Amendment of the Market Ancillary Service Specification (MASS) – DER and General consultation

Market National Electricity Market
StageFirst Stage
ConvenorAEMO NEM
Accepting submissions?No

The Australian Energy Market Operator (AEMO) is conducting a consultation on the Market Ancillary Service Specification (MASS) with regards to measurements requirements for DERs to participate in the Contingency Frequency Control Ancillary Services (FCAS) markets. AEMO is also taking this opportunity to consult on other important issues in a ‘General MASS Review’ and to undertake a simplification and clarification of the MASS document. 

This consultation is being conducted in compliance with clause 3.11.2(d) of the National Electricity Rules (NER) which requires AEMO to “comply with the Rules consultation procedures when making or amending the market ancillary service specifications.”


General MASS Review

AEMO last conducted a review of the MASS in 2020. This was a limited review aimed at addressing a key issue pertaining to disincentives to providing Primary Frequency Response (PFR). That review, along with feedback from participants, general developments in the FCAS markets and the rollout of the PFR rule have highlighted a range of issues to do with the MASS that should be given due consideration. In addition, AEMO believes there is an opportunity to reformat the MASS to make it a clearer and more useful document for setting out the purpose and nature of the different FCAS products.


In June 2019, AEMO in collaboration with the Australian Renewable Energy Agency (ARNEA), the Australian Energy Market Commission (AEMC), the Australian Energy Regulator (AER), and members of the Distributed Energy Integration Program (DEIP) established the VPP demonstrations. 

This demonstration provided the opportunity to trial the capability for DER to deliver contingency FCAS through VPPs using interim arrangements in the VPP Demonstrations FCAS specification.

The Issues paper for this consultation references evidence and learnings from the VPP Demonstrations and outlines key questions to industry regarding the ongoing arrangements for DER. The paper presents two options for what happens next in relation to DER participation in FCAS markets, and seeks stakeholder feedback on each option. The principles that will guide AEMO in its assessment of these options are also outlined in the paper.

Indicative Consultation Timeline

Following the review of all submissions in the first stage of the MASS consultation, AEMO deemed that meetings with specific stakeholders were required to obtain further clarity on their formal submissions and to assist AEMO in this stage of the consultation. Details of these meetings will be available on the MASS Consultation website before the publication of the draft determination.

Two stakeholders also requested a meeting with AEMO to discuss their formal submissions, and concerns around the current and future operational requirements of VPPs.

Note – The NER Rules Consultation procedure Part F (8.9 (f)) provides guidance on the period allowed to accommodate meeting requests.

As a result of the number of submissions and the complexity involved in determining the ongoing measurement arrangements for DER, the first stage submission review will be extended by 25 business days, with the new date for the draft determination on 17 May 2021 to provide sufficient time to consider the varied views put forward by stakeholders.

AEMO will also extend the second stage of consultation by 5 business days to allow sufficient time for stakeholders to consider and respond to the draft determination.

The below timeline has been updated to reflect the new dates: 

Process Indicative Date Status
First Stage
Issues Paper and Notice of First Stage of Consultation Tuesday, 19 January 2021 Complete
Submissions Close Thursday, 11 March 2021 Complete
Second Stage
Draft MASS and Notice of Second Stage of Consultation Monday, 17 May 2021 To be commenced
Submissions close Tuesday, 8 June 2021 To be commenced
Final MASS determination published Tuesday, 20 July 2021 To be commenced

For more information, or if you have questions please contact


AEMO will hold 2 stakeholder forums to facilitate discussion, clarification and Q&A regarding the broader MASS review and DER MASS review components under consultation. Forums for the broader MASS review and DER MASS review will be held at different times on the same day. Please see below for dates of the forum(s):

4 February - complete

  • General MASS Review: 10:30 – 11:30am (AEDT)
  • DER MASS Review: 11:30am – 12:30pm (AEDT)

26 May 2021

  • General MASS Review: 10:00 – 11:00am (AEDT)
  • DER MASS Review: 11:00am – 12:00pm (AEDT)

If you are interested in attending the forum on 26 May 2021, please contact by Friday 21 May 2021 and provide the following details:

  • Name
  • Organisation
  • Email address
  • Forum(s) that you would like to attend

If you have already received an invite, this will be updated to reflect the new dates.


AEMO received requests for meetings from the following stakeholders:

  • Reposit Power
  • SwitchDin

AEMO also sought to meet with the following stakeholders to understand components of their submissions in further detail:

  • IntelliHub
  • Landis+Gyr
  • Planet Ark Power
  • Solar Analytics

A summary of the outcomes of those meetings will be available on the MASS consultation webpage before the draft determination is published.

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