solar tracker circuit schematic

DIY Solar Tracker System

The solar panels are operating at optimal parameters when they are at the perfect right angle to the sun. Unfortunately this is accomplished only if solar panels are rotated by the sun. This is the purpose of this diy solar tracker system or if you have an Arduino board then you can build this one that uses a servo.

The solar tracker circuit uses a window comparator to maintain the motor in a idle state as long as the two LDRs are under the same illumination level. In this case, half the voltage is applied to the noninverting input of A1 and to the inverting input of A1.

Solar Tracker Circuit Schematic

solar tracker circuit schematic

simple diy solar tracker system schematic

solar tracking components

  • T1, T3 = BD239, BD139
  • T2, T4 = BD240, BD140
  • A1, A2 = 1/2 of LM324
  • Diodes = 1N4001

When the sun position is changing so does the illumination level on the LDRs and the input voltage for the window comparator is no longer half of the supply voltage thereby the output of the comparator generates informations for the motor that rotates the panels for tracking the sun.

diy sun tracking sensor

diy solar tracker sensor

diy sun tracking sensor

P1 and P2 are adjusted in such way that the motor stands still when the LDRs get the same amount of solar light. If less light reaches LDR2 than LDR1, the voltage in point A increases to more than half of the power supply voltage. As a result the output of A1 is HIGH and T1 and T4 transistors conduct. In this situation the motor is starting.

If the angle of the solar light is changing again and the voltage in point A decreases at less than power supply voltage, the output of A2 goes HIGH and T3 and T2 transistors conduct. As a result the motor is rotating in opposite direction.

For solar panels control is best to use small motors with a suitable voltage and a maximum working current of 300 mA. This solar tracker system is used for tracking the sun only in one plane, the horizontal one. If you want to track the solar light in the vertical plane you need to build a separate sun tracker circuit.

Analog Solar Panel Tracker Circuit by Bien Fallaria

analog solar tracker

analog solar tracker circuit schematic by Bien

This is a simple and practical analog solar panel tracker circuit. Using four LDR (light dependent resistor) as a sensor in detecting the light source arranged as illustrated. When the light hit the LDR in a certain position, it will activate the circuit and trigger the relay to turn the slewing motor in the right direction until the sensor is fully shaded under its cover stopping the motor to its rest condition.


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  • sreenija

    where do i get this ldr circuit plzzz tell i want to do this project

  • Daniel Villanueva


    I don’t have yet any comment/s
    at this time, but I want it to know if you have a latest designed
    Of this automatic sun tracker that
    Suitable for solar panel up to 2 Kwatts??

    Thank you for your reply!


  • Matolo

    Good circuit. two questions though: what is the angle of incline between the two LDR’s and what is the length of the tubes and their diameters?,

  • dogman

    hi, i’m a total newbie but setting up a small power unit at my bush camper and making as much as i can from scratch and learning but what i’m wondering is i’m going to be making some pcb’s for a bedini generator i’m making and was wondering if you had a pcb layout diagram to make my own boards when i make these ones i have sitting here,

  • Roger

    Having a hard time finding those specific transistors, can you suggest more available ones?
    This is a very elegant circuit!



  • B.Tschacher

    Hysteresis would be a very good addition to this plan. Use a 4.7 m or higher pot so it can be tuned for feed back sensitivity. Also you could replace the Q’s with FET’s but the G terminal will need 2 voltage dropping R’s from outputs to G to grnd. so the Gate is not over driven , it will add some components but the difference between the gain of the Q’s with their resistance compared to the FET’s is much more effective at driving the servo -AKA Linear Actuators, these are the Spend-ee parts. As far as using the other 2 comps., this is another great idea. The other 2 will track seasonal changes which obviously will be very unnoticeable from day to day, but does make the system more productive. This will also give the system a tilt to south for keeping the snow clear in the winter and take the panels out of a direct hail shot if you are using the Micro P. . Here is the biggest problem with this type of system. Solar panels are as everyone know covered with glass, so if they take a hit from a large piece of hail they are toast. It takes a lot but it does happen. The best way to build a solar tracking device is with a Micro P. and use the same basic circuit here, the H Bridge, the sensor circuit, but the code is the tough part. You want the code to include a portion that will take the panels to a neutral point if the ambient light falls below a certain level, as if on a cloudy day or night time. By having this, the panels and sensor will be closer to the new day light. With a micro P. hysteresis is written into the code so that is critical to get stable, otherwise the system does the Hoochy Koochy dance and it that is ‘BAD’! Like someone with a terrible case of Parkinsons. The diodes used across the E and C of the Q’s or the S-D of the FET’s MUST be a higher PRV then the 1n4001’s though,TVS’s are even better since DC motors cause V spikes in both polarities. Use a TVS of a V rating above the DCV but below the Max of the Q’s.( these little 1n4001 diodes are fine for bench testing for design but will only cause you grief in the finished system ) especially if you are using a larger more powerful series wound drive motor ! I would always go to OVERKILL on these! Like a 1 watt or even a 5 watt @ 400v or more on the diodes, the TVS’s are another deal. There is nothing wrong with doing this but a blown diode and transistor will really kill your day. Spend a little more here or spend more there during the rebuild. I have a worked out circuit for the Micro P and a start on the code but I am not a code type guy so I am looking for someone that is into this that can finish that part and I also have an array that I am needing to test this on.

  • mistry kushal

    how many voltages motor used in this cicuit.
    reply me fast..

  • Ebin

    Which motor is used ?
    A stepper motor or ordinary?

  • Ashok

    Sir as per your schematic diagram i assemble the circuit i was worked some time as LDR not responding very effectively. After some time when testing towards sun direction it shut down i dont get where is the problem. Can you give some guidance?

  • sindhuja

    its really simple cicuit.sir i have one more doubt..where will i connect solar panel??

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