How much solar and battery capacity you'll need will depend on your usage, and when and where you camp. Our coach is as power-hungry as they come. With a large residential fridge, three entertainment centers, a 12 cup A/C coffee maker and large microwave oven, all of which operate off the 2800 watt inverter, we consume a relatively high amount of power. We love to boondock, so we wanted to determine if we could install enough solar to replenish all the power we use in a 24 hour period.
I ended up buying a Kill-O-Watt meter to measure our coach's AC power consumption, and a Trimetric battery-monitor that measures exactly how many amps are going into, or out of, the house-batteries at any given time. I won't bore you with all the numbers, but in the end, we needed 800 Amp Hours of battery capacity, and 900 watts of flat-mounted solar panels to fully recharge our batteries on a sunny, winter So Cal day. We ended up with 970 watts of solar and 840 AH of battery capacity, but even so - if it's a cloudy day, we're going to have to run the generator.
As long as the sun shines, we don't need to run our generator at all... unless... we want to run an air conditioner. It's just not practical to run a 13000/15000 btu AC unit off battery power. Fortunately, in the winter, we usually don't need air conditioning. Keep this in mind about boondocking - power is just one limiting factor, holding tank capacities are another. Most people fill up their gray water tank first. Running out of fresh water usually means breaking camp, and as I've always said, "The party is over when the black tank is full."
Kev