Is my idea crazy or should I pursue it further? (EV as sole house battery)

[Rolfe]

If they can extract enough heat from the sea water of the north Atlantic to heat Iona abbey, you'd be laughing.

 

[Bam Bam]

We have a bit of a pond out the front, the Murray River, but that's a long way to run the pipes

I bet that is a good temperature all year round. Pipes would need to be well-insulated as well, though. Otherwise you'll end up with the same temperatures as an air-source!

but we could always put a few coils in the rain water tank, it'd take a while to heat up 10,000 ltrs, but I'm not sure how much heating it would provide in winter ..... although it only drops to 0* for a few hrs in the morning maybe 3 days a yr ..... so it would probably store enough heat for that ......
Thanks for the idea, certainly worth a try ......

Interesting!

No chance you'd boil it then?