Plumbers do not usually think of themselves as certificate traders, but heat pump water heaters have pulled many into the scheme. The discount on the customer’s invoice is delivered through certificates, and getting them right is part of doing the job properly.
This article covers how STCs for air-source heat pumps work, what you need to collect, and how Victoria adds a second certificate on top. Rules shift, so confirm current detail with the Clean Energy Regulator (CER).
How STCs for heat pumps work
An eligible air-source heat pump water heater, installed to replace or supply a water heater, creates STCs under the Small-scale Renewable Energy Scheme. The certificates reflect the energy the heat pump is expected to save or displace over the deeming period.
Three things drive the count:
- The model. Each approved model has a registered figure for the energy it displaces, based on testing.
- The climate zone. The same model creates a different number of certificates in a cooler zone than a warmer one.
- The deeming period. The number of years the scheme counts, which shortens each 1 January through to 2030. See what changes in January for how it works on the solar side.
CER-registered models
Only models registered with the CER as eligible can create certificates. Registration is by model, not by brand. Variants with different tank sizes may be listed separately, so check the exact model code on the invoice and the nameplate.
Check on the installation date. A model that was eligible when you quoted may not be when you install, and the claim is tested against the register as it stood on the day.
Zones
Australia is divided into climate zones by postcode. For hot water, the zone affects the certificate count because it reflects how much work the heat pump does compared with the baseline. The zone table is published by the CER, and our deeming period and zone ratings explainer shows where to find yours.
Illustrative certificate counts
Real counts depend on the registered model. These numbers are illustrative only, to show the shape of the effect.
| Zone type | Illustrative STCs, one heat pump | Comment |
|---|---|---|
| Cooler zone | Lower end of the range | Heat pump works harder, so less saving against baseline |
| Mild zone | Middle of the range | Typical suburban install |
| Warmer zone | Higher end of the range | Greater saving against baseline |
As a rough guide, a single residential heat pump may create somewhere in the low double digits of certificates, depending on the model and location. At an illustrative $38 per STC, that is several hundred dollars off the invoice. Use the CER figures for the real number.
What plumbers need to collect
Plumbers do the physical work well. The risk is paperwork that was never collected. For each job, get:
- Signed assignment form from the owner, transferring the right to the certificates
- Product model and serial number, with a clear photo of the nameplate
- Installation photos, geo-tagged, showing the unit in position
- Installation address and postcode, matching the zone used
- Installation date, consistent across all documents
- Details of the old unit being replaced, with a photo, where relevant
- Plumbing and electrical compliance documents as required in your state
- Your licence and accreditation details
Our photo requirements checklist shows what a good set of images looks like. Plumbers who treat the photo set as part of the job rather than an afterthought tend to have far fewer queries.
Common slip-ups
- Model number photographed at an angle and unreadable
- Postcode in the claim differs from the install address
- Assignment form unsigned, or signed by the wrong person
- Installation date on the claim differs from the compliance certificate
- No photo of the old unit when the claim calls for it
A pre-check desk finds these before lodgement. Ours reviews every claim and tells you straight away if something is missing. Details are on the hot water STCs page.
The Victorian overlap
In Victoria, the same job can also create Victorian Energy Efficiency Certificates (VEECs) under the Victorian Energy Upgrades program. That is a second certificate stream on the same installation, with its own accreditation and records.
The practical lesson is to run both through one process. We explain who can claim what, and how to avoid collecting the same information twice, in VEECs and STCs on the same job. The VEEC trading page covers the Victorian side.
Getting paid
Plumbers often run smaller books than solar crews, but cash flow matters just as much. You buy the unit, pay the apprentice and wait on the certificates. A trader that pays within 24 hours of sign-off, with no fees and a rate you can see on the pricing page, makes the discount easier to carry.
The process is the same as for any other job: upload, pre-check, clear, paid. The how it works page has the four steps.
A simple routine
- Look up the model and zone before quoting.
- Calculate the certificates and show the discount on the quote.
- Collect the paperwork on site, in one visit.
- Upload it the same day.
- Fix anything the desk queries and move on to the next job.
If you are a plumber who has been leaving certificates on the table or waiting too long to be paid, start trading and let the desk look at your next heat pump claim.