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TL;DR: A 6.6kW solar system costs $4,784 to $7,875 after the federal STC rebate in 2026. Queensland and WA are cheapest, Tasmania and NT are most expensive. The price swings mostly come down to panel quality and whether you go with a string inverter or microinverters. For the average household, 6.6kW is still the sweet spot.
If you have been getting solar quotes, you have probably noticed that 6.6kW keeps coming up. There is a practical reason for that: most Australian homes run on single-phase power, which limits the inverter to 5kW. But under the Clean Energy Council's 133% oversizing rule, you can connect 6.6kW of panels to that 5kW inverter.
What does that actually mean for you? You get more energy during the morning and late afternoon, when the sun is lower and panels are not at full capacity. A 5kW panel array on a 5kW inverter would clip early and late in the day. A 6.6kW array on the same inverter captures those extra hours without costing you for a larger inverter.
It is, for most households, the most cost-effective setup you can get. The extra 1.6kW of panels costs roughly $600 to $800 more than a straight 5kW system, but adds 15 to 20% more daily production. That is an easy win.
6.6kW solar system price by state
Prices vary across Australia based on installer competition, labour costs, and how far panels need to travel. Here is what you will pay for a fully installed 6.6kW system after the federal STC rebate in each state.
| State | Price Range | Daily Output | Payback |
|---|---|---|---|
| NSW | $5,200 – $7,500 | ~26 kWh | 3.5–5 yr |
| VIC | $4,940 – $7,125 | ~22 kWh | 4–5.5 yr |
| QLD | $4,784 – $6,900 | ~30 kWh | 3–4.5 yr |
| SA | $5,304 – $7,650 | ~28 kWh | 2.5–4 yr |
| WA | $5,460 – $7,875 | ~30 kWh | 3.5–5 yr |
| TAS | $5,616 – $8,100 | ~20 kWh | 4.5–6 yr |
| NT | $5,980 – $8,625 | ~32 kWh | 4–5 yr |
| ACT | $5,200 – $7,500 | ~24 kWh | 4–5 yr |
South Australia is worth calling out. Despite higher system prices than QLD, SA has the fastest payback because electricity costs are significantly higher there (around 42c/kWh vs 30c in QLD). Every kilowatt-hour you use from your panels instead of the grid saves you more. Our rebates page covers state-specific incentives on top of the federal rebate.
Want to see what a 6.6kW system costs in your area? Check local pricing for Sydney, Melbourne, Brisbane, Perth, Adelaide, or Gold Coast.
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Over 3.6 million homes already claiming rebates
What makes one 6.6kW quote $3,000 more than another
Two installers quoting on the same roof can be $3,000 apart. That is not unusual, and it is not always because one is ripping you off. The three biggest cost drivers:
Panel quality tier
Budget panels (Risen, entry-level Jinko) run about $0.25 to $0.35 per watt. Mid-range panels (Trina Vertex S+, Longi Hi-MO 7) sit at $0.35 to $0.50/W. Premium panels (REC Alpha, SunPower Maxeon) cost $0.50 to $0.70/W. On a 6.6kW system, the difference between budget and premium panels alone is $1,650 to $2,310. Mid-range is the sweet spot for most homes.
Inverter type
A quality string inverter (Fronius Primo, Sungrow SG5.0RS) costs $1,000 to $2,000. Microinverters (Enphase IQ8+) cost $2,500 to $4,000 for a 6.6kW system. String inverters work well on simple, unshaded roofs. Microinverters earn their premium on complex roofs with multiple orientations or shading issues, and they come with 25-year warranties compared to 10 to 12 years for most string inverters.
Roof complexity
A single-storey tin roof with one north-facing plane is the simplest and cheapest installation. Multi-storey homes add $300 to $1,000 for scaffolding. Tile roofs take longer than tin. Split arrays across multiple roof faces need extra wiring and potentially optimisers. A “difficult” roof can add $500 to $2,000 to the price.
Always compare like-for-like. If one quote is $5,200 with budget panels and a basic inverter, and another is $7,000 with mid-range panels and a Fronius, the second one is probably better value. Our full solar cost guide breaks down every component in detail.
The STC rebate on a 6.6kW system
Every price in this article is listed after the federal STC rebate. For a 6.6kW system in 2026, that rebate is worth roughly $2,800 to $3,400, applied as an upfront discount on your quote. The exact amount depends on your postcode zone (sunnier areas get more certificates) and the current STC trading price ($36 to $40 per certificate in 2026).
The rebate shrinks every year and phases out completely in 2031. Each January, the number of certificates your system generates reduces by one-fifteenth. In practical terms, waiting another year costs you roughly $200 to $400 in lost rebate value. For more detail, see our STC rebate guide or use the STC calculator for your exact postcode.
Should you go 5kW, 6.6kW, or 10kW?
The right system size depends on your electricity usage, roof space, and whether you plan to add a battery or EV charger down the track.
| 5kW | 6.6kW | 10kW | |
|---|---|---|---|
| Price (after rebate) | $4,000 – $6,500 | $5,000 – $7,500 | $7,500 – $12,000 |
| Daily output | ~20 kWh | ~26 kWh | ~40 kWh |
| Panels | 10–12 | 14–16 | 22–24 |
| Roof space | ~22m² | ~30m² | ~46m² |
| Best for | 1–2 people, low usage | 3–4 people, average home | Large family, pool, EV, battery |
| Phase | Single | Single | Single or three-phase |
For most Australian homes, 6.6kW is the right answer. It covers the average household's daily usage with some room to spare. If you are a couple in a small home, 5kW saves you a few hundred dollars. If you have a big family, a pool pump, or you are planning an EV, jump to 10kW. The panel calculator can tell you exactly how many panels your usage needs.
One thing worth considering: if you plan to add a battery in the next few years, oversizing your panels now makes sense. A bigger array charges a battery faster and maximises your self-consumption. The marginal cost of extra panels is small compared to the cost of a second installation later.
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Over 3.6 million homes already claiming rebates
What should be included in the price
A legitimate fully installed price for a 6.6kW system should cover all of this. If your quote does not itemise these, ask for a breakdown before signing.
- check_circle15 solar panels (440W each) – specific brand and model named
- check_circleInverter – brand and model (e.g. Fronius Primo 5.0, Sungrow SG5.0RS)
- check_circleRoof mounting system – rails, clamps, brackets for your roof type
- check_circleAll electrical wiring – DC/AC cabling, conduit, isolators
- check_circleInstallation labour – typically 1 day for a standard 6.6kW
- check_circleGrid connection paperwork – application to your DNSP
- check_circleSTC rebate applied as discount – shown as a line item, not hidden
Switchboard upgrades ($500 to $1,500), meter reconfiguration ($0 to $300), and multi-storey access charges ($300 to $1,000) are common extras that may or may not be included. Ask specifically. A good installer will flag these during the site inspection, not surprise you after the panels are on the roof.
Frequently Asked Questions
How much does a 6.6kW solar system cost in Australia in 2026?expand_more
Between $4,784 and $7,875 fully installed after the federal STC rebate, depending on your state, panel quality, and inverter type. Queensland and Victoria tend to be cheapest, while NT and Tasmania are most expensive.
Why is 6.6kW the most popular solar system size?expand_more
Most single-phase homes have a 5kW inverter limit. The CEC's 133% oversizing rule lets you connect 6.6kW of panels to a 5kW inverter, giving you more energy production in the morning and afternoon without a more expensive inverter.
Is 6.6kW enough for my home?expand_more
A 6.6kW system produces 22-30 kWh per day depending on your location. That covers the average Australian household using 15-25 kWh/day. If you have a pool, multiple ACs, or an EV, consider 10kW or larger.
How long does a 6.6kW system take to pay for itself?expand_more
Typically 3 to 5 years. South Australia sees the fastest payback (under 3 years) due to high electricity prices. After payback, your system generates free electricity for another 20+ years.
The next step
If you have any questions about the information in this guide, feel free to get in touch:
Email: hello@whysolar.com.au
Tel: +61 455 221 921
If you're considering solar panels or batteries for your home, Bec and the team can help you get quotes from trusted, pre-vetted local installers:
Written by
Bec RamirezAussie Mum & Energy Expert
Helping families navigate the switch to solar with practical, real-world advice. Bec focuses on the financial side — rebates, bill savings, and financing options — so everyday Australians can see real value from going solar.
Learn more about Bec Ramirez