On the farm where I spend my summers they've got a big generator, driven by the tractor. It's hooked up via transfer switch and a wall-mount male CEE connector and feeds the entire system of the house (3ph). It was supposed to feed the 2nd building (garage, workshop and holiday apartment) as well,m but this didn't work out too well, all I got was a faint glow from the light bulbs, barely noticeable.
Otherwise I've never seen generators being used for anything but temporary power at market stands or whatever. I once used one on a red-cross training to power the fog machine. (We simulated an earthquake with fire and everything else, train accident, explosion at a chemiocal plant, I had to act injured along with many other young people from Junior Red Cross)
