Why add a new Inverter when adding Solar to your RV?

I can currently charge my tablet and cell phone in my MH when hooked up to land line connection, but I just realized this is AC and not DC.

I've not tried to charge them on just battery. I would suspect it would work right? I have a 1995 Jamboree Rallye. I suspect it has an inverter built in. I may have been thinking about this wrong. I may need to rethink this.

I haven't tried to run a TV on battery yet so will have to try this. Don't MH have a built in inverter?

Thanks