Hi,
Are you looking at a fifth wheel or motorhome? Most all electric RV's are larger motorhomes, where the alternator is rated at 150+ amps, and they can carry an extra 4 batteries at 75 pounds each without a problem. Most RV's are a bit limited when it comes to adding an additional 300 pounds of batteries.
That said, you can install well over 600 watts of solar panels on most RV's, and many are now sold at close to $1 per rated watt.
SunElec.com is one supplier of the lower cost panels.
My suggestion is to get 100 - 150 watt panels, and plan carefully where to place them around the rooftop A/C units, vents, antenna, ect. Larger than 150 watts, they become difficult to find a location that is 40" wide and 60" long, or larger. Check the panel size and lay it out in cardboard before ordering the solar panels.
As for factory installed panels, they typically are stuck in the 90's when solar panel prices where $5 per rated watt, and they where able to sell a 120 watt solar system as a $875 option. It is difficult to find a RV manufacture that will install a pair of 150 watt solar panels for a reasonable price.
Yes the big advantage is not needing to be nearly as level, and not needing such a large propane tank (if any propane at all). Propane refrigerators are not energy efficient at all. They consume about 300 watts per hour running on electric, and might run 15 to 19 hours on a 105F day. While a electric refrigerator might use only 150 - 200 watts per hour and run about 8 hours per day at 105F. They do tend to use more power while the ice maker is on, as it also has a 300 watt heater that runs about 5 minutes during each ice harvest, and requires the freezer to be colder, and puts heat into the freezer during each ice harvest.
I would recommend a pure sine wave inverter, they are more efficient at running motors, like refrigerators use. Samsung seems to make the most RV friendly and energy efficient refrigerator.
Sun Frost makes a 12 VDC compressor refrigerator. However they are very expensive, compared to a conventional 120 VAC refrigerator, and have extra thick insulation, taking up valuable space.
There are a few other 12 VDC refrigerators sold to people who live in homes powered by 12 VDC.
Fred.
