Understand your local electricity network

The aim of this activity is to help you understand:

Find a map of your electricity network

A number of systems provide maps of electricity infrastructure. Some stop at your Zone Substation. Some provide the location of medium voltage lines but not the low voltage system. Some include transformer locations and embedded details when you click on the map. You may need to check each of the systems below to find the best result for your region.

  1. AREMI (Australian Renewable Energy Mapping Infrastructure). Turn on the Energy > Electricity Infrastructure > Network Opportunities layers to explore information related to your community.

  2. Search for DAPR (Distribution Annual Planning Report), portal or network map at the website of your network provider because many are starting to put their own maps online.

  3. You can use government Geographic Information System (GIS)-based mapping systems. Often the planning and property department in your state government has electricity infrastructure layers on their public maps. (for example, searching map, infrastructure and sa.gov.au leads to online searchable map by SA Government.)

  4. Look up and Live maps infrastructure in the Energex, Ergon, Endeavour, Essential, SA Power Networks, Jemena and Ausgrid service regions.

Interpret the information

1. Zone substations:

Zone substations transform high voltages to medium voltages. They typically serve 3,000 or more homes and can range in size from 1MW (small) to 20MW or more. Each Zone Substation might have 4 to 8 feeders radiating out to local suburbs or towns. Large industries are often located close to a zone substation. Many places will be connected to one main zone substation with a backup connection to a second zone substation in case there are failures in part of the system.

2. Medium voltage (MV) infrastructure

Medium voltage (MV) feeders are typically 33kV, 22kV, and 11kV and transport electricity at this voltage from the zone substation to distribution transformers. The distribution transformers (sometimes called distribution substations) convert the medium voltage to low voltage which is the three phase power (415V) and single phase power (240V) that most of us use. In regional areas medium voltage systems do the bulk of the long distance criss-crossing to serve every location. In some places the distribution transformer will only serve one or two customers. Larger commercial businesses and industrial energy users sometimes buy their electricity at medium voltage and privately own transformers onsite to convert the power to low voltage.

3. Single wire earth return (SWER)

In some communities, particularly in remote or rural areas, single wire earth return (SWER) systems are utilised. SWER systems are commonly used when extending all three phases of medium voltage is not economically viable. SWER lines take a single phase to serve a few customers over a long distance. Any customers on SWER systems in your community are likely to have lower reliability, larger voltage fluctuations, and can cause imbalance challenges for your network provider.

4. Low Voltage (LV) Distribution

The low voltage (LV) distribution network is responsible for the final stage of electricity distribution to individual consumers. The distribution transformers which convert the medium voltage electricity to low voltage - ie three phase power (415V) and single phase power (240V) - can be as small as 25kW for one or two homes and as large as 500kW. A typical transformer will be sized with 1-2kW per home but as we install more solar, build larger homes and use electricity instead of gas, this is moving toward 5-7kW per home.

Sometimes the size of the transformer is clearly marked on it, so you can guess how many homes are connected. 100kVA, 200kVA, 315kVA and 500kVA are typical transformer sizes. 150 homes served by a single low voltage feeder is normal, which means low voltage systems abound in the denser urban areas of our towns and in our suburbs.

Where possible, low voltage systems are connected as a mesh so if there is a failure in one part of the system, homes can be switched to another distribution transformer and have power restored, even while the fault is being fixed.

For a more understanding of the features and challenges of urban, rural, and remote electricity systems, you can refer to the explainer on the difference between an urban, rural or remote community.

Think about boundaries

To identify potential opportunities for microgrids and local energy options, it helps to understand the boundaries and connections within your local electricity network. Determine the areas that are electrically connected to each other and, if the map allows, explore the location and capacity of transformers.

Bottlenecks

The maximum capacity of each element of your electricity network determines how much electricity can flow through the transformers and along the lines. The lines are often sized to match the transformer capacity, so the best guide to where the bottlenecks are, is the transformer capacity.

AREMI provides the capacity of each Zone substation. If you add the Available Distribution Capacity layer and click on it you can see information about the zone substation serving your community and its current and future load. This network opportunity mapping takes its information from the annual planning processes. You can also read the DAPR (Distribution Annual Planning Report) produced by your network provider and updated every year.

Information about the capacity of distribution transformers is less likely to be made available online but you may be able to see this information when you look at the transformer in real life. The transformer may be mounted on an electricity pole or in a cabinet on the side of the road. Traditionally peak evening load on cold or very hot evenings caused the peak load on just one day per year. The transformer can tolerate short amounts of overloading but if this occurs too frequently the network provider will change it to a larger transformer.

Distribution transformers are the main bottleneck for export solar. A 100kVA transformer might be allowed to export much less than 100kVA of solar energy. This is known as hosting capacity and the electricity industry is exploring many ways to manage or improve hosting capacity limits. Often the limit is not the electricity flowing through the transformer, but the voltages that are caused by power flowing in opposite directions to normal. Your community or local solar installers may know if:

These are all signs that distribution transformers in your community are a bottleneck for the flow of surplus solar energy. Finding ways to use the surplus solar energy instead via flexible use of energy and storage of energy will often be better than waiting for your network provider to change the limits.