6.6kW Solar system: Cost, output and savings

A 6.6kW solar system is one of the most popular install size options for households wanting to save money and offset their energy use.

There are several benefits to 6.6kW systems:

• They typically produce enough energy per day to offset average electricity use
• They can save you money and reduce your electricity bills
• They are suitable for 10 – 14 kWh batteries
• They typically fall within network export limits

This guide to 6.6kW solar systems will tell you everything you need to know about installation, energy production, prices, savings, roof area required and pairing the system with a battery.

How much does a 6.6kW solar system cost?

The average cost of a good quality 6.6kW solar system in Australia typically ranges from $5,500 to $8,000 with the average coming out to $6,407. 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 costs in major Australian cities:

Average 6.6kW system prices in major cities across Australia:

* It's possible to get a rebate on the installation of solar panels in Melbourne that can further reduce prices by $1,400.

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

It is quite common for a 6.6kW solar system to be paired with a 5kW inverter. By oversizing the panels, you can maximise energy output and overcome the efficiency losses associated with rooftop solar panels.

The price of a 6.6kW system with a 5kW inverter is the same as for a 6.6kW system, expect to pay between $5,500 - $8,000.

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 6.6kW 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 solar panel prices for good quality, reliable systems that will last 25 years.

How much energy will a 6.6kW solar system produce?

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

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

Average 6.6kW system energy output in major cities across Australia:

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.

Average Savings and payback period on a 6.6kW solar system

One of the most important considerations when buying any solar system is to shift the focus on cost and prices to how much will it save me?

While the cost of the system is an important consideration, your buying decision should focus on the savings and value of the system. Savings for 6.6kW systems vary depending on a range of factors, but typically fall between $1,100 - $1,800 per year and lifetime savings can exceed $50,000.

The image below shows savings and payback results from our calculator for a 6.6kW system in Brisbane:

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 make up a 6.6kW system?

A 6.6kW system can be made up of anywhere between 14 – 17 solar panels, depending on the power output of the panels.

The higher the power output e.g. 475W, the less panels you will need to make up a 6.6kW system. For example, if you select 475W panels, you will only need 14 of them, but if you go for 390W panels, you will need 17 of them.

Roof space required for a 6.6kW system?

The roof space required for a 6.6kW system depends on the power output of the panels and how many are needed to make up the system. The standard solar panel dimensions are 1.7m x 1.0m, an area of 1.7m2.

As a guide, for a 14-panel 6.6kW system, you will need at least 23.8m² of roof space. While for 17 panels, you will need 28.9m² of roof space.

The table below shows the number of panels and roof space you will need based on the output capacity of the solar panels:

6.6kW system with a battery

If you’re wanting to make more savings, take advantage of rebates, or increase your energy independence; adding a battery to a 6.6kW system is now more viable than ever. For many households, a 6.6kW solar system produces enough energy to power daytime and night time electricity use.

How much is a 6.6kW solar system with a battery?

A 6.6kW solar system with a suitable size battery costs anywhere between $13,000 - $22,000 depending on the quality of panels you select and the size capacity of the battery. The table below provides a price guide for different battery sizes:

What size batteries suit a 6.6kW system

Typically, a 10 kWh or 13.5 kWh battery, like a Tesla Powerwall, is a good size to pair with a 6.6kW worth of panels. This means that effectively half the energy produced by the system can be stored in the battery.

You can use our guide to sizing a solar battery for more information.

Battery payback

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.