Hello Sebastian,
Here are a few ideas. (We're in South West France where I imagine it's slightly cooler in summer)
Wall fridge :
In old stone houses, there is often an recessed area under the sink (presumably the water from the sink kept the wall damp and cool) which was used as a space to store food.
I didn't want to live with wet walls so I copied this idea but used a slightly different principle and we made a recess in an uninsulated north wall beside our sink, with an insulated door which makes an effective fridge. (11-14°c in summer, 4-8°C winter)
Make a clay refrigerator :
https://www.instructables.com/id/Homemade-clay-refrigerator-BEING-ECOFRIENDLY-/
Second-hand compression fridge :
A compression fridge uses very little power but they are expensive. We bought a good size Dometic freezer/fridge a few years ago but only use it in the summer.
https://www.olx.pt/anuncio/frigorifico-camiao-IDCsnVr.html#04dccf692f
We have a good sized 22 year old Gram low energy 24v fridge which uses only 3 amps and it doesn't come on very often, so it consumes very little power. We bought it for 350€ about four years ago.
Buy a Capillary Thermostat to convert a freezer :
"This is a great way to do it as the thermostat is not powered so has absolutely zero drain on your solar power. It can work on any AC or DC powered freezer, as it is just acting as a switch.
Put the silver thermostat end in the bottom of the freezer. You can either simply tape it to the side at the bottom and then have the tube come up out of the top of the freezer, or you can drill a hole and insert it into the bottom if you want a neater/better job. Make sure you seal the hole up well afterwards. If you are putting it just out of the top of the freezer you will want to put a little protection around the tube that comes out the top so that you don’t squash it when you close the lid (the digital option below doesn’t have this issue).
Then you simply use the terminals on the thermostat as a switch. You can cut the positive wire on the power cable coming to the freezer and connect the incoming live side to the middle terminal, and the other side going to the freezer to the left hand terminal.
It’s a manual control from 0C so you can set it to the fridge temp you want."
Capillary Thermostat Temperature Control Switch, 0-40C 16A (AC or DC)
https://www.bimblesolar.com/offgrid/solarfridge/capillary-thermostat
Dig a cellar :
We dug ours on the south side of our house to stabilise a severe slope but it would work better on the shaded north side of a house. We had to cover ours with a gloriette and terrace it on the south side with a lot of shrubs and climbing plants for shade. It works well, wine comes out with condensation on the bottle.
In winter, I still leave things on a table outside in the cold, protected in a big pot.