Solar hot water FAQs

What size system will I need?

Use the table below as a guide to choosing the appropriate-sized solar hot water system for you. However, consult your supplier for specific size recommendations.

Number of people in your house

Capacity (litres/day)

Solar collector size (m2)

1 – 2

160 – 200


3 – 4

300 – 370


5 – 6



Will I also get power from this system?

No. Solar hot water systems only provide hot water that is stored in the tank.

Does solar hot water work in cooler climates?

Yes. While they work best in the warmer, northern parts of Victoria, they still perform well in the cooler, southern regions.

Will I run out of hot water?

No. Solar hot water systems are generally designed to store larger amounts of hot water than conventional systems. A correctly sized system will have hot water left over from the previous day.

However, on cloudy or rainy days, or days when lots of hot water has been used, the water in the hot water tank may need to be heated by a booster (commonly gas or electric) when the water temperature drops below the thermostat setting.

Can I retrofit a solar collector and tank to my existing electric hot water system?

Yes, but it’s likely to be more efficient and economical to buy a new gas or electric-boosted solar system complete with new tanks. This way you will have a warranty for all the components of your new hot water system.

How much does it cost?

Solar hot water systems vary in price depending on the model, tank size, number of panels or tubes, and the capacity of the booster. The cost will also depend on whether or not an incentive is available and the size of the incentive.

Is solar a good investment?

In terms of the environment, solar hot water is an excellent investment and should be considered. However, to determine whether solar hot water is a good financial investment, the following factors need to be considered:

  • your geographic location
  • your roof area and orientation
  • your hot water usage
  • the performance of the system
  • the type and cost of the system
  • the type of auxiliary heating used
  • the installation costs and requirements
  • if there are incentives available to you.

More information

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Get advice on energy efficient hot water systems with the Smarter Choice retail program, where trained retail staff can advise you on energy efficient heating choices in store.

Find your nearest retailer to take that next step towards being a more energy efficient household.

Download the Smarter Choice fact sheet on solar hot water below.

Document | PDF | 127KB
Fact sheet: Solar hot water