9kW Solar System: Installation Cost, Savings, ROI, And More

Feature image of the 9kW Solar system blog. Image shows 2 solar installers installing a 9 kilowatt solar system on a Victorian home's rooftop.

A 9kW solar panel system can generate about 14,180 kW of solar power per year. The installation is likely around ~$10,300 and will take under three years to fully pay off.

The positive side is that this investment will save you ~$3,900 per year on energy bills. This, among many other reasons, is why people are going solar.

And so, here’s everything you need to know about installing a 9 kW solar system.

How much does a 9kW solar system cost in Australia?

The average solar system cost in Australia is around $1,146 (per kW). Since it’s different for each state, check quotes from CEC-certified installers for more accurate numbers.

But here’s a list you can refer to:

CityCost per kW ($)Total Cost for 9kW System ($)

By the way, the 9kW solar system prices above aren’t final. Make sure to speak with your provider or installer for the final cost since it’ll all depend on so many factors.

How much power does a 9kW solar system produce?

This, too, depends on a few factors. We’ve got dedicated articles about this stuff, but just to speak about it a little here, the factors that affect solar production are:

  1. panel’s angle and tilt
  2. power ratings
  3. install location
  4. daily weather patterns

But let’s illustrate an answer for conversation’s sake. I listed the estimated daily, monthly, and yearly outputs for each Australian capital city below. This was computed using the PV Watts calculator under the following 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 9kW solar system?

To calculate this, we need:

  1. the panel’s power rating
  2. your system size (9 kW or 9,000 watts)

Let’s illustrate. Say you install Jinko Solar’s Jinko Cheetah HC 330W (JKM330M-60H). These panels have a rated capacity of 330 watts (W).

  • number of solar panels = system size ÷ solar panel rated capacity
    • 9,000 W ÷ 330 W/panel = 27.27 (then round up because you can’t have a fraction of a panel.)
    • 28 solar panels

Let’s view a different option. For example, say you’re installing panels with rated capacities of 250 watts only.

  • number of solar panels = 9000 W ÷ 250 W/panel
    • 36 solar panels

For further reading:

How much roof space would you need for a 9kW solar system?

This, again, depends on a few things. We need the dimensions of your panels. Since every brand has different measurements, let’s use the average (1.7m x 1m) for this illustration. Then, we need to multiply that by the number of panels you need to install (28 panels).

Remember, the higher the wattage rating for each panel, the fewer you need to install. Which, conversely, means that you’ll need less roof space. Once again, let’s illustrate!

You’re installing 28 pieces of 330W panels at average dimensions (1.7m x 1m). This means you need 47.6 square meters of roof space. Now that you have this number, make sure you have enough space on your roof to accommodate this system size. Here is 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 28
      • 47.6 m2

The financial implications of a 9kW solar system

Moving on, let’s take a gander at your monthly savings, ROI, and when you can expect your payback period. Spoiler alert: sooner than you think!

How much money can you save with a 9kW solar power system?

How much money you save depends on your geographical location, how much you spent initially, your monthly energy consumption, and your area’s specific electricity cost.

We also have a deep dive into this in another one of our articles. If you’re in a rush, you can find below wide estimates of the monthly and yearly savings you may get with each capital city.

CityMonthly Savings ($)Annual Savings ($)

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What about ROI and payback periods?

As I’ve alluded to before, the payback period might not be as far into the future as it seems. Let me illustrate your payback period calculations and your ROI.

To calculate this, we need numbers 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.

CityROI (%)Payback Period (years)

Now you can see that your ROI is nearly 1000%. Wow! And your payback period is just under three years. Of course, these are averages and oversimplified calculations. It’s even likely that payback comes around the 6th to maybe 10th year, depending.

Still, though, since these panels are warranted for 25 years, that gives you about 23 years of free solar energy. Even if you had excess solar power that was sent back to the grid instead of being used for your own consumption, that’s still a major win.

Conclusion: Would your household benefit from a 9kW solar system?

Most definitely! Just make sure you know how much energy you need and how many solar panels you have to install to achieve a 9kW power system. The solar industry is vast, and it may differ from provider to provider.

Also, depending on your electricity usage, just make sure to account for a battery storage system. Maybe you need it, maybe you don’t, but it’s worthwhile to have a conversation about it. Especially during peak sun hours, you may already have enough power for your needs.

Solar systems and how they all tie into your power bill can be complex things. If you still need help, we have a lot of resources ready for you to read. But we can also just have a conversation. Our network of pre-vetted solar installers can give you 3 FREE quotes right away, too. Contact us!