For solar panels commissioned in calendar year 2026 the deeming period is 5 years. It is the largest it will be from here, because the scheme steps down one year at a time until it closes at the end of 2030.
What 5 years is worth by zone
The formula is kW x zone rating x deeming period. Zone ratings are 1.622, 1.536, 1.382 and 1.185 for zones 1 to 4. For a 6.6 kW system in 2026:
| Zone | Rating | Approx. STCs | At $38 to $40 |
|---|---|---|---|
| 1 | 1.622 | 53 | $2,000 to $2,100 |
| 2 | 1.536 | 50 | $1,900 to $2,000 |
| 3 | 1.382 | 45 | $1,700 to $1,800 |
| 4 | 1.185 | 39 | $1,480 to $1,560 |
Certificates are rounded down, and the price is a moving market, so use these as a guide only. Your postcode decides your zone, and the Clean Energy Regulator publishes the zone table.
Timing
The date that counts is the date the system is installed and commissioned. A contract signed in 2026 for an install in January 2027 will earn the 4-year amount. Installers often have busy December calendars, so late jobs can slip.
Compared with 2027
In 2027 the same 6.6 kW zone 3 system earns about 36 STCs, about 20 per cent fewer than in 2026. See the 2027 changes.
A caution for late-year installs
The last quarter is the busiest in solar, and delays are common: network approvals, meter changes, supply shortages and weather. If you have a firm 2026 target, ask your installer for the realistic date and a plan if it slips. An honest answer now is better than a surprise in January.
What this means for installers and homeowners
For installers, sell the jobs you can complete before 31 December and quote the rest on the 2027 numbers. For homeowners, treat the date as part of the deal. The deeming period resource, the schedule by year and the STC trading pillar have more detail, and our pricing page shows the current STC rate.