A solar hot water system installed will cost you on average between $3000 and $7000. There are many factors affecting the price, including the system and size you choose, installation costs, rebates available in your area and the government-regulated Small-Scale Technology Certificates (STCs) pricing at the time of purchase.
It might surprise you to know that on average, one third of your overall energy bill is from hot water usage. While a solar hot water system is a bigger upfront cost than electric or gas alternatives, you can expect to save 70-80% on your hot water bill so they definitely pay themselves off in the long run as well as being better for the environment.
The main systems to choose from are:
Flat plate systems
These start from $3000 for an imported system. The most popular Aussie made brand, Solahart, sized for a family of 4-5 will cost around $4000.
Flat plate collectors use copper pipes running through a glass covered collector, often connected to a water storage tank on the roof. The sun heats the copper pipes and the resulting hot water is thermo-siphoned out of a storage tank.
Evacuated Tube Systems
These cost from $6000 and are recommended for colder climates, such as Tasmania or Victoria. They are generally more efficient and require less roof space, but are more costly upfront. Evacuated tubes have two glass tubes fused at the top and bottom and the space between forms a vacuum. A copper pipe runs through the centre that is then connected to a slow flow circulation pump which pumps water to a storage tank below to heat the water. The hot water can be used at night or the next day due to the insulation of the tank. They can extract the heat out of the air on a humid day and don’t need direct sunlight.
For both flat plate and evacuated tube systems to service a four-person household, you will need two panels and a larger tank (300-360L) to compensate for cloudy days.
Heat Pump Systems
These range from $2500-4000 and are an alternative for those who don’t have the roof space for solar panels. They use the same connections as an electric system so are easy to install. They work like a reverse refrigerator, transferring heat in the air outside of the unit to the water inside through a heat exchange system. The pump produces 3-5 times the amount of renewable energy than electricity to power the unit. Be aware that the compressor can be noisy, much like an air conditioning unit compressor.
A 270–315L tank will generally service a four-person household.
Other things to consider include:
Be sure to check your roof is suitable for solar panels. There could be extra costs associated with making it structurally sound to take the extra weight.
Electric and gas boosters
On cloudy days your system will need a lift through an electric or gas booster system. With a gas water heater, boosting only occurs when hot water is used, whereas an electric system boosts when the internal temperature lowers.
Retrofitting for solar
If your existing hot water system still has plenty of life left in it, you can convert it for solar heating too.
Pricing information correct as of March 2018.