As electricity flows through the transmission and distribution networks, energy is lost due to electrical resistance and the heating of conductors. The losses are equivalent to approximately 10% of the total electricity transported between power stations and market customers.

Energy losses on the network must be factored in at all stages of electricity production and transport, to ensure the delivery of adequate supply to meet prevailing demand and maintain the power system in balance. In practical terms, this means more electricity must be generated than indicated in simple demand forecasts to allow for this loss during transportation.

The impact of network losses on spot prices is mathematically represented as transmission and distribution loss factors. Loss factors are calculated and fixed annually to facilitate efficient scheduling and settlement processes in the NEM.

Methodology

• Methodology for Calculating Forward-Looking Transmission Loss Factors

Guidelines

• Treatment of Loss Factors
• Proportioning of Inter-Regional Losses Within Regions

Transmission Loss Factors

• Regional Boundaries and Marginal Loss Factors for the 2015–16 Financial Year
• Regional Boundaries and Marginal Loss Factors for the 2014–15 Financial Year
• Regional Boundaries and Marginal Loss Factors for the 2013–14 Financial Year
• Regional Boundaries and Marginal Loss Factors for the 2012–13 Financial Year
• Regional Boundaries and Marginal Loss Factors for the 2011–12 Financial Year
• Regional Boundaries and Marginal Loss Factors for the 2010–11 Financial Year
• Regional Boundaries and Marginal Loss Factors for the 2009–10 Financial Year
• Regional Boundaries and Marginal Loss Factors for the 2008–09 Financial Year

Distribution Loss Factors

• Distribution Loss Factors for the 2018–19 Financial Year (682 KB, pdf)
• Distribution Loss Factors for the 2017–18 Financial Year (673 KB, pdf)
• Distribution Loss Factors for the 2016–17 Financial Year (657 KB, pdf)
• Distribution Loss Factors for the 2015–16 Financial Year (253 KB, pdf)
• Distribution Loss Factors for the 2014–15 Financial Year
• Distribution Loss Factors for the 2013–14 Financial Year
• Distribution Loss Factors for the 2012–13 Financial Year
• Distribution Loss Factors for the 2011–12 Financial Year
• Distribution Loss Factors for the 2010–11 Financial Year
• Distribution Loss Factors for the 2009–10 Financial Year
• Distribution Loss Factors for the 2008–09 Financial Year

Archived loss factor documents may be obtained upon request from the AEMO Information & Support Hub.

Provision of indicative marginal loss factors

Interested parties may on occasion require marginal loss factors (MLFs) under conditions that differ from the Forward Looking Loss Factor (FLLF) methodology. Examples include:

• A proponent may wish to assess the potential impact on published MLFs if a generating unit is installed or upgraded at a particular connection point.
• A market customer may wish to assess the impact on the published MLF at a connection point without the contribution of a nearby generating unit.
• A market participant may wish to assess the MLF of an embedded generator for which AEMO does not normally calculate and publish an MLF.

To assist interested parties with such requests, AEMO currently provides a service to calculate indicative MLFs under non-standard assumptions for a nominal fee.The following document provides details of the indicative MLF calculation process, including fees and data requirements.

Indicative extrapolation input data for 2018-19 Marginal Loss Factors

AEMO conducted an indicative extrapolation study to assist generators in determining whether the historical generation data used by AEMO is reasonable for the 2018-19 MLFs calculation.

Indicative extrapolation input data for 2018-19 Marginal Loss Factors:

• Indicative extrapolation input data for 2018-19 loss factors (391 KB, pdf)
• Indicative extrapolation results for 2018-19 loss factors (100 KB, xlsx)