One grid, many local markets
The SWIS is a systems story: a weakly interconnected electricity system managing high rooftop output, falling operational demand and a steep evening return. But solar is bought, installed, aggregated and constrained locally. A system total cannot tell an installer where the remaining owner-occupied detached homes sit, a network planner where the existing solar base is already deep, or an investor where published flexibility needs meet a plausible customer fleet.
This edition treats the grid as both things at once. It brings the SWIS demographic atlas, the DER adoption and network opportunity map, and the daily operating record into one reference frame. The purpose is orientation and evidence, not a forecast, tariff recommendation or premises-level hosting-capacity claim.
The reference stack
| Layer | Reading | What it does not claim |
|---|---|---|
| Local cohort | 246 SA2s, 234 core and 12 network-edge areas | A licensed Western Power service territory or substation catchment |
| Rooftop solar | 564,139 allocated CER installation records; 3,167.3 MW | A premises-level asset register |
| Battery adoption | 43,150 allocated CER records; 933.6 MWh | A complete history before the CER battery series began |
| Addressability | 575,045 owner-occupied detached homes in the 2021 Census baseline | A forecast of future installations |
| Network need | 15 published Western Power non-network opportunities | Available export capacity or an open procurement |
| Grid operation | 1,019 AEMO WEM operating days | A settlement-demand or investment model |
CER records are apportioned from postcode to SA2 with ABS 2021 residential Mesh Block shares. The values are useful for local-market screening and deliberately retain that allocation boundary. The live maps expose the relevant source release, method and caveat beside the data.
The installed base
The cohort contains 564,139 allocated small-scale solar installation records and 3.17 GW of allocated capacity through May 2026, alongside 43,150 battery records and 933.6 MWh of usable capacity. The totals show the scale of the transition. The market underneath them is not uniform, which is why the local map combines installed stock, recent uptake, detached-home scale and population movement: each answers a different question.
The source snapshot records 33,498 allocated installations in the earlier 12-month window and 31,021 in the most recent. The gap between those bars is not a demand reading. CER allows STCs to be created up to 12 months after installation, so the recent window is structurally incomplete and will keep rising as certificates are validated. The reliable layer is the area-level adoption history: recorded stock and its spatial distribution.
575,045 detached homes
The spatial cohort held 575,045 owner-occupied detached homes in the 2021 Census baseline. That is an addressable-rooftop proxy, not a list of unserved customers: tenure, roof condition, household cash flow, existing systems, tariffs and technical constraints all remain outside it. It is nevertheless a better starting point than population alone, because it separates the potential residential building stock from the electricity system total.
The demographic atlas keeps the distinction visible. Its annual ABS population series runs from 2011 to 2025; ABS classifies 2025 as preliminary, 2022-2024 as revised and earlier observations through 2021 as final. Its 2030 and 2050 scenarios are transparent sensitivities rather than forecasts. A locality can have a deep existing DER base and still have a different household profile, growth path and remaining detached-home stock from its neighbour.
The network opportunity layer
Western Power’s published opportunity map contributes 15 non-network opportunity records to this edition, each carrying status, treatment objective, technology eligibility and published requirements. That is public evidence of where a flexibility or network-service question has been articulated. It is not a premises-level export-capacity map, a connection offer, an assessment of current procurement availability or a claim that one SA2 can satisfy a listed requirement. The network overlay sits beside the local DER and housing context rather than being folded into a single commercial score. The working order runs from the published opportunity to the local cohort, and only then to a specific proposal tested against its own network, tariff, customer-consent and technical constraints.
The system record
The retained AEMO WEM record now covers 1,019 operating days from 2 October 2023 to 17 July 2026. Across that record, rooftop PV averaged 52.4 per cent of the implied underlying-demand proxy at its daily peak; the maximum was 80.8 per cent. The largest retained evening ramp was 2,412 MW, and the minimum operational-demand observation was 504 MW. These are measures of the operating record, not a battery revenue estimate.
23 minutes
Roughly how long the cohort's 933.6 MWh of usable battery capacity could supply the largest retained evening ramp of 2,412 MW.
The daily operating record, stress-day ledger and recurring operating archetypes let the local adoption story be read against an observable system context. Readers wanting a cross-market screen can continue to the SWIS opportunity dossier, which keeps evidence, scoring and model boundary separate.
Start with the question
Start with the question. For local sales or fleet formation, use the DER map to distinguish established solar stock from remaining detached-home scale. For an area study, use the demographic atlas to test whether growth and household structure support the story. For flexibility or system-service work, begin with the operating record and published network opportunity evidence. Do not invert that sequence by treating a map score or a system headline as a project decision.
Every layer refreshes on its own cadence. This reference edition fixes the source versions named above so its figures remain citable, while the linked data surfaces show the current release and preserve their own provenance.