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3kW Solar Systems

Power generation of a 3kW solar system in Adelaide

To give you a better understanding of the power output of a 3kW 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, 3kW of panels with a 3kW inverter would produce 3kWh 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 3kW system will generate 16.8kWh 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 16.8kWh becomes 12.6kWh! That’s a significant difference, and worth noting in your decision to purchase a system.

Suitable For

Low to moderate energy users, with no plans to add a battery in future.

Maximum Peak Sun Output

2.26kW (3kW, less 25% for efficiency losses)

Average Daily Power Generation


Real World Usage

(Simultaneous Usage During Peak Sun)

1x Small Fridge (200W)
1x Small wall split A/C at maximum power (2kW)


2x 55” QLED TV (200W ea)
1x Retina 5k 27-inch iMac (262W)
1x Sound Bar + Subwoofer (45W)
1x PS4 (140W)
2x Medium to Large Fridge (700W ea)

3kW solar system prices

In South Australia, a decent 3kW solar system could cost anywhere from $2500 - $7500.*

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 3kW solar systems

The payback period for 3kW 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 3-5 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:
  • $3,800
  • ~$800
  • 4.5 Years

Should I consider a larger system?

If you have minimal electricity usage, are not at the property during the day, have no intention of adding a battery and have no intention of powering an electric vehicle, then a 3kW system could be sufficient.

However, even if you meet all of the above criteria, selecting a larger system can result in lower payback periods and greater savings. A larger system also gives you the flexibility to add a battery later, should you change your mind.

Should I add batteries?

If you are considering adding a battery to a 3kW solar panel system, you need to consider whether or not your system will generate enough power to charge the battery. Typically, a 3kW system is likely to be large enough if you consume less than 10 – 12kWh per day.

If you plan on buying a battery ready system and adding solar storage at a later date, we suggest you consider a larger system, either a 5kW or 6.6kW system.

How many panels make up a 3kW system?

A 3kW solar system is typically made up of between 9 – 12 panels (15 – 20m2). If you select the best solar panels that are highly efficient, you may only need eight panels to make up a 3kW system.

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.

5kW Systems6.6kW 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.