One important question to answer is how to size a solar power system? What size solar system do I need? Here is the simple way to choose what kind of RV solar system size you need. First of all charge your batteries completly using generator. After that do your usual activities without charging batteries and see how long will your batteries last for. Take your battery capacity and divide it on the number of days it lasted for. This will tell you how much electricity do you use daily.
Usually RVers use between 50 and 100 amper hours of electric energy per day. 100 Watt rated panel produces about 80 Watts in a real world conditions. 80 Watts with 12 volts comes to about 6.5 ampers. If you take a 5 peak sun hours per day, then you can estimate that one 100 Watt rated panel will give you about 30 amper hours of elecricity, don’t forget that some power is lost in a charger and wires (they heat up). So if you consume 50 amper hours of energy you will need about two 100 watt panels to break even.
You can find solar system size calculator on the web too, here is how it works (if you want to get 100% of your electricity from solar panels):
Your system size in Watts = 1000 / 30 * Your monthly electricity consumption in KwH / Peak sun hours you get in your area. Typical peak sun hours per day in United States is between 4 and 5.5. For example if you consume 100 KwH of electricity per month, then you need
1000 / 30 * 100 / 5 = 670 Watt system (if you want 100% of your electricity come from solar panels and you live in the area which gets 5 peak sun hours a day)