theres a large amount of space on the other side of the fridge for a battery, perhaps large enough to fit an old EV battery mounted vertically

Yeah the solar panel needs sunlight but I’ll bet the fridge doesn’t have to work as hard if it’s not in direct sunlight all day. And it’d protect it from the rain. I think they usually run these inside a library or co-op where someone will tend it and keep an eye on it.