if you are running the fridge during the day on solar, is the solar still not going to be running the fridge when your driving during the day? I can see going to a bigger dc to dc if your solar isn't keeping up and you need a little more power to charge during that drive, but there is no way topick which one your powering your fridge from unless your turning off the solar panels.
There are these things called cloudy and rainy days. There are also times on the year where solar in the Northern Hemisphere produce very little solar due to low sun angle and shortness of the day. November December January February being the worst 4 out of 12 months for power production. During those months, the DC DC charger is your best friend in the world. Everytime I take a drive, the truck alternator charges the house batteries. In summer, I can switch off the DC Charger if needed. The solar is at peak performance 3 to 5 hours a day. After that, any assistance is desirable. The BMS manages the charge of the batteries flawlessly. Too much power has never been an issue. Too little power, that's a problem I've never had. The Victron units both sense the state of charge of the batteries and adjust their outputs accordingly.
