The short answer
What "solar hot water" really means in 2026
Hot water is the single biggest slice of energy you can power with your own roof, because it stores the sun as heat for free. Yet most buyers still picture roof thermal panels, and most installers still wire the heater to run overnight on off-peak power. In 2026 the smarter setup is usually a heat pump hot water system on a midday timer, soaking up the solar you would otherwise export for a few cents and turning it into stored hot water worth your full usage rate. This page explains the two technologies, why heat pumps now win, how the rebates really stack, and the one free change that beats them all.
Here is the core takeaway in one line: the best solar hot water for most Australian homes is a heat pump run on a midday timer, not roof thermal panels and not an overnight off-peak circuit. Hot water is about 15 to 25% of a home's energy use, and it is the one big load you can store cheaply as heat. A heat pump uses a small amount of electricity to move a lot of heat, with a coefficient of performance of around 3 to 4, so it cuts hot-water energy by roughly 70 to 80% versus an old electric-resistance tank. Power it at midday from the solar you would otherwise export for about 5 c, and that surplus becomes hot water worth your full usage rate of about 30 c. The heater is only half the decision; the other half is when it runs.
Reframe the assumption: most guides compare heaters in isolation and stop there. The bigger lever is timing. The default install puts hot water on an overnight off-peak (controlled load) circuit, which made sense before rooftop solar but now wastes your free midday surplus. Get a heat pump and a timer right and an average unit pays for itself fast; leave it on overnight off-peak and you are paying for power at night while giving away free power at noon.
Interactive explainer
What would a heat pump on your solar save?
Set your household size, then compare an electric-resistance tank against a heat pump, run overnight off-peak or at midday on your own solar. The calculator values midday-solar power at the export rate you forgo, not your usage rate, so you see the true saving.
Optional: check your roof can run it
A heat pump needs only a fraction of a typical roof's surplus. Nothing is stored.
Yearly saving, heat pump on solar vs resistance
$/year
Illustrative only. Resistance use is people × kWh/person/year; a heat pump uses about 1/3.5 of that (COP 3.5). Off-peak power is valued at your off-peak rate; midday-solar power at the 5 c export you forgo. Net price assumes a ~$3,500 unit less a ~$1,200 typical rebate (higher in VIC where rebates stack). Real results depend on your tariff, climate and habits. Sources: Clean Energy Regulator, Solar Victoria, Victorian Energy Upgrades, AER DMO 2025-26.
The blind spot
Why most solar hot water guides leave money on the table
Most articles about solar hot water do three unhelpful things, and each one quietly costs buyers money.
First, they assume "solar hot water" means roof thermal panels. They spend pages on flat-plate collectors and evacuated tubes, the technology that dominated a decade ago. In 2026 the great majority of rebated hot-water upgrades are heat pumps, because they cost less to install, fit any roof, and let you choose when they run. A guide stuck on thermal panels steers you toward a pricier, less flexible system.
Second, they compare the heater and stop there. The running cost is treated as fixed once you pick a model. But the same heat pump can cost very different amounts depending on whether it draws overnight off-peak power or your own midday solar. The heater is half the decision; the timing is the other half, and almost no guide mentions it.
Third, they quote a stale or single rebate. Hot-water incentives stack differently in every state, and the federal STC value drifts as the scheme winds down. A guide that quotes one flat figure can be hundreds of dollars out, especially in Victoria where four separate rebates can combine. Numbers like these belong in a dated box, which is why every figure on this page is stamped with the date it was checked.
How hot water economics actually work
Expert analysis: the machinery behind the saving
Solar thermal vs heat pump, and why heat pumps usually win now
Solar thermal heats water directly: roof collectors warm a fluid that heats a tank, with an electric or gas booster for cloudy days. It uses almost no grid power on a sunny day, and in warm, north-facing-roof homes it still performs well. A heat pump is different. It runs on electricity and works like a fridge in reverse, pulling heat from the surrounding air into the tank. It needs no special roof position and no collectors. In 2026 heat pumps usually win because they cost less to install, qualify for the same or larger rebates, and crucially can be scheduled to run whenever power is cheapest. Once you have rooftop solar, that scheduling is the whole point.
The COP mechanism: why a heat pump is the cheapest heater to run
The number that defines a heat pump is its coefficient of performance, or COP. A COP of 3.5 means the unit delivers 3.5 units of heat for every unit of electricity it draws, because it is moving heat from the air rather than creating it from scratch. An electric-resistance element has a COP of 1: every unit of power becomes one unit of heat. So a heat pump uses roughly 70 to 80% less electricity for the same hot water. That efficiency is what makes a heat pump the cheapest heater to run even before you add solar, and it is why the rebates favour them.
The timing trick: controlled load vs midday solar, and the duck curve
Here is the lever almost everyone misses. By default, installers wire hot water to a controlled-load (off-peak) circuit that runs overnight. That was smart before rooftop solar, when overnight power was genuinely the cheapest. But the grid now floods with cheap solar in the middle of the day, the shape known as the duck curve, and your own panels export that surplus for only a few cents. If you put the heat pump on a timer to run from about 10am to 3pm, it drinks your own free midday solar and stores it as hot water. You stop paying for overnight power and stop giving away midday power. A timer is a free upgrade that can beat even the off-peak rate.
How the rebates stack, and the eligibility traps
Hot-water rebates layer on top of each other, but only in some states. A 270 to 280 L heat pump earns around 24 federal Small-scale Technology Certificates, worth roughly $860 in New South Wales through the federal scheme and the NSW Energy Savings Scheme. Victoria is the standout: a Solar Victoria hot-water rebate (about $1,000 to $1,400, income-tested), Victorian Energy Upgrades (about $560), federal STCs (about $600 to $900) and an Australian-made bonus (about $400) can total around $2,560 to $3,260, bringing a $3,000 to $4,500 unit down to roughly $440 to $1,240 net. The trap is the fine print: buy before your rebate is approved, or pick a unit that is not on the approved list, and you can disqualify yourself from the lot.
What this costs real households
How good systems end up underperforming
The mechanism above is not theory. It is exactly how well-meaning buyers leave money on the table.
They buy the right heat pump, then leave it on overnight off-peak
A household installs an efficient heat pump and assumes the job is done. But the installer left it on the default controlled-load circuit, so it runs at 2am on power they pay for, while their solar exports for cents at noon. A timer change costing nothing would have made the same heater materially cheaper to run.
They pay for solar thermal when a heat pump was cheaper
A buyer follows an older guide and orders roof collectors plus a tank, a pricier and more disruptive install. A heat pump would have cost less, qualified for the same rebates, and let them choose when it ran. They bought the more expensive answer to a question that changed.
They buy before the rebate is approved
Keen to get started, a household orders and installs the unit, then applies for the rebate. In several schemes the approval has to come first, so they forfeit hundreds, sometimes a thousand dollars or more in Victoria, on a system that was otherwise eligible.
They forget to re-shop the plan
After switching to a heat pump in a competitive state, they stay on the plan they had with the old tank. A plan tuned to daytime self-consumption, or with a fairer controlled-load rate, would have squeezed out more saving. In WA and NT there is no plan to switch, so the lever there is purely the heater and the timer.
The insider insight
Your hot water timer is a free battery you already own
Here is the part the heater reviews never mention. People agonise over whether to buy a home battery to soak up their midday solar, a $10,000 decision. But a hot water tank is already a battery, one that stores energy as heat rather than electricity, and you almost certainly already have it. A 270 to 315 L tank holds a full day of hot water. If you run a heat pump on a timer at midday, you are charging that thermal battery with surplus solar that would otherwise export for about 5 c, and discharging it as hot showers worth your full usage rate.
The non-obvious truth: the default overnight off-peak circuit is the enemy of solar self-consumption, even though it looks like the "cheap" option. Off-peak power still costs you 12 to 30 c a kilowatt-hour and uses none of your free midday surplus. A simple timer flipping the run window to roughly 10am to 3pm can beat the off-peak rate outright once you have solar, and it costs nothing to set. Most households never touch it because the installer never offered.
The practical consequence: before you price a battery to use your midday solar, set your hot water to run at midday first. It is the cheapest, fastest way to lift self-consumption, and for many homes it captures a large share of the surplus on its own.
Grounded in the analysis
What you should actually do
Specific moves that follow from how hot water is priced, not generic advice.
Choose a heat pump, then set a midday timer
For most homes a heat pump beats solar thermal: cheaper install, any roof, and you control when it runs. The moment it is in, set the timer to roughly 10am to 3pm so it drinks your own solar surplus instead of overnight power. The calculator above shows the difference.
Stack the rebates, but approve before you buy
Check eligibility and get approval BEFORE purchase, and pick a unit on the approved list. In Victoria, Solar Victoria, Victorian Energy Upgrades, federal STCs and the Australian-made bonus can stack toward a near-free unit. In NSW the Energy Savings Scheme plus STCs apply; QLD, SA and the ACT have their own.
Already have solar? Move the heater to daytime
If your heater is on an overnight controlled-load circuit and you have panels, ask your electrician or use a timer to shift it to the middle of the day. It is a free change that turns a 5 c export into a 30 c saving. In VIC, NSW, SA, QLD and the ACT, also re-shop your plan.
See how to size your solar panels around self-consumption, or how the solar rebate works before you buy.
Current figures, last updated 2026-06-15
Australian solar hot water figures for 2026. Sources: the Clean Energy Regulator (STC scheme), Solar Victoria, the Victorian Energy Upgrades program, the NSW Energy Savings Scheme and the Australian Energy Regulator (DMO 2025-26). Confirm current figures before purchase, as rebates and tariffs are reviewed regularly.
The bottom line
Why this matters right now
Two trends are reshaping the right answer. Heat pumps have become cheaper and heavily rebated, while the value of exporting solar keeps falling as the grid fills with midday power. Together they make a clear case: for most Australian homes, "solar hot water" now means a heat pump, not roof thermal panels, and the biggest saving comes from when it runs, not just which model you buy. Pick an efficient, approved heat pump, stack the rebates your state offers before you buy, set the timer to soak up your midday solar, and in the competitive states put it all on a sensible plan. Do that and your hot water becomes the cheapest, most reliable battery on your roof, one you already own.
Common questions
A Selectra expert answers your solar hot water questions
Not quite, and the difference matters. "Solar hot water" has two meanings. The original one is solar thermal: roof collectors heat water directly and store it in a tank. The other is a heat pump, which runs on electricity, ideally your own solar, and works like a fridge in reverse to pull heat from the air. In 2026 most rebated "solar hot water" upgrades are heat pumps, because they are cheaper to install, work anywhere on the roof, and pair perfectly with rooftop solar.
Moving from an electric-resistance or gas system to a heat pump typically saves about $140 to $400 a year on hot water. The reason is efficiency: a heat pump has a coefficient of performance (COP) around 3 to 4, so it delivers 3 to 4 units of heat for every unit of electricity, cutting hot-water energy use by roughly 70 to 80% versus resistance. Run it on your own midday solar and the saving climbs higher, because that power would otherwise have exported for only a few cents.
It depends on your state. A 270 to 280 L heat pump earns around 24 federal STCs, worth roughly $860 in New South Wales. In Victoria the rebates stack: a Solar Victoria hot-water rebate (about $1,000 to $1,400, income-tested), Victorian Energy Upgrades (about $560), federal STCs (about $600 to $900) and an Australian-made bonus (about $400) can total around $2,560 to $3,260. That can bring a $3,000 to $4,500 unit down to roughly $440 to $1,240 net.
If you have solar, run it during the day. The default install wires the heater to an overnight off-peak (controlled load) circuit, which made sense before rooftop solar. But that overnight power still costs you, while your midday solar surplus exports for only about 5 c. Flipping the timer to roughly 10am to 3pm means the heater drinks your own free surplus and stores it as hot water worth your full usage rate of about 30 c. It is a free upgrade, just a timer change.
For most homes with rooftop solar, a heat pump now wins. Solar thermal still makes sense in very sunny, mild climates with simple north-facing roof access, and it uses no grid power on a good day. But a heat pump is cheaper to install, fits any roof, and lets you choose when it runs, which is the whole game once you have panels. If you already export surplus solar at midday, a heat pump on a timer turns that surplus into hot water rather than a near-worthless export.
In Victoria, New South Wales, South Australia, Queensland and the ACT you can choose your retailer and compare plans, and the right plan changes how cheap your hot water is. In Western Australia (Synergy) and the Northern Territory (Power and Water) there is no retail competition, so the lever is the heater and the timer, not switching. Wherever you are, once a heat pump runs on midday solar, the usage rate matters less and the export rate barely matters at all.
