Heat Pump to Solar Hot Water: Is It Worth Upgrading?
Heat Pump to Solar Hot Water: Is It Worth Switching?
Sometimes - but a working, well-sited heat pump is already one of the most efficient hot-water options, so solar thermal should solve a real problem before you change.
Heat pump and solar hot water are both efficient storage technologies and both can be eligible for STCs. The main difference is where the renewable energy comes from: a heat pump extracts heat from the surrounding air using electricity, while solar hot water captures heat directly through dedicated roof collectors and uses a booster when required.
Should I Replace My Heat Pump With Solar?
This is a preliminary guide. Final suitability depends on the condition of the current system, roof exposure, collector layout, structural and access requirements, booster arrangement, tank position and household demand.
1Why are you considering leaving heat pump?
2What is the roof like?
3Do you already have rooftop solar PV?
Guide only. Solar collector orientation, shading, roof condition, safe access, tank configuration, booster requirements, electrical supply and household hot-water demand must be checked before finalising a conversion.
Can You Replace a Heat Pump With Solar Hot Water?
Yes. A heat pump can be replaced with either split solar hot water, which keeps a storage tank at ground level and adds roof collectors, or close-coupled solar, which places the tank and collectors together on the roof. The conversion is practical when the property has the right roof, access and booster arrangement.
Heat Pump vs Solar Hot Water: What Actually Changes?
Both systems store hot water efficiently, but they solve the energy problem in different ways. Solar thermal uses roof collectors to capture sunlight directly. Heat pump uses electricity to move heat from the surrounding air into the tank.
| Consideration | Heat Pump Hot Water | Solar Hot Water |
|---|---|---|
| Main heat source | Heat from surrounding air + electricity | Direct solar thermal + booster |
| Roof equipment | None required for thermal collection | Dedicated collectors or evacuated tubes |
| Solar PV compatibility | Strong advantage Can run from household PV electricity | Separate technology using its own collector area |
| Operating noise | Compressor and fan operate while heating | Usually quieter No heat-pump compressor; some split systems use circulation equipment |
| Ground-level tank | Normally yes | Yes with split solar; not necessarily with close-coupled solar |
| Roof access dependency | Low | Higher |
| STCs | Eligible listed models may qualify | Eligible listed systems may qualify |
| Strongest case | Existing site works, PV exists, roof space is limited or simpler servicing is preferred | Excellent sunny roof, quiet operation matters and direct solar thermal is specifically wanted |
When We Would Keep the Heat Pump
A heat pump is already an efficient renewable hot-water technology. If it is operating properly and the location works, there should be a clear practical reason before replacing it early with solar thermal.
The Current Heat Pump Works Well
There is little value in replacing a healthy system simply to change technologies. Use it until meaningful repair or normal replacement is due.
You Already Have Solar PV
A heat pump can use household-generated electricity during the day, reducing the reason to dedicate additional roof area to a separate thermal collector array.
Roof Space Is Valuable
Keeping hot-water generation at ground level preserves roof area for existing or future PV.
Roof Access Is Difficult
Heat pump keeps the main hot-water hardware accessible from ground level and avoids collector installation and servicing on the roof.
You Want Simpler Replacement Later
A ground-level tank and heat-pump position can reduce dependence on roof-specific hot-water work at the next replacement.
The Site Is Already Proven
If airflow, noise separation, drainage and electrical supply have all worked well, another heat pump can be a very natural replacement.
Already Have Solar PV? We Would Usually Stay With Heat Pump
This is the strongest reason not to change to solar thermal. Rooftop PV is already producing electricity that can power a heat pump, and the heat pump needs only a fraction of the electrical energy of conventional resistance heating.
Use Existing Generation
Schedule the heat pump during daytime solar production and use the PV system already on the property.
Preserve Roof Area
There is no need to sacrifice additional roof area to dedicated solar-thermal collectors.
One Solar Platform
PV can support hot water, appliances, air conditioning, EV charging and batteries rather than creating a separate solar technology used only for hot water.
If the current heat pump is due for replacement and the home already has useful PV capacity, we would generally replace it with another suitable heat pump unless compressor noise or another site limitation creates a compelling reason to change.
When Solar Hot Water Can Be the Better Move
Solar becomes genuinely compelling when it solves a problem the heat pump does not - particularly noise, roof-specific design goals or a strong preference for direct solar thermal.
Excellent Sunny Roof
Strong, unshaded solar exposure gives dedicated thermal collectors their best opportunity to carry a large share of the water-heating load.
Heat-Pump Noise Is a Real Problem
If compressor and fan noise cannot be acceptably managed through model choice or relocation, solar can provide a quieter renewable pathway.
You Specifically Want Direct Solar Thermal
Some households prefer a system that captures the sun's heat directly rather than using a refrigeration cycle powered by electricity.
You Want to Free Ground Space
A suitable close-coupled solar system can move both tank and collectors onto the roof, subject to roof structure, loading and access.
The Heat-Pump Site Is Poor
A cramped location with airflow or neighbour-noise constraints may make a solar layout more attractive if the roof is excellent.
Booster Use Can Be Kept Low
Good solar exposure, appropriate collector area and correct tank sizing help minimise reliance on electric or gas boosting.
Split Solar or Close-Coupled Solar After a Heat Pump?
Your existing ground-level heat-pump tank position can make split solar the more natural physical conversion, while close-coupled solar can free the ground-level area entirely.
Ground-Level Tank + Roof Collectors
This is usually the closest layout to an existing heat-pump installation. The ground-level tank position may be reusable if the base, services, drainage and clearances suit the selected solar storage cylinder.
- Existing tank footprint may help.
- Hot and cold services are already nearby.
- New collector pipework is required to the roof.
- An electric or gas booster may be required depending on the system.
Tank + Collectors on the Roof
This moves the stored water and collectors onto the roof, potentially freeing the old heat-pump footprint at ground level.
- Roof structure and loading become critical.
- Safe roof access matters more.
- Hot and cold pipework may need substantial alteration.
- Future servicing remains roof dependent.
Can the Existing Heat-Pump Tank Position Be Reused for Split Solar?
Often potentially yes. The old heat-pump position already has a storage footprint and water services, but the selected solar tank can have different dimensions, connection positions and booster requirements.
Base & Footprint
The existing slab or support needs to suit the new storage cylinder's size and loaded weight.
Hot & Cold Plumbing
Existing services can often be adapted, although connection locations and pipework may change.
Drainage
Relief-valve drainage still needs to comply with the selected solar system's requirements.
Collector Pipe Route
Split solar needs a practical path between the ground-level tank and the roof collector array.
Electrical Booster
The existing heat-pump electrical supply may be useful, but the new booster circuit and controls still need to suit the solar system.
Removed Heat-Pump Components
The old compressor and tank are removed, leaving the site to be configured for the new solar storage cylinder.
What Happens When There Is Not Enough Sun?
Solar hot water still needs backup heating for poor weather, winter conditions, unusually high demand or periods when the collectors cannot provide enough useful heat.
Electric Boosting
An electric element can bring the stored water to the required temperature when solar contribution is insufficient.
Gas Boosting
Some solar configurations can use gas backup, although this adds gas infrastructure and ongoing fuel dependency.
Sizing Matters
Collector area, tank capacity, household demand and local solar conditions influence how often boosting is needed.
Can Heat-Pump-to-Solar Replacement Qualify for STCs?
Yes, potentially. The federal Small-scale Renewable Energy Scheme includes eligible solar water heaters and eligible air-source heat pumps. The new solar system must be a listed model and installed in its approved configuration within the eligibility period.
Eligible Systems Can Receive STCs
The exact collector, tank and system configuration must match the Clean Energy Regulator register and installation rules.
Old Eligibility Does Not Decide the New Claim
The previous heat pump's certificate history does not automatically determine whether the replacement solar system qualifies.
Confirm the Claim Pathway Before Installation
Product eligibility alone does not complete an STC or state incentive claim. Confirm the installer, registered agent and any pre-approval requirements first.
Current Heat Pump Starting Price vs a Solar Conversion
A like-for-like heat-pump replacement can often use the existing ground-level hot-water site. Solar adds roof collectors, mounting, solar pipework and possibly structural or access work, so compare the complete installed conversion rather than product price alone.
Usually the simpler replacement where the existing heat-pump site remains suitable, particularly when rooftop PV already exists.
Current Installed Today heat-pump collection starting price. Final installed cost depends on model, location and installation scope.
Solar can be the stronger choice where roof exposure is excellent and direct solar thermal or quieter operation is a genuine priority.
Allow for collectors, mounting, roof access, solar pipework, booster requirements and any changes to the existing tank position or services.
How a Heat-Pump-to-Solar Conversion Usually Works
The exact scope depends on whether split or close-coupled solar is chosen. Start with the roof and system layout, then determine how much of the existing heat-pump site and services can be reused.
Assess the Roof
Check solar exposure, shading, collector area, roof material, pitch, structure and safe access.
Choose Split or Roof-Mounted Solar
Decide whether to retain a ground-level tank position or move the full system onto the roof.
Confirm Booster & Services
Check electrical or gas boosting, plumbing routes, drainage and any required service changes.
Remove Heat Pump & Commission Solar
Remove the old heat-pump system, install the solar tank and collectors, complete the booster connection and commission the new system.
Supply Only vs Supplied & Installed
Installed Today sells hot-water products online with supply-only ordering across supported Australian metro areas and supplied-and-installed options where available in eligible Brisbane and Gold Coast service areas. Solar conversions can involve roof work and system-specific installation requirements beyond a standard heat-pump replacement.
Confirm the Full Solar Layout First
Arrange appropriately licensed trades to confirm collector position, tank layout, booster, plumbing, roof work and incentive pathway before purchasing the system.
Availability Depends on Product & Location
Where an Installed Today installation option is offered, review the product's installation inclusions and any additional roof, relocation, electrical or plumbing work required for the property.
Heat Pump to Solar Hot Water FAQs
Can I replace a heat pump with solar hot water?
Yes. A heat pump can be replaced with split or close-coupled solar hot water where the roof, tank location, services, booster and installation conditions suit the selected system.
Is solar hot water better than a heat pump?
Not automatically. Solar can be excellent on a strong sunny roof and offers quieter operation without a heat-pump compressor. Heat pump is often stronger where rooftop PV already exists, roof space is limited or easier ground-level servicing is preferred.
Should I replace a heat pump that is still working?
Usually not solely to change technologies. If the heat pump is reliable, correctly sized and well located, keeping it until major repair or normal replacement is generally sensible.
Is solar hot water quieter than a heat pump?
Generally yes because solar thermal does not use a heat-pump compressor and large fan. Some split solar systems use circulation equipment, and booster operation depends on the system design.
Can I reuse the heat-pump tank position for solar?
Potentially with split solar. The base, footprint, plumbing, drainage and booster arrangement still need to suit the selected solar cylinder.
What if I already have rooftop solar PV?
Existing PV usually strengthens the case for staying with heat pump because the heat pump can be scheduled to use household-generated electricity without adding a separate thermal collector array.
Does solar hot water still need a booster?
Yes. Solar systems normally require backup heating for low solar contribution, poor weather or high hot-water demand. The booster may be electric or gas depending on the system.
Can the new solar system qualify for STCs?
Eligible listed solar water-heater systems can create STCs when installed in the approved configuration within the model's eligibility period and all scheme requirements are met.
Should I choose split solar or roof-mounted solar?
Split solar is often the more natural conversion from a heat pump because the home already has a ground-level tank site. Close-coupled solar may suit properties wanting to free ground space but places the tank and collectors on the roof.
When would you recommend solar over another heat pump?
We would favour solar where the existing heat pump is genuinely due for replacement, the roof has excellent solar exposure, compressor noise is a real unresolved issue or the homeowner specifically wants direct solar thermal heating. If rooftop PV already exists and the heat-pump site works, we would usually stay with heat pump.
Heat Pump Due for Replacement? Compare the Roof Before You Switch to Solar
Solar hot water can be an excellent replacement where the roof is genuinely strong and direct solar thermal or quieter operation is the goal. But if your existing heat-pump site still works - especially with rooftop PV already installed - another well-matched heat pump will usually remain the simpler pathway we compare first.
