Solar payback calculator
What a system would generate where you live, what share of it you would actually use, and how long it takes to pay for itself — priced at your own electricity rate rather than a national average.
The part most calculators leave out is the third question, and it is the one that decides the answer.
Your roof and your household
Your bill gives it, usually as a daily average — multiply by 365. Leave it and we estimate from your household size.
The rate the savings are priced at
These are New South Wales’s published reference rates. They are a starting point, not what you necessarily pay — put the numbers from your own bill in and every figure on this site changes with them.
The usage rate on your bill, sometimes called the peak or anytime rate.
Saved in this browser and nowhere else. No account, no email, nothing sent to a server.
Which size, for your household
Each of these is the same roof, the same household and the same day pattern. What changes is how much of the generation has somewhere to go.
What moving load into daylight is worth
This is the part no other Australian solar calculator can do, because it needs to know what your hot water and your pool pump actually cost — and this site has already worked both out for your household.
Nothing here needs new equipment. It is a timer setting.
Tick anything you could move into the middle of the day and this will price it. Nothing here needs new equipment — it is a timer setting.
What your exports are worth
In New South Wales the model prices exported solar at 5.0c per kilowatt hour, against a retail rate of 33.1c for the same unit used at home. Using it is worth 7 times as much as selling it.
Retailer-set: Retailer-set. IPART publishes a non-binding benchmark range of 4.8c to 7.3c for 2026; the model uses the bottom of it.
The benchmark is guidance, not a floor. Retailers are free to pay less and some do.
The federal rebate on this system
A 6.6 kW system in New South Wales creates 45 certificates — 6.6 kW × 1.382 (zone 3) × 5 years of deeming, rounded down — worth about $1,710 at $38 each.
Australian installers almost always quote a price with that already taken off, so it is shown here for information rather than subtracted again. If a quote does not say, ask.
It shrinks every year. The deeming period falls by one year each January and the scheme ends in 2030. The same system installed next year creates 36 certificates, worth $1,368 — $342 less for waiting.
How to read the answer
Three numbers on this page decide everything, and they are not the three most calculators lead with.
Self-consumption matters more than generation
The percentage in the "where the value is" panel is the share of what your panels make that you use in the house rather than export. In New South Wales a kilowatt hour you use is worth 33.1c and the same kilowatt hour exported is worth 5c, so the two outcomes differ by about seven to one. That ratio is why this calculator asks who is home during the day — a question almost no other Australian solar tool asks, and the one that moves the answer most.
On the same 6.6 kW system and the same household, the difference between being out on weekdays and being home most days is 17% self-consumption against 32%, which is $946 a year against $1,344 and a payback of six years against four years and two months. Same roof, same panels, same bill — different life.
A worse roof can pay back nearly as fast as a good one
This surprises people. A north-facing array generates the most, but it concentrates that generation in the middle of the day, when a house that is empty cannot use it. A split east–west array generates about 13% less over a year and self-consumes more of what it does make, so the payback moves from 4.9 years to 5.2 — much less than the generation gap suggests.
Even a south-facing array, which loses a third of the generation, comes out at 5.8 years rather than the disaster the raw output implies. If an installer tells you a non-north roof is not worth doing, ask them to show you the self-consumption figure rather than the generation figure. It does not mean south is a good idea — it means the penalty is smaller than the brochure suggests.
Bigger stops paying somewhere, and the calculator shows where
Every system in the size comparison saves more money in total than the one above it. That is not the same as paying back faster. Past the point where daytime generation exceeds daytime demand, the extra panels are producing electricity that can only be exported at a few cents, so total saving keeps rising while payback lengthens. For a typical three-person household the crossover is between 5 and 6.6 kW; for a household with a pool, a heat pump on a timer, or an electric car, it is much further out.
This is the one place where the honest answer and the sales answer differ systematically, because nobody selling panels is paid to talk you down a size.
What to ask an installer
Four questions, in the order they are worth asking. All four are things the quote should already answer and often does not.
- Is the price net of the certificates? Australian quotes almost always are, which is why this page reports the certificate value rather than subtracting it again. If the quote does not say, it is the first thing to clarify — it is worth about $1,710 on a 6.6 kW system in New South Wales.
- What is the inverter rated at, and what is the panel array rated at? They are different numbers. A 5 kW inverter may legally carry a third more panels, which is why 6.6 kW is the default Australian system size. In Western Australia the inverter rating also decides whether you qualify for the buyback scheme at all.
- Has the distributor approved the export limit? Many networks cap export on single-phase connections, and a system that generates more than it is allowed to export changes the arithmetic on this page considerably. Ask before signing, not after.
- What happens to the feed-in tariff? Retailers set it and can change it. Three states regulate a minimum; the other five do not, and one of them abolished its minimum outright in 2025. A payback built on today's rate is a payback built on an assumption.
What this does not include
Batteries, which are a separate decision with separate arithmetic. Meter changes, which some retailers charge for. Any state rebate or interest-free loan, because those come and go — the rebate pages track the ones that apply to water heating and heating and cooling.
It also assumes the panels degrade at half a per cent a year and that you keep the system twenty years, and it deliberately does not escalate electricity prices or discount future savings. Both of those adjustments would shorten the payback, which is exactly why they are not here: a payback figure is easier to trust when nobody has had a thumb on the scale.
Frequently asked questions
Is solar still worth it in Australia now that feed-in tariffs have collapsed?
Yes, but for a different reason than it used to be. The old case was that you sold what you did not use and the feed-in tariff paid for the system. That case is gone: Victoria abolished its minimum feed-in tariff in 2025 after the regulator's final calculation came out at 0.04 cents a kilowatt hour. The case now is the electricity you do not buy, which is worth the full retail rate — three to seventeen times the export rate depending on your state. On a typical 6.6 kW system in New South Wales that is about $1,145 a year, of which roughly two thirds is avoided purchases rather than export income.
Should I buy the biggest system my roof will hold?
Not automatically, and this is the question where the incentive of whoever is advising you matters most. A bigger system always saves more money in total, but past the point where its daytime output exceeds your daytime use, the extra generation can only be exported at a few cents — so the payback period gets longer even as the annual saving grows. Work out the crossover for your own household using the size comparison above. It moves a long way out if you have a pool pump, an electric car or a heat pump you can put on a midday timer.
Does a south-facing or shaded roof rule solar out?
No, and the penalty is smaller than the generation figures imply. A south-facing array loses about a third of its annual output, but it also spreads what it does produce more evenly across the day, so a higher share of it gets used in the house rather than exported. On our model that turns a 4.9 year payback into 5.8 years rather than into something unviable. Shade is the more serious problem, because on a string inverter one shaded panel drags down the whole string — ask about microinverters or optimisers before accepting a shaded-roof quote.
How much is the federal solar rebate worth, and is it running out?
It is not a rebate but a certificate scheme, and it is winding down on a fixed schedule. A system creates certificates equal to its capacity times a zone rating times the number of years left in the deeming period, and that period drops by one year every January until the scheme ends in 2030. A 6.6 kW system in Sydney creates 45 certificates today, worth about $1,710. The same system next year creates 36, worth $1,368. Waiting a year costs about $342 for identical hardware, which is the one piece of timing advice on this site worth acting on.
Is a battery worth adding?
Deliberately not modelled here, because it is a separate decision with separate arithmetic and adding it would let this page flatter solar by borrowing a battery's savings. The short version: a battery is bought to raise self-consumption, and everything on this page that raises self-consumption for free — a timer on the hot water, running the pool pump at midday, putting the washing on during the day — should be exhausted first, because those cost nothing and a battery costs several thousand dollars. Once they are exhausted, a battery is the next lever rather than the first one.
What does solar actually save in emissions?
More in some states than others, and it tracks how dirty the grid it is displacing happens to be. A 6.6 kW system on a New South Wales household saves about 1,510 kg of CO₂-equivalent a year on the electricity it displaces, because the NSW grid runs at 0.64 kg a kilowatt hour. The same system in Tasmania displaces power already generated at 0.20 kg a kilowatt hour, so it saves less than a third as much carbon while saving a similar amount of money. If emissions are the reason you are buying, the ranking of what to do first is not the same as the financial ranking.