In winter 200-300W load? How do you heat your house?
I'm from EU, a relatively "cold" (French Alps at 1030m) place but definitively not that cold (peak cold -25℃/-13℉ in early morning, -8/10℃ (14/18℉) during the day between January and February), with a new home witch means well insulated, with a proper VMC, water-water heat-pump etc, and well... The MINIMUM load during night and early morning is around 1kW. IF Sun shine during the day, well, the load is not much an issue from 9h30 AM to 3 PM, but for the rest is on grid.
Of course old homes heat with gas/oil/wood/* so need far less electricity (still IME a bit more than 2-300W base load though) BUT apart of wood coupled with large hot water storage (to been able to sleep instead of charging wood every hour) if you are not living in a relatively cold place I doubt you have a 6-12 month gas/oil/wood reserve at home and during such "cold episode", being very rare so far, getting new "fuel" would probably be not that easier...
I've made a small p.v. with lithium storage as a very expensive UPS for the house, being relatively autonomous in summer I hardly can be autonomous in winter: in some RARE winters like the last one where Sun shine almost all day I can survive a day to the next cutting the heating depending on battery SOC, but in case of a day without enough Sun light I'm still on grid or on emergency generator backup... Having a real autonomy IME is more a dream than something feasible, at least something feasible at human prices because spending the price of a house just in batteries who might last at maximum 10 years for some rare episode is not really a sustainable price...