Skip to main content


This folder provides access to datasets that relate to the operation of the retail electricity market.


The wholesale folder provides access to a wide range of data relating to the operation of the wholesale electricity market. For example, final pricing raw case files, vSPD input GDX files, and CSV files containing final prices, half hourly metered data, bids and offers, and much more.

Ancillary services

This folder provides access to datasets that relate to the operation of markets for ancillary services. Electricity markets require ancillary services to ensure the quality and reliability of the electricity supply is maintained at acceptable levels. Offers to supply frequency keeping services are an example of the data available to be downloaded.

Forward markets

This folder provides access to information and datasets relating to forward markets. For example, the weekly report summarising activity on the ASX New Zealand electricity futures and options exchange and the New Zealand electricity hedge disclosure system. Forward markets can take many forms, and enable parties to manage price or location risks by trading contracts derived from the spot market for electricity.


Environmental factors such as weather can significantly influence outcomes in the electricity market. This folder provides access to environmental datasets. For example, lake levels and inflows into hydro storage reservoirs.

Supplementary information

This folder provides access to supplementary information that supports reports published elsewhere by the Electricity Authority. For example, the analysis undertaken to support a consultation project or an industry study.


vSPD is an independently audited, mathematical replica of the Scheduling, Pricing and Dispatch (SPD) market clearing engine used in the administration and operation of the New Zealand electricity market.


GEM, which stands for Generation Expansion Model, is a GAMS-based, long-term capacity expansion model of the New Zealand electricity sector.


Doasa is a version of the stochastic dual dynamic programming technique applied to the solution of hydro-thermal scheduling problems.


The Hydro Supply Security (HSS) test applies a deterministic methodology to calculate the risk of a storable hydro supply shortage by assuming that storable hydro is treated as the last resort supply of energy. The HSS test is encapsulated in a simplified version of the vSPD model.

A fundamental requirement of competitive and efficient electricity markets is access to reliable data and performance metrics. The EMI website is the Electricity Authority's avenue for publishing data, market performance metrics, and analytical tools to facilitate effective decision-making within the New Zealand electricity industry.


Welcome to our Electricity Market Information (EMI) website.

EMI complements the Authority's corporate website at by focusing on data, insights, analytics and modelling tools, including vSPD-online. The EMI website works best with modern web browsers.

The Authority maintains a comprehensive data warehouse and the EMI website has secure access to a portion of the data warehouse. Service providers, subscription data services, participants and the Authority itself are the main sources of data collected in our data warehouse. Only public domain information is able to be accessed from EMI.

The glossary and legal information pertaining to the EMI website, as well as some links back to key parts of the corporate website, are accessible from the footer section of all EMI pages.


Dashboards are collections of reports providing a convenient overview of related information in a single view. Selecting the title of any report appearing in a dashboard will navigate you through to that specific report. The parameter settings for the report may then be modified to reveal further insights into the underlying data.


Reports allow users to interact with and interrogate large quantities of data by making selections from a range of input parameters. The resulting information can be viewed graphically as a chart or a map, or in table form. Reports and their underlying data are able to be downloaded.


Datasets on EMI provides browser-based access to the Authority's FTP server.

Datasets are collections of files that often contain large volumes of data and are available for immediate download. Dataset users are typically analysts familiar with the electricity industry and have a need to obtain specific data on a regular basis. Supplementary material may also be found in datasets and would include items such as large quantities of analysis prepared in support of a consultation paper or an industry study.

Much of the data available from the datasets collections could alternatively be extracted from our data warehouse directly using reports. In some cases, the collections found on datasets are reports the Authority is obligated under the Code to publish. For example, Market Administrator reports.


We have constructed many modelling tools over the years to support our monitoring and investigative activities. The workhorse from this suite of models is our widely-used vSPD model. The Authority is pleased to make these tools available to the wider community of analysts with an interest in investigating and studying the electricity market.

The Authority considers that making these tools accessible will lead to a greater focus on market performance monitoring and more informed decision making within the electricity sector. This in turn has a pro-competitive effect and aligns with the Authority’s statutory objective to promote competition in, reliable supply by, and the efficient operation of, the electricity industry for the long-term benefit of consumers.

An online code repository and change management facility of models and scripts under development is maintained on the Electricity Authority's GitHub page. Analysts wishing to make use of these codes or contribute to their development are welcome to do so.

The legal information page, accessible from the footer section of all EMI pages, contains important copyright and licensing information pertaining to our modelling tools.


The EMI forum is an online platform where the community of analysts and technicians making use of the EMI website can post questions, and discuss and share ideas related to the data, insights, analytics and modelling tools.

It is a valuable addition to the Authority’s existing communications channels, such as Market Brief, Market Commentary, and Twitter, and offers an innovative point of difference—direct engagement with Electricity Authority staff members. Authority staff members play an active role in the forum to facilitate discussion and offer educational assistance.

We encourage forum contributors to ask questions about the data, materials and tools on the EMI website so that we can provide answers and, in doing so, provide visibility to the entire forum. We also encourage contributors to share the insights they have gained, or to raise issues they may be struggling with. As these conversations develop and grow, the EMI forum will become a transparent and trusted knowledge base.

It should be understood that the EMI forum is a moderated forum. Users are encouraged to engage in an open and transparent manner, and observe common standards of civility and decorum. Inappropriate or abusive posts will be removed and the sign-in privileges of the user will be revoked. Finally, EMI forum users should familiarise themselves with the EMI legal information.


The Authority is keen to facilitate access to data in order to drive innovation and choice for consumers. In addition to receiving information through reports, datasets or FTP access, data can be obtained from our application program interface (API) platform. APIs allow users to automate information flows by subscribing to feeds or requesting specific results.

Users of APIs need to sign in to the API portal – this is a separate sign-in facility from our EMI sign-up.

We use the forum to keep EMI users up-to-date with items of interest. Newsworthy items might include changes or enhancements to EMI website itself, new reports or datasets released, scheduled outages, or items we feel the community will be interested in. Users can subscribe to follow the EMI news tag and receive these notifications by joining the forum.

Tell us what you think

If you wish to provide us with feedback about the EMI website or you have suggestions on how we could improve it, please email us at Alternatively, use the EMI forum to start a discussion with ourselves and others.

Data documentation

Reports on EMI have notes associated with them containing material that users will find helpful in interpreting and understanding the reports. The files found in datasets are explained in the following document. APIs are described on the API website.

Last updated: 20th May 2016

FTP access to datasets

Files on the Authority’s FTP server may be directly accessed via anonymous FTP. Our FTP server can be found at Direct access using FTP means that automated procedures can be prepared to obtain selected files at predetermined intervals.