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Solar-powered hot water systems

Trust the Caloundra solar hot water specialists. We provide fast, compliant installation, repair and replacement of both roof-mounted and split solar hot water systems — durable workmanship and reliable service.

Solar hot water systems are available in two distinct types

Solar hot water systems come in two primary configurations—roof-mounted and split—offering a variety of tank capacities and design choices to suit different homes, climates and locations. Aside from the environmental upside of lowering energy consumption, the main benefit is the noticeable reduction in your electricity bills.

Electric hot water units operate similarly to a kettle, using a heating element, and in Queensland they’re typically found in 1.8kW, 2.4kW and 3.6kW sizes (the larger 4.8kW elements are rarely used because of their heavy power demand). These element sizes are common across leading brands such as Rheem, Dux, Vulcan, AquaMAX and Rinnai.

Remember that element size does not affect the efficiency rating. A 1.8kW element consumes half the power of a 3.6kW element, but will require about twice as long to heat the same volume of water to the same temperature.

Contemporary electric hot water systems are constructed with either:

– Mild steel tanks finished with vitreous enamel and safeguarded by a sacrificial anode, or

– Stainless steel tanks for greater longevity.

Traditional copper-style water heaters are no longer manufactured.

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Roof-mounted thermosyphon solar hot water systems.

Roof-mounted solar hot water systems This is the classic solar hot water arrangement where both the storage tank and solar collectors sit on the roof. These units have been common across Australia for decades and remain a reliable option for heating household water. How they work The system relies on simple thermosyphon principles: Cooler water falls to the lowest part of the tank and moves into the solar collector panels. As the water in the panels warms, it rises and returns to the storage tank. This natural circulation keeps the tank topped up with hot water. Modern improvements Older installations frequently discharged excess water through the pressure and temperature relief valve when the system overheated. Contemporary thermosyphon models feature a flow control valve that limits circulation once water reaches about 60°C. This reduces unnecessary water loss, though it can also mean a slightly lower usable hot water capacity compared with older designs. On very hot days these systems can sometimes make a rumbling sound when taps are opened, caused by superheated water moving through the collectors as pressure drops. Tank & collector options Collectors vary in size by manufacturer, offering different levels of solar capture. Evacuated tube collectors are generally not advised in Queensland — they can produce excessive solar gain and risk boiling off water for much of the day. They are better suited to cooler, more southerly climates. Storage tanks are commonly available in stainless steel or vitreous enamel lined mild steel. Considerations The primary disadvantages of roof-mounted systems are their visual impact and weight: A full storage tank can exceed 500 kg, which places a substantial load on the roof structure. Many homeowners also dislike the prominent appearance of the large tank. Call Caloundra Hot Water on 1300 218 122 for clear, professional advice from your local Caloundra plumber on the best solar hot water system, installation or repairs for your home — including gas and electric options.

Ground-mounted split-system solar hot water units

A split solar hot water system positions the storage tank at ground level while only the solar collectors sit on the roof. Collectors may be flat plate panels or evacuated tubes — however, evacuated tubes are generally not suited to Queensland’s climate because they can overheat, lose water and produce avoidable rumbling sounds. How they work Storage tanks commonly come in 250L, 315L and 400L capacities. A temperature sensor at the panels and another at the tank track the difference in heat. When the panels are at least 10°C warmer than the tank, a small circulation pump (typically 25W or less) starts, circulating around 2–3 litres per minute through the collectors. This process moves heat from the collectors back into the tank, and natural convection causes the hottest water to rise to the top. The pumps run quietly and use very little electricity — often less energy in a day than the display on your microwave. Build & installation Copper flow and return piping should always be used to cope with high temperatures. At Caloundra Hot Water, we install these pipes in one continuous run with no joints or fittings in the roof cavity, and insulate them with 25mm high-temperature, UV-rated insulation to reduce heat loss. Performance Collector temperatures can reach up to around 120°C, and some systems allow storage tanks to climb to about 75°C. Once the tank hits its set temperature, water will stay in the collectors until usage lowers the tank temperature enough to restart circulation. Why quality matters Selecting a reputable brand is essential. Many low-cost imports use inferior components that lead to significant problems and unexpected expenses for homeowners. The additional upfront cost for a dependable system is minor compared with the long-term reliability and peace of mind. Contact Caloundra Hot Water on 1300 728 122 for straightforward, impartial advice on selecting the right solar hot water system, installation and repairs.

Flat-panel solar collector

Flat plate collectors are the most widely used solar hot water panels across Australia and perform well in nearly any climate or setting.

How they operate

Each panel contains a copper manifold fitted with flat plates that are powder-coated black to absorb maximum heat.

Water moving through the copper piping picks up heat and circulates by either:

Thermosyphon action (in roof-mounted setups, where hot water naturally rises and cold water sinks), or

A circulation pump (in split systems with the storage tank located at ground level).

The collectors are sealed beneath toughened glass and within fully insulated frames to trap warmth and provide lasting reliability.

Efficiency

These panels will produce heat even without direct sun exposure.

On cloudy days they can still attain roughly double the surrounding air temperature — for instance, with an ambient 26°C the panels can heat water to about 52°C.

Installation

The required panel count is determined by the size of your storage tank.

Typically two to three panels are needed to suit the capacity of most common hot water storage tanks.

Evacuated-tube solar collectors

Evacuated tube systems consist of multiple glass tubes, each housing a copper heat pipe filled with a thermal transfer fluid. The tubes slot into a top-mounted manifold on the collector, where solar heat is captured and conveyed to the storage tank. System design They are offered in arrays of 12, 18, 24 or 32 tubes, selected to suit tank capacity and the specifics of the installation. Extremely efficient—under strong sun the glass surface of the tubes can reach temperatures approaching 250°C. Suitability These systems were developed for cooler European-style climates with lower sun angles and less intense sunlight. They perform well in Australia’s cooler regions such as southern NSW, Victoria, South Australia and southern WA. In Queensland, however, their high efficiency often causes issues like overheating, increased water loss and audible rumbling from boiling within the tubes. Considerations Only a small number of suppliers still carry evacuated tube systems in Australia. They typically cost around $1,000 more than flat plate collectors and rarely provide advantages in Queensland’s climate. For most Caloundra homes, we don’t recommend evacuated tubes—flat plate hot water systems usually offer superior value and more reliable performance locally.

Contact Caloundra Hot Water on 1300 728 122 for professional, impartial, fact-driven guidance from a local Caloundra plumber with over 20 years’ experience serving South East Queensland.

You can call us evenings and weekends on 0413 861 166 for after‑hours assistance.

At Caloundra Hot Water, we carry a broad selection of solar hot water systems on-site for prompt installation. Because we stock the leading models we supply, you won’t be left waiting for deliveries—your new hot water system can be fitted quickly without unnecessary delays.

We also provide Easy Payment Plans to help spread the initial cost. With terms ranging from 1 to 3 years and fortnightly payments following a small deposit, your repayments can be comparable to the savings you’ll see on your electricity bills.