How to work out solar payback
Every kWh your panels make either powers your home or goes to the grid. Power you use saves your full usage rate. Power you export earns your feed-in tariff, which is now far lower. So the yearly saving is:
(kWh used at home × usage rate) + (kWh exported × feed-in tariff)
Divide the installed price by that saving to get the years to pay back. The share you use at home depends on when you use power. A household that is out all day might use 20 to 30% of its solar; one that runs the dishwasher, pool pump and hot water at midday can use half or more.
Solar payback in each capital city
| City | Price | Output a year | Usage rate | Feed-in | Payback at 30% self-use | At 50% |
|---|---|---|---|---|---|---|
| Adelaide | $5,320 | 8,292 kWh | 41.91c | 2c | 4.6 years | 2.9 years |
| Brisbane | $6,210 | 8,292 kWh | 27.97c | 3c | 7.1 years | 4.8 years |
| Canberra | $5,700 | 8,292 kWh | 36.95c | 3c | 5.2 years | 3.4 years |
| Darwin | $9,890 | 9,216 kWh | 31.68c | 9.33c | 6.7 years | 5.2 years |
| Hobart | $6,950 | 7,110 kWh | 24.75c | 9.28c | 7.0 years | 5.7 years |
| Melbourne | $5,810 | 7,110 kWh | 31.98c | 1c | 7.9 years | 5.0 years |
| Sydney | $5,750 | 8,292 kWh | 33.14c | 3c | 5.8 years | 3.8 years |
| Perth | $5,030 | 8,292 kWh | 33.26c | 2c | 5.3 years | 3.4 years |
Adelaide pays back fastest because South Australia has the highest usage rates, so every kWh used at home saves more. Melbourne, Brisbane and Hobart are slowest: Melbourne and Hobart sit in the lowest sunshine zone, and Brisbane has lower usage rates. Darwin has the dearest installations, but the Northern Territory feed-in tariff is high, so exports earn more there.
Ways to pay back faster
Move usage to the middle of the day
Run the dishwasher, washing machine, pool pump and hot water on timers between about 10am and 3pm. A heat pump water heater on a timer is one of the biggest wins.
Pick a plan that suits solar
Homes that use most of their solar often do better with a lower usage rate than a higher feed-in tariff. See the best feed-in tariff retailers and the Solar Sharer Offer.
Size the system to your day
A bigger system lowers the price per watt but exports more at a low rate. See what size system you need.
Consider a battery later
A battery stores midday solar for the evening peak. It costs more up front and has its own payback. See whether a battery is worth it.
What simple payback leaves out
- Electricity prices change each July. Rises shorten payback; falls lengthen it.
- Panels lose a little output each year, typically less than half a percent after the first year under most current warranties.
- An inverter may need replacing within the life of the panels.
- Time-of-use tariffs change the value of each kWh depending on when you use it.
Run your own numbers
Our solar calculator uses the same method with your state, system size, power price and feed-in tariff.
Common questions
Under about eight years is generally good, since panels carry performance warranties of 25 to 30 years. On our worked figures, a standard 6 kW system pays back in roughly three to eight years across the capitals, depending on how much solar the home uses.
Every kWh you use saves your usage rate, which is about 25 to 42 cents in the capitals on 2026-27 regulated prices. Every kWh you export earns a feed-in tariff that is often only a few cents. Using solar at home is worth several times more.
A little, but plans with high feed-in tariffs often charge more for the power you buy. Compare the whole plan, not just the feed-in rate.
Sources
System prices are from the Solar Choice Price Index. Output uses Clean Energy Regulator zone ratings. Power prices are the 2026-27 regulated rates on our state pages, and feed-in rates come from regulators or the AER plan data. Last checked October 2026. Prices include GST unless we say otherwise.