You ask a question that can be pretty simple or very complicated. I am a retired Ph.D. System Engineer, just getting into RV and solar. I'm one of the guys that could design a $400 hammer (metaphor), and for the guys that needed hammers like that, it would be worth it!
I like the book by William Prowse, and if you don't over-think problems like I do, that will get you going. I'm currently several exhausting, OCD-inspired months into my own analysis and design, and I'll be installing a bunch of stuff soon. Early on I bought the cheap Harbor Freight inverter and plugged it into a 30A fuse off my D.C. Panel, but it's noisy as hell. I bought a little Morningstar 300/600 W with no fan on Craig's list cheap, but my inverter in a couple years will be one of the big boys. My only advice is to read before you buy!