Little generator little power little money little trouble, big generator big every thing else.
Our water generator (hydro electric) was 7.5 kilowatts three phase using a cross flow turbine, 12 inches wide 14inch diameter running at 200rpm, driving a generator at 1500 rpm, and a head of water of 4 metres and a water flow of 3,000 gallons / minute. this might sound complicated and to the untrained it is.
If you have any questions I will try to answer them here. cheers Stewart