If you have a question about solar hot water not covered below, try our FAQ or please feel free to contact our friendly team. They’ll be glad to assist you. Don’t forget to check out our great range of solar hot water systems and rebate information. Or you can complete a brief form for a free, no-obligation solar hot water quote! In the mean time, read on to see how solar hot water works.

How solar hot water works

Aside from cost and greenhouse gas emissions savings, the beauty of a solar hot water system is its relative simplicity and durability.

There are two types of collectors in solar hot water services:

  • flat plate collectors (suitable where tank roof mounting is necessary)
  • evacuated tubes (more efficient and great for frost prone areas)

Flat panel and evacuated tube solar collector

Flat plate solar collectors

Flat plate collectors work on copper pipes running through a glass covered collector, often connecting to a water storage tank on the roof. The sun heats the copper pipes and the resulting hot water is thermo-siphoned out of storage tank.

Evacuated tube solar collectors

Evacuated tubes consist of two glass tubes fused at the top and bottom. The space between the two tubes is evacuated to form a vacuum. A copper pipe (called a heat pipe) running through the centre of the tube meets a common manifold. That then connects to a slow flow circulation pump that pumps water to a storage tank below, thus heating the water during the day. The hot water can be used at night or the next day due to the insulation of the tank.

Evacuation tube systems are superior as they can extract the heat out of the air on a humid day and don’t need direct sunlight. Due to the vacuum inside the glass tube, the total efficiency in all areas is higher. There’s also better performance when the sun is not at an optimum angle. This could include times such as when it’s early in the morning or in the late afternoon.

View our range of evacuated tube systems.

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Evacuated tube vs. flat panel – which is more efficient?

The short answer is evacuated tube. It’s not only more efficient, but also more durable and cheaper to repair should there be accidental damage. Learn more about evacuated tube vs. flat plate collectors.

The water tank and thermal mixing

As heat rises, the hot water delivering to the tank from the solar collector comes from the top for use in the house.

Solar water tank and thermal mixer: How solar hot water works

The temperature of the water may exceed 60 degrees Celsius (a requirement to kill bacteria). In order to ensure a safe temperature at the taps, a tempering valve will reduce the temperature to around 45 degrees.

Electric and gas boosters

While the sun can provide sufficient energy to provide you with plenty of hot water for most of the year, there may be extensive periods of cloudy, cold days where your system will need a helping hand. This functionality comes in the form of an electricity boosted or gas booster system.

Gas and electric boosting for solar hot water

Boosting using a tankless gas water heater is the most efficient method as boosting only occurs when hot water usage occurs. With an electric system, the tank heats as soon as the internal temperature drops.

Retrofitting for solar hot water

If your current hot water system has plenty of serviceable life left or you’ve recently purchases a gas/electric hot water system, you can still go solar with a retrofit kit!

Hot water and household energy usage

Electric and gas hot water systems account for approximately 20% of a household’s greenhouse gas emissions. Aside from Energy Matters’ discounted prices on solar hot water equipment and generous government rebates, by installing a solar water system you will reduce these emissions and also save up to 75% of your water heating costs! the table below comes from the Department of Environment and Climate Change NSW.

NSW Energy Usage

A gas-boosted solar water heater will be the most environmentally friendly option as shown below.

 Solar Hot Water Greenhouse Gas Emissions

Annual water heating costs comparison

Using the table below, determine an approximate annual cost of water heating with your current unit and what it would cost with a solar hot water system. As you’ll see, solar hot water savings are substantial. The information is from Sustainability Victoria and assumes energy tariffs of:

  • natural gas (1.75 c/MJ),
  • LPG (4 c/MJ),
  • peak electricity (28 c/kWh),
  • off-peak electricity (18 c/kWh)


These savings, in addition to solar hot water rebates, make solar hot water not only the right environmental move, but also financially rewarding one in most circumstances!

Get a solar hot water quote today!

Start now on your environmentally friendly and cost-saving solar hot water system! Contact our team of friendly experts for free, no-obligation advice or try our solar hot water quoting system! Don’t forget to check out any applicable rebates and our specials. We can also arrange for installation of your system just about anywhere in Australia!