You can tie in a batch water heater with a tankless very easily.
These would be most useful in sunny climates and could be drained in
winter. you might not even use the tankless in summer which would
save money. I usually like room temp showers on hot days anyway so I
don't even turn on the tankless (it has a switch for that purpose
and sits right next to my shower.)
As to being sustainable you might be interested to know that propane
is a by-product of natural gas and oil processing. No one drills for
propane and if not sold to us it would have to be burned by the
processing plants to keep it from building up. It should be much
cheaper than it is but of course the price is controlled by the oil
and gas companies. Just thinking out loud.
http://www.freewebs.com/simplesolarhomesteading
Labels: Wind Turbine