Per-kilowatt numbers are the quickest way to sense-check a quote, and they come straight from two inputs: the postcode’s zone rating and the deeming period.
Per kW, by zone, for a 2026 install
The 2026 deeming period is 5 years. STCs per kW are the zone rating times 5.
| Zone | Rating | STCs per kW | Value at $38 to $40 |
|---|---|---|---|
| 1 (Alice Springs) | 1.622 | 8.11 | $308 to $324 |
| 2 (Darwin) | 1.536 | 7.68 | $292 to $307 |
| 3 (Sydney, Brisbane, Perth, Adelaide, Canberra) | 1.382 | 6.91 | $263 to $276 |
| 4 (Melbourne, Geelong, Hobart, Launceston) | 1.185 | 5.93 | $225 to $237 |
The prices are indicative: spot has been roughly $38 to $40 at the time of writing, and the amount an installer is paid depends on the buyer.
Zone 3 in particular
Most of Australia’s solar is installed in zone 3, so a quick rule: in 2026 a kW of zone 3 solar is about seven STCs, or about $265. A 6.6 kW system gives 45 whole STCs. Do not multiply per kW and then round; the rounding is applied once, at the end.
It falls every year
The deeming period steps down by one year each January until it reaches 1 year in 2030, and the scheme ends on 31 December 2030. The value per kW in zone 3 at $39 looks like this:
- 2026: about $269
- 2027: about $215
- 2028: about $162
- 2029: about $108
- 2030: about $54
So a system installed in 2027 earns 20 per cent fewer STCs per kW than one installed this year, at the same price. See what changes in January 2027.
What this means for installers
Use the per kW figure for the sales conversation and the calculator for the quote. For batteries the maths is different, because the battery factor and kWh tiers apply; see the battery STC calculator. If you are deciding when to sell, the key is that deeming steps down on a known date.
Check any postcode in the STC calculator, compare the rate on pricing, and read the FAQ for more.