The south roof of your house looked like an excellent solar hot water location to me, but you'd have a better idea how it lies relative to the sun, being there all the time.
Most of the benefit of gas tankless is that it only heats as needed, rather than keep a big thermal mass hot 24/7/365 like a tank heater or your oil furnace. You can get tankless electric, but the economics are not so good. I am not aware of any tankless oil units. We use solar as pre-heat for our gas tankless, so it doesn't run much in the summer, and not as much as it would otherwise in the winter.
You can always locate the propane tank well away from the house, or underground. Yes, a gas leak in the house may blow it up, but a serious oil tank leak generally leaves you with a demolished house and your own personal brownfields site.
Re: Prophet without honor...
Most of the benefit of gas tankless is that it only heats as needed, rather than keep a big thermal mass hot 24/7/365 like a tank heater or your oil furnace. You can get tankless electric, but the economics are not so good. I am not aware of any tankless oil units. We use solar as pre-heat for our gas tankless, so it doesn't run much in the summer, and not as much as it would otherwise in the winter.
You can always locate the propane tank well away from the house, or underground. Yes, a gas leak in the house may blow it up, but a serious oil tank leak generally leaves you with a demolished house and your own personal brownfields site.