6kW & 6.6kW Solar System Information And Pricing

Last Updated: 3rd Jun 2024

Installations of 6kW (and 6.6kW) solar power systems are a very common sight on rooftops around Australia in 2024, largely due to the ongoing plummeting cost of solar energy components, the still-generous subsidy, and feed-in tariffs.

These systems may have 6kW/6.6kW of solar panels, but only a 5kW inverter – see notes on “oversizing” below.

How many solar panels will I need for a 6kW system?

That will depend on the size (output) of the solar panels used in the installation. Just as an example, if 415 watt panels are used, then a 6kW solar system will consist of 15 modules, which is a little over 6kW – or 16 for a 6.6kW array.

How much roof space is required for a 6kW solar power 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 6kW solar power system installation (or 32 square metres for 6.6kW). Here’s a general idea of how much space 6kW occupies, based on 415 Watt panels.

Scale drawing of a 6kW solar power system

How much electricity generation can I expect from a 6kW system?

Factors such as installation location, solar panel orientation and component quality come into play, but generally a 6kW 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.

How much does a 6kW solar power system cost?

The cost of a 6kW system using quality components that are professionally installed will generally range between $5,200 – $8,700 as at early 2024. This price range takes into account the solar subsidy.

What is the payback period on a 6kW 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 6.6kW

While 6kW system installations have grown in popularity, savvy Australians are installing 6.6kW solar systems – or even larger.

Let me clarify – if your house is on single phase electricity supply (and most Australian homes are), then you should get at least a 5kW inverter and 6.6kW of solar panels.

Why 6.6kW of solar panels?

This may seem like an odd figure and one I’ve pulled out of a hat. Basically, a 6.6kW configuration gives you great bang for buck in terms of kilowatts for your dollars. And if you’re getting a decent feed in tariff (8c a kilowatt-hour or more), a 6.6kW solar system will absolutely, on all the numbers I’ve run, give you a great return on your investment. 

About oversizing 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 5kW inverter? Why not 6kW?

Aside from a 5kW inverter possibly being cheaper than 6kW, solar panels rarely produce as much power as their rated capacity for a number of reasons; a major one being temperature. 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 6kW (or 6.6kW) 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 to be connected to the grid.

What’s the price of a 6.6kW solar system?

The cost of a 6.6kW solar system of good quality is just a little more than a 6kW – in the $5,500 – $9,000 range in early 2024; again depending on components selected and installation specifics.

So, for around $300 more, you’ll be getting 2 extra panels assuming a module capacity of 415 watts. The reason the extra panels are so cheap, aside from the influence of the subsidy, is that the installer is already on-site and it’s not much effort to add a couple of extras to the system.

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 6kW solar power 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 6kW (or 6.6kW) 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. 

I put solar power installers through the wringer so you don’t have to!

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