Solar is no longer an export business
Ten years ago rooftop solar paid you to sell power. That is over, and it changes what a good system looks like.
In May 2025 the Victorian Parliament amended the Electricity Industry Act 2000 so that the Essential Services Commission no longer sets a minimum feed-in tariff at all. The last figure the commission calculated before the change, for 2025–26, was 0.04 cents per kilowatt hour — four hundredths of a cent, against 3.3 cents the year before. That is a regulator's own arithmetic on what a unit of exported solar is worth in a state that has a great deal of it.
The number that decides everything now
A kilowatt hour you generate and use yourself is worth the retail rate you did not pay. The same kilowatt hour exported is worth the feed-in tariff. Those two numbers used to be close. They are not close any more:
| State or territory | Exported solar is worth | Set by | The same unit used is worth | Ratio |
|---|---|---|---|---|
| New South Wales | 5.0c/kWh | Retailer-set | 33.1c/kWh | 7× |
| Victoria | 3.0c/kWh | Retailer-set | 27.5c/kWh | 9× |
| Queensland | 5.0c/kWh | Retailer-set | 28.0c/kWh | 6× |
| South Australia | 5.0c/kWh | Retailer-set | 41.9c/kWh | 8× |
| Western Australia | 2.0c/kWh | Regulated | 33.3c/kWh | 17× |
| Tasmania | 9.3c/kWh | Regulated | 28.0c/kWh | 3× |
| Australian Capital Territory | 5.0c/kWh | Retailer-set | 37.0c/kWh | 7× |
| Northern Territory | 9.3c/kWh | Regulated | 31.7c/kWh | 3× |
The last column is the whole modern case for solar in one number: a kilowatt hour you use yourself is worth several times what the same kilowatt hour earns exported. Victoria abolished its minimum feed-in tariff on 1 July 2025 — the last figure the Essential Services Commission calculated before the change was 0.04 cents. Tasmania and the Northern Territory, the two smallest solar markets, pay the most.
So the question is no longer how much will it generate. It is what share of the generation will you actually use. That share is called self-consumption, and it is where solar calculators quietly cheat: assume you use all of it and a system looks about twice as good as it is.
The calculator models it explicitly — it asks when you are home, and it prices what shifting your hot water and pool pump into daylight would be worth, using the figures the rest of this site has already worked out for your household.
Which means bigger is not better
The standard advice is to fill the roof. That made sense when export paid. It does not now, and the arithmetic shows exactly where it stops making sense:
| System | Generates | Share used at home | Saves a year | Installed | Payback |
|---|---|---|---|---|---|
| 5 kW | 7,300 kWh | 32% | $1,028 | $4,850 | 4.7 yr |
| 6.6 kW | 9,636 kWh | 24% | $1,145 | $5,650 | 4.9 yr |
| 10 kW | 14,600 kWh | 16% | $1,393 | $9,000 | 6.5 yr |
| 13.2 kW | 19,272 kWh | 12% | $1,627 | $11,500 | 7.1 yr |
Priced for your household in New South Wales with someone home some days. The share used at home falls as the system grows, because the extra generation has nowhere to go but the grid at 5.0c a unit. That is why the fastest payback is not the biggest system — though a bigger one still saves more in total, and if you are adding a car or a battery later it is the one to buy.
Every extra panel generates the same as the last one. What changes is where that generation goes: once the system is making more during the day than the house can absorb, the surplus is sold at a fraction of what it would have been worth used. The system keeps saving more in total — it just takes longer to pay for itself.
That is not an argument for the smallest system. It is an argument for buying the size that matches your household rather than your roof — and for buying bigger only if you are about to add something that uses the surplus, like an electric car, a heat pump, or a battery.
What the roof faces
Most people do not get to choose. It is still worth knowing what it costs, and the answer is less obvious than it looks:
| Roof orientation | Of a north-facing roof | Generates | Saves a year | Payback |
|---|---|---|---|---|
| North facing | 100% | 9,636 kWh | $1,145 | 4.9 yr |
| East or west facing | 85% | 8,191 kWh | $1,073 | 5.3 yr |
| Split east and west | 87% | 8,383 kWh | $1,082 | 5.2 yr |
| South facing | 65% | 6,263 kWh | $976 | 5.8 yr |
| Partly shaded | 75% | 7,227 kWh | $1,025 | 5.5 yr |
A 6.6 kW system in New South Wales. North wins on raw generation and it is not close, but east and west spread the output across the morning and afternoon rather than concentrating it at noon — and since what matters now is the share you use rather than the amount you make, that is worth more than the table can show.
North wins on raw generation and it is not close. But east and west spread the output across the morning and the afternoon instead of concentrating it at noon, and since what matters now is the share you use rather than the amount you make, a split east–west array often beats its generation figure. In Western Australia, where the buyback scheme pays five times as much for exports after 3pm as before it, a west-facing array is arguably the right answer outright.
How much sun, and what the rebate thinks
Two Commonwealth figures, and they disagree. The first is what a kilowatt of panels actually generates where you live. The second is what the certificate scheme deems the same kilowatt will generate, which is what your rebate is calculated on.
| City | Per kW per day | Per kW per year | STC zone | Deemed for certificates | Deeming vs reality |
|---|---|---|---|---|---|
| Sydney (NSW) | 4.0 kWh | 1,460 kWh | Zone 3 | 1,382 kWh | 5% under |
| Melbourne (VIC) | 3.6 kWh | 1,314 kWh | Zone 4 | 1,185 kWh | 10% under |
| Brisbane (QLD) | 4.2 kWh | 1,533 kWh | Zone 3 | 1,382 kWh | 10% under |
| Adelaide (SA) | 4.2 kWh | 1,533 kWh | Zone 3 | 1,382 kWh | 10% under |
| Perth (WA) | 4.4 kWh | 1,606 kWh | Zone 3 | 1,382 kWh | 14% under |
| Hobart (TAS) | 3.5 kWh | 1,278 kWh | Zone 4 | 1,185 kWh | 7% under |
| Canberra (ACT) | 4.3 kWh | 1,570 kWh | Zone 4 | 1,185 kWh | 24% under |
| Darwin (NT) | 4.4 kWh | 1,606 kWh | Zone 1 | 1,622 kWh | 1% over |
Daily generation is the Australian Government's own table, produced with the Australian PV Institute and the UNSW School of Photovoltaic and Renewable Energy Engineering. The deemed figure is the Clean Energy Regulator's zone rating, used to work out how many certificates a system creates. Canberra is the outlier worth noticing: it sits in the lowest-paying certificate zone while receiving more sun than Sydney, so its rebate understates its output by about a quarter.
The deeming is deliberately conservative — it is a basis for issuing tradeable certificates, not a forecast — so it sits below reality almost everywhere. The Australian Capital Territory is the case worth knowing about: Canberra gets more sun than Sydney and sits in the lowest-paying certificate zone, so its federal rebate understates its output by about a quarter.
And the rebate is on a countdown
The federal solar rebate is not a grant. It is the value of Small-scale Technology Certificates, which your installer creates and takes off the invoice. How many you get depends on the system size, your zone, and the deeming period — the number of years of future generation the scheme credits you for in advance.
That period falls by one year every January, and the scheme ends in 2030. This is legislated, not under review:
| Installed in | Deeming period | Certificates | Worth | Lost by waiting |
|---|---|---|---|---|
| 2026 | 5 years | 45 | $1,710 | — |
| 2027 | 4 years | 36 | $1,368 | −$342 |
| 2028 | 3 years | 27 | $1,026 | −$342 |
| 2029 | 2 years | 18 | $684 | −$342 |
| 2030 | 1 year | 9 | $342 | −$342 |
A 6.6 kW system in New South Wales (zone 3). The deeming period falls by one year every January and the Small-scale Renewable Energy Scheme ends in 2030, so the federal solar rebate is on a countdown rather than under review. Certificate prices are assumed flat; what shrinks is the deeming.
Worth being clear about what that does and does not mean. It is a real reason not to sit on the decision for years. It is not a reason to rush a purchase you have not thought about — a bad system bought this year will outlast the difference by two decades.
Frequently asked questions
Is solar still worth it in Australia?
Yes, and for most households comfortably — but for a different reason than it used to be. The payback now comes almost entirely from the electricity you do not buy rather than the electricity you sell, so it depends on your household as much as your roof. A house with someone home during the day, or with a hot water heat pump and a pool pump that can be moved into daylight, does far better than an empty house with the same panels. On our figures a well-matched system pays for itself in roughly four to seven years and then runs for another fifteen.
What size solar system should I get?
The one that matches what you use during the day, not the one that fills the roof. Past the point where the system generates more in daylight than the house can absorb, every extra panel is selling power at a fraction of what it would be worth used — so the payback lengthens even though the total saving rises. On an average household the fastest payback is usually a 5 to 6.6 kW system. Buy bigger deliberately: if you are about to add an electric car, a heat pump or a battery, the surplus has somewhere to go and a larger system is the right call.
What is self-consumption and why does it matter so much?
It is the share of what your panels generate that gets used in the house rather than exported. It matters because those two outcomes are now worth very different amounts — between three and seventeen times different depending on the state. A typical Australian household without a battery self-consumes somewhere between 15% and 35% of its generation. Moving load into the middle of the day is the cheapest way to raise it, and it costs nothing but a timer.
Why did feed-in tariffs collapse?
Because so much rooftop solar was installed that the middle of the day stopped being valuable. A feed-in tariff is loosely tied to what your power is worth on the wholesale market at the moment you export it, and in states with a lot of solar that price now regularly falls to zero or below at noon. It is not a conspiracy; it is the scheme working. The states paying the most today — Tasmania and the Northern Territory — are the two with the least rooftop solar competing with them.
Should I add a battery?
It depends on a number this site can give you: how much you are currently exporting, and at what rate. A battery converts exported power into self-consumed power, so its value is the gap between your feed-in tariff and your retail rate, multiplied by how much you can shift. Where that gap is widest — Western Australia at seventeen to one — the case is strongest. Before spending on one, though, do the free version first: shifting your hot water and pool pump into daylight captures part of the same benefit for the price of a timer.