6.6kW Solar Systems

Power generation of a 6.6kW solar system in Adelaide

To give you a better understanding of the power output of a 6.6kW system, let’s consider the theoretical possibilities.

In peak sunlight (more on peak sunlight below), 1kW of panels with a 1kW inverter would produce 1kWh of electricity per hour. By extension, 6.6kW of panels with a 6.6kW inverter would produce 6.6kWh of electricity per hour.

So how much will this actually generate on an average day in Adelaide? As we know, the sun isn’t a light globe you can just switch on and off, directly above your panels whenever you need power. Instead, it moves across the sky under varying cloud and atmospheric conditions.

Peak sun hours refer to the quantity of solar energy available in an area during a typical day.

With that in mind, how do we estimate power output? Enter, ‘peak’ sun hours. Peak sun hours are not just hours of daylight, but they refer to the quantity of solar energy available in an area during a typical day. A peak sun-hour, specifically, is an hour during which the intensity of sunlight is 1,000 watts per square meter.

In Adelaide, we receive an average of 5.6 peak hours of sunlight a day, over the period of a year. Based on that figure, we could deduce that a 6.6kW system will generate 36.96kWh per day.

But, wait! There are some variances that ultimately reduce this figure. For example, panel angle, direction and degradation, as well as efficiency losses due to energy transfer and heat (yes, solar panels are less efficient in higher temperatures). On average these losses can reduce a system’s performance by around 25%. All of a sudden our 36.96kWh becomes 29.97kWh! That’s a significant difference, and worth noting in your decision to purchase a system.

Suitable For

Moderate electricity users, particularly if there is someone home for around 50% of the week, or for moderate users who want to add batteries to offset evening usage.

Maximum Peak Sun Output

4.95kW (6.6kW, less 25% for efficiency losses)

Average Daily Power Generation


Real World Usage

(Simultaneous Usage During Peak Sun)

2x Medium to Large Fridge (700W)
1x Small wall split A/C at maximum power (3.5kW)


1x 55” QLED TV (200W)
1x Medium to Large Fridge (700W)
1x 1000W Microwave
1x Average Clothes Dryer (3000W)

6.6kW solar system prices

In South Australia, a decent 6.6kW solar system could cost anywhere from $4,350 - $13,250*

The pricing variation comes down to the quality and reputability of the inverter(s), the panels, and the installation. In some cases you might also have site-specific requirements, such as splitting your panel arrays across multiple roof faces.

Looking for an indication of pricing for your situation? Start by getting an instant solar quote.

Instant Solar Pricing

Savings and payback on 6.6kW solar systems

The payback period for 6.6kW systems varies according to your electricity usage, roof orientation and pitch, shade and other property specifics. In general, however, you could expect to recover the cost of the system within a 2.5-7.5 year period, in South Australia.

The figures below are a guide, and may not reflect your actual costs.

Possible Payback Scenario

  • System Price:
  • Annual Savings:
  • Payback Period:
  • $5,200
  • ~$2,000
  • 3 Years

Should I consider a larger system?

A 6.6kW configuration offers a great return on investment and is a prime place to start with solar panels. This configuration is also very popular among Australians.

Jumping up to the 10kW system could be a good option for you if you’re a high-energy household, or plan to power an electric car in the future. However, it would also require more roof space.

Should I add batteries?

If you’re a high-energy household, but don’t necessarily have the roof space or budget to move up to a 10kW system, adding batteries could be a good option for you. That being said, there are a few variables worth considering - energy production in winter, your provider’s feed-in tariff and your energy usage. If you’re If you’re still unsure about whether a battery is right for you, reach out to us and we’d love to help you out.

How many panels make up a 6.6kW system?

A 6.6kW solar system is typically made up of between 16 and 21 panels (27m2 – 36m2). If you select the best solar panels that are highly efficient, you will also decrease the number of panels needed.

This number could change as panel technology improves over time.

If you’ve made it this far, well done!

We hope this has given you a good baseline to make your decision on solar. However, if you’re more lost than when you started, that’s ok, it’s complex stuff! We’d love to help - give us a call on (08) 8374 1491, or contact us here.

In the meantime, why not check out some other common system sizes.

3kW Systems5kW Systems10kW Systems

*This price accounts for the STC government rebate (accurate October 2020), which is scheduled to end in 2030. However, each year that you delay your installation, the rebate amount is reduced, and therefore the out of pocket expense on the purchase of a solar system increases.