Dave, if he switched the whole subpanel then how would he still have lights?
He'd have to have a separate sub panel for the lights and batteries and
whatever else he didn't want switched. I think that was an original
requirement....not sure if it changed.

I'd switch the whole subpanel rather than a bunch of individual breakers,
it's cheaper that way. Current capacity of the contacter (relay) should
be
more than the total current of the breakers it's feeding.

Dave Hinz