The federal small-scale scheme is best known for rooftop solar, but it also pays certificates for efficient hot water. The question homeowners and plumbers ask is simple: is the system I am looking at eligible? The answer turns on three things, the type of technology, whether the exact model is registered and how the job is classified.
At the time of writing STCs have been roughly $38 to $40 each. This article covers eligibility at a general level. The Clean Energy Regulator (CER) publishes the register and the rules, and they change, so confirm on the day of installation.
The technologies that can qualify
Two technologies create STCs for hot water:
- Solar water heaters. Collectors, with a tank, that heat water from the sun, with electric or gas boosting.
- Air-source heat pump water heaters. Units that move heat from the air into the tank, using a fraction of the electricity of a conventional element.
Both are rewarded because they displace electricity or gas that would otherwise heat the water. Conventional electric resistance storage tanks, continuous-flow gas heaters and gas storage systems do not create certificates. Ground-source and hybrid configurations are assessed against the register, not by category, so check the model.
The register decides, not the brand
Each eligible model is listed on the CER’s register of solar water heaters and heat pump water heaters, with an energy rating used in the STC calculation. A few rules follow:
- Registration is per model. A different tank size or controller code can mean a different listing, or no listing.
- The date matters. The model must be eligible on the installation date. A unit listed when you quoted may be delisted by install.
- Serial and plate evidence. The nameplate and serial number must be clear in the claim photos, as they tie the installed unit to the listing. See the hot water checklist.
Installation type changes the count
Eligibility also depends on what the installation replaced. The categories are new, replacement and additional, and each has its own rules for the STC count and the evidence needed. A replacement usually needs proof of the old system, with a photo before removal. A new install, such as in a new dwelling, follows the new-system rules, and an additional unit is treated differently again. Read the installation type guide and the answer on what makes a solar water heater eligible.
How the count works
The number of STCs depends on the registered rating of the model, the climate zone of the installation postcode and the deeming period. For hot water, deeming runs to the end of the scheme in 2030, so the count falls over time as the period shortens. Hot water uses its own zone table, separate from the rooftop solar zones, so look up the hot water postcode zone, not the solar one.
As an illustration, suppose a heat pump registers a count of 25 STCs for an installation in its zone on the install date. At $38 to $40, that is $950 to $1,000. A second model with a rating that creates 18 STCs would be worth $684 to $720. The $270 to $300 difference is the reason to check the exact model before quoting. These counts are illustrative only. The real number comes from the CER’s calculator or your trader’s tool; see our heat pump STC calculator answer and how many STCs a heat pump earns.
A quick eligibility test
| Question | If yes | If no |
|---|---|---|
| Is it a solar or air-source heat pump water heater? | Continue | Not eligible |
| Is the exact model on the CER register on the install date? | Continue | Not eligible |
| Is the job classified correctly as new, replacement or additional? | Continue | Fix before lodging |
| Is the installer licensed and the work compliant? | Continue | Fix before lodging |
| Is there a signed assignment form and the full photo set? | Ready to lodge | Collect before lodging |
State schemes layered on top
State programs sit alongside the federal one. In Victoria, a heat pump replacement can create VEECs under Victorian Energy Upgrades, and Solar Victoria runs a rebate with an income test; the household income cap fell to $150,000 on 1 July 2026. In NSW, hot water upgrades can be supported through the Energy Savings Scheme. We cover both in separate articles: heat pump rebate in Victoria and in NSW. State eligibility is not the same as federal eligibility, so a system that qualifies under one may not qualify under another.
From the desk: the most expensive hot water mistake is quoting from the brochure instead of the register. Imagine promising a customer a $1,000 STC discount on a model that comes off the register before install day: the certificates are not created and the discount comes out of your margin. Check the model on the day you quote and again on the day you install, and write both dates on the job sheet.
What does not qualify
- Electric resistance and gas systems, even efficient ones.
- Models not on the register, including grey imports.
- Systems installed without the required licence, such as plumbing, or without compliant installation.
- Second-hand or relocated units that are not newly installed under the scheme’s rules.
For plumbers and installers
If you quote hot water jobs, add a register check to your quoting template and a photo and serial check to your install template. Our desk pre-checks every hot water claim before lodgement, so problems are caught early. See the hot water STCs page and our pricing page for the published rate.
How to explain eligibility to a customer
Customers rarely ask about registers. They ask, “Do I get the rebate?” A clear way to answer is in three sentences. First, name the technology: “This is an air-source heat pump, which is one of the two technologies the federal scheme rewards.” Second, name the check: “I have confirmed the exact model is on the Clean Energy Regulator’s register as of today.” Third, name the number: “That creates about this many certificates for your postcode, which I have taken off your price at this assumed rate.”
If any of those three cannot be said honestly, the quote is not ready. For the follow-on question of who gets the certificates, see who owns the STCs and for the customer’s side of the form, the assignment form explained.
Documents that settle disputes
When a claim is queried months later, memory is useless and files are everything. Keep the register screenshot or printout from the quote date and the install date, the model and serial photos, the signed assignment form and the compliance certificates in a single job folder. A job folder that can be handed to an auditor in five minutes is also one that can be handed to a trader for a pre-check on the day of install.
What to do next
- Look up the model on the CER register for your install date.
- Confirm the installation type and the climate zone for the postcode.
- Calculate the count and the dollar value, and show it on the quote.
- Read heat pump hot water STCs explained for the full paperwork routine, and see the pillar page on hot water.
For the wider hot water picture, see the hot water hub.