An Op-Amp Based Mini Solar Tracker (no Need of Programming and It Works 100%)




Introduction: An Op-Amp Based Mini Solar Tracker (no Need of Programming and It Works 100%)

About: Hi I am Anand Unnikrishnan, formerly known as AppleXAnand. I am an Electrical engineering student at FCRIT Vashi. I have huge interests in smartphones, computer hardware, renewable technology and other consume…

Hello everyone! Welcome to my first Instructable! I am Anand and here I am going to show how to build a working Mini Solar Tracker which can be used to turn the direction of solar panel towards the direction of light

This project was one of a series of projects made during the global Coronavirus pandemic, including a solar MPPT controller, an LED audio visualizer, a 6V PCB full wave rectifier, and a light based automatic fan - exhaust system.

So without further delay, let's get to the project.

Below are the list of components you require to make a mini solar tracker (I don't know why I can't rename the "Supplies" tab)


  • 2x LDR (Light Detecting Resistor)
  • 2x 10k resistors
  • 3x 20k resistors
  • 2x TDA2030 op-amp ICs
  • 1x DC Motor (Preferably Gear DC Motor)
  • 1x 9V alkaline battery

Board used - perfboard

Step 1: Circuit Diagram

Above is the schematic for the mini solar tracker.

Here in the circuit diagram, as you can see, two LDRs are connected in the opposite sides to the op-amp and motor.

The 10k resistors are connected in series to the LDRs.

In between the LDR resistor connections, the non inverting terminal of the op-amps will be connected, forming a node.

The three 20k resistors will be connected in series and in between the middle and lower resistances, the inverting terminal of both the op-amps will be connected.

The output terminals of the op-amps will be connected to the motor terminals.

The circuit diagram was made and simulated using Proteus.

Step 2: Working

The supply is given to the circuit via a 9V alkaline battery

The voltage divider sets the reference voltage of 3V (obtained from voltage divider formula) at the inverting terminal.

Now when light falls on one of the LDRs (with the other LDR in the dark), if the light has enough intensity that causes the voltage across the non-inverting terminal to be greater than 3V, then the op-amp, which functions as a comparator, will give positive output. The other comparator, since the other LDR was in the dark, will give voltage across the non-inverting terminal less than 3V and give negative output

The positive output in one op-amp and negative in the other will turn the motor in the direction where you have placed, and the negative output in one op-amp and positive in the other will turn the motor in the opposite direction as of the first case.

Using this we can mount the panel on to the motor shaft and position it in such a way that when light hits the LDR, the motor should move the panel towards the light.

Step 3: Hardware

The entire circuit was made with Perfboard, with the LDRs connected to the sides and the voltage divider in the center.

In between the voltage divider and the LDR - resistance connection, the TDA2030 op-amps were placed. The op-amp is a 14W audio amplifier which is able to drive my motor without the need of an H-bridge. It has 5 terminals, 1 - non-inverting, 2 - inverting, 3 - GND, 4 - Out, 5 - +Vcc

The LDR-resistance is connected to pin 1 of both the op-amps, forming a node, and the voltage divider is connected to pin 2 of the op-amps.

The motor is connected to pin 4 of both the op-amps.

The motor shaft was connected to a cardboard which is imitating as our panel.

The original plan for the tracker was to mount the LDR on the panel (cardboard) and flash the light on it to showcase the output, but the motor was not able to rotate the mechanism, so I mounted the LDRs in the Perfboard itself.

In the actual circuit, you must mount the LDR on the panel itself. Otherwise your motor will keep on rotating and won't stop.

I have used a 5V DC motor since gear motors were expensive for me. So in order to not let the motor rotate continuously, I placed a limiter (it was the plug-in terminals of a USB charging brick) and stuck the motor with insulation tape. That way, the motor movement is limited.

A cardboard was placed between the LDRs to act as a shade.

Step 4: Final Working

The above two videos will help you understand how this circuit exactly works as a tracker.

1)The first video showcases the working of the tracker

2)The second video showcases how the tracker resets the panel when dawn hits the tracker.

The DC motor rotates quickly in this video. This is because it is a DC motor, not a gear motor.

The connection of LDR should be like I mentioned above, otherwise the motor will keep on rotating and tracking action will not take place.

A torch was used to imitate the sun and with the help of cardboard shades, the shadows will make the other LDR dark.

Step 5: Conclusion

So this is it!

You now have a full working Mini Solar Tracker which you can use to connect small solar panels and move them towards light of maximum intensity.

You can alter the circuit to make it a better version of solar tracker. Also I am open to suggestions and questions.

Thank you for reading my first Instructable!

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1 year ago

It is necessa rry to move the panels to the sun in the morning. will this do that or must a separate system do it?


Reply 1 year ago

Technically if you observe, that at first light the tracker would go back to the starting position. But if you want to reset the panel in the night, or just after the sun has set, then you can incorporate a set-reset circuit with transistors and relays. But that would be a manually operable circuit, since it uses push switches. It is not a programmed solar tracker, to reset the position automatically.
Thanks for viewing my project by the way.


Reply 1 year ago

Quote "Technically if you observe, that at first light the tracker would go back to the starting position"
I don't see how that can happen . Could you explain please.


Reply 1 year ago

I think you haven't seen the video
It is shown there clearly