Micro-hydro relies on falling water, of course, so the siting is much more specific and limited than it is for any other renewable energy source. The farther any volume of water falls, the more powerful your micro-hydro system will be.
If you have a stream on or near your property, preferably one that runs throughout the year (though this is not absolutely necessary), then you may be able to take advantage of its energy.
A fall of water as short as five feet with a volume of a gallon of water per second can be a sensible supplement to any other energy source you use.
If you have water that flows through your property, you may be able to redirect its flow down an incline and through a small hydro system.
Short glossary of micro-hydro terms (and how to use them):
Head is the height that water falls, measured in feet. Estimate this with a measuring tape.
The net head is determined by adding up the total drop and subtracting friction losses.
Flow is the volume of water, measured in gallons per minute (gpm). Measure this with a gallon bucket placed in the falling or flowing stream; time how long it takes to fill; then divide the number of seconds into 60 to obtain your gpm. e.g. a bucket full in 3 seconds will equal 20 gpm.
Output is the energy output of your micro-hydro system, measured in watts. Be sure to account for seasonal variations (e.g. summer is dryer in most areas, winters may freeze).
Calculating site feasibility
Here is a rough calculation of the amount of watts available at a micro-hydro site:
Output (watts available) = head (ft.) x flow (gpm) divided by 10
e.g., 30 feet x 120 gal per minute / 10 = 360 Watts
This will determine if there is enough power available. If you want to attain an exact and accurate measurement of the power available, you may want to hire a professional to come in and survey the site or you can use this handy Micro hydro Power Calculator (Windows program from www.energyalternatives.ca)
Keeping in mind that an average home requires 300 to 400 watts (or more) of continuous output, you can use these figures to calculate how much electricity is available at your site.
Be sure that your site is legally and a financially realisticfeasibility.