Propane isn’t much cheaper. I pay $200/mo for 11 months of oil which includes yearly maintenance/cleaning with 24/7 support, all parts included besides the boiler crapping out. The market violitility has increased on propane, almost making the difference not as it once was. Most newer homes here are going with propane though, it’s deff the ‘cleaner’ of the two.
Solar energy is the next big ticket item, as you, but just waiting for the tech and pricing to improve.