Relevant Level Method
Intermittent generators such as wind and solar by their nature have variable, weather-dependent output. This variability must be considered when determining the extent to which intermittent generators can be relied on to have capacity available when needed to meet peak demand periods and support reliability in the South West Interconnected System (SWIS). The Relevant Level Method (RLM) is the framework used to determine the quantity of Peak Certified Reserve Capacity (CRC) assigned to intermittent generators in the Reserve Capacity Mechanism (RCM).
Who is eligible for RLM?
AEMO applies the RLM to determine Peak CRC for components of Semi-Scheduled Facilities and Scheduled Facilities that are Intermittent Generating Systems (IGS) and Non-Scheduled Facilities (NSF) (except for NSFs that are an Electric Storage Resources (ESR) and have not been in operation for the entire RLM Reference Period).
New RLM for 2026 Reserve Capacity Cycle onwards
The 2026 Reserve Capacity (RC) Cycle introduced a new RLM, replacing the existing RLM, as part of the Reserve Capacity Mechanism review. The new RLM is intended to address the increasing share of wind and solar and better measure the capacity contribution of IGS and certain NSF in the SWIS.
How the RLM works?
The steps for the new RLM calculation are set out in Appendix 9 of the ESM Rules and the WEM Procedure: Relevant Level Method. The overview below summarises how the RLM is determined:
The new RLM uses probabilistic numerical models to simulate system conditions and better evaluate the contribution of different forms of generation and storage under system stress simulations. These simulations are used to test how the power system performs under stress conditions and to quantify how much Candidate Facilities (those subject to the RLM) contribute to meeting reliability needs.
At a process level, the RLM uses WEM Electricity Statement of Opportunities (ESOO) annual energy target, then simulates the availability of Non‑Candidate resources to establish a baseline and adds Candidate supply based on observed or independently modelled output. It then applies demand adjustments in the simulations until the target is met, producing a single fleet‑wide contribution measure (Effective Load Carrying Capacity, or ELCC). That Fleet ELCC is allocated back to individual Candidate Facilities in proportion to their average performance during the Peak SWIS Trading Intervals, and each Facility’s allocated share becomes its Relevant Level.
Key concepts
| Term | Description |
|---|---|
| Effective Load Carrying Capacity | ELCC estimates a Candidate fleet’s contribution to system reliability. It represents a MW value of extra demand the SWIS could reliably supply because a fleet of Candidate Facilities exists. |
| RLM Reference Period | The five-year period ending at 8:00 AM on 1 October of Year 1 of the previous RC Cycle. For example, for the 2026 RC Cycle, the RLM Reference Period is from 8:00 AM, 1 October 2020 to 8:00 AM, 1 October 2025. Energy sent-out data provided by an accredited independent expert report should cover the RLM Reference Period for new facilities and upgrades to existing facilities. |
| ELCC Reference Period | The RLM Reference Period, excluding the Capacity Year with the lowest peak demand. |
| Candidate | A Facility or component of a Facility that applied for CRC for the relevant RC Cycle and is being assessed via the RLM. |
| Non-Candidate | A Facility or component of a Facility that is not assessed under the RLM, but has previously been assigned Peak Capacity Credits, and is expected to continue receiving Peak Capacity Credits for the current RC Cycle. |
| Peak SWIS Trading Intervals | For a Hot Season (December to March), the 3 Trading Intervals with the highest Total Sent Out Generation on each of the 4 Trading Days with the highest maximum demand in that Hot Season. There are 12 Peak SWIS Trading Intervals in each Capacity Year. Current and historical Trading Intervals are published on the WEM Website. |
| Facility Average Performance Level | The average value of a Candidate’s historical output during Peak SWIS Trading Intervals in the ELCC Reference Period. |
Data publication
Under Step B.9.1 of Appendix 9 of the ESM Rules, AEMO is required to publish a series of RLM inputs on the WEM Website by the date specified in clause 4.1.9 (as modified or extended) for the relevant RC Cycle. The RLM inputs include:
- Observed Demand for the RLM Reference Period
- DER Adjusted Demand Profile for the RLM Reference Period
- Reference Demand Profile for the ELCC Reference Period
- Candidate Historical Output (after Commercial Operation) for each Committed Candidate published as meter/Facility Sub-Metering data only
- Facility Average Performance Level for each Committed Candidate (based on meter data where available or independent expert report data where required)
Under Step B.9.2 of Appendix 9 of the ESM Rules, AEMO is required to publish a series of RLM results on the WEM Website by the date specified in clause 4.1.16 (as modified or extended) for the relevant RC Cycle. The RLM results include:
- Relevant Level Fleet Capacity for each Candidate Fleet
- Candidate Historical Output for each Candidate
- Facility Average Performance Level for each Candidate
Relevant Level Method workshops
New facilities and upgrades – Accredited independent expert report
AEMO has developed an independent expert report guideline to assist accredited experts in their understanding of the report requirements and the purpose it serves in the RCM.
The expected energy output estimates are to be provided using the templates below.
- For SSF and SF: Energy output data submission SF & SSF template
- For NSF: Energy output data submission NSF template
- A 5% probability of exceedance of the Facility’s expected generation output value (in MW) for all the Trading Intervals that occurred within the last three years up to, and including, the last Hot Season.
Accredited independent expert report
The information below shows the experts AEMO has accredited to provide these reports.
Organisation: DNV Australia Pty Limited
Contact: Kevin Bleibler, Head of Section, Energy Analytics & Measurements (ANZ)
Phone: 0419 673 111
Email: [email protected]
Organisation: WSP
Contact: Lillian Patterson, Director – Renewables
Phone: (03) 9286 8621
Email: [email protected]
Organisation: UL International Australia Pty Ltd
Contact: Yang Zhang, Engineering Manager
Phone: +61 473 454 115
Email: [email protected]
Organisation: SpringCity Pty Ltd
Contact: Emran Malhi, Managing Director
Phone: (08) 9460 3795
Email: [email protected]
Note: Only for Solar Generators, and NSF ESRs (Hybrid systems (solar PV and Battery Energy Storage Systems combined) and Solar-charged independent Battery Energy Storage Systems).