A few things:
1) Check out Solar Blvd for very competitive pricing on solar panels and associated hardware and electronics. (I do not have any relationship with them other than as a customer)
2) What came with your camper is, most likely, a "converter" not an "inverter." A converter takes 120 Volts AC and "converts" it to 12 volt DC required to charge your battery and run the 12 volt items (like lights). An "Inverter" is usually an after market add-on that "Inverts and boosts" 12 volt DC battery power and "makes" 120 volt AC. "Pure Sine Wave" inverters are preferred as they make the smoother waveform AC (makes computers and electronics more reliable) than the cheaper "Modified Sine Wave" inverters that make a "choppy, more square wave like" waveform. Most electronics will work with a Modified sine inverter, but some, like microwave oven magnetrons, hate it.
3) Inverters need LOTS of amps from your DC system to make 120 VAC.
250 watts of solar panels (at 20 volts output) in full sun with 90 degree sun angle will produce about 12.5 amps to your battery system. Your solar controller will take that 20 volts and moderate it to a 13.5 volt output with resulting loss of efficiency. Using the conversion "without loss" formula of controller output amps = (12.5 x 13.5)/20.5 You get a controller output of 8.2 amps at 13.5 volts (or
If you power your inverter directly (and ignore internal loss in the inverter), your 120 VAC output is 120 VAC x 8.2 amps = 110.7 watts This is not enough to run most AC appliances directly.
4) What your solar bank WILL do is replace amps pulled from your battery bank by your inverter powering your appliances over time and reduce dependence on your generator (which you will still need).
5) Since a 1200 watt AC load on your inverter (say a TV and computer) will require 100 amps from your battery bank (12 volts DC X 100 Amps = 1200 Watts), you will need quite a large bank of deep discharge batteries to feed that inverter. The solar system will reduce the load on your batteries from 1200 watts to 1100 watts; extending their useful life before needing recharge.
As you can see, a large capacity battery bank and generator will still be required even with solar panels to augment your system.
There are many online resources to explain this way better than I can, (in fact Solar Blvd has an extensive FAQ section). Good luck! Herk