Solar water pumps are electrical devices that run one electricity generated by photovoltaic (PV) panels used to deliver(pump)water for drinking, livestock, or irrigation purposes. They consist of three main parts, the pump itself, a controller and solar panels. The solar panels are used to generate electricity from the Sun to run the pump. The controller is used to match the output power t the pump receives with the input power from solar panels connected to the system. It also provides a low voltage or high voltage protection which reduce maintenance cost. Water is usually pumped up into a storage tank for use. One advantage of solar pumps is their reliability in remote areas due to their low maintenance cost once installed. Solar pumps can have four systems of operation that is, centrifugal, rotary motors, diaphragm or piston. Rotary pumps operate in a circular motion and displace a constant amount of liquid with each revolution of the pump on the other hand, centrifugal pumps rely on kinetic energy mechanical means to move liquid . Centrifugal pumps are best in pumping situations that require high quantity of water but low head where as helical rotor pumps operate better with higher heads but lower quantity of water required. Centrifugal pumps also operate better in silted water than their helical rotor counterparts.
There are basically two types of solar pumps, submersible and surface pumps, submersible pumps are submerged in a borehole or well while surface pumps are connected to a pipe that goes into the source of water. Submersible pumps are quiet where as surface pumps can be noisy.
Solar pumps work like other pumps the difference is that they use direct current produced by solar panels. Centrifugal water pump work by the use a series of discs called impellers. They rely on kinetic energy. When the pump starts running, the discs rotates, which makes the fluid around it rotate. This rotation causes centrifugal force on the water particles, which causes the water to move radially up and out.
Helical rotor pumps use mechanical means by using a rotor to move the liquid up by positive displacement.
Centrifugal pumps are best suited for shallow depths but high volumes where as helical rotor pumps are used for deep wells but where lower volume of water are needed. Centrifugal pumps also are less susceptible to silt in the water.
