People search “heat pump hot water STCs zone 3” or “zone 5” because quotes mention a zone and nobody explains it. This page covers all five.
What the zones are
The Clean Energy Regulator has divided Australia into five postcode zones for air source heat pump water heaters, based on regional climate. A heat pump works harder, and saves less, in a cold climate than in a mild one, so the same model is credited with a different amount of energy displaced depending on where it is installed. A system in a higher-performing region creates more STCs than the same system in a lower-performing one.
Do not confuse these with the rooftop solar zones. Solar PV uses four zones with ratings of 1.622, 1.536, 1.382 and 1.185, where Sydney and Brisbane are zone 3 and Melbourne zone 4. Heat pump zone numbers are a different table. Do not assume a postcode’s solar zone matches its hot water zone; check each table separately. See STC zone rating by postcode for the solar table.
Zone 1, 2, 3, 4 and 5
Each zone has its own entitlement for each registered model. We have not reproduced the postcode list here because it is long and the regulator updates it, so the postcode table on the Clean Energy Regulator’s site is the authority. What matters in practice:
- Zone 1, 2, 3 and 4. Look up your postcode to see which one you fall in, then read the figure for that zone on the register. Solar water heaters use four zones, so these numbers apply to them as well.
- Zone 5. Applies to air source heat pumps only. Solar water heaters have four zones, so you will not see a zone 5 figure for them. A heat pump in zone 5 is eligible in the same way as any other zone, and the count simply comes from the zone 5 column. See heat pumps in zone 5 and other eligibility questions.
How to find the count for your zone
- Get your postcode zone from the regulator’s table.
- Find the exact model and tank size on the Clean Energy Regulator’s register of solar water heaters.
- Read the STC figure for that zone and your install date.
- Compare it with the quote.
The figure is built from the model’s tested performance over a 10-year life, and then the install-year factor applies (0.5 for 2026, 0.4 for 2027, and so on). The register shows the result for the date you select. See how many STCs a heat pump gets.
Zone and state rebates
Federal STCs are zone-based. State schemes, such as Victorian Energy Upgrades or NSW certificates, work differently and have their own rules for heat pumps. See heat pump VEECs in Victoria for the Victorian side.
What this means for you
Your zone affects your discount, but you do not control it. What you can control is picking a model that registers well in your zone and getting the install year right. For installers, our hot water STCs page explains how claims run, pricing shows the settlement rate and the hot water checklist covers evidence.