Cadence, Timestamps, and Data Points – in the RenewEconomy widget

This NEMwatch widget shows the supply and demand balance across Australia’s two main electricity grids:

1) In the east, Australia’s National Electricity Market (NEM) covers only ½ of the Australian land-mass but accounts for roughly 90% of electricity consumed across the country.

2) The second major grid is the South-West Interconnected System (SWIS) that supports Wholesale Electricity Market (WEM) which supplies the cities of Perth and Fremantle, and surrounding areas of south-western WA. Note that this does not cover the whole of WA (there is a sizeable grid in the North-West, for instance), but it is the only data we have access to at this point.

3) We’re well aware that the widget does not provide visibility of other grids (e.g. NT, Mt Isa, NWIS) … see the FAQs for more explanation of why these are missing (and why you can’t see ACT explicitly either).

The widget shows data aggregated together from several different providers – so the data has slightly different cadence and timestamps. We have designed the widget to show the most current data available – you can mouse-over a particular data point to understand more.

The following table provides a few pointers about different data sets – with more detail provided here on this page:

In Western Australia

(The WEM operates in local Perth time, which is UTC + 8 hours … though all data in the widget is shown in UTC+10 to be consistent)


Data for most of the fuel types is supplied by the AEMO West (formerly the IMO) and is of a 30-minute cadence.

This widget was updated (March 2015) to include “APVI Small Solar”, which is the estimated production from small-scale (i.e. predominantly rooftop) solar PV – described here .

Demand Data

Being an isolated grid, supply always equals demand in the SWIS.

The SWIS is the second largest electricity grid in Australia.

Across Queensland, NSW, Victoria, South Australia and Tasmania (the NEM).

(The NEM operates in Eastern Standard Time (UTC + 10 hours) and does not shift with daylight savings. Hence for clarity it is known as “NEM time”)


Data for most of the fuel types is supplied by the AEMO East and is of 5 minute cadence.

1) It comes from the AEMO’s “Initial MW” SCADA readings taken from most of the larger generators that operate in the NEM and are allocated to respective Fuel Types using information in our Asset Catalog.

2) In some cases where generation by a particular fuel type is relatively small (such as the case of the few bagasse-fired power stations in QLD that have data reported by AEMO) we have taken the step of leaving them classified as “Other” to save space in the legend.

3) Where a new station appears with fuel type that is not yet set, it will appear as fuel type “Other” for an interim period.

Small Solar Data:

This widget was updated (March 2015) to include “APVI Small Solar”, which is the estimated production from small-scale (i.e. predominantly rooftop) solar PV – described here . In July 2021 the “APVI Small Solar” was updated to use a new (and, APVI thinks, more accurate) methodology.

In November 2022 the widget was updated to present AEMO’s small solar estimates for NEM regions (measurement-based actuals). This data has a 30-minute cadence.


What is shown as “AEMO Operational Demand” is a number we calculate from unit level data in order to ensure that we can correctly provide visibility to consumption for charging of storage (either battery charging, or pumping to pumped storage hydro). This means that the figure for AEMO Operational Demand does not match to a single raw data field published by AEMO.

Pumping to pumped storage hydro, being a scheduled load, is reported explicitly by AEMO.

Similarly, charging of large-scale batteries (starting with Hornsdale Power Reserve) is reported explicitly by AEMO.

Finally, there are a number of points of consumption that the AEMO can’t see (especially in real time) – such as where it is supplied by generators that operate “behind the meter”. Small-scale PV is one example of this, but there are others (such as embedded generation on industrial sites). As we are able to access (or estimate) other aspects of this, we will evolve our representation.

Inter-Regional Flows

The NEM operates as 5 interconnected “regions” approximating state boundaries (with the ACT part of the NSW region).

By seeing the difference between supply and demand in a particular region, you are able to understand the extent to which the region is importing (or exporting) at that time.

All data is shown as close to your current viewing time as possible.