I am currently doing a solar tracker project. Can I use the LDR as position sensor by detecting the sunlight intensity? I mean if light intensity on LDR east is greater than LDR west, the LDR east will send a data to microcontroller and tell the motor where the sun now and rotate to that position.

  • $\begingroup$ @MadMarky's point is key - why do you need to actively track the sun? Is the device itself driving around during the day? $\endgroup$ Mar 14, 2018 at 16:03
  • $\begingroup$ Yup, actually the tracker will track itself. $\endgroup$
    – Geddoe
    Mar 15, 2018 at 5:15
  • $\begingroup$ Can you provide more details on the project? E.g. is it used outdoors in a dirty environment? Do you have any cost targets? Is hitting those more important than maximum reliability? etc etc. The more information you can give, the higher quality answers you will receive. $\endgroup$ Mar 15, 2018 at 11:46

1 Answer 1


You already answered your own question: yes it is possible. The question that remains is whether it is the best option. LDR's tend to foul and get less reliable, especially when used outdoors. Also the object that you are tracking (the sun) tends to be very predictable. At noon it will be at the same point in the sky each day. If you have a clock you do not need to actively track the sun with sensors. Depending on your geographical location the height of the sun over the horizon may vary each day, but also this is very predictable.

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    $\begingroup$ LDR arrays can be used e.g. thingiverse.com/thing:859602 $\endgroup$ Mar 14, 2018 at 16:01
  • $\begingroup$ Is the LDR arrays more reliable? Other than LDR, what sensor I can use for the tracker? $\endgroup$
    – Geddoe
    Mar 15, 2018 at 5:16
  • $\begingroup$ No, the sun will NOT be in the same point in the sky each day at noon. The position will change by about 47 degrees seasonally. $\endgroup$ Mar 15, 2018 at 11:30
  • $\begingroup$ @OlinLathrop which i already mentioned in my last sentence. Also this only applies when you want to track the sun over multiple axis, Geddoe only talks about one. $\endgroup$
    – MadMarky
    Mar 15, 2018 at 13:26
  • $\begingroup$ Actually the last sentence isn't right either: "Depending on your geographical location the height of the sun over the horizon may vary each day". This is independent of location. The sun angle at noon varies by 47 deg over a year everywhere on earth, although in some locations that angle is actually negative part of the year, meaning the sun is below the horizon at noon. $\endgroup$ Mar 15, 2018 at 13:41

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