A small hydroelectric system can also work well with solar modules, both charging the same batteries. Whenever rainy, the solar modules are putting out less power, but the hydroelectric system will likely be producing at its peak.

A typical AC power hydroelectric system designed to deliver on-demand 120/240 VAC power is not practical for most people because you need a constant water supply large enough to supply the peak power output that will be required, usually a minimum of several thousand watts requiring hundreds or even thousands of gallons per minute, depending upon the pressure available. Besides requiring large amounts of water, these turbines require large pipe diameters and expensive regulating systems to maintain proper frequency and voltage at all times.

For most small to mid-sized alternative energy systems even smaller DC units can provide you with a full range of power. For example, a 500 - 1000 watt unit is sufficient to supply enough energy for a variety of applications, whether to act as a primary charge source or be used in a hybrid system.

Power output of a hydroelectric generator is determined by the pressure of the water at the nozzle and the amount of water flowing out of the nozzle. The larger the nozzle, the greater the flow will be. The nozzle must also be sized small enough to keep your pipeline full and keep the speed of the water in the pipe below 5 feet per second. This table shows water flow through various size nozzles at given pressures. Use it to determine what size nozzle you need to accommodate the flow of water you have and deliver the amount of power you need.