ASEFS is the acronym of the Australian Solar Energy Forecasting System.  It’s similar to AWEFS (which was operational beforehand).


(A) Purpose of AWEFS

As at 22nd May 2024, the AEMO notes the following here as the purpose of ASEFS:

‘In 2014, AEMO established the Australian Solar Energy Forecasting System (ASEFS) to provide forecasts of solar energy generation, improving the accuracy of the National Electricity Market (NEM) forecasting processes.’


(B) Evolution of AWEFS

This Glossary Page for ‘The Semi-Scheduled Category’ provides a more detailed tabular chronology of the evolution of the Semi-Scheduled category in general terms.

In this table we just focus on the evolution of ASEFS.


Date Milestone
(re the evolution of ASEFS for producing UIGF for Solar Farms, and rooftop PV)
30th May 2014

Remember that the Semi-Scheduled category came into existence back in 2009.

1)  But, until this time, this had just served Wind Farms operating with AWEFS.

2)  There were no Large Solar farms operating in the NEM at that point.

With the arrival of Large Solar Farms (such as noted with ‘First production from Nyngan Solar Farm seen over the weekend’) the AEMO needed to replicate the process used by AWEFS

1) and so created ASEFS for the the Unconstrained Intermittent Generation Forecast (UIGF) for each Solar Farm DUID.

2)  this UIGF value then set the Availability figure in the bid used by NEMDE, and the MaxAvail figure in the bid was ignored (up until 7th August 2023, as noted here).

Let’s call this development Version 1 of AEMO’s (Large Scale) ASEFS forecast (the AEMO calls it ‘ASEFS phase 1’).   At the time the production of this forecast was outsource by the AEMO to a service provider based in Europe.

ASEFS was required to provide Availability forecasts for time horizons including:

Time Horizon #1)  In the ST PASA  time horizon (out 8 days into the future);

Time Horizon #2)  In the P30 predispatch time horizon (out until 04:00 tomorrow or the day after);

Time Horizon #3)  In the P5 predispatch time horizon (out eleven dispatch intervals into the future); and

Time Horizon #4)  In the dispatch interval time horizon (i.e. a forecast, at the start of the dispatch interval, of what was possible for the end of the interval).

30th March 2016

Let’s call this development Version 1 of AEMO’s (Rooftop) ASEFS forecast (the AEMO calls it ‘ASEFS phase 2’).

… there are principally two different methods used to produce two different sets of results:
(a)  The ‘Measured’ results utilise Sample + Extrapolation … and these are the ones we typically refer to on WattClarity
(b)  The ‘Satellite’ results utilise Observation + Power Curve + Extrapolation
and are explained further here.

Not long after its introduction, we published the article ‘The opacity of distributed, small-scale solar PV output’ to compare the results being produced by AEMO in their forecast to the APVI forecasts that had existed for some time before AEMO implemented their estimates.

23rd Nov 2022

As noted in this article at the time, AEMO began to use its improved ASEFS and AWEFS forecasts.

Let’s call this development Version 2 of AEMO’s (Large Scale) ASEFS forecast.  In contrast to version 1, this version was designed and developed internally at the AEMO, and runs internally.

Will add more here, as time permits.


(C) AEMO documentation about ASEFS

For those looking for more information, the AEMO has a sub-site here on the Australian Solar Energy Forecasting System.