Simple solar charge design question

[BertKu]

I have found a simple low cost solution on Aliexpress.com in the form of an EP Solar 10A duo battery controller for <$30. It seems you nominate the charge priority and the controller switches between battery 1 & 2 to keep both charged. As I already have a 20W panel, I hope that should sort the start batteries nicely.
For the fridge; I'm heading up to the boat today and will look for a data plate to get the 220V load info for what inverter supply I need to keep it idling. Although it is a gas/12V/220V model, I understand only the 220V option has thermost control so 220V seems to be the best option for maintained running.
Thanks again to all who offered their thoughts and advice.

Hi L'eau.Life
In the meantime you should have some experience with your little 120 mA charger. How did it go? Did the charger had a diode build in? To prevent the battery discharging when the solar panel is in the dark? Unfortunately I just discover that not all solar panels have a diode build in, to prevent the battery from discharging via the solar panel when dark. For that reason I have enclosed an update of the circuit diagram I suggested and has proven to be inexpensive and it keeps your battery charged whatever. My apology, all my solar panels have a diode build in and did not realise that very old panels and some new panels do not have anti discharge diode build in.

Bert