New to 12v fridge

it totaly depends what kind of flooded batteries you go with, if they are the "hybread starting/deep cycle" that the rv dealerships sell then you don't ever want to go below 50% and if you can stay fairly shallow like 75% or higher for a deicent life span.  so realy you have 25 to 50AH to use depending how long you want the battery to last.  if you go true deep cycle then you can constantly use 50% of the capacity and get ok life out of it, so two 6V deep cycle batteries would give you 100 Usable AH.  if you go LiFePO4 then you can use the full 100% so two 100AH LiFePO4 batteries would  give you 100AH and last 4 to 6X longer than the previous options.  so you have to factor that in, when you look at price.  as was mentioned the LiFePO4 will charge faster also, this is due to less internal resistance so they accept a little more of the charge and less of the voltage is converted to heat.  pluss they only have a short adsorbtion phase.  I am a firm believer of solar panels and I would probably still add a deicent panel if I was in your situation, unless your in a barn your going to get some charge.  even if they don't fully charge the battery every day they will add to the battery and allow you to go longer between charges and for gennys that is the whole idea, use it as little as possible.  

Steve