Lithium batteries are still new to the RV industry, be careful, they are not proven yet. I have no doubt they will be, just be careful.
The size or panels needed are based on your needs. Have everything you want to run with the inverter so whomever does it, can determine what how many watts you will need. Figure proper batteries along with the panels and controller. Don't overdo it, remember the more batteries you have the longer it will take to charge them on a given day - or two.
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