Controller acts as a kind of a "transmission" between the solar panels and the pump, matching the output of the panels to what is required by the pump. These type controllers are usually called "LCB's", or linear current boosters. An LCB is a DC to DC converter, and is a form of maximum power point tracking (MPPT). LCB's essentially trade voltage for current, providing more current, especially at lower light levels, to the pump. LCB's will typically give you about 25-30% more water pumping per day than with a direct PV panel to pump connection.
The controller comes with high / low water level sensors so the pump will not run when the well water is too low.
Operates on 12 or 24 VDC
Increases daily water output up to 30%
System starts pumping earlier in the morning
System stops pumping later in the evening
Protects pump from high or low voltage conditions
Terminals for float switch
Pump on/off switch
Water tight enclosure and cable inlets
Includes water level monitor mode with probes and cable