retail were down around seven per cent, and domestic gas sales were down around eight per cent.
Thermal generation in the UK also fell by 40 per cent during the first half to 3.6 terawatt hours (TWh) due to the closure of the Longannet Power Station.
The Big Six energy supplier also said customer numbers were down by 100,000 in the first half - from 5.4m to 5.3m - though Keith Anderson, chief corporate officer at ScottishPower, said they were "stable".
The company's renewables business performed well with Ebitda rising 32 per cent to £153.7m as onshore wind production surged 43.8 per cent to 1.7TWh due to better wind conditions and increased capacity as it has progressed with a £650m project to install eight new onshore wind farms.
We will continue to work hard to offer customers good value products, and continue to lead the large suppliers in encouraging customers to move away from standard tariffs. Abolishing standard tariffs is more effective than any price cap in ensuring more customers are on the best value deals for them.