The market analyst SunWiz published a framework on 31 August 2026 that sorts home battery markets into five stages, and places Australia at the fourth of them. The reading is drawn from SunWiz Luminate, a verified sample of installation activity taken from hundreds of installers in each of six markets and refreshed monthly since June 2024. The six are Germany, Sweden, the United Kingdom, Ireland, Spain and Australia.
Current-guidance boundary: This article records a market interpretation published on 31 August 2026 and the tariff settings current at that date. It does not establish scheme entitlements or system design requirements. Current Clean Energy Regulator and Synergy guidance, and site-specific advice, control any quote or system design.
The five stages run from emergence, where storage is still a niche add-on and most systems are solar only, through acceleration, where the economics turn and a battery starts appearing in most quotes, to the norm, where storage is simply standard fit. The fourth is the turn, where residential demand softens even as national storage capacity keeps climbing. The fifth is retrofit, where export value has collapsed far enough that the existing solar fleet becomes the market.
Spain sits at emergence, with more than four in five systems still solar only. Ireland is at acceleration, where the share of systems including a battery has climbed from under 40 per cent to roughly 70 per cent in two years, and has done so with no battery grant. The United Kingdom has reached the norm, with solar-only installations down to a small single-digit share.
Australia sits at the retrofit stage, and the numbers are the strongest in the group
SunWiz records Australian battery-only retrofits climbing from under 10 per cent of the market to around 40 per cent, and an attachment ratio near 1.4. The ratio compares battery installations against solar installations. Above 1.0 it means batteries are outnumbering new solar systems, because they are increasingly being fitted to homes that already have solar rather than sold alongside a new array. At 1.4 that is the highest ratio of the six markets tracked.
The direction is consistent with SunWiz's earlier published Australian work, which found that 58 per cent of battery installations in 2024 were retrofitted to unchanged solar systems, with a further 16 per cent coupled to systems where the solar was expanded at the same time. The metrics differ, and the two figures should not be read as the same measurement. What they agree on is that retrofit has been the dominant shape of Australian battery demand for some time, and that the federal rebate accelerated a pattern already present rather than creating one.
The export gap is what makes the arithmetic work in Western Australia
The framework attributes the Australian position to a federal rebate landing on a fleet with no export value left to defend. In this state that description is specific and checkable.
Under the Distributed Energy Buyback Scheme, Synergy pays 10 cents per kilowatt hour for energy exported between 3pm and 9pm, and 2 cents per kilowatt hour for energy exported at any other time. Those rates were confirmed against Synergy's own price schedule dated 1 July 2026 and did not change at the annual reset. The Home Plan A1 residential tariff rose to 33.26 cents per kilowatt hour from the same date.
A household with a well-oriented array exports most of its surplus in the middle of the day, which falls outside the peak window. That energy earns 2 cents. The same kilowatt hour, kept in a battery and used after dark, displaces a purchase at 33.26 cents. The gap is roughly sixteen to one, and it exists before any rebate is applied. That is why a retrofit stands up in Western Australia on its own terms, and why the retrofit stage arrived here rather than somewhere with a supportive feed-in tariff still in place.
Both figures carry annual review and should be reconfirmed against Synergy before use in a quote.
Retrofit draws on a stock rather than a flow
The stage description carries a consequence that is easy to miss while volumes are strong. Retrofit demand is drawn from a finite pool: the rooftops that already carry solar and do not yet carry a battery. Every completed retrofit removes one from that pool. New solar installations replenish it, but far more slowly than retrofits are consuming it.
That makes the current volumes a different kind of number from the ones a growth market produces. They describe the rate at which an existing asset base is being worked through, not the rate at which a market is expanding.
Germany and Sweden are already on the other side of the turn
The framework places both at the turn, and the German position can be checked independently of SunWiz. Figures from the German solar industry association show residential storage additions in the first quarter of 2026 falling 19.9 per cent in power terms and 17.8 per cent in energy terms against the same quarter of 2025. Residential additions in March 2026 came to 132.5 megawatt hours, and in the same quarter utility-scale storage additions overtook residential additions for the first time.
National storage capacity in Germany is still climbing. The residential segment inside it is not. SunWiz records the same shape in its own measure, with German battery energy installed per installer slipping below its mid-2024 level, and describes Sweden as having reached an attachment ratio of about 1.0 by late 2025 before halving within months once grid-balancing revenue dried up.
Neither market is a forecast for Australia. The settings differ, and the Swedish reversal in particular followed a revenue change rather than a saturated retrofit pool. What they establish is that the turn is a stage that markets reach, not a risk that only exists in theory, and that it can arrive quickly once the thing driving demand changes.
Sourcing
The five-stage framework, the stage assignments, the Australian retrofit share and attachment ratio, the German per-installer measure and the Swedish attachment figures are SunWiz's, published on 31 August 2026 and drawn from the SunWiz Luminate sample. That sample is a verified panel of installers rather than a census, and the figures should be attributed rather than treated as official statistics.
The 2024 Australian retrofit proportions are from SunWiz's earlier published market work as reported in the trade press. The German first-quarter 2026 figures are from the German solar industry association's published quarterly data. The DEBS rates and the Home Plan A1 tariff were confirmed against Synergy's own published schedules for 1 July 2026.
Current-status note
This analysis records the position as published on 31 August 2026. Tariffs, feed-in rates and certificate settings all carry review dates and can change. DEBS rates and the Synergy residential tariff are reviewed annually with effect from 1 July. Before using any figure here for system design, quoting or investment purposes, confirm the current position with Synergy (opens in a new tab) and the Clean Energy Regulator (opens in a new tab), and obtain site-specific advice from an appropriately qualified provider. Related records are available in Pulse, and the editorial standards explain how dated commentary is handled.
