6 kW & 6.6 kW Solar Systems: Prices and Information
Last Updated: 8th May 2026
Installations of 6 kW (and 6.6 kW) solar systems are a very common sight on rooftops around Australia, largely due to the downward trend of solar panels, the still-generous subsidy, and feed-in tariffs.
If you’re wondering what causes the difference between 6 kW and 6.6 kW, read about “oversizing” below.
How Much Does a 6 kW Solar System Cost?
The cost of a 6 kW system using quality components that are professionally installed will generally range between $6,000 – $8,000. This price range takes into account the solar subsidy. The graph below details the prices 1659 people have reported paying for their 6.6 kW system over the last 2 years.
How Many Solar Panels Will I Need For A 6 kW System?
That will depend on the size (output) of the solar panels used in the installation. Just as an example, if 440 Watt panels are used, then a 6 kW solar system will consist of 15 modules, which is a little over 6 kW – or 16 for a 6.6 kW array.
How Much Roof Space Is Required For a 6 kW Solar System?
Based on a panel measuring approximately 1.8 metres x 1.1 metre, around 30 square metres of suitable rooftop will be required for a 6 kW solar power system installation (or 32 square metres for 6.6 kW). Here’s a general idea of how much space 6 kW occupies, based on 440 Watt panels.
How Much Electricity Generation Can I Expect From a 6 kW System?
Factors such as installation location, solar panel orientation and component quality come into play, but generally a 6 kW PV system should generate around 24 kilowatt-hours of electricity a day, which is more than the average Australian household uses daily.
Don’t forget you’ll be receiving feed-in tariff payments for your surplus electricity. Also, it’s large enough to normally eliminate grid electricity consumption on sunny days from before midmorning to beyond midafternoon for typical households. Bear in mind self-consumption is key to getting the most from a system of this size.
What Is The Payback Period on a 6 kW System?
You should see a simple payback period of around 5-6 years assuming a good installation, you’ve paid a reasonable price and have a significant level solar energy self-consumption. You can use our solar calculator to get a better sense of the returns.
You could also be cash flow positive from the get-go if you’re able to secure cheap solar finance, and not have to pay anything (or very little) up-front.
But Wait, Think a Little Bigger – Think 6.6 kW
While 6 kW system installations have grown in popularity, savvy Australians are installing 6.6 kW solar systems – or even larger.
Let me clarify – if your house is on a single-phase electricity supply (and most Australian homes are), then you should get at least a 5kW inverter and 6.6 kW of solar panels.
Why 6.6 kW of Solar Panels?
This may seem like an odd figure and one I’ve pulled out of a hat. Basically, a 6.6 kW configuration gives you great bang for buck in terms of kilowatts for your dollars. And if you’re getting a decent feed-in tariff, a 6.6 kW solar system will help give you a great return on your investment.
What Does It Mean To Oversize Solar Systems?
Installing solar panel capacity greater than inverter capacity is called “oversizing”. It’s quite common these days, totally safe, won’t harm the inverter and I highly recommend it. As Australia’s solar subsidy (still often called the “solar rebate“) is based on panel capacity rather than inverter size, this means you’ll extract the best level of incentive possible.
A 5 kW Inverter? Why Not 6 kW?
Aside from a 5kW inverter possibly being cheaper than 6 kW, solar panels rarely produce as much power as their rated capacity for a number of reasons; a major one being temperature. This is reflected by a solar panel’s temperature coefficient. Most solar panels lose around 10% of their rated power on a 25°C day, and more if it is hotter – and Australia is no stranger to warm days.
Other factors affecting output include dirt and grime on the panels and wiring losses. So, by using a 5kW inverter with 6 kW (or 6.6 kW) of solar panels, you’ll actually be ensuring the inverter is working at its designed performance level for more of the time.
Another very important reason for using a 5kW inverter is that it is the maximum capacity some Network Service Providers allow for connection to the grid.
So Why Not Go Even Larger and Add More Solar Panels?
Aside from rooftop space limitations in some cases, installation guidelines only allow for a maximum 133% oversize of panel capacity vs inverter capacity – and 5kW x 133% = 6.65kW. While you may not be able to get a system exactly 6.65kW, aim for as close to it as possible – but not a single watt over in order to remain within the approved oversizing limit.
Getting Quotes On 6 kW Solar Systems
Even with the subsidy, solar panels are a significant investment and as with any trade, there are good installers and not-so-good.
If you want to go solar and are looking for a price for a 6 kW (or 6.6 kW) system, you’re definitely in the right place. Use our free service to get up to 3 solar quotes from installers servicing your area that I’ve hand-picked and trust to prepare a quote on a system that best suits your needs and circumstances.