Thanks @readiescards for the comprehensive update. Very helpful. I think the upfront costs seem worth it for the long term saving in maintenance, electric generation and storage costs.
My main worry is the siting "a good distance away" as I won't be able to put it further than 10m from the house. I can disguise the visual impact but smell probably not.
Presumably even the air blower type units have to have some kind of air outlet? Or does that blown air find its way out by traveling back up the soil pipe to the the house roof-level vent?
