Solar Tracker system Using LM358

Solar Tracker system Using LM358

We all know that a Solar Panel can be used to convert light energy to electrical energy. The amount of converted energy depends on the amount of light falling on the Panel. Generally Solar Panels are stationary devices which is fixed at a position. The produced electrical energy can be increased if we move the solar panel as the movement of the Sun. Here is a simple low cost Solar Tracker circuit which automatically moves the solar panel in the direction of Sun. The movement of the Sun is detected using two LDRs which are arranged on the Solar Panel in such a way that the intensity of light falling on it varies as the direction of Sun changes.

Circuit Diagram

Simple Solar Tracker Circuit Diagram

Simple Solar Tracker Circuit Diagram


The heart of the above circuit is two voltage comparators made using LM358 Dual Op-Amp. We all know that when the intensity of light  falling on a LDR increases, its resistance decreases. Here LDR is connected with a series resistor (R3 & R4), hence when the intensity of light falling on a LDR increases, voltage across corresponding resistor (R3 or R4) increases.

The output of the voltage comparator will be high when the voltage at non-inverting terminal (+) is higher than the voltage at the inverting terminal (-). Inverting (-) terminals of both comparators are shorted and connected to a variable resistor (RV1), which is used to set the reference voltage. Thus the sensitivity of both LDRs can be adjusted by varying the 10K pot shown on the left side of the circuit diagram. When the light falls on a LDR increases, voltage at the non-inverting (+) terminal of corresponding comparator increases and its output goes HIGH.

Solar Tracker - Various Modes

Solar Tracker – Various Modes

The direction of motor rotation is controlled by the H-Bridge formed by the complimentary symmetry transistors BC547 and BC557. Consider the case when the output of first comparator (U1:A) is high and output of second comparator (U1:B) is low. In this case transistors Q1 and Q4 will turns on and the resulting current rotates the motor in clockwise direction. Consider the case when the output of the first comparator is low and the output of the second comparator is high. In this case transistors Q2 and Q3 will turns on and the resultant current rotates the motor in anticlockwise direction. If the output of both comparators are low, transistors Q3 and Q4 turns on, but no current will flow through the motor. Similarly if the output of both comparators are high, transistors Q1 and Q2 turns on, but no current will flow through the motor.

The DC Motor should be connected to the panel in such a way that, the rotation of motor rotates the panel in the direction of movement of  the Sun.

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  • Mohamed Mashood P says:

    Does this circuit work on 6v battery and 3v or 4v geared motor??

  • sharad says:

    so why we using diodes in this circuit

  • Justine says:

    Is it the motor can move clockwise and counterclockwise?

  • Jewel Christian Puse says:

    I dont get the power input. Is it 2 trrminal? Or 1 terminal? How can i make this work thank you

  • rutagengwa eyal says:

    plz tell me what to do because your circuit is not running

  • Pinkal says:

    Plz send me pic. Of this circuit diagram in to pcb

  • Chris79 says:

    hello , i’ve just been realize it with old motor 7V and mecanical reducting from washmachine , it runs well , but the difficultie is getting back to sun in the morning , because it stops right eastwhen night appears , how to desequilibrate OP when morning light appear on west ? pulse with Ne555 ? or LDR impulse with Ua741 , ? thank’s for your opinion, (i’m french)

  • Kajal Kapadiya says:

    can u give me the block diagram of this project with explaination ? and project specification?

  • arif says:

    If the two LDRs are at the same intensity of light, resistance and hence voltage drop across them should be identical. If so, the output of the opamps seem to be either 0 or 1 for both opamps. Then the motor should not run. So please specify how to place the LDRs for proper functioning.

  • Patricio paiva says:

    sorry. can you help me.i have problem. i need read with ADC_READ (pic18F4520)the tension above 380v but my resolution its 10 bit.. exemple
    volt = (volt*40000)>>10; // input tension ref 0v and 5v

    volt = adc_read(2);
    volt = (volt*40000)>>10;

    mil1 = volt/1000;
    cen1 = (volt%1000)/100;
    dez1 = (volt%100)/10;
    uni1 = volt%10;

    lcd_chr_cp (cen1+48);
    lcd_chr_cp (‘.’);
    lcd_chr_cp (dez1+48);
    lcd_chr_cp (uni1+48);
    lcd_chr_cp (‘V’);

  • Bhuvana Chandra says:

    Sir I need any preparing video can u provide any links

  • Bhuvana Chandra says:

    Sir can u send document to me or link of any preparing video

  • john says:

    good evening,
    may you modify the code of ultrasonic sensor sh-r04
    to be 6 sensors and take the results to raspberry pi through spi.
    also, if u donot mind give me ur email???
    i am waiting your reply
    faithful: john

  • Maheshsetty Bokka says:

    sir, Is there any number for LDR………

  • Abhi says:

    Sir I constructed the circuit and it works well when I give leds but the motor is not rotating I have used the small.dc motor used in toys pls help with this

  • Ligo George says:

    Sorry, we don’t have any report for this.

  • Maheshsetty Bokka says:

    Can you please send me the report, components list for the DUAL AXIS SOLAR TRACKING SYSTEM to the mail—– [email protected]

  • cuyler says:

    I’ve building circuits for 45 years and I keep saying “This must be some kind of floating ground”! I had serious doubts about this ever working but Yes I built it anyway.
    Turned the power on and SMOKE! Fried up all the components.Then i read the rest of your statements made in this post. “Do not have a prototype at the moment”
    I went berserk-You kids get on here and post this to impress your boyfriends or girlfriends just to say “Hey look at me i;m on the internet!” Come to America and iI’ll stomp your ASS and get back my $5 for parts that you owe me for not even testing this in the real world.”F”ing Engineer . You couldn’t wipe my goats ass!

  • Ligo George says:

    LM358 is very popular and commonly available.

  • Ligo George says:

    Sorry, currently we don’t have any images of the prototype. Yes you can power it from 12V batteries.

  • CHISOM says:


  • Gavin says:

    Hi Sir

    Is it possible to use an alternative to the LM358?

  • Pravin Nair says:

    Hi Sir,Good day,
    Sir Is it possible if the source for the circuit system is using 12V batteries ?
    If it is possible, how does it affects the circuit and Sir is there any images of these prototype built ?


  • Ligo George says:

    Yes, it won’t stop. You need to use some mechanical stoppers.

  • Mohamed Up says:

    Hi sir the motor i got a problem . the motor doesn’t stop

  • Ligo George says:

    No programming is required. It uses simple op amp ic.

  • Nimish Saxena says:

    does it require any programming?

  • Ligo George says:

    Don’t you try changing the sensitivity ?

  • Kirandeep Kaur says:

    sir i made my tracker using the exact same specifications as you did, but the response or say the rotation of the motor is very less, almost negligible. How can i improve the response?

  • PAVANI G says:

    What will be the specifications of dc motor being used in above experiment.

  • mehdi says:

    hi. i have a question.
    can you help me ?

  • Ligo George says:

    Please use our forums ( ) for asking doubts not related to above topic.

  • Engr Ijaz says:

    sir i waiting plzzzzz as soon possible

  • Engr Ijaz says:

    hi respected sir ….
    sir how i will interfacing digital light sensor(TSL45313CL) with 8051 micro controller to get value on 16×2 LCD….plz help …..
    waiting for urs positive response …………

  • Ligo George says:

    Try changing the resistance values.. 10K resistor and preset…
    You should arrange LDRs properly… otherwise it won’t work..

  • Ligo George says:

    Hi, you can use any NPN power transistor… eg: 2N3055

  • amit says:

    the sensitivity of this tracker is very low!!!!!!!!!! so that it cant track the sun!!!!!!! can you tel me that how i can increase the sensitivity of system?

  • amit says:

    hi, i have 12v and 1amp gear motor to run a pack of panels can you tel me what kind of transistor or other elements should use in my project??????? can you give me some information using my email address?
    thank you
    youre sincerely

  • Nagahree Kashyap says:

    please give us the description of LDR used in the circuit, Sir !

  • Ligo George says:

    I haven’t yet used TINA..

  • Daniel says:

    I am trying to simulate it before trying it but is not doing anything, I am using TINA. Have you use a simulator for this? If so, can you share the file? Thanks in advance

  • Ligo George says:

    They are freewheeling diodes or flyback diodes..
    They are intended to cancel the effect of back emf produced in the motor wingdings.. Just search and read about it..

  • Ligo George says:

    Hello, 12V, 1W solar panel will not provide enough current for the working of motors..

  • sandeep G says:

    How the diodes are useful in the above given circuit…..

  • Bilal Yasin says:

    thanks for thz i want to make the project ll you plz give me some detail on my email [email protected]

  • Javier says:

    Hey don’t work!. I have everything like diagrams said

  • Vachan PraJapati says:

    hey i made same circuit . brother it’s not working :/

  • xavier says:

    dear Ligo George , could u suggest the suitable transistors at Q1,Q2,Q3,Q4 for the power rating 12v 5A

  • Amirul says:

    hello sir..i use a 12V 1W solar panel as the source 9-12V as the schematic diagram says. the motor doesn’t move even tough the ldr have been stimulated with bright light at one side. the output voltage gain are very small, in millivolt. can i know what is the prolem??

  • Ligo George says:

    It might be the problem of the IC…
    The output of the comparators will be +Vsat or -Vsat.. Which will be approximately equal to your Vcc..

  • Hasan Abu Zayyad says:

    thank U ^_^

  • Hasan Abu Zayyad says:

    I try it also it does not work !! , when shading LDR 1 i have 9 volt as output the VCC i used is 11 volt , when shading the other LDR2 i have onle 2 volt !! what would be the problem ? i tried to reconstruct the circuit for + 10 times , !! please HELP

  • Ligo George says:

    Then you may use two reference 10K variable resistors.. for each comparators..

  • Hasan Abu Zayyad says:

    if the LDR1 and LDR2 has not equal resistance at the same level of lighting – which is the case i just face when i bought the circuit elements – also the 10k & 10k hasen’t the same value exactly (+ 4% or -4%) , does that affect ?? if yes , how could we solve this problem ?

  • Ligo George says:

    It should be calculated depending upon the torque required….
    You can change the driving transistors as per the current requirements..

  • Akhilesh Agrawal says:

    what is the Power rating of motor you used? also can you suggest some motor for 1- 1.5 kg solar panel ? also what changes has to be made in the circuit according to the power of motor please. Thanks in advance 🙂

  • Ligo George says:

    I think it will automatically turn back.. .according to the light falling on it..

  • ehsan says:

    Hi.can you tel me how i can turn back it to east next morning for solar panel uses?

  • darma says:

    ok thanks a lot.

  • Ligo George says:

    Yes you can use mosfet………. base resistor is not required while using mosfet.. consider the current consumption of motos while choosing mosfet..

  • Darma says:

    Ok thanks. Will mosfet do the job also?

  • Ligo George says:

    Ya, sure… just replace 4 transistors depends on your current requirements..

  • Darma says:

    Hi. Find this circuit while searching for a solar tracker on the net. Just assembled & tried it. Seems that the transistors burned out because the motor was drawing too much current. Can they be replaced by a higher amp transistor?

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