4kW Solar system: Prices and output

Depending on your household’s energy consumption, a 4kW solar system may be enough to completely offset your entire energy use. For others, a 4kW solar system is an ideal way to dramatically reduce energy consumption and lower electricity bills with the option to rely on the grid for additional power when needed.

If you are planning to switch gas appliances over to electric, or charge an electric vehicle with solar power, you should consider a larger system.

If you can afford it and you have the roof space, a larger system will equip you better in future years.

How much does a 4kW solar system cost?

The cost of a 4kW solar system in Australia averages $4,831 and ranges from $3,800 - $5,600+ (including installation). By comparison, 5kW system prices are lower per kW.

The cost of a 4kW system will vary depending on your location, the quality of the system, and the complexity of the installation.

Competitive solar markets like Sydney generally attract more competition between solar providers which translates to lower prices for the end consumer.

We always recommend choosing the best quality system for your budget. The higher upfront cost of a premium solar system will invariably result in more consistent, long-term results.

Average prices for a 4kW solar system based on location

*Note: these are indicative average figures for a 4kW solar system in these locations. Individual factors including location, quality of unit, and the complexity of installation will influence pricing.

How much power does a 4kW solar system produce?

A 4kW solar system will typically produce between 16kWh to 18kWh of electricity each day, just above the average kWh usage per day in Australia. Factors like where you live, seasonality, and the positioning of your solar panels will all play an important role in determining your system's daily solar output.

Expect to see higher outputs on long summer days and lower outputs during the cold and dark winter months. Remember, your 4kW solar system won’t be producing energy around the clock. Your daily solar production of 16kWh to 18kWh will come during daylight hours.

Estimated daily output for a 4kW solar system based on location (Table 1)

Roof space needed for a 4kW solar system

A 4kW solar system typically uses between 8 - 11 solar panels and requires between 14 - 19m² of roof space to fit. An average residential panel is 1.7m² in area and better modules are up around 475W per panel.

The exact number of panels and amount of space required on your roof will depend on the output of each panel. It’s worth noting that while you may only require 14 - 19m² of roof space to accommodate the required 8 - 11 solar panels, you’ll likely need some more space to make it easy to access the panels for any future cleaning or maintenance that is required.

Average roof space required for a 4kW system (Fig 2)

4kW Solar system savings

A 4kW solar system can potentially save your household approximately $800 - $1,240 each year depending on your location, electricity prices, and the quality of your system.

For example, in Adelaide, where we assume an average electricity price of 43.2c / kWh (in the table below) and average daily electricity usage of 16.5 kWh , we could expect to see yearly savings of as much as $1,241.50. If you use more than 37% of your electricity during daylight hours, or your electricity use is higher than 16.5 kWh per day, then your savings may be even greater.

It’s worth noting that these figures do not account for any potential bonus feed-in-tariff rates (FIT), rather standard rates have been used. Even though a 4kW solar system will typically produce 16 kWh to 18 kWh of electricity each day, greater than the average Australian household energy consumption, the system will still earn feed-in-tariffs as it is highly unlikely all of the solar energy generated by the system will be self-consumed.

Feed-in tariff rates are an important component of solar savings for smaller systems, just as they are for larger 10kW, or 13kW solar systems.

4kW Solar system savings (Table 2)

*Note: Savings figures are calculated based on an average daily output rate for each state found in (* Table 1).

4kW Solar system payback period

The average solar payback period for a 4kW solar system in Australia can range from 3 years, 11 months in Adelaide to 6 years, 2 months in Melbourne.

These indicative figures consider the upfront cost to purchase and install a 4kW solar system, the average electricity prices in each location, and the amount of time it would take for the savings to “pay back” the initial upfront cost of the system.

Indicative payback period for a 4kW solar system based on location (Table 3)

Note: The data found in the indicative payback period for a 4kW solar system based on location (* Table 3) considers the average upfront costs and the estimated savings found in (* Table 2).

Is a 4kW solar system right for me?

A 4kW system is ideal for homes with low – medium energy requirements and with limited available roof space.

Choosing between a 4kW and a larger 5kW or 6.6kW system will largely depend on your property and your energy requirements. Using our free solar system size calculator, you can get a better idea of whether a 4kW system is going to be right for your home.

If you are interested in powering a popular battery like the Tesla Powerwall 3, consider a larger system if your roof space and budget will allow.