You could run the refrigerator on this, assuming it draws about 400 watts:
http://www.powerenz.com/store/index.php?_a=viewProd&productId=156
Thing is under your scenario it might be a good idea to have four of them so you cycle them as power is drawn from reserves and you can charge the others when daylight permits.
Cost? More than $5000 ea or more than $20,000 total.
Who needs a fridge in gird down anyway? Better to prepare using foods that do not require refrigeration before use.
Another idea is this and it costs less than $60 bucks per unit to make and always cools food.
The Zeer Pot - a Nigerian invention keeps food fresh without electricity
http://www.scienceinafrica.co.za/2004/september/refrigeration.htm
Regardless of what size you get, get a propane or diesel powered unit. For the sizes mentioned above, (10Kw+) the amount of fuel you go through will be substantial. A buried 500 gallon propane or diesel tank is much safer than a buried gasoline tank, plus gasoline degrades much faster than diesel or propane. I think 90 days or so for gasoline, without using additional stabilizers.
Another reason not to use gasoline ; it’s hard to buy without paying road taxes. Red diesel and delivered propane don’t usually include road taxes in their price.
I got a small about 1.5 cubic foot fridge at a yard sale last summer. Old GE, probably 25 years old, but it’s built like a Sherman tank!
I think it only draws about 100 watts.
I use it for my beer (I brew at home) but if I needed to take some of the stuff out of my main fridge for any reason, heck, it would keep the stuff good and cold!
While purusing the Northern Tool and Equipment catalog this weekend, I saw they sell low wattage fridges and freezers made for use with solar panels,alternative energy...they are smaller and better insulated with smaller capacity(and smaller motors)