The term ‘pump controller’ can be used to mean any one of the following.
The controller functions to turn the pump on and off electrically. This device can be a programmable timing device, or its ‘on-off’ function can be activated by a ‘float’ switch triggered by the water storage level in or discharge into a tank, dam, or other storage facilities.
A more complicated device that incorporates a maximum power point tracker (MPPT) and provides the functions explained previously. The MPPT converts the DC power produced by the solar array to match the voltage and current operating requirements of the system’s solar pump. The MPPT ensures that (i) the pump operates at its maximum performance levels and (ii) it will operate in less-than-perfect sun conditions, such as on cloudy days.
When the pump controller is operating as described in the first point above, that is, when a float switch triggers it. This controller can track the water level using various options, from a simple float switch to an electronic pressure control.