Hot water rebates and running costs in Western Australia
No off-peak tariff, and gas priced the opposite way round.
What a hot water system costs to run in Western Australia, what you can claim towards replacing it, and the local facts that change the answer here — the tariff structure, the climate and the grid.
What you can claim in Western Australia
Federal Small-scale Technology Certificates
$800–$1,200 off an eligible heat pump or solar thermal system
Available in every state. The installer claims the certificates and discounts your quote, so there is nothing for you to lodge. Western Australia sits in STC Zone 3. Gas and electric resistance systems create no certificates.
Administered by the Clean Energy Regulator. Official scheme page. Last verified 5 September 2026.
Federal certificates only — and gas is the reason to look twice
Western Australia runs no state rebate for replacing a hot water system. The federal Small-scale Technology Certificate discount applies as it does everywhere, worth roughly $800 to $1,200 off an eligible heat pump or solar thermal system.
The reason to read further here rather than stopping at that number is gas. Western Australia's regulated gas tariff charges about double the eastern states per megajoule while charging roughly a third of their daily supply charge, which inverts the usual arithmetic: a WA household running gas hot water is paying for the fuel rather than for the connection, and the case for leaving gas is stronger here than the missing rebate suggests.
Why Western Australia is different
Western Australia is outside the National Electricity Market and its energy pricing works differently enough to change the answer.
First, Synergy's standard residential plan has no controlled load or off-peak rate. In every eastern state an electric storage tank can run overnight at roughly two thirds of the standard price; in Perth it runs at the full 33.3c around the clock. The cheapest way to heat water with electricity simply does not exist here, which strengthens the case for a heat pump considerably.
Second, gas is priced inside out. The regulated tariff set by Energy Policy WA charges 19.06c per unit for the first 12 units a day, where a unit is 3.6 megajoules — that is 5.29c per megajoule, about double the eastern states. But the daily supply charge is only 27.6c against 84c to 96c in the east. Western Australia loads its cost into consumption rather than connection, so light gas users do comparatively well and heavy ones badly. For hot water specifically, which is a steady moderate load, the two effects roughly cancel.
There is no Western Australian state rebate for hot water. Federal certificates apply as everywhere, worth roughly $800 to $1,200 on a heat pump.
Every system at Western Australia prices
A three-person household using 120 litres of hot water a day, at Western Australia's reference rates and the Perth climate. On these assumptions the cheapest system to run in Western Australia is solar thermal with gas boost at about $259 a year.
| System | Cost per year | Rebates | 10-year total | CO₂e a year |
|---|---|---|---|---|
| Solar thermal with gas boost | $259 | −$800 | $8,287 | 155 kg |
| Heat pump | $409 | −$800 | $7,943 | 539 kg |
| Solar thermal with electric boost | $484 | −$800 | $10,543 | 637 kg |
| Gas instantaneous | $529 | — | $7,636 | 476 kg |
| LPG instantaneous | $686 | — | $9,211 | 555 kg |
| Gas storage | $736 | — | $9,765 | 668 kg |
| Electric storage | $916 | — | $11,062 | 1376 kg |
| LPG storage | $997 | — | $12,372 | 786 kg |
A three-person household in Western Australia using 120 litres of hot water a day, at 33.3c/kWh and 5.29c/MJ for gas, with the Perth climate and the Western Australia grid's emissions factor of 0.5 kg CO₂e per kWh. Change any of it in the calculator.
Your own household will differ. Put your bill figures into the calculator and every number above recalculates.
The certificate value is falling every January
The federal scheme is winding down on a fixed schedule. Certificates are deemed over a period that shortens by one year every 1 January, and the scheme ends in 2030 — so the same system installed in Western Australia in December earns about a fifth more than it would a few weeks later.
| Install year | Deeming period | Indicative value |
|---|---|---|
| 2025 | 6 years | — |
| 2026 (now) | 5 years | $800–$1,200 |
| 2027 | 4 years | $640–$960 |
| 2028 | 3 years | $480–$720 |
| 2029 | 2 years | $320–$480 |
| 2030 | 1 years | $160–$240 |
The certificates a heat pump creates are deemed over a period that shortens by one year every 1 January until the scheme ends in 2030. Waiting from December to January costs about a fifth of the discount, for exactly the same system. It is the one piece of timing advice on this site that is worth acting on.
How Western Australia compares
The Northern Territory shares Western Australia's lack of a controlled-load tariff, though for a different reason — the Territory simply doesn't offer one, while Synergy's standard plan here has no off-peak rate at all. Queensland is in the same position on state rebates: federal certificates only, nothing from the state.
Frequently asked questions
What's the cheapest hot water system to run in Perth?
Solar thermal with a gas boost, at about $259 a year for a three-person household on 120 litres a day — the lowest figure on this page, though it also costs the most upfront, so check the ten-year total before choosing it.
Is there a WA rebate for replacing a hot water system?
Only the federal one — $800 to $1,200 off an eligible heat pump or solar thermal system, since Western Australia runs no state scheme. The precise amount depends on system capacity and the certificate price on the day of your quote.
What does WA electricity cost for hot water?
The reference rate is 33.3c per kilowatt hour with a daily supply charge of $1.19, from the WA Government Standard Electricity Prices 2026–27 effective 1 July 2026. Western Australia has no residential controlled load tariff, so unlike the eastern states there is no discounted overnight rate for an electric tank. Retailer market offers often beat the reference rate regardless — use your own bill in the calculator instead.
Does a heat pump work well in Perth's climate?
Yes — an effective coefficient of performance around 2.34 against a 3.2 nameplate, close to the national middle. With no off-peak rate to make an electric resistance tank cheap here, the heat pump's efficiency advantage counts for more in Perth than in states that do have one.