most of the systems here are "backyard" and rely on the grid..
of course the more you put into a system the more you want "failovers".. that being said, i'm thinking biodiesal generator might be an option for when "TSHTF", but if something major happens, i think "defense" would be the number one priority..
take it a step further and look up info on preppers, there was a recent show on natgeo that led me to this guy;
http://gardenpool.org/
some great stuff there, but i'm not sure how i feel about the chicken poo into the ft