The solar panel(s) produce DC, which charges a battery ( often through a "charge controller. Desirable for any "large" system. You qualify ).
The refrigeration apparatus may run off of DC or AC, as some units are capable ov "dual power" operation. You need to know.
IF the refrigeration apparatus use AC, them the path is: Panel charges BigBattery -> BigBattery is the source for an Inverter -> which powers the AC load ( refrigerator(s) )
Calculating the total daily power requirement for refrigeration is difficult, bordering on impossible. Actual consumption depends on many variables, including ( but not limited to ): Ambient temp, Refrigerator efficiency, how often you open the door ( and how long ) how much ( and at what temp ) you add items to chest ...
You can guess what the "typical usage" might be, since you are nearly killing your battry bank. If you know the capacity of the battery bank, measure the time till it gives up. Divide capacity by hours to get a somewhat useable number.
BTW: You say, "I think I need about 30 or 40 amps". You may be making a common error.
You need the "rate" and the "total usage" Your power delivery system must be able to deliver at the "rate", but the "charging system" must be able to, in one day, produce greater than or equal to your expected "total usage.
Typical nomenclature can be confusing. A Type 31 deep cycle might typically have a capacity of 12V at 100A. You only want to use 50% to 70% of this capacity ( 50% gives longer service life ) SO, a type 31 can hold "50 Amps". Which is ( rpoughly, seen note ) 50 Amps delivered in one hour, or 10 Amps per hour, for 5 hours.
Note: Max battery capacity is delivered at "low rates, ie: over 20 hours ). If you discharge at a high rate, there is less capacity. ( ie: at a rate of 25A / hour, cap might be one half of the slow discharge rate )
All above is "general" and generic. All numbers are "typical". You need to know and measure to get a good result.
Have fun; it is interesting.
