Hot water pricing is easier to follow when you split it into three numbers: the gross installed price, the STC discount, and anything from a state scheme. This page works through an example. Treat it as an illustration, not a price guide.
A worked example
Take a heat pump that costs $4,200 installed before incentives. Say the model, zone and installation type give 25 STCs, with the market around $39 each at the time of writing.
| Line | Amount |
|---|---|
| Installed price before incentives | $4,200 |
| STC discount, 25 at about $39 | about $975 |
| Price payable before any state discount | about $3,225 |
The 25 is illustrative. Real counts are generally in the tens, depending on the model. Use the heat pump STC calculator for an estimate and ask your installer for the exact count on your quote. See how many STCs a heat pump earns.
What drives the discount
- The registered model. Efficient models earn more.
- Climate zone. The zone is set by postcode. Melbourne is zone 4, Sydney and Brisbane zone 3.
- Installation type. New, replacement or additional.
- Installation year. The count falls as the scheme runs towards 2030. See will the discount go down in 2027.
- The STC price the installer assumes when quoting.
Upfront discount versus waiting
The discount is applied upfront because the installer takes the assignment. You pay less on the day. If you instead paid in full and claimed later, you would be doing the claim process yourself, which is not how the scheme normally works.
Solar hot water
Eligible solar water heaters also create STCs, with the count set by the registered model, the zone and the system’s output. They tend to cost more than heat pumps to buy and install, and the certificate discount is a bigger share of the difference in some cases. The comparison is in heat pump vs solar hot water and solar hot water STCs.
State layers
NSW can add ESCs and Victoria can add VEECs and a Solar Victoria rebate, so the same unit can cost less in those states. See NSW and Victoria.
From the desk: two quotes with the same headline price can assume different STC values per certificate. Ask for the count and the dollar value, not just the total discount.
What this means for you
Compare quotes on the final price after all discounts, check the model is on the register, and ask what happens if a certificate is refused. For the full cost view see much a heat pump costs after rebate, the hot water STC pillar, and what an STC is worth.
Running costs matter too
The upfront price is only half the picture. A heat pump typically uses much less electricity than a resistance electric unit, so the running cost can repay part of the difference over the years. That calculation depends on your tariff and household size, so ask your installer for an estimate against your current system.