6.6kW Solar Systems

A 6.6kW solar system is 14 panels, a 5 kW inverter and a question

For years 6.6 kW was the system nearly every Australian home was sold, and it's still the system size people search for most. It's 14 or 15 panels on a 5 kW inverter, it makes about 25 kWh on an average day, and on the right house it's all the solar that house needs. The question is whether yours is the right house. That's the part no price list can answer.

Deionno Electrical & Solar has installed solar across Adelaide for ten years and now on the Sunshine Coast, more than 4,000 solar and battery systems in all, with our own licensed electricians on every roof. This page covers the 6.6 kW system honestly: the numbers, the rules behind them, the price, and how to tell whether it is enough.

What a 6.6kW solar system is

The 6.6 kW is the combined size of the panels. With the 475 watt panels we fit most often, that is 14 panels (6.65 kW). With 440 watt panels it is 15, and with the newest 510 watt panels it is 13. They feed a 5 kW inverter, which turns the panels’ DC into the 230 volt AC your house runs on.

So a “6.6 kW system” never delivers 6.6 kW to the house. The most it can deliver at any moment is the inverter’s 5 kW. That’s deliberate, and the next section explains why.

Why 6.6kW of panels goes on a 5 kW inverter

Panels rarely produce their full rated output. Heat, the angle of the sun, a thin layer of dust and the time of day all take a slice. An array a third bigger than its inverter keeps the inverter busy for more hours of the day: it fills in the mornings, the afternoons and the cloudy days, and only on a few perfect hours in spring does the inverter have more than it can use.

The industry design guidelines that the solar rebate depends on set the limit: the inverter has to be at least three quarters the size of the array. For a 5 kW inverter that works out at 6.65 kW of panels, which is where the number comes from.

And the 5 kW inverter itself came from the networks. For most of the last decade, 5 kW was what a single-phase home could connect and export without further questions. Those rules have since loosened in both states, which is one reason the 6.6 kW system is no longer the automatic answer.

How many panels, and how much roof

A modern panel is about 1.8 metres tall and 1.1 metres wide, so 14 of them cover roughly 28 square metres. They do not have to sit on one face. Many of the 6.6 kW systems we install are split across two faces of the roof, east and west or north and west, and the inverter manages each face separately.

What decides the layout is shade, the direction each face points, and where the vents, skylights and antenna already are. That is measured on the roof, not from a satellite photo.

How much power a 6.6kW solar system generates

Adelaide, Brisbane and the Sunshine Coast all sit in the same zone on the Clean Energy Regulator’s solar map, and its rating for that zone puts a 6.6 kW system at about 9,100 kWh a year, or 25 kWh on an average day [1].

The average hides the seasons. Modelled for a north-facing roof at a 20 degree pitch [2]:

Adelaide has the bigger summers and the leaner winters. The Sunshine Coast is steadier all year. East and west faces make a little less in total and spread it across more of the day, which suits a house that is busy at breakfast and after school.

What a 6.6kW solar system will run

Solar runs whatever is switched on while the sun is up. In the middle of a clear day a 6.6 kW system has up to 5 kW to give, which covers the fridge, the lights, the washing machine, the dishwasher, a pool pump and a split system air conditioner all at once, with some left to export.

What it won’t do is run the house at night, and it won’t keep up with the biggest loads on its own. A large ducted air conditioner can draw more than 5 kW by itself. An electric car on a 7 kW charger wants more than the whole system makes. Those homes still save with 6.6 kW. They just buy more from the grid than they need to.

The honest way to answer “what will it run” is with your own bills: how much you use, and when. A home using most of its power between 4 pm and 10 pm gets less out of the same panels than one with someone home all day.

SA Power Networks and Energex rules for a 6.6kW system

• South Australia. A new system either takes a fixed export limit of 1.5 kW per phase, or signs up to flexible exports, which lets it send out up to 10 kW per phase whenever the local network has room. Flexible exports needs an inverter that stays connected to the internet [3]. For a 6.6 kW system the flexible option is nearly always the better one.
• South East Queensland. Energex has to approve every solar system before it is installed. It offers a connection with a fixed export limit, or a dynamic connection that lets the system export up to its full rating when the network allows [4].

We lodge the application in both states and tell you which connection you are getting before you sign.

The solar rebate on a 6.6kW system

The federal solar rebate is paid in certificates, and the number depends on the size of the system, where you live and the year it is installed. A 6.6 kW system installed in Adelaide or on the Sunshine Coast in 2026 earns about 45 certificates [1]. The number steps down every January until the scheme ends in 2030, so the same system installed in 2027 earns fewer.

The installer claims the certificates and takes their value off your price. Our solar rebate calculator gives the figure for your postcode and install date.

What a 6.6kW solar system costs

From us, a 6.6 kW system starts at about $6,500 for a single-storey home with an easy roof and a short cable run to the switchboard. It runs up to about $8,000 where the job is harder: a second storey, a tile roof, panels split over several faces, a long cable run, or a switchboard that needs work before solar can go on it.

Every system is designed from your bills, not a package off a price list. Your price comes from the site visit, in writing, and it doesn’t change on install day.

A warning about the $5,000 system

You will see 6.6 kW advertised for around $5,000, and sometimes less. In the trade these are backyarder prices. Nobody can supply good panels, a good inverter, new cable and isolators, pay licensed electricians for a proper day on your roof and still be in business at that number. So something has been taken out, and it’s nearly always something you can’t see from the ground: the hours on the roof, the parts behind the panels, or the company that was supposed to answer the phone in year six.

Three questions sort a real quote from a backyarder one.

• Who is on my roof? The company’s own employees, or whichever subcontractor was cheapest that week?
• What is every part? Brand and model of the panels, the inverter, the isolators and the racking, in writing.
• How long have you traded under this name? The panels may carry a 25-year warranty, but the workmanship is only covered while the installer is still trading.

A solar system sits on your roof for twenty years or more. It’s worth paying more for a team that will still be here.

What the extra buys with us

Ten years in business. More than 4,000 solar and battery systems installed. Our own licensed electricians on every job, with no subcontracted installs. A site visit before the quote, so there are no extras on install day. A 10-year workmanship warranty, product warranties of up to 25 years, and a commitment written into the contract that if something is not right, we come back and fix it. 4.9 stars on Google from more than 530 reviews, and SunWiz’s Best Rated Overall award for 2025.

On the numbers, a well-designed system pays for itself in three to six years. That payback only arrives if the system is still running, and a cheap one that fails in year four never gets there.

A 6.6kW solar system with a battery

A 6.6 kW array and a battery can work together, and we install them. At Twin Waters we replaced an old system with 14 new panels, a 5 kW GoodWe hybrid inverter and 24 kWh of GoodWe batteries, with the lights and power circuits backed up.

The limit is winter. On a June day a 6.6 kW system makes 17 to 21 kWh, the house uses part of that as it is made, and what is left has to fill the battery. If a battery is in the plan, the roof usually wants to be bigger. Batteries are a big reason the average new system in Australia has grown past 10 kW [5].

Is a 6.6kW solar system the right size for your home?

Nobody can tell you that from a web page. That includes this one.

The average new solar system in Australia is now 10.3 kW [5]. Homes use more electricity than they did when 6.6 kW became the default: induction cooktops, heat pump hot water, air conditioning in every room, and more electric cars each year. And the export rules that made 5 kW the natural ceiling have loosened.

But on a small roof, in a small household, with the evening as the busy time and no car to charge, 6.6 kW is still the right system, and anything bigger is money spent on exports.

The only way to know which house yours is: someone who designs solar for a living sits down with a year of your bills, sees when you use power and how much, walks the roof, opens the switchboard, and asks what’s coming, whether that’s a car, a pool or a baby. That’s our free on-site assessment. It takes about an hour, it’s done by a solar specialist, not a salesperson, and you get a design and a price in writing. If 6.6 kW is enough, that’s what we’ll quote, and whatever size it lands on, you’ll see the reason in your own bills. Book one and you’ll know which house yours is before the specialist leaves.

6.6kW solar systems in Adelaide and on the Sunshine Coast

Adelaide and South Australia

Our Adelaide crews have put 6.6 kW systems on tile roofs in Blackwood and Hillcrest, on a shed at Verdun with an EV charger beside it, and at Port Julia on the Yorke Peninsula. We cover the metro area, the Hills, the Fleurieu and the Barossa from Salisbury Plain. See the Adelaide solar installer page.

Sunshine Coast and South East Queensland

On the Coast, recent 6.6 kW jobs include Mountain Creek, Yandina, Ringtail Creek and Twin Waters, on tile and tin. Our electricians cover Caloundra to Noosa, the hinterland, Gympie and north Brisbane from Corbould Park. See the Sunshine Coast solar installer page.

Sizing solar for the whole house

The home solar installer page covers how we size a system from your bills at any size, and how to compare quotes line by line.

Sources

1. Clean Energy Regulator, Postcode zone ratings and zones for solar panel systems. Zone 3 rating 1.382; deeming period of five years for 2026.
2. European Commission Joint Research Centre, PVGIS solar yield model, run 10 November 2026 for Adelaide and the Sunshine Coast.
3. SA Power Networks, Flexible exports.
4. Energex, Solar connections and other technologies.
5. Clean Energy Regulator, small-scale renewable energy scheme data for the March quarter of 2026.