Electricity cost and price monitoring
This page has 2 types of data: household sales-based electricity cost data, and publicly advertised retail electricity tariff data.
About electricity cost and price monitoring
We use 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
We monitor national residential electricity costs, using information about national electricity sales.
- is based on the actual volume of electricity sold and the total revenue, giving the average cost per kilowatt-hour paid by residential consumers
- is available only at a national level
- is updated quarterly
- prompt payment, multi-fuel and online discounts
- incentive and retention payments
- rates paid by customers on fixed-term plans.
Care with interpretation
Changes in the quarterly cost per unit data should be interpreted with care, because:
- 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.
Method for sales-based electricity costs
Residential cost data is derived from information obtained primarily from electricity retailers, and is based on sales of delivered electricity.
We collect the:
- total value of sales
- total volume of electricity sold, and
- 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.
The survey also reports the 'lines' component of the residential costs. This covers both the distribution and transmission components of the residential costs.
Quarterly Survey of Domestic Electricity Prices (QSDEP)
The QSDEP is an average price series based on certain assumption, which complements the sales-based electricity cost data.
The QSDEP indicator:
- monitors tariffs publicly advertised in the retail electricity market on a particular date, and
- is a measure of how the published residential electricity tariffs have changed over time.
Note: A time-series of the price indicator is available in the raw data sheet of the Excel version above.
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) with a typical metering configuration in cents per kWh (c/kWh).
An average regional price across all retailers is published, weighted by market share.
- include Goods and Services Tax (GST)
- assume that prompt payment discounts are claimed
- represent the total cost of electricity to a residential consumer, including the line charge component
- don't include multi-fuel and online discounts, incentive or retention payments, or rates paid by customers on fixed-term plans
The line charge figures represent the total (fixed and variable) cost of electricity transmission and distribution.
For more technical information about this survey, see the key assumptions document.
An electricity retailer may charge a consumer 100 cents/day and 22c/kWh of electricity consumed.
This would cost an 8,000 kWh per annum customer:
- $2125 per annum — that is, ((100x365)+(22x8000))/100, or
- 26.6 c/kWh — that is, (2125/8000)x100.
If the Retailer offered a 10% prompt payment discount, the final cost to the consumer would be 23.9 c/kWh.
The line charge component is calculated in a similar manner (all figures include GST).
Discounts and distributions
Prices in the QSDEP don't include any ownership-based discounts and distributions from consumer trusts. If these were included, the prices would be lower.
More information about these discounts and distributions can be found in the analysis report.
From the release of the 15 May 2014 QSDEP, no retailer-specific information is published. Information about retailer-specific prices within a region is available from the PowerSwitch website.
For older surveys, our Archive page has information about how to access archived publications and documents.