The outlook for keeping the lights on has shifted to a more positive one in the past few weeks.
In the Electricity Authority’s weekly snapshot of supply released on Tuesday, national hydro storage had increased over the past week, but remained below the historic average.
Demand for power had fallen over the past four weeks, largely due to warmer spring temperatures and moderating spot prices.
The decrease in wholesale prices was driven by high wind generation levels and lower demand.
A report by the authority showed hydro in-flows in the first three months of the year were the lowest on record, dating back 99 years.
Hydro had picked up since and wind, which was also low during January to March, had also improved.
Southern wind farms have also increased their output.
Mercury Energy said since stage one of the Kaiwera Downs wind farm was commissioned in August 2023, it had produced enough energy to power the equivalent of about 36,000 average residential homes.
In the first 17 days of this month, it produced about 50% more power than average for the period.
The average wind speed in September so far has been 11m per second, or about 39.6kmh — an increase of about 40%.
Mahinerangi Wind Farm has an installed capacity of 36MW, whereas Kaiwera Downs Wind Farm stage one has an installed capacity of 43MW.
Mahinerangi’s performance from September 1-19 has surged ahead, with 75% more production than average for September so far.
The average wind speed for September 1-12 was 12.7m per second, or about 45kmh.
The average wind speed for the site over the past two years has been 8m per second, so it had been about 60% windier than average over the period.
Mahinerangi has generated 118GWh in the past year — September 2024 to August 2025 — enough to power the equivalent of about 14,700 average homes.
Mercury also kept track of "turbine availability" — the percentage of time a turbine is ready and able to produce power when the wind was blowing.
Mahinerangi has been a very reliable site for generation.
Its turbine availability has averaged more than 96% over the past two years.
Turbine availability at Kaiwera Downs wind farm had been very high, 97.5% of the time since it was commissioned in August 2023.
