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A 6.6kW solar system is one of the most common sizes on Australian roofs. It sits between a small starter array and a larger 10kW solar system, so whether it suits your home depends on three things: how much of your electricity use happens in daylight, how much roof you have, and what your local network allows. This page sets out the numbers that matter, using Australian Government figures, so you can judge a quote yourself. For the wider picture, see our residential solar overview.
The 6.6kW figure is the combined rated output of the panels, not the inverter. Many installers pair a 6.6kW array with a 5kW inverter, which is good value because panels rarely produce at full rated capacity.
A rule sits behind this. If the total panel rating is higher than the inverter manufacturer's specification, the system can't access the Small-scale Renewable Energy Scheme rebate. Ask your installer to show in writing that the inverter's specification allows your panel total.
Your network operator can also limit exports. energy.gov.au gives the example of a 10kW single-phase inverter allowed to connect with exports capped at 5kW, with the excess curtailed. Find out about any export limit before you sign.
Most new 6.6kW systems in Australia use 14 or 15 panels. The exact number depends on each panel’s wattage. Divide the system size by the panel rating:
14 panels of 475W make 6.65kW
15 panels of 440W make 6.6kW
16 panels of 415W make 6.64kW
With 475W panels, 14 is the limit. That’s the most panel capacity a 5kW inverter can take under the Clean Energy Council’s oversizing rules.
the roof area for a 6.6kW system at roughly 29 to 32m². Higher-wattage panels are physically bigger, so fewer panels doesn’t save much roof space. Ask your installer for a roof layout showing where each panel sits. Also check for shade from trees, neighbouring buildings and roof features, because shade can noticeably cut output.
A 6.6kW system averages about 26 kWh on a sunny day in Sydney, about 28 kWh in Brisbane and about 23 kWh in Hobart. Output is lower in winter than in summer, so treat those as good-day figures rather than yearly averages.
Australian homes use roughly 11 to 23 kWh a day, and your bill shows your own average. On a sunny day, a 6.6kW system can generate more than a typical household uses in total. The more useful question is how much of that you will use at home as it is generated, because the rest is exported.
Compare the sunny-day figures above with the daily average on your bill, then think about when you are home.
Network limits also frame the choice. They commonly allow up to 10kW per phase on a single-phase connection and up to 30kW on three-phase. If your daytime use is high or you have three-phase supply, compare a 6.6kW solar system against a 10kW system before deciding.
A hybrid inverter combines the solar inverter and the battery inverter in one unit, so ask which type is in your quote even if you only plan to add a battery later. Our hybrid solar system covers that setup.
The federal Cheaper Home Batteries Program was adjusted from 1 May 2026. The Minister described the discount as around 30%. The first 50kWh of capacity is eligible, batteries up to 100kWh remain eligible, and support per kWh moderates for medium and larger batteries.
There is no fixed battery size for a 6.6kW system. It depends on how much you use after sunset. Check the current rules on the DCCEEW website before buying, as the program is still changing.
Quotes differ because of the panels and inverter chosen and the conditions of the install. One line you can compare across quotes is the STC discount.
Most home systems qualify for small-scale technology certificates (STCs). Their value depends on system size, up to 100kW, and your climate zone. Your installer normally applies for them and shows the value as a discount, and you sign over the certificates in exchange.
The number of certificates falls each year because the deeming period shrinks. It is 5 years for systems installed in 2026, then 4 in 2027, 3 in 2028, 2 in 2029 and 1 in 2030, when the scheme ends. State and territory rebates and loans vary by location. We haven't listed dollar figures, because prices differ between installers and locations.
Rebate rules change often, so confirm current figures with the Clean Energy Regulator and DCCEEW.
