If you have a site for a microhydro system, it can be the best value of all the renewable sources you might use to power your home. As long as the water flows, your turbine will provide electricity. That means that a 1 kW hydro turbine can produce as much daily energy as a 5 kW solar-electric array, and with less reliance on batteries.
Hydro and solar electricity can work well together since the best solar season is often when streams are at their lowest flow. Off-grid hybrid systems help to keep the engine generator silent, come rain or shine.
What is a Microhydro System?
There are many parts to the whole system that you will need. The turbine is not likely to be the most expensive, although you should choose it with care. You will need:
Since the electrical energy produced is often more than is consumed by a home, consider what’s to be done with the excess. If the system is grid-tied, this energy can be put on the grid and, often, credited to your utility bill through “net metering.” For off-grid systems (or in places without net-metering or other utility payment programs), heating water or even heating your house in winter are good uses for the extra energy. This can be done using normal AC heaters and controlled by “auxiliary relays” in charge controllers or inverters, or by independent control devices.
Siting your intake and turbine is the first step. Look for the best flow of water falling the most height over the shortest penstock length, and not too far from your home. Learn to measure the head and flow accurately (see “Methods: Hydro Measurements” in HP170). Then see the table (or equations) below to estimate energy production. Compare this to your current usage and future needs. Take into account that stream flow varies over the year. Most turbines can be adjusted to use less flow and still produce useful energy.