The options for home scale micro-hydroelectric systems are very limited. A few companies will custom design and build a system, assuming you have a high enough head. But their systems are not really designed for the single home site. The price is very high! The Alternate Energy Source book published by the Real Goods Trading Corporation offers two hydroelectric systems. Both of these systems are designed too operate on a minimum head of 20 feet and 100 gallons of water flow per minute. The standard" output is 400 watts @ 12 Volts Direct Current or 700 watts @ 24 Volts Direct Current. In their book they site the following as a "typical" installation:
Site Conditions: Head 100 feet Flow 15 gallons per minute Pipe Length 300 feet Pipe Size 2" PVC Distance To Battery 30 feet Output 100 watts Costs: (from a few years ago) Pipe $100 Turbine $875 Regulator $340 Batteries $180 Wire, etc $50 Total Costs $1545