Refrigeration

During the winter the kitchen entrance and storage entrance has doubled as a fridge, with temperatures around zero to 5 C, even when the main rooms in the house have been at 20+.  A good temperature to keep dairy, meat and vegetables. Now that it's warming up outside I'm using the Paul CD method: a coolbox which I open overnight to get down to 5 degrees and it stays down under 10 until evening as long as I don't open it.  This works while I'm working and while night time temperatures are low, but won't hold up in the summer.

So I'm looking for a good offgrid solution (I have a generator, but it's not on all the time) and have come up with the following list.  Any further ideas are welcome.

• The family who owned the property before have left me with a gas fridge, but it's big and I'd prefer to use the space for storage.  I also don't know how much fuel it uses and to be honest I'd prefer something that doesn't add to the carbon budget for the house.
• Before they had the fridge, they used to use the smaller well.  Anything to be stored was wrapped in waterproofing and lowered down.  It sounds great for beer, but the well lid is a big slab of concrete and I'd rather not be shifting it on and off all the time.
• Evaporation cooling.  This Mexican solution looks good, and there's a flower pot version looks do-able.  The question is whether I can get big enough pots for it to be useable, but this looks like something worth testing.
• Hooking up a 12V coolbox  (something like this) to a battery that gets charged when the generator is on.  I have the battery and charger already, so this looks do-able to me.