Where to start, eh! So most everything to do with off grid specifications can be listed as "nominal", ish, depending on, etc.Not knowing this means that persistance will provide the circumstance to be educated. There are a number of ways to get things wrong and melt stuff, or get hurt. Batteries should always be treated as unpredictable dangerous beasts, happy as a clam if they are treated just right, but capable of producing trouble and disaster, or just del8vering a viscious bite to the unsuspecting and surviving to do it again. A 48volt (nominal) battery bank will happily turn the required 10mm wrench into single demonstration of a wide range of metelurgical and other phenomina. For fun on a cold morning take the leads from a 3 kw solar array, off, and then strike the wires to produce a realy big fat arc, h3y hey! The simple fact, that I tell enthused,nice, but clearly unprepared people who express interest in "off grid", is that I do it, but it's not for everybody, as there is a significant technical learning curve, plus the required physical skills to mount panels, run wireing, deal with battery banks,set up the systems, and if costs are to be kept to a minimum then source parts from distributors or import directly.