System security and resilience
Improving the accuracy of intermittent generation forecasts
Improving the accuracy and frequency of intermittent generation forecasts in the spot market.
Overview
New centralised forecasting arrangement
On 31 July 2025 the Electricity Authority introduced a new hybrid forecasting arrangement to improve the accuracy of intermittent generation forecasts and offers.
The Authority's centralised forecast provider is DNV Services. By default, all intermittent generators must use centralised forecasts for their offers.
Onboarding a new intermittent generator/site
If you are a new intermittent generator or setting up a new intermittent generation site, please complete this onboarding form so the Electricity Authority and DNV Services can set you up to use the centralised forecasting arrangement. You need to allow up to six weeks for this process.
Alternative to the centralised forecast
If you are an intermittent generator and wish to use an alternative forecast provider, you need to apply and meet minimum performance standards to obtain the Authority’s approval to do so. Please read this guidance on the process and requirements and apply using this application form. You need to allow up to 10 weeks for this process.
Contact
For any queries, contact forecasting@ea.govt.nz
Timeline
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25 July 2025
Guidance —Guidance on the timing and frequency of approved forecasts
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21 February 2025
Decision paper — -
11 October 2024
Consultation —Review of forecasting provisions for intermittent generatorsView consultation -
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17 October 2022
Review —Accuracy of wind generation, demand forecasts and bids from April 2021-March 2022
Project background
Incorrect forecasting by wind generators was a contributing factor in the 9 August 2021 grid emergency, which resulted in the disconnection of approximately 34,000 customers without warning.
In response to this grid emergency, the Electricity Authority (and other organisations) conducted a number of reviews and investigations to:
- understand the causes of power supply interruptions
- understand the industry’s response on the night
- learn lessons from the event to identify and recommend improvements to ensure similar circumstances are better managed in future.
In response to one of the review’s recommendations, we published an information paper about the accuracy of wind generation, demand forecasts and bids leading up to real time from April 2021 to March 2022. We found that intermittent generation forecasts are often inaccurate and unreliable until the last three and a half hours before real time.
Inaccurate forecasting is prevalent because there are minimal obligations around the accuracy of intermittent generation forecasts. Intermittent generators have few incentives to forecast accurately as there is little correlation between forecasting accuracy and revenue earnt in the spot market.
Following consultation, the Electricity Authority introduced a new hybrid forecasting arrangement on 31 July 2025 to improve the accuracy of intermittent generation forecasts and offers.
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