As others have said, do the math then you will know what you need, I also think a 5KW MEP-002 or 10 KW MEP-003 may be good choices , but keep your mind open to some of the better civilian models like the Onan DJB and DJC (same basic engine block as the above mentioned MEP generators). Like has been mentioned most of us around here buy from GL or other surplus auction source, these can be a dice roll though, even if they look good cosmetically there is no telling if the engine may be seized, etc. Pricing varies, but has been generally trending up the last few years (around here MEP-002's the appear is cosmetic running condition have been selling for around $1,200 and MEP-003's for around $2,000 on GL, having said that I think a member here posted about buying a MEP-002 in the south east a couple of weeks ago for under $300 on GL). Fuel cost is likely to be a big concern as you are looking at something around .5 gal/hr at full load on a 5KW generator and around 1 gal/hr on a 10KW, therefore life as normal when generating your own power can get expensive very quickly, it is far better when looking at off grid living to consider investing in a large battery bank and inverter for daily casual needs (lights, tv, computer, etc.), and only run the generator when needed to recharge the battery bank or run high load devices like well pumps, etc. You might designate a certain 2-3 hour block of time during the day to do all hour high load demands at once so as to limit generator run time, of course when talking about air conditioning all bets are off as it will be your single largest draw in most installations.
Ike
p.s. as to service life, there are many people out there running Onan J series diesels with over 10,000 hours between rebuilds with proper maintenance.
