6 kW & 6.6 kW solar system: Cost, Savings, And So Much More

The 6.6 kW solar system is the most common system size in all of Australia. It can potentially generate 9,508.5 kW of solar power per year, saving you about $3,100 annually on electricity bills.

Installing solar panels of this size will cost you roughly ~$7,500 and take about two and a half years to pay off.

Plus, modern 6.6kW solar systems are built so well that they’re warranted for 25 years. That means you have about 22.5 years of free electricity.

Neat, huh? Let’s get into all that you need to know about 6.6 kW solar systems.

How much does a 6.6kW solar system cost in Australia?

The average cost of solar systems in Australia is about $1,146 per kW. Of course, it’s different for each state. It’s better to get quotes from CEC-certified installers for super accurate numbers, but here’s a list you can refer to:

CityCost per kWTotal Cost (6.6 kW)

Note that the 6.6kW solar system prices shown above aren’t unalterable. The final cost will depend on a variety of factors. I hate to repeat myself but, again, it’s best to speak directly to your provider or installation team.

How much power does a 6.6kW solar system produce?

One question, but many different answers. There’s a multitude of things that go into the equation of it all. We have a separate page that tackles this topic specifically, but to summarize, the factors that affect solar production are:

  1. angle and tilt of solar panels
  2. solar power ratings
  3. system location
  4. the weather

However, just to answer the question, I listed the estimated daily, monthly, and yearly outputs for each Australian capital city below. These numbers were calculated using the PV Watts calculator under these settings:

  • Roof pitch: 22.5%
  • Inverter efficiency: 96%
  • Quality and type of solar panels: Standard
  • Installation type: fixed, roof-mounted
CityDaily Output (kWh)Monthly Output (kWh)Annual Output (kWh)

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How many panels are in a 6.6kW solar system?

To start, we’ll need your solar panel’s power rating. Once we have that, we then divide your system size (6.6 kW or 6,600 watts) by that rating. The answer you get is the number of panels you need. Pretty straight-forward.

Let’s say you choose to install REC Group’s Alpha Pure Series, which has a rated capacity of 410 watts (W).

  • number of solar panels = system size ÷ solar panel rated capacity
    • 6,600 W ÷ 410 W/panel
    • 17 solar panels

Just as another example, let’s say you go for a cheaper option. Say you’re installing panels with rated capacities of 280 watts only.

  • number of solar panels = 6,600 W ÷ 280 W/panel
    • 24 solar panels

For further reading:

How much roof space would you need for a 6.6kW solar system?

It’ll depend on the specific dimensions of your solar panels. Keep in mind that every brand has different dimensions. However, on average, residential solar panels are 1.7 meters tall and 1 meter wide.

Also, we need to consider how many panels you’re going to install. The higher the wattage rating per panel, the fewer panels you’d need. Which means you’ll need less roof space.

For this discussion, let’s assume you’re installing 410W panels at average dimensions. You’ll need 17 panels to complete a 6.6kW solar system. The panels mounted flush on your roof space will need to occupy a total surface area of 28.9 square meters. Here’s the calculation:

  • Step 1: Calculate the area of one solar panel.
    • Area = height x width
      • 1.7m×1m
      • 1.7 m2
  • Step 2: Multiply the area of the solar panels by how many of them you need.
    • Required roof space = solar panel area x number of panels
      • 1.7 m2 x 17
      • 28.9 m2

The financial implications of a 6.6kW solar system

Let’s figure out how much you get to save each month, your ROI and how soon it can be achieved (within reason), and finally, your payback period. We have other articles tackling those, but let’s talk a bit about them here.

How much money can you save with a 6.6kW solar power system?

Once again, how much money you save also depends on a few things. Some of which are

  • geographical location
  • initial investment
  • energy consumption (monthly)
  • your area’s electricity cost

You can find below wide estimates of the monthly and yearly savings you may get with each capital city.

CityMonthly Savings (AUD)Annual Savings (AUD)

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What about ROI and payback periods?

Your saved amount should wow you. If not, surely the ROI will. Most people assume that the payback period will take a long time, but, as we’re here to say, it’s actually much sooner than you think.

To calculate this, we need data on installation costs and savings.

Here’s an easy equation you can use:

  • ROI = (total savings ÷ total cost) x 100
  • Payback period = total cost ÷ annual savings

Feel free to use the numbers listed above if you want an estimate, or check the table below.

CityTotal Cost (AUD)Annual Savings (AUD)ROI (%)Payback Period (years)

Long story short, the ROI is over 1000%. Plus, your payback period is just around two and a half years. Please note that these are mostly close estimations with a bit of oversimplified calculation. To get extremely specific numbers would be nothing short of precognition (seeing the future).

Typically, your output won’t always be at max. Even in ideal conditions, payback is expected to be around five to ten years. However, even then, that leaves you with about twenty years of free solar energy. That’s why people go into solar energy.

Conclusion: Would your household benefit from a 6.6kW solar system?

Absolutely! Especially if you have the energy needs of the average Australian household.

I should say, though, that if you predict that your energy use and power bills will ramp up fast in the coming years, then maybe it’s best to install a bigger system to account for that rising cost.

Plus, bigger systems tend to have good quality components, are safe from frequent power outages, and can handle surplus electricity better as well. Just be sure to pair it with the proper inverter capacity.

Still need help? You can always ask a professional. In that case, we have a network of pre-vetted solar installers that can give you 3 FREE quotes right away.