It's fairly easy and there are a lot of forums around with knowledgeable people.

My main issue was ensuring wire gauges were correct. One's intuition about dealing with house wiring @15A changes when you're dealing with 50A circuits. Also you need to pay attention to things like equal cable lengths between battery banks so you don't overcharge one battery in a series.

However, I'm dealing with an off-grid cabin so I don't need to deal with any grid-tie circuitry, which would make it much more difficult and I'd definitely get an electrician for that.