I was wondering if anyone had any particular knowledge about the relative benefits (economic and ecological) of these two methods of heating water for a home.

According to the manufacturers of heat pumps, they're more efficient than solar roof top systems, particularly in winter. But they also suggest that climate can play a part.

I live in Canberra in Australia. Our climate is fairly dry, and we have a fairly large temperature variation through the year, from minimums between 0 and -10 C in winter, to maximums over 35 in summer.

Another issue with the heat pumps is that if they draw heat in from the air around the pump, would it make sense for them to be placed where the air is going to be warmer? The main problem is that we don't really have anywhere convenient on the sunny sides of the house to place the system. Will the system still operate okay on the shady side? Or would it be better to place some part of it on the roof?

Cheers

Air sourced heat pumps are very inefficient at providing heat in cold weather although they work adequately down to around 5º C. They are also better utilized in humid climates.

Geothermal heat pumps work much better as long as the coil is properly sized, there is plenty of moisture, and the coil is buried well below the frost line. Burying the coil increases the cost of course.

Solar water heaters work quite well in the summer, if you can spare some sun-facing room on the roof and somewhere to hide an extra water tank. You can even power the recirculation pump with a solar cell. Their efficiency depends more on cloudiness and latitude than the temperature outside. In the winter they are still usefull at preheating the water for a regular heater of better yet a demand heater.


A local dealer would know your regions requirements the best. I would personally want to talk to some former customers though.

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