Our Market Operations Weekly Report contains the latest information about the electricity market, including security of supply, wholesale price trends and system capacity.
It is published every Tuesday. Click here to receive the report via email every week.
If you have any comments or questions please contact the Market Operations Team at [email protected].
Latest Report / More Information
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Current Storage Positions
Overview
New Zealand hydro storage increased to 115% of the historic mean last week as inflows continued across the motu. Demand continues to ease with warmer spring weather.
This week’s insight looks at variability of solar generation output and discusses its consequences for management of grid security.
Security of Supply and Capacity
Energy
Inflows across the motu last week resulted in national hydro storage levels increasing to 115% of the historic mean from 108% the week prior. South Island hydro storage increased from 104% to 112% of historic mean and North Island storage increased from 132% to 135%.
Capacity
While capacity residual margins were high for most of last week, residual dropped to 304 MW on the morning of Monday 6 October. This was the highest demand peak for the week and coincided with a period of low wind generation. We continue to monitor capacity closely during the spring shoulder season despite decreasing demand. Outages, reduced thermal unit commitment, and the possibility of cold snaps or large swings in wind generation mean that capacity can be tight despite much lower peaks than in winter.
The N-1-G margins in the NZGB forecast are healthy through to the end of November. Within seven days we monitor these more closely through the market schedules. The latest NZGB report is available on the NZGB website.
Electricity Market Commentary
Weekly Demand
Total demand last week decreased from 778 GWh the week prior to 750 GWh, reflecting warmer temperatures across the motu and lower school holiday demand. Total demand is similar to that observed at this time of year over the past three years. The highest demand peak at 5,744 MW occurred at 8:00 am on Monday 6 October.
Weekly Prices
The average wholesale electricity spot price at Ōtāhuhu last week decreased to $34/MWh from $65/MWh the week prior in line with higher than average wind generation and increased hydro storage. There were long periods of very low pricing throughout the week, particularly on Friday and the weekend.
Wholesale prices peaked at $1,192/MWh at Ōtāhuhu at 8:00am on Monday 6 October during the highest peak of the week when wind generation was low and high priced thermal peaking generation was required. Sustained instantaneous reserve prices spiked in both islands at the same time. The market currently has high hydro storage, low average prices, low thermal unit commitment, and increased generation outages during the spring shoulder season. Periods like this can be prone to price volatility.
Generation Mix
Renewable generation contributed 98% of the generation mix last week. Wind generation increased its share of the mix from 10% to 16% of the mix, above its average contribution of 9%. Hydro generation decreased to 59% of the mix from 62% the week prior but remains above its average contribution, at 56% of the generation mix. Thermal generation decreased from 3% to 1% reflecting lower demand, high wind and hydro generation, and a shutdown of Huntly unit 5 to make gas available to other commercial and industrial users. The geothermal share decreased to 21% of the mix, below its average level of 23%.
HVDC
HVDC flow last week was predominantly northward with the exception of some very brief overnight periods of low southward flow. These periods coincided with periods of high wind generation and lower North Island demand. In total, 47 GWh were transferred north and 1 GWh was transferred south.
SOSFIP Consultation Open
Consultation on a draft amendment to the System Operator Forecasting and Information Policy (SOSFIP) is now open. The closing date for submissions is 5pm on Tuesday 4 November 2025, with cross-submissions due by 5pm on Tuesday 11 November 2025.