Dont just power the fridge from a panel. Use the panel to charge a battery and power the fridge, and whatever else you want to power, from the battery. That way the fridge will be powered even when the sun is not available.
You'll need to size your panel based on the average current draw of your fridge (and other gear). You'll need to check the specs for the current in amps, and also estimate the cycle on/off of the fridge - this will vary a lot depending on whether the ambient temp is warm or cold.
For example, if your fridge draws 2 Amps and runs for 30 minutes in every hour, that's an average load of 1A. In a 24 hour period that's a total of 24Ah. So you need a panel which can put at least 24Ah into your battery in a day. If you estimate 6 hours of peak solar generation per day, then you need a panel that can produce 4Amps (4 amps x 6 hours = 24Ah)
A typical '12V' panel runs at about 17volts, so that's a requirement for a 68 Watt panel.
If you're powering more gizmos, then you'd need to up the capacity.
You'll need a charge regulator too so the battery doesn't get boiled.
There are many losses in the electronics and unknowns in the insolation effects, so these are all just estimates, and of course it all goes to custard when the sun don't shine :-)
Hope that helps!