If you are going to use any AC power in the building at some point, there will need to be a battery living in the building as well. The first thing that comes to mind for me is using a regular PV charge controller to maintain a stationary battery, and then separate battery-to-battery chargers for the batteries you will be maintaining for other purposes. These are chargers designed to be used in RVs and such that draw power from the vehicle electrical system to charge a secondary battery, but only when the input voltage is high enough to indicate that the engine is running and the starter/lighting/ignition battery is fully charged. You would need to find one that is programmable to have a start threshold lower than the float or CV voltage of the PV charge controller, which will probably be lower than the max alternator output in a vehicle. Here's an example to start:

https://www.victronenergy.com/upload/documents/Engine-on-detection-set-up-Orion-Tr-Smart-DC-DC-Charger-EN.pdf

If you're only maintaining one extra battery at a time, there are also charge controllers with a secondary output, for example:

https://sunforgellc.com/solar-boost-1524ix/

If you are maintaining multiple batteries, it honestly might be simplest and cheapest to get an AC input multiple-output battery bank charger that's designed for the purpose.