It's not really practical to run an absorption refrigerator from the batteries. Absorption refrigerators work by using heat (from a flame or an electrical heating element) to provide the power to run the cooling unit. This is much less efficient than using a motor driven compressor to do the same thing.
An absorption refrigerator uses heating elements that draw between 350 to 600 watts, depending on the size of the refrigerator, or about 10 times as much power as a conventional compressor driven refrigerator uses.
Two 10 watt solar panels making their full rated power produce 20 watts. If your refrigerator uses 400 watts, that's 20 times as much power as your solar panels produce under ideal conditions.
To put it another way, an absorption refrigerator will use an hour's worth of solar power in 3 minutes.
Running it from the inverter while you're going down the road and the vehicle's alternator is charging the batteries may work, but you'll be increasing the load on the vehicle alternator by a significant amount to supply the extra power that the refrigerator is drawing from the batteries. Make sure it's up to the task of doing that while also producing enough power to run the rest of the vehicle.