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].
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Current Storage Positions
Overview
National hydro storage continued to decline last week, hitting 77% of the historic mean for this time of year. Storage dropped to below the 6th percentile, meaning it is near the lowest level in 93 years of records. Inflows continued to remain below average last week.
In this week's insight we demonstrate the correlation between hydro storage and the wholesale price of electricity, and the changes in the relationship observed in recent years.
Security of Supply and Capacity
Energy
New Zealand hydro storage decreased from 80% to 77% of the historic mean last week. South Island hydro storage dropped from 78% to 76%, and North Island storage dropped from 99% to 90% of the historic mean for this time of year. Inflows during January and February have been the lowest on record resulting in national storage currently sitting below the 6th percentile for this time of year.
Capacity
National capacity margins were healthy last week, with over 1,000 MW available during all peaks. The lowest residual was 1,550 MW on Monday evening. Recent high residual is due to increased thermal unit commitment for this time of year related to the declining hydro storage, as well as relatively low demand.
The N-1-G margins in the NZGB forecast are healthy through to early May. 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 weekly demand remained at 714 GWh last week. Demand peaked at 5,215 MW at 8am on Thursday 13 March. Lower demand than previous years is largely due to reduced industrial demand.
Weekly Prices
The average wholesale electricity spot price at Ōtāhuhu last week increased from $265/MWh the week prior to $284/MWh. Wholesale prices at Invercargill peaked at $552/MWh on Thursday 13 March at 6:30am during a period of price separation.
Energy prices in the South Island have been higher than the North Island due to the reduced hydro storage. For instance, the average wholesale electricity spot price at Invercargill last week increased from $308/MWh the week prior to $338/MWh. There were many periods of high SI FIR prices across the week to provide reserves to cover high overnight HVDC southwards transfer.
Generation Mix
The average renewable percentage last week dropped to 76% with below average hydro generation. Wind generated 10% of the mix last week. Hydro generation decreased from 45% to 42% in line with declining hydro storage, and geothermal contributed 23% of the generation mix. Thermal generation increased to 22% of the mix from 19% the week prior in part due to TCC coming online from 11 March. Solar almost reached 1% of the generation mix last week.
HVDC
HVDC flow was predominantly southward last week. In total, 37 GWh was sent south and 6 GWh was sent north. Net southward flow is increasing as hydro storage declines and thermal generation increases. Peak southwards flow was 646 MW on Thursday 13 March at 1:30am, allowing South Island hydro generators to conserve water.
SOSFIP Review Issues Paper
On 10 March we published a Security of Supply Forecasting and Information Policy (SOSFIP) Review Issues Paper. Submissions are due by 5pm on Monday, 24 March 2025. This is followed by a one-week period for cross-submissions. Cross-submissions are due by 5pm on Monday, 31 March 2025.