I know a lot about care and feeding of individual 12V flooded cell batteries, but not much about living off grid. I have a feeling that it would be difficult to keep a long series string of batteries matched, so that all the batteries have equal capacities, especially as they age. As batteries age, the failure mode even in a series string of 6 cells (i.e. a 12V battery) is always that one bad cell develops, which necessitates replacement of the other five cells. I believe that from a battery utilization that a parallel connection of batteries would be better than connecting them in series. I understand that inverters and wind generators might be more efficient at higher voltages, but that requires great effort to keep the batteries matched...