Solar Hot Water without solar panels

Whilst the most efficient way to get your hot water is solar with a gas boost, putting panels on your roof may be a no-go for some people.

Your roof may be chock full of solar electricity panels, or you may have particularly delicate or shaded roof, or live in a heritage listed house. If that is the case then you may be surprised to know that there is an alternative that is just as energy efficient as solar panels with an electric boost.

It is called a ‘heat-pump’ system. It is basically a reverse cycle air conditioner running permanently in heating mode. And whilst people may argue that it is not true solar, I’d say they are wrong. That’s because a heat pump transfers the heat that is already in the surrounding air and ‘pumps’ it into the water. This heat’s original source is, of course, the sun. So I’d argue that a heat pump is solar powered with an electric boost.

A heat pump is driven with electricity, but is about 5 times more efficient than a conventional ‘kettle’ style electric heater. In fact the CSIRO calculate that it will use the same amount of electricity over a year as a solar panel hot water system with an electric boost.

Typically the whole shebang comes as one unit, so everything is mounted on the tank like in the picture. The fan is on top with the tank underneath.

Here are the pros and cons of a heat pump system over a ‘conventional’ solar hot water system:

PROS:

• No roof mounted hardware.
• Doesn’t require direct sunlight.
• No danger of overheating in summer.
• Relatively simple installation, as it is an all-in-one unit.
• Easy to protect from hail.

CONS:

• Federal rebate is only $600 for heat pumps compared to $1000 for conventional solar HW.
• The compressor can be noisy.
• Work best in warm-hot climates.
• They may use ozone-depleting CFCs in their coils.
• The neighbours won’t know you have a solar powered hot water system (less green street-cred)!

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