Do your research if considering a heat pump
Just came across this podcast on heat pumps in Australia. 403 Forbidden (this link looks weird but works for me)
From units that have a back up heating element, to uncertainty about controls over end of life capture of high potency green house gas refrigerants.
Our old immersion unit recently died and we had a look at going to a heat pump, but decided to stay with the old fashioned one again and moved it to a central location in the house rather than way at the opposite end from the main hot water usage rooms. We also had it connected to the tariff 11 supply rather than off peak tariff 33 and installed a timer and a contact so it only draws from 9am-3pm, the peak solar times. The unit also has only a small element that only draws 1.8kW, so on a sunny day (and even with some overcast) will be completely supplied by solar. The unit has been in a couple of weeks now and we see it heat from 9-10 only, which corresponds to us using about 35l of raw (not tempered) hot water a day.
So the win win for us is 1) we have a more efficient location for the unit, 2)we heat mostly on solar now, not fossil fuel electricity, 3)we eliminated tariff 33 and the ongoing fees for having that service and 4) we don't have to worry about the destiny of the refrigerant at end of life.