If you wanted to spend,
this setup will do a lot, fridge and window unit no problem, likely for a couple days or more without recharge. Battery is around $1200-$1400, all in one inverter/charge controller is around $600-$700, and solar panels are cheap on Craigslist. Then it's just little bits and bobs from Home Depot.
If you wanted to go lower specs and price, something like
this,
this, and
this may be enough to run a fridge as long as the startup current from the compressor isn't too high. The battery may or may not be enough to run overnight, but you really don't need 24hr fridge operation to keep food cold. When the power is out here in the summer when it's in the 90's, we'll run the generator starting from around 10am-noon depending on how hot it's getting, to about 10pm, then it's off overnight. Something like ice cream would be soft, but not melt, and meat would still be frozen.
If you're flexible, you might let a good bargain guide you, like
this looks like a deal. And if you wanted super budget,
this charge controller is fine. Then maybe gamble on something like
this. It's possible this performs just as well as the above, but for hardly any moneys.
Then you just need to find some solar panels on CL that fit within the max DC input of whatever charge controller is at the price point you like. Panels are pretty cheap and plentiful these days. Better to buy used on CL, because shipping generally makes low quantities not worth ordering new, though you may find some places like Home Depot that will ship to a local store for free.
But, just for learning, a small battery box for charging phones/laptops will teach you just as much as any of the above,
this,
this, and
this.
I think maybe pick a ballpark price point of what seems interesting.