If you are lucky enough to have running water such as a stream or river, water turbines are an ideal solution for providing reliable long-term renewable energy.
You can easily calculate the available power at your site using the following equation:
Power (watts) = Head (m) x Flow (litres/sec) x 9.81 (gravitational constant ‘g’)
A typical water to wire efficiency is around 70%, so you should multiply the result by 0.7 to get the actual amount of electricity that you can expect from the site.
Most sites vary considerably in flow between winter and summer, reflecting the differences in rainfall. It is important to make sure that the flow is sufficient to run the turbine, and if you wish extract maximum power from the turbine site, it is often desirable to install two turbines, switching in the second machine, when the water flow allows. Alternatively, a twin nozzle machine may be used, which incorporates a valve to isolate the second nozzle when insufficient flow is available to run both nozzles.