Solar Hydronics: Thermal Energy for Your Water and Household Space

Information verified correct on October 21st, 2016

The average household’s biggest energy use is heating water. What if we told you that there could be a way to reduce this and save money?

The sun does a great job of heating water. It’s called solar hydronics, or solar thermal. It's a pipe system that gets attached to your roof and they're filled with fluid that gets heated by the sun. The hot fluid then gets sent to a storage tank that heats fresh water. The water gets pumped around your home, to your central heating and hot water faucets.

How does it work?

There are three parts to a solar thermal system.

  • Rooftop tube collectors. These a row of black pipes that will sit on top of your roof. They’re made of heat conductive materials and will attract and store the heat generated by the sun. They are filled with a special fluid which is heated up before being passed on to…
  • The hot water storage system. This tank then stores the heated fluid in specially designed coils which minimise heat loss and maintains a high temperature. These coils are then used to heat water for your...
  • Standard in-home water systems. This will include central heating if you have it, and your regular hot water shower and sink systems around the house.

Does it actually work?

Yes. The sun is an extremely efficient heater, and even on days when it may feel cold to you, the sun consistently produces energy. The pipes which your rooftop hydronic systems are made from are extremely efficient at capturing this energy and storing it as heat. The hot water is then sent to heat exchange coils within the storage tank, which are specialised and heavily insulated to minimise heat loss.

How much can I save using solar hydronics?

The total cost will depend on your personal situation But we can provide a rough idea.  A 1,000 litre system can offer a 57% return and pay for itself within 2 years of installation. So despite the fact that there is an additional expense in installation, you could find yourself getting free hot water within 2 years.

How much does it cost?

This will vary based on your home size and location, but as a general rule a solar heating system should cost around $32,000 for an average 50 sq. metre home, or $40,000 for a 10sq. metre home. Though it's expensive, it could also save you an estimated $2,000 per year on your current energy usage.

What about when it’s winter?

Solar thermal is designed to work well in all climates including cold. Here in Australia, where we enjoy a very moderate climate the cold shouldn’t be a problem and your system will continue to generate hot water even on cooler days. In unusually prolonged periods of cloud cover or extended periods of extreme low temperatures your system may work with less effect. However, in these times you can use your backup hot water system to heat water.

Generally speaking you don’t get solar thermal to replace your traditional boiler, you get both and use your solar system the majority of the time, but the boiler will still be there if required. If you live in an area that experiences extreme cold temperatures, then speak to your energy consultant about whether solar hot water is right for you.

Shirley Liu

Shirley is's publisher for banking and investments. She is currently studying a Masters in Commerce (Finance) and is the author of hundreds of articles. She is passionate about helping Aussies make an informed decision, save money and find the best deal for their needs.

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