[widgeon13]

15kw should be plenty. General makes a 15kw and Onan makes a 12w which i believe would also work fine for you. Most likely you will not be running max demand unless you are having a party. We've had multiple day long outages up here and get along just fine. Our system is fully automatic with transfer switch and it works very smoothly, noting for me to do. Had it now for ten years and just normal service.