Solar Power System Payback Calculator
The tables on this page have been generated using the solar payback calculator on the SolarQuotes.com.au website, for more accurate and up to date results visit SolarQuotes.com.au and enter your own data.
New South Wales 20yrs @25c per kWh
| System Size | System Price | Total Cost | Annual Output | Net Savings | Payback Time |
|---|---|---|---|---|---|
| 2kW | $4,000 | $4,800 | 2,847kWh | $10,893 | 10yrs |
| 3kW | $4,500 | $5,300 | 4,270kWh | $19,376 | 8yrs |
| 5kW | $7,000 | $7,800 | 7,117kWh | $33,949 | 7yrs |
| 7kW | $9,000 | $9,800 | 9,964kWh | $49,322 | 6yrs |
| 10kW | $12,000 | $12,800 | 14,235kWh | $72,385 | 6yrs |
ACT Canberra 20yrs @25c per kWh
| System Size | System Price | Total Cost | Annual Output | Net Savings | Payback Time |
|---|---|---|---|---|---|
| 2kW | $3,900 | $4,700 | 3,139kWh | $10,906 | 10yrs |
| 3kW | $4,500 | $5,300 | 4,708kWh | $19,156 | 7yrs |
| 5kW | $7,000 | $7,800 | 7,847kWh | $33,582 | 7yrs |
| 7kW | $9,000 | $9,800 | 10,986kWh | $48,808 | 6yrs |
| 10kW | $12,000 | $12,800 | 15,695kWh | $71,651 | 5yrs |
Victoria 20yrs @25c per kWh
| System Size | System Price | Total Cost | Annual Output | Net Savings | Payback Time |
|---|---|---|---|---|---|
| 2kW | $3,900 | $4,700 | 2,628kWh | $9,953 | 10yrs |
| 3kW | $4,500 | $5,300 | 3,942kWh | $17,730 | 8yrs |
| 5kW | $7,000 | $7,800 | 6,570kWh | $31,203 | 7yrs |
| 7kW | $9,000 | $9,800 | 9,198kWh | $45,476 | 6yrs |
| 10kW | $12,000 | $12,800 | 13,140kWh | $66,886 | 6yrs |
Tasmania 20yrs @25c per kWh
| System Size | System Price | Total Cost | Annual Output | Net Savings | Payback Time |
|---|---|---|---|---|---|
| 2kW | $3,900 | $4,700 | 2,555kWh | $7,429 | 12yrs |
| 3kW | $4,500 | $5,300 | 3,832kWh | $13,941 | 9yrs |
| 5kW | $7,000 | $7,800 | 6,387kWh | $24,891 | 8yrs |
| 7kW | $9,000 | $9,800 | 8,942kWh | $36,641 | 7yrs |
| 10kW | $12,000 | $12,800 | 12,775kWh | $54,268 | 7yrs |
South Australia 20yrs @25c per kWh
| System Size | System Price | Total Cost | Annual Output | Net Savings | Payback Time |
|---|---|---|---|---|---|
| 2kW | $3,900 | $4,700 | 3,066kWh | $12,958 | 9yrs |
| 3kW | $4,500 | $5,300 | 4,599kWh | $22,238 | 7yrs |
| 5kW | $7,000 | $7,800 | 7,665kWh | $38,716 | 6yrs |
| 7kW | $9,000 | $9,800 | 10,731kWh | $55,995 | 5yrs |
| 10kW | $12,000 | $12,800 | 15,330kWh | $81,913 | 5yrs |
West Australia 20yrs @25c per kWh
| System Size | System Price | Total Cost | Annual Output | Net Savings | Payback Time |
|---|---|---|---|---|---|
| 2kW | $3,900 | $4,800 | 3,212kWh | $11,334 | 9yrs |
| 3kW | $4,500 | $5,300 | 4,818kWh | $19,802 | 7yrs |
| 5kW | $7,000 | $7,800 | 8,030kWh | $34,656 | 6yrs |
| 7kW | $9,000 | $9,800 | 11,242kWh | $50,311 | 6yrs |
| 10kW | $12,000 | $12,800 | 16,060kWh | $73,793 | 5yrs |
Northern Territory 20yrs @25c per kWh
| System Size | System Price | Total Cost | Annual Output | Net Savings | Payback Time |
|---|---|---|---|---|---|
| 2kW | $3,900 | $4,700 | 3,212kWh | $14,520 | 8yrs |
| 3kW | $4,500 | $5,300 | 4,818kWh | $24,581 | 6yrs |
| 5kW | $7,000 | $7,800 | 8,030kWh | $42,622 | 5yrs |
| 7kW | $9,000 | $9,800 | 11,242kWh | $61,463 | 5yrs |
| 10kW | $12,000 | $12,800 | 16,060kWh | $89,724 | 4yrs |
Queensland 20yrs @25c per kWh
| System Size | System Price | Total Cost | Annual Output | Net Savings | Payback Time |
|---|---|---|---|---|---|
| 2kW | $3,900 | $4,700 | 3,066kWh | $10,477 | 10yrs |
| 3kW | $4,500 | $5,300 | 4,599kWh | $18,516 | 8yrs |
| 5kW | $7,000 | $7,800 | 7,665kWh | $32,514 | 7yrs |
| 7kW | $9,000 | $9,800 | 10,731kWh | $47,312 | 6yrs |
| 10kW | $12,000 | $12,800 | 15,330kWh | $69,508 | 6yrs |
Below is a list of the inputs you can enter in the calculator followed by an example of the results displayed in a easy to read graph.
| Field | Variable |
|---|---|
| State | e.g. NSW |
| System size | 1.5kW to 10kW |
| Cost of quoted system | $=??? |
| Annual output in kWh | ???=kWh |
| Current electricity price per kWh | kWh=cents |
| Display results in years (max 30) | 1 to 30 |
There are also some more advanced input options available to help refine your results even further such as: annual bill inflation, energy exported to grid, feed in tariff rate, feed in tariff length and system maintenance or repair costs.
The result is a graph similar to the one below and a list displaying:
- Total system cost
- Total power savings
- Net savings
- Payback time
- Cost of electricity
- Rate of return
What Size Solar Power System?
The average Australian three bedroom home will generally use about 11kWh to 18kWh of power per day.
As a general rule a 1kW solar power system will generate roughly 4kWh to 5kWh of power per day depending on the location of the system and how many actual power producing hours are in a day a 3kW solar system should be large enough to supply power to an average Australian home.
Your location can have a big effect on the actual viability of a solar power system, for example if you live on a wide open and flat area with no hills your solar panels will receive much more sunlight per day than if you live in a deep valley surrounded by mountains. During different times of the day, morning, midday and late afternoon go outside and see if the sun is striking your rooftop, and remember the solar panels only produce power when the sun is shining on them so in some cases a solar system may not even be worth installing if you only get a couple of hours sunlight in the middle of the day.
The table below shows a rough guide to solar system sizing.
| Solar System Size Guide | ||
|---|---|---|
| 1.5kW Small Home 1-2 People | 3kW Medium Home 2-3 People | 5kW Large Home 4+ People |
|
Items Covered: |
Items Covered: |
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Using the amount monthly kWhs from your utility bill, and the amount of sun hours your location receives, you can find the size of your system, in DC watts, needed to cover 100% of your usage.
|
Sun Hours
Monthly Usage |
< 3.0 | 3.5 | 4.0 | 4.5 | 5.0 | 5.5 | 6.0 | 6.5 |
| 50kWh | 0.7kw | 0.6kw | 0.5kw | 0.5kw | 0.4kw | 0.4kw | 0.3kw | 0. kw |
| 100kWh | 1.4kw | 1.2kw | 1.0kw | 0.9kw | 0.8kw | 0.8kw | 0.7kw | 0.6kw |
| 150kWh | 2.0kw | 1.7kw | 1.5kw | 1.4kw | 1.2kw | 1.2kw | 1.0kw | 0.9kw |
| 200kWh | 2.7kw | 2.3 kw | 2.0kw | 1.8kw | 1.6kw | 1.6kw | 1.4kw | 1.2kw |
| 250kWh | 3.4kw | 2.9kw | 2.5kw | 2.3kw | 2.0kw | 2.0kw | 1.7kw | 1.6kw |
| 300kWh | 4.1kw | 3.5kw | 3.0kw | 2.7kw | 2.4kw | 2.4kw | 2.0kw | 1.9kw |
| 350kWh | 4.7kw | 4.1kw | 3.5kw | 3.2kw | 2.8kw | 2.8kw | 2.4kw | 2.2kw |
| 400kWh | 5.4kw | 4.6kw | 4.1kw | 3.6kw | 3.2kw | 3.2kw | 2.7kw | 2.5kw |
| 450kWh | 6.1kw | 5.2kw | 4.6kw | 4.1kw | 3.6kw | 3.6kw | 3.0kw | 2.8kw |
| 500kWh | 6.8kw | 5.8kw | 5.1kw | 4.5kw | 4.1kw | 4.1kw | 3.4kw | 3.1kw |
| 550kWh | 7.4kw | 6.4kw | 5.6kw | 5.0kw | 4.5kw | 4.5kw | 3.7kw | 3.4kw |
| 600kWh | 8.1kw | 6.9kw | 6.1kw | 5.4kw | 4.9kw | 4.9kw | 4.1kw | 3.7kw |
| 650kWh | 8.8kw | 7.5kw | 6.6kw | 5.9kw | 5.3kw | 5.3kw | 4.4kw | 4.1kw |
| 700kWh | 9.5kw | 8.1kw | 7.1kw | 6.3kw | 5.7kw | 5.7kw | 4.7kw | 4.4kw |
| 750kWh | 10.1kw | 8.7kw | 7.6kw | 6.8kw | 6.1kw | 6.1kw | 5.1kw | 4.7kw |
| 800kWh | 10.8kw | 9.3kw | 8.1kw | 7.2kw | 6.5kw | 6.5kw | 5.4kw | 5.0kw |
| 850kWh | 11.5kw | 9.8kw | 8.6kw | 7.7kw | 6.9kw | 6.9kw | 5.7kw | 5.3kw |
| 900kWh | 12.2kw | 10.4kw | 9.1kw | 8.1kw | 7.3kw | 7.3kw | 6.1kw | 5.6kw |
| 950kWh | 12.8kw | 11.0kw | 9.6kw | 8.6kw | 7.7kw | 7.7kw | 6.4kw | 5.9kw |
| 1000kWh | 13.5kw | 11.6kw | 10.1kw | 9.0kw | 8.1kw | 8.1kw | 6.8kw | 6.2kw |
| 1050kWh | 14.2kw | 12.2kw | 10.6kw | 9.5kw | 8.5kw | 8.5kw | 7.1kw | 6.5kw |
| 1100kWh | 14.9kw | 12.7kw | 11.1kw | 9.9kw | 8.9kw | 8.9kw | 7.4kw | 6.9kw |
| 1150kWh | 15.5kw | 13.3kw | 11.6kw | 10.4kw | 9.3kw | 9.3kw | 7.8kw | 7.2kw |
| 1200kWh | 16.2kw | 13.9kw | 12.2kw | 10.8kw | 9.7kw | 9.7kw | 8.1kw | 7.5kw |
| 1250kWh | 16.9kw | 14.5kw | 12.7kw | 11.3kw | 10.1kw | 10.1kw | 8.4kw | 7.8kw |
| 1300kWh | 17.6kw | 15.0kw | 13.2kw | 11.7kw | 10.5kw | 10.5kw | 8.8kw | 8.1kw |
| 1350kWh | 18.2kw | 15.6kw | 13.7kw | 12.2kw | 10.9 kw | 10.9kw | 9.1kw | 8.4kw |
| 1400kWh | 18.9kw | 16.2kw | 14.2kw | 12.6kw | 11.3kw | 11.3kw | 9.5kw | 8.7kw |
| 1450kWh | 19.6kw | 16.8kw | 14. kw | 13.1kw | 11.7kw | 11.7kw | 9.8kw | 9.0kw |
| 1500kWh | 20.3kw | 17.4kw | 15.2kw | 13.5kw | 12.2kw | 12.2kw | 10.1kw | 9.3kw |
| 1550kWh | 20.9kw | 17.9kw | 15.7kw | 14.0kw | 12.6kw | 12.6kw | 10.5kw | 9.7kw |
Solar Panel Roof Space Calculator
If you have decided on the size of the system you want then you need to determine if there is enough space for the solar panels.
An average size for a 250W solar panel is around 1.7m x 1m so a surface area of 1.7m2, round that up to at least 2m2 to allow for access and installation.
The table below shows some system sizes and area required.
| 3kW | 4kW | 5kW |
|---|---|---|
| 12x250W Panels | 16x250W Panels | 20x250W Panels |
| 20m2 Roof Area | 27m2 Roof Area | 34m2 Roof Area |
| Daily Output 13 kWh | Daily Output 17 kWh | Daily Output 22 kWh |