SWIS Rooftop Solar Atlas, 2026

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

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 is large. The local shape matters more.

The cohort contains 564,139 allocated small-scale solar installation records and 3.17 GW of allocated capacity through May 2026. It also contains 43,150 battery records and 933.6 MWh of usable capacity. Those totals make the transition visible, but they do not make the market uniform. The local map combines installed stock, recent uptake, detached-home scale and population movement precisely because 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 window. Those raw windows are not a demand-momentum measure. CER allows STCs to be created up to 12 months after installation, so the recent period is structurally less complete and will continue to rise as certificates are validated. The useful next step is therefore to inspect the area-level adoption history as a recorded stock and spatial distribution, not infer a market slowdown from the apparent gap.

Addressability is a housing question before it is a generation question

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.

Network opportunities are evidence of a need, not a permission slip

Western Power’s published opportunity map contributes 15 non-network opportunity records to this edition. They carry status, treatment objective, technology eligibility and published requirements. That is valuable 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.

That is why the network overlay is kept beside the local DER and housing context rather than folded into a single commercial score. The useful sequence is to inspect the opportunity, examine the local cohort and then test a specific proposal against its own network, tariff, customer-consent and technical constraints.

At the system level, flexibility is already the question

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% of the implied underlying-demand proxy at its daily peak; the maximum was 80.8%. The largest retained evening ramp was 2,412 MW, and the minimum operational-demand observation was 504 MW. These are measures of a daily operating record, not forecasts or a battery revenue estimate.

The point is not that every local battery solves the same system problem. It is that 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; it deliberately keeps evidence, scoring and model boundary separate.

How to use this edition

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 will refresh on its own cadence. This reference edition fixes the source versions named above so its figures remain citable; the linked data surfaces show the current release and preserve their own provenance. That separation is intentional: a report should be stable enough to reference, while a monitor should be free to keep moving.