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    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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    19 Responses to "DIY Solar Tracker System"

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    1. Alexei says: on January 17, 2013 at 1:08 pm

      For the vertical plane can I use the other 2 amplifiers inside LM324? I see you are using 2 of them and as I know the IC has 4.

      Like or Dislike: Thumb up 0 Thumb down 1

    2. :) I really like this circuit, it is so simple yet can help a lot in harvesting the free solar energy!

      Like or Dislike: Thumb up 0 Thumb down 0

    3. abbas babannan says: on January 19, 2013 at 11:12 pm

      sure this circuit is so simple, but can i replace the resistor 15k and 47k so that it can be use as the gate controller or use it as door opener? thanks

      Like or Dislike: Thumb up 0 Thumb down 0

    4. Timelord says: on February 1, 2013 at 4:11 pm

      It’s a great circuit.
      I just have one question.
      Doesn’t it have to be reset in the evening ?
      What I mean is :
      is LDR1 set in such a position to the east that it will turn the solar panel back in the morning ?

      THX T L.

      Like or Dislike: Thumb up 0 Thumb down 0

      • Actually it doesn’t go back to its original position automatically. But it will track back the sun in the morning. The most important thing is the design of the tracking sensor.

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      • Timelord says: on February 12, 2013 at 10:49 am

        Of course Marian.
        The design is simple and nifty.
        I’ve been looking and digging around,
        and the gain is about 15 – 20% with this design integrated.

        Like or Dislike: Thumb up 0 Thumb down 0

    5. photon says: on February 10, 2013 at 5:01 pm

      Could 3 ldr’s make it so it resets to the east as soon as the “east” ldr revives light ?

      And could you amend the circuit to show 3

      Like or Dislike: Thumb up 0 Thumb down 0

    6. Wagnerj says: on April 12, 2013 at 1:17 am

      What motor do you use ?
      Can i use 12 volts motor ?

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    7. I am an electrical engineer and I like making electronic circuits . I will surely make this circuit as my mini project.
      Thx alot for the circuit sir

      Like or Dislike: Thumb up 0 Thumb down 0

    8. what is the cost of this project?

      Like or Dislike: Thumb up 0 Thumb down 0

    9. I think the circuit should add a hysterisis of a few millivolts to both the comparators as in a practical situation, the output might tend to oscillate at the point of equality which may even harm the motor.
      correct me if i am wrong :) .

      Like or Dislike: Thumb up 2 Thumb down 0

    10. can we reset the motors position by using any controller ic for every 24 hrs

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    11. Rami-Sharif says: on October 22, 2013 at 3:48 pm


      Hi above link for perfect device tracking sys.

      Like or Dislike: Thumb up 0 Thumb down 0

      • Timelord says: on October 22, 2013 at 4:06 pm

        Hey Rami-Sharif,
        Been looking at that , it’s great !
        And now for full size panels ;)

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

      Like or Dislike: Thumb up 0 Thumb down 0

    13. 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?

      Like or Dislike: Thumb up 0 Thumb down 0

    14. Which motor is used ?
      A stepper motor or ordinary?

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    15. mistry kushal says: on April 5, 2014 at 3:51 pm

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

      Like or Dislike: Thumb up 0 Thumb down 0

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