There is a major difference between DC (Solar/battery/converter output or 1in the rv world 12 volt) systems and AC (120 volt)
IN AC Systewms. if you parallel two sources (Generator and inverter for example) unless they are specifically designed to play nice together (not likely save for same make inverter generators) very bad things cah happen.. Very bad things indeed.
But in DC systems you can safely parallel any and all same voltage systems. this includes Solar, Battery, engine alternator and shore power via the converter. No problems.
The worst thing that happens is that one or another system will idle while another provides all your needs.
