TrustPower sold more electricity in the first nine months of the financial year, but lost customers.
TrustPower sold 3071 gigawatt hours of electricity in the nine months to the end of December, 1% less than in the same period a year earlier.
But it lost 4000 customers during the quarter, with customer numbers now 7000 lower than at the same time last year, as competition remained intense across the industry.
Generation was 2028 gigawatt hours in the nine-month period, 15% higher than in the same time a year earlier because of strong hydro production.
Wind generation fell 1% at the Tararua wind farm, but rose 17% at the Snowtown wind farm in Australia.