3kW Solar Panel Systems: Costs, Output, and Returns (2024)

How much does a 3kW solar system cost in Australia, and how much energy can you expect it to produce? This article takes a look at these questions, as well as returns and payback periods for 3kW solar systems.

How many panels & how much roof space for 3kW of solar panels?

As residential solar panels are generally rated between 330 watts and 400 watts these days, a 3 kilowatt (3,000 watt) solar system will require about 7-10 solar panels. A typical solar panel is around 1m x 1.7m, therefore a 3kW system will require about 12-17 m² of roof space, depending on the wattage of the panels. You can explore how many panels will fit on your roof using satellite imagery via Solar Choice’s quote comparison platform.

As per the top image, most residential roof spaces will have sufficient room for a 3kW solar system.

How much does a 3kW solar system cost?

Solar Choice tracks the price of solar power systems in Australia through our network and database of over 200 solar installers. We publish average prices monthly through the Solar Choice Price Index which you can refer to at any point. The latest average price for a fully installed 3kW solar system is $4,270 which included the STC rebate and GST. See the full breakdown in the table below which is updated every month:

Average Price of 3kW Solar System by Australian City

There are many factors that will influence the price you will be quoted. To give you an idea of some of the main things to look out for:

1. The quality of products used in your system – be wary of quotes that look too cheap
2. Double-story houses require additional equipment to get installers and the solar panels up to the roof
3. Tile or concrete roofs are more expensive as different mounting systems are required

History of prices for 3kW solar systems in Australia.

Taking a historical view of the Solar Choice Price Index we can see that prices more than halved in the last 8 years.

Power output for a typical 3kW solar system

How much solar energy will a 3kW solar system produce? That depends on a number of situational factors such as location, , the presence of shading and the overall efficiency of the components in the system.

It’s convenient to summarise solar system output in a single figure – namely, kilowatt-hours per day (kWh/day) as in the below table. In reality, there will be a significant difference in the sunlight a solar panel receives during winter months and summer months. In most cities in Australia, a solar system will on average produce over twice as much energy in January than in July.

The table below provides some rough figures on average daily outputs from 3kW solar systems in a handful of Australia’s capital cities (keep in mind that figures will be higher in summer and lower in winter). All situations assume the solar panels are mounted with a north-facing aspect with a tilt equal to the latitude of the city and an overall system efficiency of 80%. (Data source: Bureau of Meteorology.)

Getting the most from your system by maximising ‘solar self-consumption’

These days, the best way to save money with solar is to use the energy yourself (‘self-consumption‘). For every unit (kWh) of solar energy that you use directly, you reduce the amount of energy that you have to purchase from the grid – at rates around 25c/kWh in most of Australia. In contrast, if you let your solar energy go into the grid, you will currently earn about 5-12c/kWh. As a result, the percentage of energy that is ‘self-consumed’ will affect the system’s overall financial return.

By running appliances during the day when your solar panels are generating power, you automatically consume solar energy instead of grid electricity; only the excess solar energy is ‘exported’ to the grid. In general, Solar Choice would recommend selecting a system size where you expect to self-consume a minimum of 30% to make sure the system can pay for itself within the first 3-5 years.

Home energy management systems, hot water diverters and timers are some popular strategies for increasing solar self-consumption. Home battery storage is also increasingly in demand, but high out-of-pocket costs for battery systems make this approach less attractive for the time being (although battery system prices are expected to come down dramatically in the coming years).

Typical financial return and payback period for a 3kW solar system

Using Solar Choice’s Solar PV System Payback Calculator, we have calculated the payback period and IRR for typical scenarios in each of the state capitals in Australia. This is designed to be a guide and we recommend getting a recent energy bill and using our calculator for your own circ*mstances. All of the below returns are better than what you can get by leaving your money at the bank and ignores the environmental benefits of putting solar panels on your roof!

The prices used are reflective of the recent average costs for 3kW solar systems as observed in the Solar Choice Price Index. You can enter your specific quoted price and parameters into our calculator.

• This assumes that 50% of the total energy consumption (15 kWh) is used during the daytime.
• Pricing per watt installed is unfavourable for 3kW systems in most states, it could improve the payback period to look at a larger system
• Pricing is based on the Solar Choice Price Index from July 2023

What about a larger system size?

If you’re reading this article, you may very well have decided that 3kW is the right size for your home. If you’re not yet sure about the right size for you, however, it might be useful for you to know that6.6kW is now the most popular solar system size in Australia. In fact, we’ve worked out that a 5kW system may even be a better investment for many homes than a 3kW system –see this article.