The short answer
If your solar hot water is lukewarm or cold, especially in winter, check the booster is switched on and has power or gas. Many Perth solar systems need that booster when the sun isn’t enough. Roof tanks and collectors can also leak, and a tank leaking from the base usually means replacement, not a patch. For solar hot water repairs and booster faults, call McDermott Plumbing on (08) 6187 3999 or text 0406 882 648. Gas booster work is licensed gas fitting; electric booster circuits may need an electrician as well as a plumber.
Winter lukewarm water — start with the booster
Perth winters still have sunny days, but short days and cold nights mean many solar hot water systems rely on a gas or electric booster to finish the job. If the booster is off, tripped, or faulty, you’ll get water that’s only as warm as the collectors managed — often not enough for a morning shower for a full household.
Before you assume the panels have failed, check the obvious: booster isolation switch or circuit breaker on, gas supply on for gas boosters, and any controller set to allow boost. Controllers and timers differ by brand — use the label on the unit, not a random YouTube guide for a different model.
- Electric booster: check the hot water / booster circuit breaker and any off-peak timer
- Gas booster: pilot or ignition path, gas on, error codes on continuous-flow boosters
- Controller set to “boost,” “holiday,” or a timer that never enables boost
- System only warm on clear afternoons — classic booster or circulation issue
Roof tanks, collectors and leaks
Close-coupled systems put a tank on the roof with the collectors. A leak up there can show as damp ceilings, water in the eaves, or a tank that’s emptying itself. Leaks at fittings and valves can often be repaired. Water weeping from the tank shell or base usually means the inner tank has failed — the same end-of-life story as a ground storage unit.
We work on the plumbing and gas side: tanks, valves, tempering, gas boosters and consumer pipework. Roof access and safe work at height are part of how we plan the job. We don’t claim solar-electric panel or inverter work — that’s an electrician or solar tech if the fault is on the PV side of a heat-pump or hybrid setup.
Repair or replace a solar system?
Boosters, valves, sensors and some circulation faults are worth repairing when the tank and collectors are sound. Replacement enters the conversation when the roof or ground tank is leaking from the shell, when the system is very old and parts keep failing, or when a household’s hot water use has outgrown what the collectors and booster can deliver.
If you’re moving off solar to a storage, continuous-flow or heat-pump unit, see our hot water systems page for the options we supply and install. We’ll give a straight opinion based on what’s on your roof or wall — not a sales script.
What to tell us when you call
- Roof tank, split system, or ground tank with solar collectors.
- Gas or electric booster — and whether other gas/power in the house is fine.
- Only cold in winter, or cold year-round.
- Any ceiling damp, roof stains, or water under a ground tank.
- Brand/model photos to 0406 882 648 and your suburb.
Common questions
- Why is my solar hot water not hot enough in winter?
- Most systems need the gas or electric booster when solar input drops. Check the booster is on and working. If it is and water is still cold, call us — it may be a booster fault, circulation issue or tank problem.
- Can you repair a solar hot water booster in Perth?
- Yes for the plumbing and gas side: gas boosters, valves, tanks and related pipework. Electric booster elements and circuits may involve an electrician. Call (08) 6187 3999 or text 0406 882 648.
- My roof solar hot water tank is leaking — can it be fixed?
- Leaks at fittings or valves are often repairable. Water from the tank shell or base usually means the tank has failed and needs replacing. Turn off the water supply to the unit if you can do it safely and call us.
- Do you install replacement hot water if solar isn’t worth fixing?
- Yes. We supply and install storage, continuous-flow and other options on our hot water systems page. We’ll say honestly when repair still makes sense.
- Is solar hot water repair the same as a gas leak call?
- No. A booster or tank fault is a booked repair. If you smell gas at a gas booster or anywhere else, leave and call ATCO 13 13 52 first — see our gas leak page.
Related pages
Official sources
Last updated 2 October 2026. General information only. Every property is different, so call us to talk about yours.