Start with the basics.
your stock RV running on batteries will only supply 12V DC.
if you need 120V ac house electric, your stock RV must be plugged in to the AC outlet.
Next you have the option of buying a 12v to 120v power inverter.
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These are available at most stores, and start in the $20.00 range.
this takes 12v battery and converts it to 120V AC house hold current.
But this will not make your RV electric outlets work, this works by plugging that cig lighter plug into 12V, than plug the cable from your AC device into the face of inverter.
The problem is if your household object draws 1 amp at 120V, you will need more than 10 amp @ 12v from your battery.
So as you can see, this type of draw can deplete your batteries faster.
So now you can add solar to charge your batteries :).
More Math.
If you want to run 10A @ 12V for 24 hours straight, you need to be able to recharge at least that much energy back into your batteries.
But sun is only good for maybe 8 hours at most. so in 8 hours you will need to be able to charge at 30A to fill what you use from batteries.
Now if you want your batteries to power your AC outlets in RV, you will need a bigger inverter, and it will need to be hard wired to RV outlets.
Next is inverter type selection. your house has pure AC sine wave. But these devices use square waves to imitate the AC sine wave. this is called modified sine wave.
the pure sine wave inverters cost more than the modified.
it is very common to see arguments on forums like this will make you think any electronic device will receive instant death using modified sine wave.
I use a 600w modified sine wave inverter to power my outlets in the RV when needed. this will only produce maybe 5 amp @ 120V but can draw around 60a @ 12v).
I have been running a 20" TV and satellite receiver off this inverter for 2 years now. I only use it when needed, but I bet I have 30 days of use, running TV maybe 2-3 hours per day on this system with no problems.
I also charge my HP and or Dell laptops off this inverter some times.
But for cell phones, I charge from a 12V source with a car adapter plugged in