I can't be certain about tax or legal matters.
I read "system placed in service". I could imagine that adding panels to an existing system, or replacing inverter of an existing system, might not qualify. But if you have or had a system, and you bought a new system and placed it in service, I read that as qualifying. If you later added to that system some panels you salvaged from the fire, so what?
I would consider each system that captures photons and delivers electricity to be a system. Electricity as 60 Hz AC wired to your electric panel seems like a good dividing line, and you could have more than one of those.
I would think a drop-in cooktop, clamped to the counter top, is real property. Same a built-in dishwasher and a water heater.
Slide-in range, refrigerator, laundry machines, those I could consider personal property. They may have been itemized as such when property was bought from previous owner.
If real property, unlike personal, you can probably shift around where the insurance money is spent. I shop a lot on eBay, Craiglist, and at ReStore (Habitat for Humanity's thrift store.) You could replace appliances for a fraction of new.
Much of the cost of building is the high markup each of the trades will charge you as a retail customer, compared to what they would get if contracted for a subdivision. But buying skill and quality is not easy or cheap.