Australian households are adjusting their rooftop solar ambitions, with new data from energy consultancy SunWiz revealing the national average system size dipped slightly to 9.98 kilowatts (kW) in September 2026. This marks a notable shift from the larger systems observed earlier in the year, yet the 10-15 kW bracket remains the dominant choice for homeowners and small businesses.
The latest figures, released this week by Renew Economy citing SunWiz analysis, indicate a recalibration in consumer behaviour. While September’s average of 9.98 kW is an increase from August’s 9.86 kW, it sits well below the peak of 11.75 kW recorded in April 2026 and the 12.07 kW high from December 2025.
“The 10-15 kW bracket remains the clear backbone of the market, 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.”
This trend suggests that while Australians continue to embrace solar power at record rates – with total new rooftop solar capacity reaching 311.8 MW in September and the January-September tally being the highest on record, running 43% ahead of last year – the sweet spot for system sizing is evolving. The Clean Energy Council’s latest bi-annual Rooftop Solar and Storage Report (Jan-Jun 2026), released on October 4, 2026, also highlighted record installations for both rooftop solar and home batteries, further underscoring the strong market activity.
The Influence of Rebates and Energy Demands
SunWiz managing director Warwick Johnston attributes some of this sizing shift to the evolving landscape of home battery rebates. Earlier, more generous incentives for larger battery capacities encouraged households to install significantly larger solar arrays to match. As battery rebate structures have been dialled down and refined to incentivise capacities closer to 20-25 kWh, the corresponding average solar system size has also seen a reduction.
Despite the slight dip in the average, the continued dominance of the 10-15 kW system size underscores a broader trend: Australians are seeking substantial energy independence. Rising electricity costs and the desire to power larger homes, electric vehicles, and all-electric appliances are driving demand for systems that can significantly offset grid consumption. For those considering a full home electrification, understanding the Real Costs, Rebates & Savings Up to $15,000+ is crucial.
What Does a 10-15kW System Mean for Your Home?
A 10kW to 15kW solar system is typically well-suited for larger Australian households with high energy demands, often exceeding 25-30 kWh per day. This might include homes with ducted air conditioning, swimming pools, multiple occupants, or those planning to add a home battery or an electric vehicle.
Indicative Costs for Popular System Sizes (October 2026)
| System Size | Typical Fully Installed Cost (AUD) | Daily Output (approx. kWh) |
|---|---|---|
| 10 kW | $9,000 – $12,000 | 38 – 44 |
| 13 kW | $11,000 – $16,000 | 50 – 57 |
| 15 kW | $13,000 – $19,000 | 58 – 66 |
Prices are indicative and vary based on location, panel/inverter quality, and installation complexity. These figures generally include the federal Small-scale Technology Certificate (STC) rebate, which significantly reduces the upfront cost.
Maximising Your Investment
Choosing a larger system, particularly in the 10-15 kW range, allows for greater self-consumption of generated electricity, which is critical given fluctuating solar feed-in tariffs. With average daily outputs ranging from 38-44 kWh for a 10kW system and 58-66 kWh for a 15kW system under favourable Australian conditions, homeowners can drastically reduce their reliance on grid power.
Federal and state government incentives, such as Small-scale Technology Certificates (STCs), continue to play a vital role in making solar more accessible and affordable. These certificates provide an upfront discount on eligible solar installations. Understanding how to Claim Up To $15,000 in Energy Rebates Across Australia can significantly impact the overall cost and payback period of your system.
Furthermore, the quality of components, such as N-Type versus P-Type solar panels, can influence long-term performance and savings. Exploring options like N-Type vs. P-Type Solar Panels in Australia 2026 can help homeowners unlock additional savings annually. The Clean Energy Regulator has also confirmed that from October 1, 2026, the STC eligibility for solar PV systems has expanded from 100 kW to 1 MW, a significant shift for mid-scale commercial projects, though applications for these larger systems will open later in November.
As the solar market continues its rapid evolution, staying informed about installation trends, rebate changes, and system sizing will be key for Australians looking to make the most of their clean energy investment.