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Last Updated on: Tuesday, June 01, 2021 03:06 PM

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More  Solar Circuits, Control, Motor Controls


A Discover Circuits visitor had a problem.  He needed a simple on/off controller for his solar powered water pump.  His system used two 12v 50 watt solar panels wired in series.  The power from the solar panels drove a submerged water pump.  However, during overcast skies the pump motor did not operate properly due to the lack of power from the panel.  He wanted a circuit which would turn off power to the motor during low sun conditions.  The circuit below performs this function.  A small 0.1 x 0.1 photodiode monitors the sunlight intensity.  The current from the diode is proportional to sunlight intensity.  An adjustable load resistor across the diode converts the current into a voltage and feeds the to a voltage comparator circuit.  The output of the comparator drives a small n-channel MOSFET, which in turn drives a high current p-channel MOSFET, controlling power to the pump motor.  When the sunlight is less than one fourth of full intensity, power to the motor is turned off.

Solar Powered Water Pump


Click on Circuit Below to view PDF of Schematic

solar-powered water pump control design by Dave Johnson, 10/3/2010

More  Solar Circuits, Control, Motor Controls

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