Hot water rebates and running costs in the Northern Territory
No gas, no off-peak, and the best heat pump conditions in Australia.
What a hot water system costs to run in the Northern Territory, 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 the Northern Territory
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. Northern Territory sits in STC Zone 1, the highest-value zone in the country. 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 no off-peak rate to fall back on
The Northern Territory runs no rebate for replacing a hot water system. The federal Small-scale Technology Certificate discount applies, worth roughly $800 to $1,200 off an eligible heat pump or solar thermal system.
The Territory has two structural differences that matter more than the rebate. There is no reticulated natural gas, so gas hot water is not an option at all outside bottled LPG. And there is no residential controlled load tariff, which removes the cheap overnight window an electric storage tank relies on everywhere else — so a resistance tank runs at the full rate around the clock here. Between them, those two facts make a heat pump or solar thermal a clearer choice in Darwin than in any capital that has a rebate.
Why Northern Territory is different
The Northern Territory removes most of the options and makes the remaining choice easy.
There is no reticulated residential natural gas in the Territory, so "gas hot water" means bottled LPG at roughly three times the price per megajoule of mains gas. There is no controlled load tariff either, so an electric storage tank runs at the full 31.7c around the clock. What is left is a heat pump, an electric tank or solar thermal, and the heat pump wins comfortably.
It wins by more here than anywhere else in Australia. Darwin's air averages 27.6 °C across the year, so a heat pump manages an effective coefficient of performance of about 2.55 — the best of any capital. The cold water coming into the house is already at about 27 °C, meaning it only needs lifting 33 degrees rather than the 47 a Hobart household needs. Between the two effects, a Darwin household heats its water for roughly half the energy of a Tasmanian one.
The Territory also has the lowest daily electricity supply charge in the country at 62.5c, less than half New South Wales's, and it sits in STC Zone 1 — the highest-value certificate zone — so the federal discount on a heat pump lands at the top of the national range. There is no Northern Territory state rebate.
Every system at Northern Territory prices
A three-person household using 120 litres of hot water a day, at Northern Territory's reference rates and the Darwin climate. On these assumptions the cheapest system to run in the Northern Territory is heat pump at about $313 a year.
| System | Cost per year | Rebates | 10-year total | CO₂e a year |
|---|---|---|---|---|
| Heat pump | $313 | −$800 | $6,982 | 465 kg |
| Solar thermal with electric boost | $367 | −$800 | $9,374 | 543 kg |
| LPG instantaneous | $544 | — | $7,793 | 448 kg |
| Electric storage | $724 | — | $9,144 | 1280 kg |
| LPG storage | $834 | — | $10,738 | 657 kg |
| Gas storage | There is no reticulated natural gas in the Northern Territory. | |||
| Gas instantaneous | There is no reticulated natural gas in the Northern Territory. | |||
| Solar thermal with gas boost | There is no reticulated natural gas in the Northern Territory. |
A three-person household in Northern Territory using 120 litres of hot water a day, at 31.7c/kWh and no reticulated gas, with the Darwin climate and the Northern Territory grid's emissions factor of 0.56 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 the Northern Territory 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 the Northern Territory compares
Tasmania sits at the opposite climate extreme — among the hardest conditions for a heat pump in the country, against the Territory's best. Western Australia shares the Territory's lack of a controlled-load tariff, for a different reason: Synergy's standard plan there simply doesn't offer an off-peak rate.
Frequently asked questions
What's the cheapest hot water system in Darwin?
A heat pump, at about $313 a year for a three-person household on 120 litres a day — cheapest here because there is no reticulated gas to compete with it, and the Territory's warm air suits a heat pump better than almost anywhere else.
Does the Northern Territory offer a hot water rebate?
Only the federal certificates, worth $800 to $1,200 — but the Territory sits in STC Zone 1, the highest-value zone in the country, so that federal figure lands at the top of the national range even without a state top-up.
What does NT electricity cost for hot water?
The reference rate is 31.7c per kilowatt hour with a daily supply charge of $0.63 — the lowest supply charge in the country — from the NT Electricity Pricing Order 2026–27 effective 1 July 2026. There is no residential controlled-load tariff, so an electric tank runs at the full rate around the clock. Retailer market offers frequently beat this reference figure.
Why does a heat pump do so well in Darwin specifically?
Warm air and warm incoming water — an effective coefficient of performance around 2.55 against a 3.2 nameplate, the best of any capital, because Darwin's air averages 27.6°C year-round. That is roughly half the energy a Hobart household needs for the same hot water.