Solar Water Pump Circuit using Battery and MOSFET

In my earlier article I showed about solar water pump circuit using relay.

That design works, but relay makes clicking sound and relay contacts can burn after long use.

So now here is the new version.

This project is Solar Water Pump Circuit using Battery and MOSFET instead of relay.

MOSFET has no moving parts, no noise and works faster.

It is more safe for battery and pump.

Very simple idea for solar panel charge battery, MOSFET switch turn pump on when voltage is good.

Circuit is easy build with low cost and is good for small garden or farm watering.

Circuit Working:

Parts List:

The 18V solar panel gives power when sun is bright.

Two diodes D1 and D2 stop battery from sending current back to panel.

Both 12V batteries connect in parallel to increase capacity.

B1 and B2 charge slowly from solar panel.

R1 sends small current to MOSFET gate.

R2 makes MOSFET gate stable, quiet and safe.

Zener diode D4 keeps the gate voltage at safe level.

When battery voltage rises above about 9V then MOSFET gate turns ON.

MOSFET Q1 IRF450 conducts and pump motor gets 12V supply.

Diode D3 protects MOSFET from motor back EMF.

Fuse protects pump and wiring from short circuit.

How to Build:

To build a Solar Water Pump Circuit using Battery and MOSFET follow the below connection steps:

• Assemble all the parts as shown in circuit diagram.
• Solar panel positive goes to D1 and D2 input pins.
• Diode outputs go to battery positive terminal.
• Battery negative goes to ground.
• From battery positive, wire goes to pump switch fuse.
• Fuse output goes to pump motor.
• Pump negative goes to MOSFET drain D3 connection.
• Motor negative goes to ground through MOSFET Q1.
• MOSFET pins source goes to ground.
• Pin drain goes to pump negative.
• Pin gate connects to junction of R1, R2 and Zener diode.
• Other side of R2 and Zener diode connects to circuit Ground.

Conclusion:

This is very easy and low-cost Solar Water Pump Circuit using Battery and MOSFET.

It uses batteries and one MOSFET only.

Parts are simple and circuit can charge battery and run pump by itself with no control needed.

Good for beginner solar project and work nice in outdoor place.

We can change pump or battery later and also can very easily upgrade it.

References:

A new MOSFET based solar charge controller for battery charger applications