Electricity cost and price monitoring

The Ministry uses sales-based data to monitor average residential, commercial and industrial electricity costs (essentially total electricity sales divided by the quantity of electricity supplied). The latest data can be found in the Prices data table.

Household sales-based electricity cost data is complemented by the Quarterly Survey of Domestic Electricity Prices (QSDEP) indicator.

Household sales-based electricity cost data

The Ministry monitors national residential electricity costs using information about national electricity sales. This data is based on the actual volume of electricity sold and the total revenue, to give the average cost per kilowatt-hour paid by residential consumers. This data is updated quarterly.


Electricity sales data includes prompt payment, multi-fuel and online discounts, as well as incentive and retention payments, and rates paid by customers on fixed-term plans.

It is important to note that the cost per unit of electricity used increases as average electricity demand decreases (and vice versa). This is because some parts of customers’ electricity bills are fixed daily costs. If demand in a given period is lower, then the average cost per unit used is higher because the fixed costs are spread across fewer units. For this reason, changes in the quarterly cost per unit data should be interpreted with care.

Method for sales-based electricity costs

  • Household cost data is available only at a national level.
  • New quarterly electricity cost data is available back to the June 2013 quarter.
  • Residential cost data is derived from information obtained primarily from electricity retailers. The Ministry collects the total value of sales, the total volume of electricity sold, and the number of connections.
  • The residential electricity cost per unit is derived by dividing the dollar value of residential electricity sales by the number of kilowatt-hours (kWh) sold to residential customers.
  • Cost data reflects any prompt payment discounts actually claimed by customers, as well as multi-fuel and online discounts, incentive and retention payments received, and rates paid by customers on fixed-term plans.
  • The cost data is based on sales of delivered energy.
  • The survey also reports the “lines” component of the residential costs. This covers both the distribution and transmission components of the residential costs.
  • Electricity sales information is collected from electricity retailers on the MBIE Quarterly Retail Sales Survey (Electricity and Gas) return attached below
  • Cost data does not include any ownership-based discounts or distributions from consumer trusts. If these discounts and distributions were included, the prices would be lower.

Improvements made to sales-based electricity cost monitoring in July 2014

The Ministry has made the following improvements to the sales-based electricity price cost data:

  • greater consistency of information between retailers. The Ministry now provides more detailed guidance for retailers on what the sales data should and should not include. In particular, the treatment of discounts is expected to be clearer and more consistent between retailers.
  • collecting data more frequently (quarterly, rather than annually) to improve the quality and consistency of information.
  • residential costs back to the year ended March 2009 have been revised based on consistent information provided by all electricity retailers. Some retailers have also provided revised data back to the year ended March 2002. This has been incorporated into the residential electricity cost data.
  • Average household electricity expenditure and average electricity demand per household have been added to the tables for sales-based electricity cost data. These figures provide additional context to assist stakeholders in interpreting the data.

The Quarterly Survey of Domestic Electricity Prices (QSDEP) – a price indicator

The QSDEP is a price indicator series that complements sales-based electricity cost data. The QSDEP indicator is a measure of how the published residential electricity tariffs have changed over time. A time-series of the price indicator is available in the raw data sheet of the excel version below.


Method for the QSDEP

  • A limited selection of publicly advertised retail tariffs are surveyed for around 40 towns and cities across New Zealand.
  • Prices are surveyed as a snapshot at the mid-point of each quarter (15 February, 15 May, 15 August and 15 November each year).
  • The average prices are quoted for a modelled consumer using around 22 kWh per day (8000 kWh of electricity per year).
  • An average regional price across all retailers is published, weighted by market share.
  • Prices assume that prompt payment discounts are claimed. They do not include multi-fuel and online discounts, incentive or retention payments, or rates paid by customers on fixed-term plans.
  • Lines prices cover both distribution and transmission services combined.
  • Prices do not include any ownership-based discounts and distributions from consumer trusts. If these discounts and distributions were included, the prices would be lower. Information about these discounts and distributions:
  • Further technical information about this survey:


From the release of the 15 May 2014 QSDEP, no retailer-specific information is published. Comprehensive information about retailer-specific prices within a region is available from the PowerSwitch website.


Archive of electricity price surveys

Archive of electricity price surveys.

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