The latest monthly update from solar and energy storage market analyst SunWiz shows the national rooftop PV (0-100 kW) market rebounded to its equal third best month this year with 237 MW of new capacity installed across Australia in September 2025, marking a 16.6% increase on the previous month.
The data also reveals that 639 MWh of small-scale battery energy storage systems were registered across the country in September, up by 55% on the previous month and equivalent to 75% of 2024’s annual tally installed in one month.
SunWiz Managing Director Warwick Johnston said the result had smashed early signs of a plateau in the deployment of energy storage systems (ESS) but there had been a shift in the market.
“After the initial rush of battery-only installations, PV plus ESS installations are the most common option, resulting in a return to growth for PV sales,” he said.
Image: SunWiz
Small-scale solar installations were above trend for the first time in months but Johnston said the market remains below where it was in Septembers from previous years.
“Overall, the latest figures highlight a sustained reduction in monthly capacity compared to historical performance,” he said. “For the first time since 2022, year-to-date installation volume is lower than the previous year, marking a clear break from the recent growth trend.”
The 237 MW of new solar registered last month is 10% below September 2024 levels but the current year-to date volume is 15% behind last year’s figure.
Image: SunWiz
SunWiz said all state volumes had improved in September with Western Australia up 28% month-on-month, though New South Wales saw the greatest MW increase.
The 75-100 kW segment had the strongest growth but Johnston noted there has been a “step-change” in volumes in the sub-3 kW range, quite likely due to PV system extensions associated with battery installations.
“There’s also been a step-change in 8-10 kW and 15-20 kW PV installations, quite likely affiliated with battery installations,” he said, adding that the national average solar system size increased to 10.4 kW, up from 10.16 kW in August 2025.
The average size of batteries being rolled out also increased in September, reaching 24.40 kWh, up from 21.36 kWh the previous month and 19.84 kWh in July.
All states reported positive growth in battery installations, with NSW registering 238 MWh, followed by Queensland at 130 MWh and Victoria at 107 MWh.
SunWiz said the 30-50 kWh market grew the greatest amount with consumers seeking to maximise their federal battery rebate, supplemented by emerging interest from small businesses.
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