Depends on what all you want solar to do from just keeping the batteries charged while the RV is not in use to running air conditioning on batteries. The place to start is to decide what all you want to run on batteries and for how long. Then do an inventory of how much electricity you want or need, then size a system accordingly. We have a 600 watt system with about 200 amp hours of batteries. It works pretty well for us in the wintertime in the Southwest. but we do still run the generator from time to time during extended cloudy weather or when we are going to run the microwave for than a minute or two.
Hope this gives you a starting point.
I can tell you now, running AC from batteries is not trivial and will require more panels than you have space for. I'll give you a ballpark figure for a small AC unit at 1000 Watts, it's approx. $4000 and that will run your AC for 4 hours then die. I'll spare you the calculations for now, but take my advice and spend that money on a good generator such as the Honda 3000, you will have AC 24/7 and a much more comfortable life.
One minor point not often mentioned, you need to be parked in the sun for solar to work. With any luck the amount of solar powered cooling you get might break even with the solar heat loading on the RV and it'll only be as hot inside as it is outside...
The data point I would consider is the number of folks in TX and AZ that want to add a 3rd air conditioner to their 2 A/C unit 50A RV's. If you figure they're pulling say, 4 kW and that's not enough, think about what that translates to for a solar installation to match that much less best it.
Running air conditioning from solar can be done with enough money, as long as you are only ever traveling to places where the air conditioner does not need to run 24x7 for 3-4 months out of the year. I know someone that is doing it on a mid size diesel pusher right now, of course they summer on Cape Cod, not Florida
sure will, as an example, say you have a single 13500BTU unit and you are at Lake Havasu in summer
running the thing continuously overnight for say 10 hours.
from the Dometic 13500 unit datasheet, the power draw is 1320 Watts at a nominal 120V
if we were powering this from a 90% efficient inverter at 12 Volts
then the total wattage draw will be in the order of: 1450 Watts and at 12 V this is approx. 121 Amps.
to run over 10 hours will consume 1450*10 = 14500 Watt/hours
if we had Lithium batteries and we draw to 10% SOC then our Ah requirements are in the order of
1330 Ah !!!! and that's just for one night, if we intended to use this the following night, we have to recharge and that's the hard part.. to recharge with solar in ideal conditions with summer sun at Havasu with 2 axis trackers we need a minimum of 2000 Watts. In less than ideal conditions we need more, for flat panel we need more than 3000 Watts of panels.. that generator is looking mighty good right now... LOL