Notice that the house system is truly redundant and independent of the other. I was luckly to get the P42 panel put in my 40.5 because it has two DC Source breakers at the Panel so I can choose either house bank (or both) without having to go to the Battery selector switch. With the 3 switches I can choose any combination of the four batteries. When the engine is running I use switch 3 to charge bank 1, or 2 or both.Future additions will be inverter with monitor, wind generator and/or watermaker.