Lots of them around (especially in my state, Queensland, which has hot summers and mostly fairly warm days in winter), but you need to use a gas or electric boo

Lots of them around (especially in my state, Queensland, which has hot summers and mostly fairly warm days in winter), but you need to use a gas or electric booster to have hot water all the time. So in a lot of places it actually turns out to be fairly similar energy use to put in a high-efficiency heat-pump hot water heater. I've just evaluated this because I want to replace the hot water system at my house, and I was initially thinking of solar because my parents have had one for years and it generally works well but the heat pump will be cheaper and I'll eventually get some PV anyway. So all in all it should be a bit cheaper and more efficient per square metre of roof space.