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
Last week saw continued inflows across the motu. As a result national hydro storage lakes continued to fill, now sitting well above the average for this time of year at 142%.
In this week's insight we look at the new Ancillary Services Cost Allocation System (ASCAS) and new requirements for entering ancillary service equipment outages into our Planned Outage Co-ordination Process (POCP).
Security of Supply and Capacity
Energy
National hydro storage continued to increase to 142% of the historic mean from 127% the week prior. South Island storage increased from 135% to 152% and North Island storage increased from 72% to 74%.
Capacity
Residuals last week were healthy as demand continued to decline as temperatures warmed across the motu. The lowest residual of 790 MW occurred during the morning of Tuesday 1 September during a period of reduced wind generation and high demand.
The N-1-G margins in the NZGB forecast continue to increase with healthy levels through to the end of October. 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 continued to decrease last week to 799 GWh from 810 GWh the week prior. The highest demand peak occurred at 6:30 pm on Monday 31 August at 6,299 MW.
Weekly Prices
The average wholesale electricity spot price continued to decrease at Ōtāhuhu last week from $43/MWh in the previous week to $22/MWh last week. Prices peaked at $146/MWh at 6:30 pm on Monday 31 August, coinciding with the highest peak demand period of the week. Similar price spikes occurred during high morning and evening peaks on Tuesday 1 September.
There were also some periods of price separation between the North and South Islands during the week as no reserves were dispatched in the South Island.
Generation Mix
Wind generation was above its yearly average last week while both hydro and thermal generation fell below theirs. Hydro generation decreased marginally to 55% of the mix. Wind and geothermal generation both increased to 17% and 25% respectively. Thermal generation dropped to below 1% of the mix, just below cogen and solar contributions which were both marginally above 1%.
HVDC
HVDC flows last week was entirely northward. In total 89 GWh was transferred north.