Aquaponics Solar Battery Eliminator

Solar powered Flood and Drain pump timer.

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This is a circuit that I designed for a Flood and Drain Aquaponics trial.

Hypothesis: If the sun is not shining the requirement to Flood and Drain diminishes and the requirement to have standby power during non-daylight hours is removed.

Prediction: Plant and fish will continue to do well if the Flood and Drain system pauses during hours of darkness.

Goal: To eliminate the requirement for a battery or mains power and minimise wear and tear on the water pump.

This circuit incorporates an adjustable timer (555) that cycles the pump on and off. Tests on this particular pump (12V bilge pump) determined that it can pump effectively at 8 volts. Increased source voltage results in more water flow but also suspect more wear and tear on the motor.

Therefore this circuit also clamps the Solar Panel to about 8.5V only when the pump is cycled on. This way the clamping transistor is only loaded when cycled on and only dissipates excess power not used by the pump.

KiCad Schematic

net - 13.24 kB - 02/17/2017 at 07:56



KiCad PCB in progress. Not yet routed

kicad_pcb - 97.45 kB - 02/17/2017 at 07:56


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justin.richards wrote 02/14/2017 at 05:32 point

I would warmly any suggestions for a better solutions for the given problem or criticisms of the proposed circuit. .

Problem: Make a viable pump controller that uses a single 21V 33 watt Solar Panel, controller and pump only. i.e Eliminates the need for a battery or mains feed.  Solar panel output continuously varies as clouds etc reduce isolation. 

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