The parts of a solar system
Collectors. Flat panels or evacuated tubes on the roof, angled to the sun. The ACT's loan scheme names evacuated tube solar hot water systems among its eligible products.
Tank. Either up on the roof with the collectors, or on the ground with a pump circulating water up and back.
Booster. A gas burner or an electric element that heats the water when there isn't enough sun. Consumer Affairs Victoria's rental standards refer to an electric-boosted solar water heater.
Signs your solar system needs a plumber
- The booster seems to run all the time, even in sunny weather.
- Water dripping from the roof unit, or stains on the ceiling below it.
- Cracked panels or broken tubes.
- Lukewarm water on clear days.
- On a ground-mounted tank, a pump that runs nonstop or never runs.
What a plumber will do
Check the booster
A plumber will look at the booster's settings and whether it's doing all the heating.
Go up on the roof
They inspect the collectors, the pipe runs and the insulation, using safe access.
Test the circulation
On a split system, the pump, the controller and the sensors all get checked.
Check the tank and valves
The relief valve, the anode and the tank body decide whether this is a repair or a replacement.
STCs and other discounts
Solar water heaters can earn STCs when the system is under 700 L and the model is on the register. The certificates lower the price; they don't cover it.
In Victoria, eligible owner-occupiers may also get a Solar Homes rebate on solar hot water. In the ACT, evacuated tube systems qualify for Sustainable Household Scheme loans. Details: STCs, Victoria and ACT.
Tempering rules that single out solar
South Australia. A temperature control device is needed on all new solar water installations, solar water heater replacements included. That's stricter than SA's rule for other replacements, which only need one where one was already fitted.
NSW. One is needed when a heater is replaced, but not when the only job is replacing a solar collection panel.
Other states are on our tempering valves page.
Who can install solar
In Queensland, solar systems must be installed by a hot water installer with a QBCC solar and heat pump endorsement. For STCs, the system must meet the installer licensing requirements of the relevant state or territory.
In a Victorian rental, from 1 March 2027, a system that permanently fails can be replaced with an electric-boosted solar water heater as well as a heat pump.
In South Australia, replacing a solar water heater, like any water heater, needs an electronic certificate of compliance from the plumber.
From the ground, not the roof
You can
- Check the booster's switch is on, or its gas supply.
- Look from the ground for broken tubes or water on the roof.
- Note whether the problem gets worse on cloudy days.
- Keep trees trimmed back from the collectors, where you can do it safely from the ground.
Leave to a licensed plumber
- Anything on the roof.
- Booster elements, burners and controls.
- Pumps, sensors and controllers.
- Replacing collectors or the tank.
Questions for a solar plumber
- Is the fault in the collectors, the booster or the tank?
- Can you replace just the collector panel, and does that need a tempering valve here?
- Is the replacement model on the register, and under 700 L?
- Do you hold the licence or endorsement my state needs for solar?
- Is the roof sound enough to carry the system again?
What we would do
If the booster is doing all the work, have the collectors and circulation checked first. A solar system that never uses the sun is just a gas or electric water heater with extra plumbing. If the tank is leaking, replace it, and compare solar with a heat pump while you're choosing. A plumber who specialises in solar will know both.