Solar Sun Tracker Sun Trackers are a great way to get maximum performance out of your solar panels. Positioning your solar panels in a fixed location will do the job, but you will be robing your self of free power and maximum efficiency! The only downfall of a solar tracker is it takes energy to move the motor to reposition the panels so they are always facing the sun. Overall an efficient Solar Trackers can produce 30-50% more amp hour making it a very worth while project.

A simple solar tracker can be built using some common radio shack parts, to upgrade this project to full size, you would simply use a heavier duty motor and relays which would be dependent on the size of your panels and how much energy is needed to rotate them.

Parts List:
3 x LDR
1 x 33 R Resistor
1 x 75 R Resistor
1 x 100 R Resistor
1 x 10K Resistor
1 x 20K Resistor
1 x 2N4401 Transistor
1 x TIP120 Darlington pair
1 x 9v Relay
1 x 5v Motor

Simple Sun Tracker Schematic

With the schematic laid out, you can see it is a very simple design. The position of the sensors is what allows this system to track the sun.

Solar Tracker Sensor Layout - Photo courtesy of McGraw-Hill

Sensor #3 is located in an inverted enclosure so that the light will only hit it when its facing directly at the sun. When the sun leaves photoresistor #3, its resistance increases switching on the Darlington pair which interns switches on the relay that drives the motor. When sun hits the photoresistor it’s resistance decreases disabling the Darlington pair and in turn stopping the motor.

Now you may ask what happens when the sun goes down or is hidden behind a cloudy sky? Does this tracker aimlessly scan the sky? well this is where photoresistor #2 comes in, Flush mounted this little guy can see the entire sky. When photoresistor #2 senses the sun is out it drives the NPN transistor low. If the sun should disappear for the evening, the lack of sun will raise the resistance which brings the NPN transistor base high turning the darlington pair to low and disabling the tracker. Sensor #1 is mounted to the east, which will sense the sun rising in the morning.

I hope this tutorial on building a solar tracker has inspired you to build your own! If you build your own large scale tracker be sure to post what you used for a motor and any upgrades to this system.



18 Responses to “Building a Sun Tracker”

  1. Eric Johnson Says:

    On your parts list, you have 1 x 33R Resistor, but your diagram shows 2. The parts list also has 1 x 100 R resistor, but the diagram shows a variable resistor above the motor.

    Could you please clarify?

    Thank You,
    Eric Johnson

  2. Terry Hamidi Says:

    Very nice drawing explanations. I can not wait until I build it.
    Can you please give some ideas on how to build the mechanical portion of the project?

    Thank You

  3. AL Says:

    Eric the resistor above the motor is 40 ohms on a circuit the same as this I found a few years ago.

    I have built 2 of these and each time the 33 ohm resistor connected to the emitter of the 2n4401 has fried while adjusting 10k potentiometer, no idea why, I found a much better circuit recently that uses two ne555 timer IC’s

    Hope this helps and gets more feedback.

    AL

  4. Darma Says:

    This “sun tracker” has no circuit to change polarity on the DC motor. This means that it will turn only in one direction, thus, spinning day after day !

  5. calvin smit Says:

    How does the motor reverse for the next days sun? Would i use a limit switch at the end of the day to reverse the motor and move the panel back to the east?

  6. ranvir singh malhi Says:

    i need a 5kw solar grid for house so help me to make solar grid and wring diagram thanks

  7. solarpanels Says:

    Hrmm that was weird, my comment got eaten. Anywho I wanted to express it’s good to know that somebody else also highlighted this as I had problems locating the similar information in other places. This is the very first place which helped me understand why. Thank you.

  8. vidhya Says:

    how do you use those variable resistors in the above circuit? what is the voltage you are giving at each point. reply is must plz….. urgent

  9. zainab Says:

    Hi
    I am electrical engineering student in university of Bahrain. I am having my senior project this course it’s about sun tracking using microcontroller 16F877A
    I saw your project and I was very impressed, so I thought maybe you are the right person that can help me in doing this, if you would do it I would appreciate it very much.
    Basically my idea is to sense the sun light, rotate the motor and supply the load which is a small fan the extra voltage will charge the batteries
    Right now I already have the solar panels and the 16F877A pic I need to think about the motor, the sensor and the batteries I will charge.
    • What do you think about the whole idea?
    • I am thinking to use a DC motor instead of stepper motor because my panel is small and does not drive much current. What do you think of that?
    • What type of sensors do you advice me to use?

    Can I have more information: papers ,websites ,circuits anything would be helpful
    Thank you

  10. Lovepreet Singh Says:

    Respected Sir,

    Sir I am a B.Tech. Final year Electronics & Communication Engineering Student. I am supposed to do this project as my final year project (working Model). So Please kindly Guide me in this regard.

    Thanking You

  11. Hamadan Says:

    Hi,
    this is my last year HD program in electrical. so, i decide to do a solar track too. My Q is how can i choose the size of the stepper motor if my solar wight around 10KG and it is rectanguler shap. and what about the steps i want it to follow the sun so i will put LDR on the solar to attract the maximum heat. plz help me to choose the motor and the gear box.

    best regards

  12. virendra Says:

    Thanks for this sir.
    Can you please give some ideas on how to build the mechanical portion of the project? Is there any changes in the given information as I have seen that someone has point out something on this explanation. Thanks and please reply as soon as possible. Regards.

  13. Aldo Santalco Says:

    To Project Free Power,

    I’m Aldo Santalco, a graduate student from LUISS University (Rome),
    Since the figure on top concerning sensors for solar panels was very useful for my thesis on technological platforms, I would ask you the permission to put it on my thesis.
    That will be particularly useful, especially since my thesis is on the way to be published,
    Obviously source and reference will be write down,

    Many thanks for your attention,

    Looking forward to hear from you,

    Best Regards,
    Aldo Santalco

  14. Mandeep singh Says:

    Respected sir,
    please give me information amout this project me for this project.

  15. muhammad naeem Says:

    Thanks for this really good design it really helped me a lot to bild my own solar trackor

  16. Sun Tracker by knossos - Pearltrees Says:

    [...] Project Free Power » Blog Archive » Building a Sun Tracker Sun Trackers are a great way to get maximum performance out of your solar panels. Positioning your solar panels in a fixed location will do the job, but you will be robing your self of free power and maximum efficiency! The only downfall of a solar tracker is it takes energy to move the motor to reposition the panels so they are always facing the sun. Overall an efficient Solar Trackers can produce 30-50% more amp hour making it a very worth while project. A simple solar tracker can be built using some common radio shack parts, to upgrade this project to full size, you would simply use a heavier duty motor and relays which would be dependent on the size of your panels and how much energy is needed to rotate them. [...]

  17. Solar by knossos - Pearltrees Says:

    [...] Project Free Power » Building a Sun Tracker Sun Trackers are a great way to get maximum performance out of your solar panels. Positioning your solar panels in a fixed location will do the job, but you will be robing your self of free power and maximum efficiency! The only downfall of a solar tracker is it takes energy to move the motor to reposition the panels so they are always facing the sun. Overall an efficient Solar Trackers can produce 30-50% more amp hour making it a very worth while project. [...]

  18. mandeep Says:

    can i use any type of microprocessor for control position…..say how i make simple sun tracker for solar panel….give me reply..

    thank you.

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