6.6kW Solar system: Cost output and savings

The output of a 6.6kW system

A 6.6kW system with a 5kW inverter will typically generate enough solar to power the average Australian household’s electricity demands. Production varies depending on where you live, a 6.6kW system in Melbourne produces 23.8kWh while in Brisbane it generates 27.7kWh of electricity per day.

The table below shows how much a 6.6kW system generates in major Australian cities:

6.6kW system output in major cities:
Adelaide 27.7kWh
Brisbane 27.7kWh
Melbourne 23.8kWh
Perth 29.0kWh
Sydney 25.7kWh

Solar panel output varies by season

The output of a 6.6kW system varies by season. If you live in Perth, you receive a proportionally lower amount of sunshine in winter than Sydney residents get.

graphic for a 6.6kW solar system showing the sun, solar panels and an inverter

Cost of a 6.6kW system

A good quality 6.6kW solar system typically costs between $5,500 – $8,000. Many variables affect the price. The solar rebate differs for a 6.6kW system depending on where you live; some markets, like Sydney, are more competitive than others, which can also impact prices. The biggest variable in cost comes from the quality of the solar panels you select and who you choose to perform the installation.

The table below shows how much a 6.6kW system generates in major Australian cities:

Average 6.6kW system prices in major cities:
Adelaide $6,462
Brisbane $6,343
Melbourne $6,555
Perth $6,270
Sydney $6,330

Cost advantage compared to 5kW systems

There are cost advantages to selecting a 6.6kW system over a 5kW solar system; we list the benefits below:

  • You likely only need a 5kW inverter
  • You receive the rebate on the additional 1.6kW worth of panels
  • There is only a slight increase in labour time to install a larger system
  • A 6.6kW system is a more suitable option if you plan to add a battery

6.6KW System with a 5kW inverter

Typically, a 6.6kW system comes with a 5kW inverter, due to panel efficiency losses and because some network distributors do not allow you to install an inverter greater than 5kWs in size. So, you do not need to pay any more for an inverter. You still receive your rebate on the additional 1.6kW of solar panels. The cost of installing a 6.6kW system vs a 5kW system is negligible. For the extra system capacity, you are only paying more for the solar panels and some small additional installation costs.

Avoid cheap 6.6kW systems

We strongly recommend you avoid buying a cheap solar panel system. You will see advertisements that show a much lower cost for a 6.6kW system than what we publish; this is because we show prices for good quality, reliable systems that will last 25 years.

Buy with confidence

Savings and payback on 6.6kW solar systems

While the cost of the system is an important consideration, your buying decision should focus on the savings and value of the system. Depending on where you live and your electricity consumption habits, it is possible to payback a 6.6kW system within five years. Lifetime savings can be upwards of $50,000 and, better quality solar panels that cost more, deliver more savings compared to inferior modules, especially in their later years. The image below shows savings and payback results from our calculator for a 6.6kW system in Brisbane:

results from Solar Calculator for a 6.6kW system in Melbourne

Our 6.6kW system calculator

You can use our savings and payback calculator to get results for a 6.6kW solar system that are specific to your consumption habits, rooftop specifics and location.

How many panels for a 6.6kW system

A 6.6kW system is typically made up of anywhere between 15 and 20 solar panels. The number of panels you need for a 6.6kW system varies depending on how efficient the panels are. For example, if you select highly efficient 440W panels, you will only need 15 of them, but if you go for 330W panels, you will need 20 of them.

Roof space

As a guide, for a 15-panel 6.6kW system, you will need at least 25m2 of roof space. While for 20 panels, you will need 34m2 of roof space.

6.6kW System with batteries

A 6.6kW panel system with batteries may be a viable option for you if you are a high energy user. A 6.6kW system with 10kWh of battery storage capacity will cost you between $16,000 – $21,000. Typically, hybrid systems take longer to pay back than solar panels systems. If you were to split the payback period between panels and battery storage, you are likely to find that the payback for batteries is right on ten years, at which point you will need to replace them.


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