Where I live the power grid is iffy at best, especially in the heat of summer. I am installing a whole house generator system and am trying to decide how much I need. I had a guy from a company come out and survey my house and needs and recommended a 25KW Genset. That seems a little overkill to me. I was thinking more along the lines of 12-18KW. It's not the cost, just getting what I need. I have been reading and researching online and it seems that the 20+ are much quieter units than the lower KW's. That is a factor, plus the run time on a tank of fuel. All the units on the island are diesel and I have had some guys tell me that their 8-11 KW units keep them up at night. I need an automatic start and will run one AC/heat unit, water heater, lights and pumps(our water system runs from a cistern with 12v pumps). With me gone so much I need a system that my wife doesn't have to mess with. Start when the power goes out and stops when it comes back on. The 25KW the guy recommended burns about 5 litre an hour at 75% load. With an 85 litre tank that should give a good run time on a tank of fuel. The longest the power has been out since we lived here has been 8 hours. So any suggestions or recommendations?