Contact Energy has been switching off its gas-fired power stations, as the generator increases geothermal capacity and copes with unseasonably warm weather.
The gas turbine plants haven't run for the past three weeks, and before that the Otahuhu site was only operating during weekdays.
The company revealed its production output when it released its results showing its annual net profit for the year ended June rose nearly 18 percent to $234 million.
Contact Energy's chief executive Dennis Barnes said they were less reliant on their non-renewable power stations.
"Year on year, we've reduced our production reasonably significantly from the thermal plant. As the hyrdo scheme has been able to sell its power in the north, we've turned off the thermal plants and increasingly we are doing that."
Mr Barnes said residential and commercial consumption across New Zealandwas down.
