On both boats we owned, a 41' sailboat and a 38' power boat I installed a marine inverter/charger. The unit was powered from the main AC breaker. The output was wired to the breaker supplying the AC outlets on the boat. So if we had AC, either shore or genset, the transfer switch would pass it through to the outlets, if not, the inverter would come on and power the outlets. Even though we had a genset, this allowed us to make coffee and run the microwave in the mornings and TV and computers at night without running the genset. I also installed the matching battery monitor so I could keep up with amp hrs used and know when and for how long to run the genset to put the amp hrs back.