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
Demand last week was relatively high for this time of year with some colder weather. With inflows near average, national hydro storage fell from 139% of the mean for this time of year to 132%. It remains well above the 90th percentile. Solar generation contributed a record 2.4% of overall generation for the week and set a new record peak generation of 519 MW.
In this week's insight we look at changes to Instantaneous Reserve Cost Allocation that take effect from 1 October.
Security of Supply and Capacity
Energy
National hydro storage decreased to 132% of the historic mean from 139% the week prior. South Island storage decreased from 148% to 143% and North Island storage decreased from 81% to 75%.
Capacity
Residual for some peaks last week dropped into the 500-600 MW range with colder weather, lower wind generation and some geothermal outages. The lowest residual was 543 MW on the evening of Tuesday 22 September, which is well
above the 200 MW threshold for a low residual Customer Advice Notice (CAN).
The N-1-G margins in the NZGB forecast continue to increase with healthy levels through to late 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 increased last week to 804 GWh from 780 GWh the week prior with colder weather. The highest demand peak occurred at 7:30 am on Thursday 24 September at 6,217 MW.
Weekly Prices
Wholesale electricity spot prices increased last week with the average Ōtāhuhu price increasing to $67/MWh, up from $48/MWh the previous week. Prices peaked at $290/MWh at 8:00 pm on Friday 25 August, coinciding with low wind generation.
Some periods of inter-island price separation occurred during the week with high HVDC transfer setting the North Island risk.
Generation Mix
Solar generation broke records this week for the highest peak generation (519 MW at 11:30 am on Thursday 24 September), the highest weekly share of generation (2.4%) and the highest total weekly generation (20 GWh). This was due to the country's two largest solar farms, Tauhei and Kōwhai Park, reaching full capacity. Solar generation will continue to increase with conditions improving as we head into summer and as more solar farms come online in the next few months.
Wind generation was above its yearly average last week at 12% with thermal and geothermal generation below average at 1.4% and 23% respectively. Hydro generation was average at 61% of the mix.
HVDC
HVDC flows last week were almost entirely northward. In total 121 GWh was transferred north.