Brushes naturally wear down after years of use, and may be easily replaced. The motor is filled with oil, to keep water out. An electronic system is used to precisely alternate the current, causing the motor to spin. DC Motor, Permanent Magnet - All DC solar pumps use this type of motor in some form. Diaphragm Pump - A type of pump in which water is drawn in and forced out of one or more chambers, by a flexible diaphragm.
Check valves let water into and out of each chamber.
Diode - An electronic semiconductor device that allows current flow in only one direction. Also called a rectifier. The electrical equivalent of a check valve in water. Drawdown - Lowering of level of water in a well due to pumping. Recovery Rate - Rate at which groundwater refills the casing after the level is drawn down.