For me the best and most comprehensive information source was the
DIY Solar Power forum run by
Will Prowse. He has a YouTube channel called
Off Grid Solar Power, which includes some useful videos on how to do stuff. I can't remember where they are now but I watched his vids on connecting a battery management system (BMS) many times. There was also a good one one the complete circuit, including battery, solar inputs, and inverter.
One the first solar battery channels I found that was not devoting to camping tips was Andy's (never discovered his surname)
Off-grid Garage. After reading more and having a bit of hands on experience, I realize that most of his tips need taking with a bucket of salt, but it was fun and an easy watch.