STC zones, explained
The federal STC rebate is calculated using your STC zone rating, one of exactly four numbers between 1.185 and 1.622 that reflects how much sun your postcode gets:
- Zone 1, rating 1.622: Remote inland NT, QLD, SA and north-west WA (no capital cities)
- Zone 2, rating 1.536: Darwin
- Zone 3, rating 1.382: Sydney, Brisbane, Adelaide, Perth, Canberra
- Zone 4, rating 1.185: Melbourne, Hobart
Your zone follows your postcode rather than your border, so one state can span several: the NT covers zones 1, 2 and 3. The STC rebate page turns your zone into a dollar figure, and solar panel installation cost shows the price after STCs in every capital.
The zone rating multiplies into the STC formula:
system kW × STC zone rating × years remaining × $39.65.
So the same 6.6 kW system in Darwin (Zone 2) generates about 30% more
in federal STC rebate than the same system in Hobart (Zone 4), and a system out at
Alice Springs in Zone 1 earns more again.
What the data tells us
The ACT wins on financing rather than on the rebate stack
Canberra sits in STC Zone 3, so the federal STC on a 6.6 kW system is about $1,784, the same as Sydney, Brisbane, Adelaide and Perth. What sets the ACT apart is not the size of the stack (at about $5,392 it sits behind WA) but the Sustainable Household Scheme's $20,000 at 3% interest and, for concession holders, up to $5,000 in Home Energy Support rebates. The financing means an eligible Canberra household can spread the cost over years instead of paying it upfront.
Darwin gets the best federal rebate of any capital city
Darwin sits in STC Zone 2, a higher rating than any other capital, so a 6.6 kW system there earns about $1,983 in federal STCs. Even without a state rebate program (the NT Home Battery Scheme reached its funding cap and closed), that is more federal STC value per kW than any other capital city gets. Combined with the NT's high irradiance (5.2 peak sun hours/day), it is the best per-kW yield in the country. Remote Territory postcodes from 0870 sit in Zone 1 and earn more again.
Tasmania compensates with regulation
Tasmania sits at the bottom of the rebate stack (Zone 4, no state upfront rebate). But every Tasmanian retailer must pay a regulated minimum feed-in tariff of 9.276 c/kWh, uncapped, on every kWh exported. The Energy Saver Loan that used to cover the upfront cost reached its funding cap and closed in September 2025, so the federal schemes are now the whole story here. Tasmania's per-kWh export economics over 20 years still beat several mainland states.
WA has the most-distorted time-of-export economics
WA's DEBS feed-in scheme pays just 2.25 c/kWh off-peak but jumps to 10 c/kWh during the 3pm-9pm peak. That spread (4.4×) is the biggest in the country and makes batteries especially valuable for WA households, charge during the day, discharge into the evening peak window.
About this data
All figures are 2026 typical values, compiled from public sources (Clean Energy Regulator, state government energy departments, AER's Energy Made Easy comparison tool). Rebate amounts and FIT rates are reviewed annually; for the live picture, check the relevant state's energy department or contact us for the current stack for your postcode.
Want the underlying data? Ask through the quote form. We publish a machine-readable JSON snapshot quarterly for journalists and researchers covering the Australian solar transition.
Common questions
What is an STC zone and why do they matter?
Australia is divided into four STC zones based on latitude and average solar irradiance. Zone 1 gives 1.622 STCs per kW installed, the most generous band (Remote inland NT, QLD, SA and north-west WA (no capital cities)). Zone 4 gives 1.185, the lowest (Melbourne, Hobart). Your zone is set by your postcode, not your state, so a single state can span several zones: the NT covers zones 1, 2 and 3.
Which Australian state gets the biggest solar rebate?
On a panels-only 6.6 kW install, NT leads on federal STC alone (about $1,983, because Darwin sits in STC Zone 2, the highest-rated band of any capital city). For panels plus a battery, WA comes out on top at about $6,692, with VIC next at about $6,554. States with no active upfront state rebate run on the two federal schemes alone.
How many Australian postcodes does solar work in?
All of them. The federal STC rebate applies to every postcode in Australia, with the amount set by the postcode's STC zone, and our postcode table covers 2,734 residential delivery postcodes in every state and territory. Installs must be done by an SAA-accredited (Solar Accreditation Australia) installer to claim it.
Which state has the highest peak sun hours?
The Northern Territory leads with about 5.2 peak sun hours per day on average. Queensland and Western Australia follow with about 4.7. Victoria and Tasmania are at the lower end (3.9 and 3.7 respectively). Lower peak sun hours means less generation per kW, not that solar doesn't work: Victoria adds a state solar rebate and Tasmania has a regulated minimum feed-in tariff, and the solar cost calculator shows the payback for any postcode.