SSE fell into the red during the six months to September 30, figures from the Perth-based energy supplier showed yesterday.
It made pre-tax losses of £81.3million, compared with profits of £644.8million a year earlier.
SSE, formerly Scottish and Southern Energy, said it supplied household energy at a loss due to soaring wholesale gas costs.
The company was also hit by a fall in average consumption of 4% in electricity and 16% in gas as hard-pressed consumers cut back on usage. SSE, which trades as Scottish Hydro Electric, Southern Electric and Swalec, raised domestic bills in September. Adjusted pre-tax profits highlighted by the group were down by 25.4% at £287.4million.
Chairman Lord Smith of Kelvin said turmoil in global energy markets and the economic uncertainty had made it a difficult time for the industry, adding: “SSE’s half-year results reflect the impact of a number of these issues, especially the high wholesale cost of gas.”