Water Solar System: How Solar Hot Water Works and What to Compare Before Buying

Nov 7, 2024

A water solar system usually refers to a solar hot water system, which uses energy from the sun to help heat water for showers, kitchens, laundries and bathrooms. These systems can reduce reliance on electric or gas boosting in the right home, but they are not automatically the best choice for every property.

The right hot water system depends on household size, roof space, sun exposure, shading, booster type, installation access, budget and whether solar hot water is more practical than a heat pump hot water system, electric hot water system, gas hot water system or instant gas hot water system.

Installed Today makes it easy to compare and order hot water systems online, with supply-only ordering available across major Australian metro areas and selected supplied-and-installed options available on eligible products in Brisbane and Gold Coast service areas.

Quick Answer: What Is a Water Solar System?

A water solar system is a solar hot water system that uses solar collectors to capture heat from the sun and transfer that heat into stored water. Most systems also use an electric or gas booster so the home still has hot water during cloudy weather, high-demand periods or lower solar gain.

As a general guide:

Solar hot water suits homes with suitable roof space and sun exposure
Most systems need an electric or gas booster
Roof orientation, shading and roof access affect performance and cost
Close-coupled systems place the tank and collectors on the roof
Split systems place collectors on the roof and the tank at ground level
Heat pump hot water may be a practical alternative where roof conditions are poor
Supply-only pricing generally covers the product only
Rebates, STCs and incentives can change

Before ordering supply only, confirm the product, roof suitability, booster type, installation requirements and full site costs with your licensed installer.

What Does “Water Solar System” Mean?

The phrase “water solar system” is commonly used by homeowners looking for solar-powered hot water. The more accurate term is solar hot water system or solar water heating system.

A solar hot water system uses solar energy for water heating, not electricity generation.

This is different from rooftop solar PV:

System Type	What It Does
Solar hot water system	Uses heat from the sun to heat water
Solar PV system	Uses sunlight to generate electricity
Heat pump hot water system	Uses heat from surrounding air to help heat stored water

If your goal is lower hot water energy use, solar hot water and heat pump hot water are both worth comparing.

How Does a Solar Hot Water System Work?

A solar hot water system generally works by collecting heat from the sun and transferring that heat into a storage tank.

The process usually looks like this:

Solar collectors capture heat from the sun
Heat is transferred to water or a heat-transfer fluid
Heated water is stored in a hot water tank
The home draws hot water from the tank when needed
A booster heats the water when solar energy is not enough

Solar hot water systems still need good system design. Roof conditions, tank size, household demand and booster setup all affect performance.

Main Components of a Solar Hot Water System

A solar hot water system may include:

Solar collectors
Storage tank
Electric or gas booster
Circulation pump on some systems
Controller on some systems
Pipework
Valves
Tempering valve
Roof mounting hardware
Insulated pipework
Plumbing and electrical or gas connections

The more complex the setup, the more important proper product selection and installer confirmation become.

Solar Collectors

Solar collectors are the panels or tubes that capture heat from the sun. They are usually mounted on the roof.

The two common collector types are:

Flat-plate collectors
Evacuated tube collectors

Both can work well when matched to the right home, climate and budget.

Flat-Plate Solar Collectors

Flat-plate collectors are a common solar hot water collector type. They generally use a flat absorber panel inside an insulated collector box.

Flat-plate collectors may suit:

Homes with good sun exposure
Moderate climates
Suitable roof orientation
Properties with enough roof space
Households wanting a conventional solar hot water setup

Cost and suitability can depend on roof access, collector size, tank capacity and booster setup.

Evacuated Tube Solar Collectors

Evacuated tube collectors use rows of glass tubes to capture solar heat. They are often compared where performance in cooler or less ideal conditions is important, depending on the system design.

Evacuated tube systems may suit:

Homes with suitable roof space
Households comparing higher-performing collector options
Some cooler climates
Properties where collector efficiency is a key priority

They can be more complex than simpler collector setups, so upfront cost, maintenance and replacement parts should be considered.

Storage Tanks

The storage tank holds heated water until the household needs it.

Tank size should be chosen based on:

Number of people in the home
Number of bathrooms
Shower habits
Bath use
Kitchen use
Laundry use
Morning and evening peak demand
Booster setup
Collector capacity

An undersized tank may leave the home short on hot water. An oversized system can increase cost and may not deliver the best value.

Booster Systems

Most solar hot water systems need a booster. This helps maintain hot water supply when solar energy is not enough.

Common booster types include:

Electric booster
Natural gas booster
LPG booster

Electric boosting may suit homes without gas. Gas boosting may suit homes already using natural gas or LPG.

Natural gas and LPG systems are different and not interchangeable. Gas work must be completed by a licensed gas fitter.

Main Types of Solar Hot Water Systems

The main solar hot water system types include:

Roof-mounted close-coupled systems
Split solar hot water systems
Electric-boosted solar hot water systems
Gas-boosted solar hot water systems

Each option has different installation, cost and performance considerations.

Roof-Mounted Solar Hot Water Systems

A roof-mounted solar hot water system usually places the collectors and tank on the roof. These are often called close-coupled systems.

They may suit homes with:

Strong roof structure
Suitable roof orientation
Good sun exposure
Minimal shading
Good roof access
Space for collectors and tank

Key checks include:

Roof condition
Roof strength
Roof pitch
Collector orientation
Tank weight
Access for installation
Future service access
Visual impact

A roof-mounted tank is not suitable for every property.

Split Solar Hot Water Systems

A split solar hot water system usually has the collectors on the roof and the storage tank at ground level. A pump and controller may circulate water or heat-transfer fluid between the roof collectors and the tank.

Split systems may suit homes where:

A roof-mounted tank is not ideal
Ground-level tank access is preferred
Roof collectors can be installed in a suitable position
The home has suitable pipe routes
The additional pump and controller setup is practical

Cost considerations can include longer pipe runs, pump setup, controller requirements and installation complexity.

Close-Coupled Solar Hot Water Systems

Close-coupled systems usually place the storage tank directly above or near the collectors on the roof.

They may suit:

Homes with suitable roof strength
Homes with simple roof access
Households wanting a roof-mounted setup
Properties where roof aesthetics are acceptable
Roofs with strong sun exposure

They may not suit homes with weak roof structure, difficult access, heavy shading or roof designs that make installation impractical.

Solar Hot Water vs Heat Pump Hot Water

A heat pump hot water system is one of the most common alternatives to solar hot water.

Heat pumps use heat from the surrounding air to help heat stored water. They do not need roof-mounted solar collectors, which can make them practical where the roof is shaded, difficult to access or unsuitable.

Option	Best Suited To	Key Checks
Solar hot water	Homes with suitable roof space and sun exposure	Roof orientation, shading, booster, roof access
Heat pump hot water	Homes with suitable outdoor space and airflow	Airflow, drainage, electrical supply, noise placement
Electric storage	Simple replacements and homes without gas	Tank size, access, electrical setup
Gas hot water	Homes with natural gas or LPG	Gas type, gas pipe sizing, water pressure

Heat pump hot water may be worth comparing if solar roof conditions are not ideal.

Relevant heat pump categories include:

Popular heat pump options to compare include:

Solar Hot Water vs Electric Hot Water

Electric hot water systems are usually storage systems that use an electric element to heat water in a tank.

Electric storage may suit:

Homes without gas
Simple like-for-like replacements
Rental properties
Homes with suitable tank space
Customers wanting a lower-complexity system
Properties where solar roof conditions are poor

Common electric storage categories include:

Popular electric systems include:

If your old electric hot water system regularly ran out, do not automatically replace it with the same size.

Solar Hot Water vs Gas Hot Water

Gas hot water systems can suit homes already using natural gas or LPG.

Gas hot water options include:

Gas storage hot water
Instant gas hot water
Gas-boosted solar hot water, where suitable

Gas storage may suit homes wanting a tank-style system. Instant gas hot water systems may suit homes wanting continuous flow gas hot water without a large storage tank.

Popular gas options include:

Natural gas and LPG models are different. Always choose the correct gas type.

Roof Requirements for a Solar Water System

Solar hot water performance depends heavily on the roof.

Before choosing solar hot water, check:

Roof orientation
Roof pitch
Shading from trees or buildings
Collector location
Available roof space
Roof age and condition
Roof material
Structural suitability
Access for installation
Access for maintenance
Distance between collectors and tank
Whether a roof-mounted tank is practical

In Australia, solar collectors generally need strong sun exposure. A shaded or unsuitable roof can reduce performance and make alternatives like heat pump hot water more practical.

Solar Hot Water Installation Considerations

Solar hot water installation can be more complex than a basic like-for-like tank replacement.

Installation factors may include:

Roof access
Roof pitch
Lifting equipment
Collector mounting
Tank location
Pipework route
Booster connection
Electrical work
Gas work where applicable
Valves
Drainage
Old system removal
Old solar collector removal
Disposal
Compliance upgrades
Service access

Solar hot water systems involve plumbing, roof work, electrical or gas boosting and safety requirements. Use licensed trades where required.

Solar Hot Water Maintenance

Solar hot water systems need maintenance to keep working properly.

Maintenance may include:

Checking collectors
Inspecting pipe insulation
Checking for leaks
Checking valves
Checking the booster
Checking the storage tank
Checking the sacrificial anode where applicable
Inspecting roof-mounted components
Checking the pump and controller on split systems
Cleaning collector surfaces where safe and practical
Following manufacturer servicing requirements

Do not climb on the roof or attempt plumbing, gas or electrical repairs yourself.

How Long Does a Solar Hot Water System Last?

A solar hot water system can last many years when correctly installed and maintained, but lifespan depends on:

Product quality
Water quality
Installation quality
Roof exposure
Maintenance
Tank condition
Collector condition
Booster condition
Local climate
Whether parts remain available

Maintenance costs and access should be considered before buying.

Solar Hot Water Rebates, STCs and Incentives

Solar hot water, heat pump hot water and some energy-efficient upgrades may be eligible for rebates, STCs or other incentives depending on product, location, supplier pathway and current program rules.

These incentives can change.

Before relying on a rebate or discount, confirm:

Whether the selected product qualifies
Whether your property qualifies
Whether the old system type matters
Whether supply-only purchases are eligible
Whether an approved supplier or installer is required
Whether pre-approval is needed
Whether the incentive is applied upfront or claimed later
Whether the rebate or STC value is already included in the price

A rebate can improve value, but the system still needs to suit the home.

What Can Affect Solar Hot Water Cost?

Solar hot water cost can vary depending on product and site conditions.

Common cost factors include:

Collector type
Tank size
Booster type
Close-coupled vs split system
Roof access
Roof pitch
Roof reinforcement
Old system removal
Old solar collector removal
Pipework changes
Electrical work
Gas work
New valves
Drainage changes
Compliance upgrades
Installation difficulty
Whether rebates or STCs apply

A product-only price should not be treated as a full installed solar hot water price.

What Is Not Included in Supply-Only Hot Water Pricing?

For supply-only products, the listed product price generally covers the product only.

It does not usually include:

Installation labour
Plumbing alterations
Electrical work
Gas work
New valves
Pipework changes
Gas pipe upgrades
Drainage changes
Tempering valve upgrades
Pressure limiting valve upgrades
Expansion control valves
Old unit removal
Disposal
Compliance upgrades
Concrete bases or slab work
Flue kits unless listed
Temperature controllers unless listed
Solar collector removal
Roof work
Relocation of the system
Rebate administration
Site assessment

Always check the product page and confirm full site requirements with your licensed installer before ordering supply only.

Supply-Only vs Supplied-and-Installed

Installed Today offers supply-only ordering across major Australian metro areas. This can suit customers who already have a licensed installer organised and want to order the product online.

Supply-only may suit you if:

Your installer has confirmed the correct product
The system size suits your household
The energy source has been checked
The correct gas type has been selected where relevant
Electrical requirements have been checked
Water pressure has been reviewed
Roof, access and drainage are suitable
You understand what is not included in the product price

Selected supplied-and-installed options are available on eligible products in Brisbane and Gold Coast service areas. Availability depends on the product, address and installation requirements.

Before choosing a supplied-and-installed option, check exactly what is included and what may be extra.

Brisbane and Gold Coast Considerations

For Brisbane and Gold Coast homes, solar hot water may be worth comparing where roof conditions are suitable. However, heat pump, electric and gas systems may also be practical depending on the property.

Common local considerations include:

Strong sun exposure on suitable roofs
Shading from trees
Roof orientation
Roof pitch
Tight side access
Replacing older electric storage systems
Comparing heat pump upgrades
Natural gas vs LPG availability
Gas pipe sizing for instant gas
Heat pump airflow and noise placement
Condensate drainage
Old unit removal and disposal
Whether selected products are eligible for supplied-and-installed options

The best hot water system is the one that suits the home, not just the one with the best headline claim.

When a Solar Water System May Be Worth It

A solar water system may be worth considering where:

The roof has strong sun exposure
Shading is minimal
The household uses enough hot water
Roof access is suitable
The booster setup is practical
Maintenance access is practical
The household plans to stay long term
The installed cost makes sense
Any rebate or STC value improves the overall result

Solar hot water can be a strong option in the right home, but it should be compared carefully against heat pump, electric and gas systems.

When Heat Pump Hot Water May Be Better

Heat pump hot water may be a better fit where:

Roof access is difficult
Roof shading is heavy
Roof structure is unsuitable
You want to avoid roof-mounted collectors
Outdoor ground-level space is available
Airflow is suitable
Condensate drainage is manageable
Electrical supply is suitable
Noise placement is acceptable

A heat pump is not automatically better than solar hot water, but it can be easier to install in many homes.

Common Mistakes When Choosing a Water Solar System

Confusing Solar Hot Water With Solar PV

Solar hot water heats water. Solar PV generates electricity. They are different systems.

Ignoring Roof Shading

Shading can reduce solar hot water performance and value.

Forgetting the Booster

Most solar hot water systems still need electric or gas boosting.

Choosing the Wrong System Type

Close-coupled, split, flat-plate and evacuated tube systems all have different installation and suitability factors.

Assuming Rebates Are Guaranteed

Rebates, STCs and incentives can change and may depend on the product, location and installation pathway.

Comparing Product Price With Installed Price

Solar hot water can involve roof work, pipework, valves, electrical or gas work and old system removal.

Ignoring Heat Pump Alternatives

Heat pump hot water may be practical where roof-mounted collectors are not suitable.

Buying Supply Only Before Installer Confirmation

Supply-only ordering should only happen after your installer confirms product and site suitability.

Before Ordering Checklist

Before choosing a solar hot water system or alternative hot water system, confirm:

Current system type
Current system size
Whether the old system ran out of hot water
Number of people in the home
Number of bathrooms
Shower habits
Peak hot water demand
Roof orientation
Roof shading
Roof pitch
Roof access
Roof structural suitability
Electric, natural gas or LPG availability
Booster type
Electrical requirements
Gas pipe sizing where relevant
Water pressure
Heat pump airflow and drainage if comparing heat pumps
Outdoor or indoor suitability
Access for delivery and installation
Drainage and overflow requirements
Whether new valves may be needed
Whether old unit removal is included
Whether solar collector removal is needed
Whether disposal is included
Whether rebates or STCs may apply
Whether supply-only affects rebate eligibility
Whether supply-only or supplied-and-installed is the right option
Installer confirmation before buying supply only

Frequently Asked Questions

What is a water solar system?

A water solar system usually means a solar hot water system. It uses solar collectors to capture heat from the sun and transfer that heat into stored water.

Is a water solar system the same as solar panels?

No. Solar hot water uses solar heat to heat water. Solar PV panels generate electricity.

Does solar hot water work on cloudy days?

Solar gain may be lower on cloudy days, which is why most solar hot water systems use an electric or gas booster.

Does solar hot water need a booster?

Yes, most systems need a booster so the home has hot water during cloudy weather, high-demand use or low solar conditions.

Is solar hot water better than heat pump hot water?

It depends on the home. Solar hot water may suit homes with good roof space and sun exposure. Heat pump hot water may suit homes with outdoor space, airflow, drainage and electrical suitability.

Is solar hot water better than electric hot water?

Solar hot water may reduce grid energy use in the right home, but electric storage can be simpler and may suit homes where solar roof conditions are poor.

Can solar hot water use gas?

Some solar hot water systems use gas boosting. Natural gas and LPG systems are different, so the correct gas type must be selected.

Are rebates available for solar hot water?

Rebates, STCs and incentives may be available depending on product, location and current program rules. Eligibility can change, so confirm before ordering.

Can I install a solar hot water system myself?

No. Solar hot water systems involve plumbing, roof work, electrical or gas boosting, valves, water pressure and compliance requirements. Use licensed trades where required.

Does supply-only hot water pricing include installation?

No. Supply-only generally means the product only unless installation is selected or clearly shown. Installation, valves, electrical work, gas work, pipework, drainage, removal, disposal and compliance upgrades are usually separate.

Final Word

A water solar system can be a strong hot water option where the home has suitable roof space, sun exposure, roof access and booster setup. It can reduce reliance on electric or gas boosting in the right conditions, but it is not automatically the best option for every home.

Before choosing solar hot water, compare heat pump, electric and gas hot water systems as well. Heat pump hot water may suit homes with poor roof conditions. Electric storage may suit simple replacements. Gas hot water may suit homes already using natural gas or LPG.

Before ordering supply only through Installed Today, confirm the selected product with your licensed installer. If choosing a supplied-and-installed option in an eligible Brisbane or Gold Coast service area, check exactly what is included before placing the order.

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