Australia has more rooftop solar per capita than almost any other country. According to the Clean Energy Council, well over 3.5 million residential systems are now installed nationally. The average system size has grown steadily as panel prices have fallen — but the right size for your home is determined by your usage profile, not by what the roof can physically hold.
This guide focuses on the three most common residential system sizes in 2026: 6.6 kW, 10 kW and 13 kW. For each, we examine what it costs, what it generates, who it suits, and how export limits and inverter sizing affect the real-world numbers.
System comparison at a glance
| System size | Installed price range (after STCs) | Est. annual generation (Sydney / Brisbane / Melbourne) | Suitable household daily usage | Typical payback range (30–50% self-consumption) |
|---|---|---|---|---|
| 6.6 kW | $7,000–$10,000 | 9,500 / 10,200 / 8,800 kWh | 15–25 kWh/day | 5–8 years |
| 10 kW | $11,500–$16,000 | 14,500 / 15,500 / 13,400 kWh | 25–40 kWh/day | 7–11 years |
| 13 kW | $15,000–$21,000 | 18,800 / 20,100 / 17,400 kWh | 35–55 kWh/day | 9–14 years |
Generation figures assume north-facing panels at optimal tilt with no shading, using ARENA solar production factors for each capital city. East/west split orientation reduces annual output by approximately 10–12%.
Why 6.6 kW is still the sweet spot for most households
The 6.6 kW figure is not arbitrary. It emerged from the economics of the standard 5 kW single-phase inverter combined with the maximum permissible panel-to-inverter ratio of 1.33:1 (i.e. 6.65 kW of panels on a 5 kW inverter). Most Distribution Network Service Providers (DNSPs) — the local grid operators that manage the poles and wires — allow a maximum export of 5 kW on a standard single-phase residential connection without additional approval.
This means a 6.6 kW system fits neatly under the standard rules: it self-consumes what it can, exports the rest at up to 5 kW, and requires no additional network approval. The price-per-watt for a 6.6 kW system in 2025–26 is typically $1.06–$1.52/W after STCs — making it the most price-competitive residential segment.
For a household using 18–22 kWh/day and at home for part of the day (working from home, young children, home-based business), 6.6 kW comfortably covers 40–55% of annual consumption. At a 32 c/kWh retail rate, that self-consumption represents $1,200–$1,600 in annual savings before counting any export earnings. Payback in the 5–8 year range is realistic for most capital city locations.
When 10 kW makes sense
A 10 kW system moves into different territory — both in terms of cost and network requirements. Many DNSPs require a formal application and network assessment before approving export above 5 kW for single-phase properties. Three-phase properties generally have an easier path to higher export limits. Before quoting on a 10 kW system, any reputable installer will check your DNSP's approval requirements for your specific address.
The households that genuinely benefit from 10 kW share a common profile: high daytime usage. This includes households with a pool pump running 6–8 hours per day (adding 3–5 kWh/day), a home office with substantial equipment, an electric hot-water system without a dedicated off-peak tariff, or an EV that is occasionally charged from solar during the day. A household using 30–38 kWh/day is undersupplied by a 6.6 kW system — especially in winter — and a 10 kW system closes that gap.
Cost is proportionally higher — typically $11,500–$16,000 — and payback stretches to 7–11 years depending on self-consumption. The incremental cost per watt over 6.6 kW is usually comparable, though installation complexity and any network application costs can widen the gap.
DNSP export limits: the constraint most installers underexplain
Every Australian state has distributors that impose export limits on residential solar. The most common limits are:
- 5 kW export: standard for single-phase connections in most NSW, QLD, VIC and SA zones. Systems above 5 kW inverter capacity require network approval and may be subject to zero-export or export curtailment conditions.
- 10 kW export: increasingly available in some zones, particularly for three-phase properties or in areas with upgraded network infrastructure. Check with your specific DNSP (e.g. Ausgrid, Endeavour Energy, Energex, SA Power Networks, CitiPower/Powercor) for your address.
- Zero export: some areas with already-congested feeders impose zero-export conditions, meaning your system must be configured to prevent any export at all. This significantly affects larger system economics.
The Australian Energy Market Operator has been working with DNSPs on dynamic operating envelopes — variable export limits that adjust in real time based on network conditions — but these are not yet widely deployed at the residential level in 2026.
The oversizing trick: more panels, same inverter
One of the most effective strategies for improving solar performance without increasing inverter size — and therefore without triggering network approval processes — is to oversize the panel array relative to the inverter. This is permitted under Australian Standard AS/NZS 5033 up to a maximum ratio of 1.5:1 for most inverter brands.
In practice, this means: rather than a 10 kW inverter (which likely requires a network assessment) with 10 kW of panels, you install a 5 kW inverter with 7.5 kW of panels. The inverter still exports a maximum of 5 kW but the additional panels generate significantly more during morning and afternoon when the sun angle is lower, increasing daily total generation by 10–18% compared to a matched 5 kW array.
This strategy is particularly valuable in Victoria and South Australia, where peak electricity demand — and the opportunity for solar self-consumption — tends to fall in the shoulder hours rather than at solar noon. It is worth discussing explicitly with your installer when comparing quotes.
When 13 kW makes sense — and when it doesn't
A 13 kW system is a significant investment: typically $15,000–$21,000 installed after STCs, requiring at minimum a three-phase supply or DNSP approval for a large single-phase export allowance. The households it suits are genuinely high-consumption: large families using 40+ kWh/day, properties with multiple air conditioning units, or households planning to add an EV and wanting the system designed for that future load from day one.
For households currently using 20–25 kWh/day who "want to future-proof", the maths rarely supports 13 kW. At a 5 c/kWh feed-in tariff, the incremental generation above your household's ability to self-consume is worth very little. The payback on the incremental capital between a 6.6 kW and a 13 kW system can exceed 20 years on the exported portion alone. A better approach for most: install 6.6 kW now, let it pay back in 6–8 years, then add more panels when prices may be lower still and your actual load growth is clearer.
To model your specific household scenario across all three system sizes, use the solar payback calculator, which allows you to adjust system size, daily usage and self-consumption independently.
A note on STC value and timing
All installed price ranges in this article include the deduction of Small-scale Technology Certificates (STCs) at the 2025–26 deeming rate. STCs reduce in value by one year of deeming each calendar year through to 2030, when the scheme ends. The STC benefit is greatest for larger systems (more certificates) but the proportional impact on the investment case is similar across sizes. Systems installed before each year's deeming reduction — which takes effect on 1 January — carry the higher STC value, though the annual reduction is modest. An experienced CEC-accredited installer will confirm the current deeming rate and STC value at the time of quoting.
Sources
- Clean Energy Council — residential solar statistics and consumer guidance
- ARENA — solar energy knowledge bank and production factor data
- AER — network access standards for distributed energy resources
Last reviewed: — generation figures and price ranges verified against Clean Energy Council and ARENA 2025–26 data.