I have a Truck camper with plenty of solar, have already gone days, could go weeks. Seriously, if you want to be prepared get a camper, large or small. Fill the roof with solar panels, as much space as you can on the roof or money you can afford. Get some good LiFePO batteries 200 Ah is reasonable and a good MPPT solar charger. As long as there is a little sun or even light I could run my little propane furnace until my propane runs out. Even if there is no sun I can charge with my Truck and the alternator as long as the diesel tank can run it. 35 gallons could charge the batteries for weeks probably. Additionally with the 3000 watt inverter I can run anything including my air conditioner. That would certainly would be a non-essential luxury though in a time of crisis. With some extra tanks of propane and mild weather I could go months.