Heat Pump vs Solar Hot Water: Which System Is Better for Victorian Homes?

There isn't one winner for every Victorian home.

A heat pump hot-water system works somewhat like a reverse refrigerator. Instead of generating all the heat electrically, it:

The system still uses electricity, but because it transfers heat rather than simply creating it with a resistance element, it can use substantially less electricity than conventional electric storage hot water.

Solar Victoria describes heat pumps as highly efficient electric hot-water systems and says they can use 60–75% less electricity than conventional electric water heaters.

A typical system consists of:

Solar hot water uses solar thermal energy directly. Typically, the system consists of:

The collectors may use flat-plate panels or evacuated tubes. Solar Victoria explains that solar hot-water systems use collectors to heat water directly from sunlight, with the heated water circulated to the storage tank.

This is the simplest way to understand the technologies.

And if you have rooftop PV:

That second pathway is one reason heat pumps have become particularly interesting for Victorian homes with existing solar electricity systems. Solar Victoria specifically recommends using timers or diverters to operate heat pumps during periods when rooftop PV is generating electricity.

This is one of the strongest reasons to consider a heat pump. Imagine your home has 8kW rooftop solar. During the middle of the day, your household might generate more electricity than it is using.

Instead of exporting all of that surplus, a controller can potentially operate the heat pump during the solar-generation window. The sequence becomes:

In effect, the hot-water tank becomes a form of thermal energy storage. Solar Victoria explicitly identifies daytime operation of a heat pump using excess rooftop PV as a way to reduce household energy costs.

Heat pumps can still make sense. You can operate them:

• During daytime
• During lower-cost tariff periods
• According to a programmed schedule
• When ambient temperatures are more favourable

Solar Victoria notes that heat pumps can be timed around off-peak tariffs, daytime ambient conditions or excess rooftop PV.

Solar hot water can use the sun's energy directly. During suitable conditions, the collector heats the water without needing the same electrical energy input as a heat pump.

Solar Victoria says solar hot-water systems can cover up to around 60% of household hot-water demand in Victoria before boosting, depending on the system and conditions.

This is where the comparison becomes more interesting.

This can be a deciding factor.

Solar Victoria says north is the optimal orientation for roof-mounted solar systems, although east or west orientations can also be used with appropriate collector sizing.

For solar hot water, therefore, assess:

• Roof orientation
• Roof pitch
• Shading
• Collector area
• Roof access
• Structural considerations

Heat Pump vs Solar Hot Water: Installation Comparison

This is where homeowners often expect a simple answer. Solar hot water can have extremely low running costs when solar conditions are good. But it still normally has a booster for periods when solar energy isn't sufficient. Heat pumps use electricity, but they are much more efficient than conventional electric resistance water heaters.

Solar Victoria says heat pumps can use 60–75% less electricity than conventional electric water heaters, while solar hot water can provide a substantial portion of demand from direct solar energy before boosting.

Think about annual energy in two parts.

That is much more meaningful than comparing the nominal efficiency of the technologies.

This can strengthen the case for using excess solar PV inside your home. If your rooftop solar exports electricity at a relatively low feed-in tariff, using some of that energy to heat water may provide more value than exporting it and later buying electricity to run your hot water.

The exact result depends on:

• Electricity import tariff
• Feed-in tariff
• Solar production
• Hot-water demand
• Heat-pump efficiency
• Operating schedule

If your existing hot water is gas-powered, the comparison changes.

This is another situation where heat pumps can be attractive. If your home is already fully electric and has rooftop PV, you can integrate the heat pump into the home's existing electrical strategy. You don't need gas supply, gas meter, or gas hot-water appliance.

Solar Victoria specifically identifies households without a gas connection as a group for whom heat pumps can be particularly suitable.

Solar hot water has no comparable continuously operating mechanical compressor. Heat pumps do. Modern heat-pump systems can be relatively quiet, but the location still matters.

Solar Victoria recommends avoiding installation close to bedrooms where possible and notes that reported noise levels can be comparable to modern refrigerators.

This is another major difference.

Let's look at realistic situations.

This isn't a product ranking. It's a property-fit comparison.

For Victorian households, eligible solar and heat-pump hot-water systems can receive a Solar Victoria hot-water rebate of up to $1,000. An eligible locally made product can qualify for up to $1,400, subject to the program's requirements.

The current household income eligibility cap for relevant hot-water rebates is $150,000 from 1 July 2026, down from $210,000. There are also product and installation requirements.

This is particularly important for Melbourne's new housing market. Solar Victoria states that its hot-water rebate is for replacing an existing hot-water system that is at least three years old and is not available to new-build homes under that rebate.

Both solar hot-water and eligible heat-pump systems can interact with Australia's Small-scale Renewable Energy Scheme. Solar Victoria's current guidance states that eligible new systems can also receive STCs, subject to the applicable federal requirements.

This is another reason an advertised "$X after rebate" price should be unpacked. Ask:

• Solar Victoria rebate?
• STC value?
• Installation cost?
• Electrical work?
• Plumbing work?
• Final customer price?

This is probably the most important comparison for modern Melbourne homes.

Both are renewable-energy pathways. But they use your roof differently.

This is a common Melbourne situation. If your home already has rooftop solar, don't automatically install a separate solar thermal system. First investigate:

Don't make the decision based only on the installation invoice. Consider:

• Upfront cost — What will you pay after applicable incentives?
• Running cost — How much electricity or gas will be required?
• Maintenance — What components require servicing?
• Replacement — What happens at the end of the product's life?
• Energy prices — What happens if electricity or gas prices change?
• Solar PV — Will you have rooftop solar for the next decade?
• Future electrification — Are you adding EV, battery, induction cooking, electric heating, other electric appliances?

A table saying:

— isn't enough to make a purchase decision. You also need to consider:

Solar Victoria itself recommends considering climate, existing solar PV, upfront cost, running cost and reliability before deciding.

Samsun Energy currently offers heat-pump solutions from brands including iStore, Emerald, Ecogenica, Reclaim Energy, Rinnai and Rheem.

The right approach shouldn't be: "We sell heat pumps, so buy a heat pump." It should be:

Samsun also provides a Heat Pump Savings Calculator for customers wanting to explore the economics before requesting an assessment.

Technology choice comes before exact sizing. Once you've decided that a heat pump is suitable, tank sizing should consider:

• Number of occupants
• Bathrooms
• Shower habits
• Peak demand
• Recovery performance
• Future household changes
• Solar PV generation

Heat Pump Hot Water

Solar Hot Water

For Victorian homes in 2026, the question isn't: "Is heat pump or solar hot water better?" It's:

Heat pump is often the stronger choice when you have:

Solar hot water is often worth serious consideration when you have:

And there is a third option worth remembering:

The best decision should therefore be based on the whole energy system, not just the hot-water appliance.

• Solar Victoria — Solar Homes Program
• Solar Victoria — Hot Water Rebate
• Energy Safe Victoria — Electrical Safety Requirements
• Essential Services Commission — Victorian Energy Upgrades Program