The Whirlpool – 18.5 Cu. Ft. Bottom-Freezer Refrigerator is a pretty efficient residential refrigerator to consider running off-grid on solar. It gives a great idea of what kind of loads you can expect in your RV for running your fridge off-grid.
This refrigerator is listed as having a 15 amp draw at 120 volts.
From experience, this would most likely be at startup only. The actual running draw on a fridge of this size averages about 720 watts or 6 amps. Depending on the ambient temperature, you may find that the duty cycle for this refrigerator will change when running off-grid. The duty cycle will determine how much power is needed from your battery and solar system in your RV.