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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MO Latest Update.pdf
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Current Storage Positions
Security of Supply and Capacity
Energy
New Zealand hydro storage dropped to 62% of the historic average last week. North Island hydro storage decreased from 41% to 37% of the historic mean for the time of year, and South Island storage decreased from 69% to 65%. Although hydro storage continues to decline, the electricity risk also shifts downward in the coming months as inflows are expected, along with lower demand over spring and summer.
Capacity
Margins remained healthy last week reflecting high thermal commitment in line with low hydrology and sustained high wholesale electricity prices. Residual generation was over 800 MW during the peaks last week.
We issued a revised NZGB CAN at the end of June which highlighted potential N-1-G shortfalls through to the end July. Some of these have been resolved but potential shortfalls remain at the end of the month. The largest potential shortfalls on 30 and 31 July are -118 MW and -119 MW respectively. This is due to a combination of high demand over the same period last year and multiple generation and transmission outages. Within seven days we monitor these more closely through the market schedules.
We recommend that participants consider the flexibility of planned outages and whether the start/end time of the outages can be rescheduled away from the peaks. We also recommend avoiding scheduling further outages during this period that may reduce generation margins.
From 1 August, NZGB will start using Yes Energy's (formerly Tesla) probabilistic load forecasting model in its calculations. The latest NZGB report is available on the NZGB website.
Electricity Market Commentary
Weekly Demand
Total demand was 843 MW last week, down 3% from the week prior. The school holiday period contributed to lower national demand. Demand peaked at 6,661 MW on the evening of Monday 15 July, 98 MW higher than last week's peak.
Weekly Prices
Average wholesale electricity prices remained high last week, with the average wholesale price at Ōtāhuhu increasing from $332/MWh to $368/MWh. The North Island and South Island reference prices are about three times higher than they were this time last year. High average prices are in line with low hydro storage, highly priced energy offers and high thermal unit commitment. Wholesale prices peaked at $761/MWh at Invercargill at midday on Saturday 20 July.
Generation Mix
The average renewable percentage of the generation mix decreased by 4% to 74% last week driven in part by a decrease in wind generation from 6% to 4% of the mix. Thermal generation increased from 21% to 23% of the generation mix, reaching an average of 200 GWh last week. This is the highest level of thermal generation since winter 2021 with all three Huntly Rankine units running, along with Huntly Unit 5 and Stratford TCC every day last week. Hydro and geothermal generation provided 49% and 21% of the mix respectively. Hydro generation remained below the 52-week average of 57%, as a result of low inflows in recent months.
HVDC
HVDC flow was predominantly southward last week and during the weekend with some periods of northward flow during daytime. The flows reflect limited inflows to South Island hydro catchments and slightly lower demand in the North Island. In total, 23 GWh was sent south and 7 GWh was sent north last week.