How many STCs does this heat pump or water heater get?

It depends on the model and the postcode, not on the size of the tank. The regulator's register gives each model a number of certificates for each hot water zone over 10 years, and the claim is that number times 0.5 for a 2026 install, rounded down. A Rheem 551270 heat pump is rated 31 in zone 3, which covers Sydney, Brisbane, Perth and Adelaide, so it gets 31 x 0.5 = 15.5, rounded down to 15 STCs in 2026. Another model in the same postcode can get quite a different number.

Hot water zones follow climate and solar radiation, and the register rates every model separately in each zone. For heat pumps there are five zones, and the figure generally rises towards the colder zones 4 and 5, because the baseline is the electricity an equivalent electric heater would use. Solar water heaters have four zones and a different postcode table. Neither is the panel zone, so use the postcode of the install address and let the calculator find the zone.

Hot water zones, explained

Four reasons. The model is not on the register under that name: register names can differ from marketing names, so ask the manufacturer or retailer what name the register uses. The model's eligible-from and eligible-to dates do not reach into the install year. The register shows no figure for that model in that zone, which means nothing can be claimed there. Or the postcode is not in the regulator's hot water postcode table. In each case the calculator says which, and shows no number rather than a guess.

The register's figure is for a 10-year system life. Since 2022 it is multiplied by a factor that falls by 0.1 a year, to 0.1 in 2030, so the same system earns fewer certificates each January. The factor is 0.5 for 2026: the Rheem 551270 above would get 12 STCs in zone 3 for a 2027 install. The install date is what counts, so a job finished in late December earns at the old factor.

It does the same sum from the same register, which we copied on 5 November 2026. The regulator's own solar water heater STC calculator in the REC Registry runs on the regulator's data, which it says may be updated from time to time, and it calls itself an approximate guide. Ours is an estimate too: the register and the install date decide what a claim is entitled to, so check the register before you quote or install.

The regulator's solar water heater STC calculator

We buy heat pump and solar hot water STCs at $38.64 per STC on a home job, where no GST applies, the same as for panels and batteries. When the system owner is registered for GST the payment is $42.50 per STC including GST. Payment is within 1 business day of an approved claim, as at 5 November 2026. The calculator shows both figures.

STCs for heat pumps and solar hot water