Residential solar power has taken Australia by storm, with the roofs of more than 1 in 10 suitable homes now equipped with solar panels. What size solar system is right for a given home depends on the incentives & prices available at the time of installation, as well as on the electricity needs of the home or business in question.
Generally speaking, 10 kilowatts (kW) is the largest size generally deployed for residential applications in Australia. A 9kW solar system–between this 10kW upper limit and extremely popular 5kW solar systems–is ideally suited for a household whose electricity usage is on the high side.
How many solar panels and roof space do you need for a 9kW solar system?
These days solar panels usually come in rated somewhere between 330 watts (W) to 400W. That means for a 9kW solar system (or 9,000 watts) you will require 23-27 solar panels. This number has reduced a lot over the last decade as the efficiency of solar panels has improved.
Each panel generally measures out to 1.7m2. You also need to take into consideration the space required between the panels for maintenance and access, along with exclusion zones near the edges and ridges of the roof. For a typical 9kW solar system you will require between 39 – 46m2 of roof space depending on the panels you use.
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How much does a 9kW solar system cost?
Solar Choice publishes solar PV system prices from across Australia based on raw pricing data from our installer network. Smaller system sizes (up to 10kW) are included in our Residential Solar PV Price Index articles, while larger systems (between 10kW and 100kW) are included in our Commercial Solar PV Price Index articles. Neither of these articles specifically includes pricing for 9kW solar systems, but it is still possible to get a good indication of where pricing would come in.
Our residential Solar PV Price Index shows that the average dollar-per-watt (1 kilowatt = 1000 watts) price for a fully installed 10kW system was around $1.04 per watt. Making the reasonable assumption that the $/W cost of a 9kW solar system would be fairly similar, we come out with an average price of $9,353 ($1.04 x 9000 = $9,353).
Average 9kW solar panel prices based on Solar Choice Price Index | ||
| City | Out of pocket cost (incl GST and incentives) | Cost per watt, installed |
| Adelaide | $7,803 | $0.87 |
| Brisbane | $9,405 | $1.05 |
| Canberra | $8,613 | $0.96 |
| Hobart | $11,151 | $1.24 |
| Melbourne | $8,208 | $0.91 |
| Sydney | $7,713 | $0.86 |
| Perth | $9,279 | $1.03 |
| Average: | $9,353 | $1.04 |
Prices per watt taken from Solar Choice’s Solar PV Price Index Solar Choice Price Index. Updated July 2023
You can receive a free and instant Solar Quote Comparison from solar installers in your area by filling out the form to the right of this page. Instant quotes will include systems sized 1.5kW, 2kW, 3kW, 4kW and 5kW, but prices for larger system sizes (including 9kW) are available on request and through consultation with our team.
How much energy will a 9kW solar system produce?
As with any solar PV system, the actual power output for a 9kW system will depend on a number of variables.
- Location and climate
- Tilt & orientation of the solar panels
- Presence or absence of shading
- How hot the solar panels get (overheating can reduce power output, while cooler conditions are generally more favourable)
- The quality and sizing of the system’s inverter(s)
- The performance of these and other components in the system
Perhaps the most basic factor included in the list above is the amount of sunlight that is available in a given region. The metric used by the solar industry to measure solar potential is ‘Peak Sun Hours’ (PSH). A Peak Sun Hour is the equivalent of one hour of full sunlight. As the sun moves through the sky, the strength of the rays it casts on a particular location varies. Most places experience peak sun around noon or 1 pm, while sunshine is weaker in the late afternoon and early morning.
The good news is that we have worked this out for you. See the below table which breaks down the output in all the major cities in Australia:
Indicative daily 9kW solar panel output by capital city | ||
| City | Average Daily Production | Estimated Annual Production |
| Adelaide | 35 kWh per day | 12,647 kWh |
| Brisbane | 36 kWh per day | 13,140 kWh |
| Canberra | 35 kWh per day | 12,647 kWh |
| Darwin | 39 kWh per day | 14,454 kWh |
| Hobart | 28 kWh per day | 10,184 kWh |
| Melbourne | 30 kWh per day | 11,005 kWh |
| Perth | 38 kWh per day | 13,797 kWh |
| Sydney | 33 kWh per day | 11,826 kWh |
Assumptions
- kWh figures worked out using PVWatts and historical sunlight data from the Bureau of Meteorology
- The system’s efficiency is conservatively estimated to be 75% for the whole system
- For this exercise, we have assumed the panels are north-facing with a tilt of 30 degrees
9kW solar systems: Payback & Returns
The payback time and returns for any solar system size is dictated by several considerations. In Australia, the relative affordability of system installation and the substantial price of electricity are the key elements that make solar power a great investment.
Formerly, state-based solar feed-in tariffs, were the main incentives to opt for solar energy however now that they have been scaled down they are considered less pivotal in the decision-making process. The majority of Australia now sees these feed-in tariffs as either optional or minimal, indicating that electricity retailers are not obligated to compensate solar-powered homes and businesses for their surplus energy. Understanding the implications of this is key to getting the most out of a system.
Focus on solar self-consumption of solar power is now the rule
If you own a solar system, you will want to consume as much of the power it produced as possible because this will save you the greatest amount of money on your power bill. The rates for electricity purchased from retailers (anywhere from 22¢-35¢ or more depending on the location, retailer, and tariff in question) are significantly higher than the feed-in tariffs offered by the same retailers for excess solar power.
We have put together an overview of some typical scenarios for consumers considering a 9kW solar system. Please take note we have assumed the energy usage is 40 kWh per day on average which is higher than the average in Australia.
| System Cost | Assumed Electricity Rate | Assumed Feed In Rate | Assumed Daily Energy Usage | Payback Period | IRR | |
| Adelaide | $7,803 | 35c | 8c | 40 kWh | 2.9 Years | 36% |
| Brisbane | $9,405 | 26c | 6c | 40 kWh | 4.5 Years | 23% |
| Canberra | $8,613 | 29c | 7c | 40 kWh | 3.8 Years | 27% |
| Hobart | $11,151 | 33c | 8c | 40 kWh | 4.6 Years | 22% |
| Melbourne | $8,208 | 22c | 5c | 40 kWh | 4.9 Years | 20% |
| Perth | $9,279 | 31c | 6c | 40 kWh | 3.8 Years | 27% |
| Sydney | $7,713 | 29c | 7c | 40 kWh | 3.4 Years | 30% |
Assumptions:
- We have assumed the household average daily energy usage is 40 kWh per day (higher than average energy usage)
- The prices are based on the latest Solar Choice Price Index
- Self-consumption rates of 40% have been selected as examples only and as you can see are very important to the financial outcome
- Data was updated on July 2023
You can experiment with the numbers yourself using Solar Choice’s Solar PV System Payback Calculator.
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