Wednesday, October 7, 2026
Australia’s rooftop solar market continues to feel the benefits of the home battery boom, with new data showing that more new PV capacity has been installed in 2026, to-date, than was installed for the whole of 2025.
But the latest report from SunWiz shows this is not the only way in which Cheaper Home Batteries is exerting an influence on rooftop PV uptake – it’s also helping to dictate solar system size.
When the federal rebate launched, households responded by installing much larger than usual rooftop solar systems – or supersizing their existing arrays – to match the supersized up to 50 kilowatt-hour (kWh) batteries they were getting at a hefty discount.
Now that the battery rebate has been dialled down and pared back, and is incentivising customers to install batteries closer to between 20-25 kWh, the average size of rooftop solar systems being installed through the SRES is falling, too.
According to SunWiz, the national average rooftop solar system was 9.98 kW in September, up from August’s 9.86 kW and well clear of the twelve-month low of 9.35 kW in May – the month the battery rebate changes were introduced.
But the September average sits well below April’s peak of 11.75 kW and December’s high of 12.07 kW, says SunWiz managing director Warwick Johnston, with the past three months holding just under the 10 kW mark.
The 10-15 kW bracket “remains the clear backbone of the market,” says Johnston, adding a total of 105.94 megawatts (MW) in September, more than double the next-largest band, 6-8 kW on 53.04 MW, with 15-20 kW at 43.41 MW.
Across the board, 311.8 MW of new rooftop solar capacity was installed in September, says SunWiz, recovering from August’s dip to roughly 290 MW and marking the second-strongest month since April’s ~505 MW high.
The January-September tally is the highest on record and is running 43 per cent ahead of the same point, this time last year.
On home batteries, SunWiz says installations came in at just under 1 gigawatt-hour (GWh) for September, reaching an estimated 966.5 megawatt-hours (MWh) up 12.5% on August and the strongest month since April’s 3,262 MWh peak, again before the rebate was changed.
Following the aftermath of the pre-May boom, the battery market has stabilised near to 1GW/month. The average battery size continues to grow, with 45% of the market now exceeding 30kWh.
“Following the aftermath of the pre-May boom, the battery market has stabilised near to 1GWh/month,” Johnston says.
And while the rooftop solar system size is averaging down, the average battery size is edging back up a bit from the April trough, with 45 per cent of the market now exceeding 30 kWh, the latest monthly report says.
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Sophie is editor of Renew Economy and editor of its sister site, One Step Off The Grid . She is the co-host of the Solar Insiders Podcast. Sophie has been writing about clean energy for more than a decade.
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