I would go 40 amp fuse with a 30 amp controller connected with #6 wire.
Maxi fuse holder with #6 leaderNothing special about a "solar panel switch".  Just needs to be rated for the DC voltage and Isc (short circuit amps) panel rating.
Trouble is I don't know a great low cost solution.  I used a high voltage cut off switch since I have series panels that can go over 100 volts.  A bit bulky.  For simplicity two of those fuse holders might do fine.  Something like Blue Sea rotary battery switch might work.  For mine I like having both wires disconnected but one should be fine.
Here is a two pole battery switch.  Not sure if this is best or how you will mount it.
DPST Master Disconnect SwitchI like this one better:
Blue Sea 2 circuit surface mount $41Should be able to mount it in the fridge compartment just above the controller.