I set up my shore power for 20 amp 120 VAC service. With everything plugged in and running I should draw less than 13 amps but the main power hogs, a hot plate and a small space heater should not pull more than 75% of the systems amp rating when run continuously, hence the 20 amp capacity. The shore power feeds into a 20 amp marine circuit breaker in the cabin, which feeds a 20 amp gfic/arc suppression outlet in the same gang box, which in turn feeds a standard 20 amp outlet in the galley. My battery power station plugs directly into the galley 120 outlet when charging on shore power. It’s all very simple with no fancy distribution panel. If you are running a TV, refrigerator, AC or other high draw electronics then a fancier system might well be called for.