Earlier quoted context omitted.
I'm jealous of the learning and hobby project. Though, the returns are (edit: "not great") if the figures above INCLUDE net metering revenues. Heatpump = Negative IRR until y8 Solar = Negative IRR until y16 Heatpump + Solar = 0 NPV through y25 | 8% discount rate
I'm jealous of your financial learnings. However, your model is not accurate as it doesn't factor in the 4 degree improvement in comfort and indoor pollution from propane furnaces: Propane furnaces can cause indoor pollution through the release of pollutants like carbon monoxide (CO), nitrogen dioxide (\(NO_{2}\)), and benzene, which are byproducts of combustion. It also doesn't include the negative externalities bec…
A modern furnace works via a heat exchanger, where the combustion produced pollutants never mix with the indoor air being pushed through. All pollutants are expelled outside via a property functioning chimney. This is one reason why you should have the furnace (and chimney function) inspected annually. Aging heat exchangers will show hotspots before there is a possibility of air being mixed, giving plenty of time to plan for a replacement. Of course there is a possibility of failure, which is why you should have a carbon monoxide detector.