Best Hot Water System for Replacing Solar Hot Water

Replacing solar hot water is different from replacing a standard electric, gas or heat pump system. You need to check whether the existing system is roof-mounted, split system, electric boosted, gas boosted, still using collectors, or ready to be fully decommissioned. At Hot Water Outlet, you can compare supply-only hot water systems online, including heat pump hot water systems, electric hot water systems, gas hot water systems, instant gas hot water systems and compatible valves, pipework and fittings.

Quick Answer

For many homes replacing old solar hot water, the best replacement option is often a heat pump hot water system, especially where the home is moving toward electric appliances or already has solar power.

A standard electric hot water system may suit if you want a simple storage replacement and the electrical setup is suitable.

An instant gas hot water system may suit if the existing solar hot water system is gas boosted and the gas supply, location and flow rate are suitable.

The best option depends on whether you are replacing the full solar hot water system, replacing only the booster, removing roof components, or changing system type completely.

Best Replacement Options for Solar Hot Water

What Type of Solar Hot Water Are You Replacing?

Before choosing a new hot water system, identify what you currently have.

Common solar hot water setups include:

• Roof-mounted solar tank and collectors

• Split solar system with tank on the ground and collectors on the roof

• Electric boosted solar hot water

• Gas boosted solar hot water

• Solar preheat system feeding a gas booster

• Old solar system with failed collectors

• Old solar system with failed tank

• Old solar system with failed booster

• Solar system being removed during roof work or renovation

The replacement path depends on which part has failed and whether the existing solar equipment is still worth keeping.

Key Buyer Checks Before Ordering Online

Before buying a supply-only replacement for solar hot water, check:

• Existing system type

• Whether the tank is roof-mounted or ground-mounted

• Whether there are roof collectors

• Whether the booster is electric or gas

• Natural gas or LPG if gas boosted

• Existing tank size

• Number of people in the home

• Number of bathrooms

• Whether the roof components are staying or being removed

• Whether old solar pipework needs to be isolated

• Electrical supply

• Gas supply if applicable

• Drainage location

• Heat pump airflow if considering heat pump

• Noise placement

• Required valves and fittings

• Access for delivery and future servicing

• Whether roof work, crane work or specialist removal is needed

Supply-only pricing usually does not include installation, plumbing labour, electrical work, gas fitting, old unit removal, roof collector removal, roof tank removal, crane work, disposal, valves, fittings, pipework changes, drainage work, switchboard upgrades, gas upgrades, regulator changes, LPG bottle work, controller wiring, compliance upgrades, concrete bases, platforms or delivery beyond what is shown at checkout.

Plumbing, gas fitting and electrical work must be completed by appropriately licensed tradespeople.

Heat Pump Hot Water as a Solar Hot Water Replacement

Heat pump hot water systems are one of the most common options to compare when replacing old solar hot water.

A heat pump does not use roof-mounted solar collectors. Instead, it uses electricity to move heat from the surrounding air into the water. This can make it a practical option when the old solar collectors, roof tank or solar pipework are no longer worth repairing.

Brands commonly compared include iStore hot water systems, Stiebel Eltron hot water systems, Envirosun hot water systems and Emerald Energy.

Heat Pumps May Suit When

• The old solar hot water system is no longer reliable

• Roof collectors are leaking or damaged

• The roof tank is difficult or expensive to replace

• You want to move away from roof-mounted hot water equipment

• The home has solar power

• There is suitable outdoor airflow

• Condensate drainage can be managed

• Noise placement is acceptable

• The electrical setup is suitable

Heat Pumps May Not Suit When

• There is no suitable outdoor location

• The unit would be too close to bedrooms or neighbours

• Airflow is restricted

• Condensate drainage is difficult

• Electrical supply is not suitable

• The household has very high peak hot water demand

• The system location is difficult to access

Heat pump rebates, STCs and incentives can change and depend on the product, installer, property, purchase type and program rules. Do not assume a rebate applies without checking current eligibility.

Electric Storage as a Solar Hot Water Replacement

Electric hot water systems may suit homes replacing solar hot water where a simple storage system is preferred.

Electric storage can be practical if the home already has suitable electrical supply and the buyer wants a familiar tank-style system without roof collectors or gas.

Brands commonly compared include Rheem hot water systems, Dux hot water systems, Vulcan hot water systems and Stiebel Eltron hot water systems.

Electric Storage May Suit When

• A simple replacement is preferred

• There is no gas connection

• The old solar system is being fully removed

• The electrical supply is suitable

• There is space for a storage tank

• Noise needs to be minimal

• Lower upfront product cost is a priority

Electric Storage Buyer Checks

Check:

• Tank capacity

• Element size

• Recovery rate

• Electrical supply

• Tariff setup if relevant

• Indoor or outdoor rating

• Physical dimensions

• Connection points

• Drainage and discharge point

• Tempering valve requirements

• Whether solar pipework needs to be capped or removed

Electric storage may be simple, but it may use more electricity than a heat pump depending on the system, tariff and household usage.

Instant Gas as a Solar Hot Water Replacement

Instant gas hot water systems, also called continuous flow gas systems, may suit homes replacing a gas-boosted solar hot water system.

Some solar hot water systems use roof collectors or a preheat tank with a gas booster. If the solar side is being removed, a suitable instant gas system may be compared as a replacement, provided the gas supply and installation location are suitable.

Common brands include Rinnai hot water systems, Bosch hot water systems and Rheem hot water systems.

Instant Gas May Suit When

• The home already has natural gas or LPG

• The existing solar system is gas boosted

• The correct gas type is known

• The gas pipe sizing is suitable

• The system can be installed externally or correctly flued

• Strong recovery is important

• Tank storage space is limited

• The flow rate suits the number of bathrooms

Natural gas and LPG are not interchangeable. A natural gas unit must not be connected to LPG unless it is specifically converted and approved by a licensed gas fitter, and an LPG unit must not be connected to natural gas unless the same applies.

External gas hot water units are outdoor/external only unless the product is specifically designed and approved for internal or flued installation.

Instant Gas Buyer Checks

Check:

• Natural gas or LPG

• Existing gas pipe sizing

• Gas meter capacity

• LPG bottle and regulator setup if applicable

• Required flow rate

• Number of bathrooms

• Whether showers may run at the same time

• Water pressure

• Minimum flow rate

• Controller requirements

• Clearances to windows, doors, vents and openings

• Whether the old solar preheat pipework is being removed or bypassed

If the old solar system had a gas booster, do not assume any instant gas unit will be a direct replacement. The system type, gas supply and pipework layout need to be checked.

Gas Storage as a Solar Hot Water Replacement

Gas hot water systems may suit some homes where gas storage is preferred or where an existing gas storage-style setup is being replaced.

Brands commonly compared include Rheem hot water systems, Dux hot water systems and Vulcan hot water systems.

Gas Storage Buyer Checks

Check:

• Natural gas or LPG

• Tank capacity

• Recovery rate

• Indoor or outdoor rating

• Ventilation

• Flue requirements

• Gas pipe sizing

• Drainage and safe discharge

• Tempering valve requirements

• Whether the solar system is being removed, isolated or bypassed

Gas storage may be an option, but many buyers replacing solar hot water also compare heat pump or instant gas depending on the home’s energy direction.

Replacing Only the Solar Booster

Sometimes the whole solar hot water system does not need replacing. The issue may be with the electric booster or gas booster.

A booster-only replacement may be considered when:

• The solar tank is still in good condition

• The roof collectors are still working

• The solar pump and controls are serviceable

• The pipework is sound

• The system is worth repairing

• The correct compatible booster is available

However, if the solar tank, roof collectors, pipework or controls are old or failing, replacing only the booster may not be the best long-term option.

A licensed plumber, electrician or gas fitter should confirm whether a booster-only replacement is suitable.

Replacing Roof-Mounted Solar Hot Water

Roof-mounted solar hot water systems need extra planning.

A roof-mounted system may include:

• Heavy roof tank

• Solar collectors

• Roof brackets

• Flow and return pipework

• Relief drain pipework

• Electrical booster wiring

• Gas booster pipework if applicable

Replacing a roof-mounted system may involve more than simply buying a new hot water unit.

Roof-Mounted Buyer Checks

Check:

• Whether the tank is staying or being removed

• Whether the collectors are staying or being removed

• Roof access

• Roof condition

• Whether crane or specialist lifting is needed

• Whether roof penetrations need to be sealed

• Whether old pipework needs to be capped

• Whether the replacement unit is going on the ground

• Where the new system will drain

• Whether electrical or gas services need to be relocated

Supply-only pricing does not include roof tank removal, collector removal, crane work, roof repairs, disposal or trade labour.

Replacing Split Solar Hot Water

Split solar hot water systems usually have collectors on the roof and a tank on the ground.

Replacing split solar may be simpler than replacing a roof-mounted tank system, but the roof collectors and solar pipework still need to be considered.

Split Solar Buyer Checks

Check:

• Ground tank condition

• Roof collector condition

• Solar pump condition

• Controller condition

• Pipework condition

• Booster type

• Whether the collectors are staying

• Whether the system is being fully converted

• New unit location

• Electrical and plumbing changes

• Drainage and valves

If the tank has failed but the collectors are also old, it may be worth comparing a full system change rather than replacing one part only.

Should You Remove the Old Solar Collectors?

Old roof collectors may be removed, isolated or left in place depending on the job, roof condition and replacement plan.

Reasons to remove old collectors may include:

• Roof leaks

• Renovation work

• Roof replacement

• Damaged collectors

• Unused equipment

• Weight or appearance concerns

• Full conversion to heat pump, electric or gas

Reasons old collectors may be left in place temporarily include:

• Removal is not included in the replacement scope

• Roof access is difficult

• Specialist lifting is required

• Roof repairs are needed separately

• The buyer wants to stage the work

Old solar collectors should not simply be disconnected without considering roof penetrations, water lines, structural fixing and safe isolation.

Best Replacement for Electric-Boosted Solar Hot Water

If the existing solar hot water system is electric boosted, common replacement options include:

• Heat pump hot water systems

• Electric hot water systems

• Like-for-like solar where suitable

• Booster-only repair if the solar system is otherwise healthy

A heat pump may suit if the home wants an efficient electric option without roof collectors. Electric storage may suit if the buyer wants simplicity and lower product cost.

Best Replacement for Gas-Boosted Solar Hot Water

If the existing solar hot water system is gas boosted, common replacement options include:

• Instant gas hot water systems

• Gas hot water systems

• Heat pump hot water systems

• Booster-only replacement if compatible and worthwhile

• Like-for-like solar where suitable

The correct option depends on whether the home wants to keep gas, move away from gas, or keep the solar thermal system.

Best Replacement for Homes With Solar Power Panels

Solar power panels are not the same as solar hot water collectors.

If your home has solar PV panels, a heat pump hot water system or electric hot water system may be worth comparing, depending on electrical setup, timer options, tariff structure and hot water usage.

When comparing hot water for a solar PV home, check:

• Solar system size

• Daytime energy production

• Hot water usage pattern

• Timer or control options

• Electrical circuit requirements

• Backup heating requirements

• Tank size

• Household size

• Whether the unit can be located correctly

Having solar panels does not automatically mean every electric hot water option is suitable. The system still needs to match the household and electrical setup.

What Size Hot Water System Do You Need After Solar?

Sizing depends on the number of people, bathrooms and usage habits.

Do not size the new system only by copying the old solar tank size. Solar hot water performance depends on sun exposure, booster use, tank size and system condition. A replacement heat pump, electric or gas system should be sized based on actual household demand.

Valves and Fittings for Solar Hot Water Replacement

Replacing solar hot water may require more parts than a standard changeover.

Depending on the replacement type, you may need compatible valves, pipework and fittings, such as:

• Tempering valve

• Pressure limiting valve

• Duo valve

• Expansion control valve

• Isolation valve

• Non-return valve

• Relief valve drain materials

• Connection fittings

• Pipework materials

• Solar pipework isolation parts

• Drainage materials

The correct valve setup depends on the system type, water pressure, hot water temperature, location and local compliance requirements.

Common Mistakes When Replacing Solar Hot Water

Assuming the Booster Is the Whole System

A solar hot water system may include a tank, collectors, pump, controller, valves, pipework and booster. A booster fault may not mean the whole system is failed, but an old solar system may also not be worth partly repairing.

Forgetting About Roof Components

If the old system has roof collectors or a roof tank, removal may require extra labour, roof work, crane work or specialist access.

Choosing a Heat Pump Without Checking Airflow

Heat pumps need suitable outdoor airflow, drainage and noise placement. They are not suitable for tight enclosed spaces.

Buying the Wrong Gas Type

Natural gas and LPG are different. Always select the correct gas type.

Using an External Gas Unit Indoors

External gas hot water units are outdoor units unless specifically designed and approved for internal or flued installation.

Ignoring Electrical Requirements

Electric storage and heat pump systems need suitable electrical supply. Changing from gas boosted solar to electric or heat pump may require electrical work.

Ignoring Gas Supply Requirements

Changing from solar gas boost to full instant gas may require gas pipe sizing checks.

Not Planning Drainage

Storage systems, heat pumps and valves need safe drainage. Heat pumps also produce condensate.

Assuming Rebates Always Apply

Rebates, STCs and incentives can change and depend on the product, installer, property, purchase type and program rules.

Comparing Supply-Only Price to Installed Cost

Supply-only pricing is not the same as total installed cost. Solar replacement may involve old unit removal, roof work, extra pipework, valves, electrical work or gas fitting.

Best Brands for Replacing Solar Hot Water

The best brand depends on whether you are moving to heat pump, electric storage, gas storage or instant gas.

iStore

iStore hot water systems are commonly compared in the heat pump category, especially for homes replacing older electric or solar-style hot water with efficient electric hot water.

Stiebel Eltron

Stiebel Eltron hot water systems may suit buyers comparing heat pump, electric and instant electric options.

Envirosun

Envirosun hot water systems are commonly compared for heat pump hot water where the site conditions suit.

Emerald Energy

Emerald Energy is often compared by buyers looking at heat pump value options.

Rheem

Rheem hot water systems are commonly compared across electric storage, gas storage, instant gas and heat pump categories.

Rinnai

Rinnai hot water systems are commonly compared for instant gas replacements, especially where a home already has suitable gas.

Bosch

Bosch hot water systems are often compared for instant gas hot water applications.

Dux

Dux hot water systems are often compared for practical electric and gas storage replacements.

Vulcan

Vulcan hot water systems are often considered for budget-conscious electric and gas storage replacements.

Buyer Checklist Before Ordering Online

Before ordering a supply-only replacement for solar hot water, confirm:

• Existing system type

• Roof-mounted or ground-mounted tank

• Split solar or roof-mounted solar

• Electric boost or gas boost

• Natural gas or LPG if applicable

• Existing tank size

• Household size

• Number of bathrooms

• Whether roof collectors are staying or being removed

• Whether a roof tank needs removal

• Whether crane or specialist lifting may be required

• Whether solar pipework needs to be isolated

• Whether gas pipework needs changing

• Whether electrical work is required

• Heat pump airflow if applicable

• Drainage and condensate requirements

• Noise placement

• Required valves and fittings

• Delivery and access requirements

• Licensed plumbing, electrical and gas fitting requirements

Supply-Only vs Installed Cost

Hot Water Outlet sells supply-only hot water systems and accessories online. Supply-only pricing is useful for comparing product costs, but it is not the same as total installed cost.

The final installed cost may depend on:

• Licensed plumbing labour

• Licensed electrical work

• Licensed gas fitting

• Old solar tank removal

• Roof collector removal

• Crane or specialist lifting

• Roof access

• Disposal

• Valve replacement

• Pipework changes

• Solar pipework isolation

• Drainage work

• Heat pump condensate drainage

• Switchboard capacity

• Gas pipe sizing

• LPG regulator upgrades

• Compliance upgrades

• Concrete bases or platforms

• Delivery access

Where appropriate, Hot Water Outlet may help organise quotes from reputable installers.

FAQ: Best Hot Water System for Replacing Solar Hot Water

What is the best replacement for solar hot water?

The best replacement depends on the existing system and household needs. Heat pump hot water is often worth comparing for homes moving away from roof solar hot water, while electric storage or instant gas may suit other properties depending on electrical or gas supply.

Can I replace solar hot water with a heat pump?

Yes, a heat pump may be a suitable replacement if there is outdoor airflow, drainage, suitable electrical setup and acceptable noise placement. It also removes the need for roof-mounted solar hot water collectors.

Can I replace solar hot water with electric storage?

Yes, electric storage may suit if the home has suitable electrical supply and you want a simple tank-style replacement. The correct tank size, element and tariff setup should be checked.

Can I replace solar hot water with instant gas?

Yes, if the property has suitable natural gas or LPG, correct gas pipe sizing, an approved appliance location and the right flow rate. Natural gas and LPG are not interchangeable.

Do I need to remove the old solar panels?

Not always. Old solar hot water collectors may be removed, isolated or left in place depending on the job. Removal is separate work and may require roof access, lifting, disposal and roof repairs.

Is replacing only the booster worth it?

Sometimes. If the solar tank, collectors, pump, pipework and controls are still in good condition, replacing only the booster may be worth considering. If the system is old or multiple parts are failing, a full replacement may make more sense.

Are solar hot water rebates available when replacing a system?

Rebates, STCs and incentives can change and depend on product, installer, property, purchase type and program rules. Always check current eligibility before buying.

What size hot water system do I need after solar?

Sizing depends on household size, bathrooms, showers, baths and usage pattern. Do not rely only on the old solar tank size, because different system types recover and operate differently.

Does supply-only pricing include removal of the old solar system?

No. Supply-only pricing generally does not include installation, old unit removal, roof collector removal, crane work, disposal, plumbing labour, electrical work, gas fitting, valves, fittings or compliance upgrades.

Can Hot Water Outlet install the system?

Hot Water Outlet sells supply-only hot water systems and accessories online. Plumbing, gas fitting and electrical work must be completed by appropriately licensed tradespeople. Where appropriate, Hot Water Outlet may help organise quotes from reputable installers.

Final Thoughts

Replacing solar hot water is not just a product swap. You need to check the tank, roof collectors, booster, pipework, gas or electrical setup, roof access, drainage and whether the old solar components are staying or being removed.

For many homes, a heat pump hot water system is worth comparing as a modern electric replacement. Electric hot water systems may suit simple storage replacements, while instant gas hot water systems may suit homes with suitable gas.

Browse hot water systems, compare heat pump hot water systems, electric hot water systems, gas hot water systems, instant gas hot water systems and compatible valves, pipework and fittings online at Hot Water Outlet.