A forecast layer, deliberately separated
The SWIS daily operating record tells us what happened: measured minimum demand, rooftop PV, generation mix and evening ramp across retained AEMO WEM observations. The WEM Electricity Statement of Opportunities asks a different question. It models whether generation, storage and demand-side capacity can satisfy the WEM Planning Criterion over ten future Capacity Years under Low, Expected and High scenarios.
This page uses AEMO's Expected scenario as a reference case. It is not Solar Analytica's forecast, and it is not an investment recommendation. AEMO itself cautions that project delivery, demand, market behaviour and model assumptions may produce materially different actual outcomes. The useful discipline is to keep each forecast number tied to its scenario, information cut and dependency.
The near term improves, then the requirement opens again
AEMO forecasts existing and committed peak capacity at 6,670 MW in 2028-29 against a 6,323 MW Peak Reserve Capacity Target, a 347 MW surplus. That balance depends on committed projects arriving on time and the assumed availability of existing facilities. From 2029-30, the same existing-and-committed series falls below the target as demand grows and thermal generation retires or becomes unavailable.
The end point is not a prediction that 2,161 MW will definitely be missing in 2035-36. It is the gap in one scenario before uncommitted future investment. AEMO identifies 622 MW of anticipated capacity in 2028-29 and 661 MW in 2030-31; if anticipated projects are delivered, the model remains balanced through 2030-31 and the shortfall begins in 2031-32. The distinction between committed and anticipated capacity is therefore central, not a footnote.
Consumer assets enter the capacity model
The 2026 methodology gives coordinated distributed energy a more explicit role. AEMO forecasts rooftop PV capacity to rise from about 3,100 MW in 2026-27 to about 6,000 MW by 2035-36, while distributed battery capacity rises from about 550 MW to 2,300 MW. Those stocks change both daytime grid demand and the shape of the evening peak.
For 2028-29, AEMO projects 640 MW of installed distributed batteries could be coordinated through Synergy virtual power plants. It applies a 50% availability factor because remote control, customer behaviour and operational performance are still uncertain, and forecasts approximately 200 MW of annual peak-demand reduction. That is a modelling assumption to be tested against the 2026-27 Hot Season, not a measured 200 MW resource already available to the system.
Longer batteries become a market requirement
The storage question is not only how many megawatts are connected. AEMO increases the Electric Storage Resource Duration Requirement from six hours in 2027-28 to seven hours in 2028-29 as the peak becomes longer and flatter. The 2028-29 target also includes a 392 MW duration uplift to account for the reduced contribution of shorter-duration batteries across the peak period.
This connects the outlook to Solar Analytica's Revenue Opportunity Lab and TBx Capture Index only at the level of a decision question: duration matters. The WEM capacity mechanism, NEM energy spreads and a household VPP are different commercial structures and should not be collapsed into one revenue assumption.
What to carry into a decision
Three readings survive the boundary. First, the 2028-29 forecast surplus is conditional on timely project delivery. Second, the model expects distributed solar and batteries to become system-scale resources, but the VPP contribution still carries an explicit availability haircut and a near-term validation task. Third, the forecast need reopens quickly after 2028-29, while transmission, storage duration and flexible capacity determine whether nominal megawatts can meet the shape and location of demand.
Use the SWIS Rooftop Solar Atlas for the current local installed base, the operating record for realised system conditions, and this ESOO brief for AEMO's forward planning case. Agreement between the three would be useful evidence. Disagreement would be the signal to investigate.