We face a simalar question with industrial electric motor applications, 120/208, 120/240, or 277/480, only we are limited most of the time to whatever grid service is allready in place.
Unless I was expecting loads with potentially high amperages and/or loads with potentially long wire runs, I would use 12 volts nominal.
If I were planning to have all 120/240 vac loads from an inverter(s), then I would consider a higher nominal battery voltage.
Two - 4000 watt inverters for example have the potential for 8000 watts of load. At 12 volts nominal that would be 667 amps, at 24 - 333, and at 48 - 167. Obviously these numbers would get cut in half for each of the two inverters, if I were using a two pole fused disconnect between them and the battery.
If so, I could use a 100 amp disco. @ 48 nominal, 200 amp disco. @ 24, but at 12 volts nominal I would need a 400 amp disconnect. Not only would this last one be expensive but they are about as big a fridge.
And I haven't even gotten into wire sizing for these examples. In all actuality the wire sizing should be done with the inverter(s) highest surge watt rating at vac and its low voltage dc cut off set point.
Have you ever seen a water hose with a whole lot of pressure and volume of water coming out and no one holding it? Wire will do the same thing when there is more amps on it than its size is rated for plus it could catch itself and other things around it on fire.
www.nfpa.orgOf course there is no way that I could fully know what all of your loads are, so I am just making up examples.
Such as, lighting loads at the nominal battery voltage. A 100 watt incandescent bulb at 12 volt nominal will draw 8 amps, so at best you could get 2 of them per 20 amp circuit on awg #12 wire. Chances are, in a conventional built home, the length of the wire for that circuit and the lower voltage would make it necessary to put only one 100 watt bulb on that circuit due to power loss. With two there would be light but not as brite.
Its all a little like building a car. You have to know what you going to do with it first, a commuter or an eliminator, then you can build it.
http://www.kronosport.com/versus
http://www.nedra.com/I would go on but its time for work. There seems to be no end to trouble shooting problems with industrial motor controls and motors.
