>> ARDUINO POWERED SOLAR TRACKER TURRET

With summer just around the corner; I am so going to replicate and play around with this project.

I came across the solar tracker turret project and I had a "damn, I wish I had thought of that" moment. Utilizing four light sensors, two servos and an Arduino - you can follow the sun as it progresses through the day. The implications for solar based projects are dramatic; as aligning the solar panels perpendicular to the sun means optimal electrical production. Of course; the angle depends on latitude and while there are guides online, you can be 100% spot on with this.

So, how does it work exactly?

The secret is in the four light sensors and a cross shaped protrusion coming out the face of the device. As light shines on the device, each light sensor will either have light shining on or, or a shadow from the protrusion. When all light sensors detect direct sunlight; the device is perpendicular. If using a UV sensor; you can more accurately determine the source is the sun.

The Arduino sketch has been posted online; the core logic (simplified, documented):

void loop()
{
  int lt = analogRead(0);  // top left   -> A0
  int rt = analogRead(1);  // top right  -> A1
  int ld = analogRead(2);  // down left  -> A2
  int rd = analogRead(3);  // down right -> A3

  int avt = (lt + rt) / 2; // average value top
  int avd = (ld + rd) / 2; // average value down
  int avl = (lt + ld) / 2; // average value left
  int avr = (rt + rd) / 2; // average value right

  int dvert  = avt - avd;  // check the delta of up and down
  int dhoriz = avl - avr;  // check the delta of left and rigt

  // vertical: tolerance check, do we need to move servo
  if (ABS(dvert) > TOLERANCE)
  {
    if ((avt > avd) && (servov < 179)) servov++;
    if ((avt < avd) && (servov > 1))   servov--;

    vertical.write(servov);
  }

  // horizontal: tolerance check, do we need to move servo
  if (ABS(dhoriz) > TOLERANCE)
  {
    if ((avl > avr) && (servoh > 1))   servoh--;
    if ((avl < avr) && (servoh < 179)) servoh++;

    horizontal.write(servoh);
  }

  delay(DELAY);
}

A nice feature the included was to use potentiometers to control the tolerance and the delay period between loop iterations. It would make sense to use these to calibrate the device, but definitely wouldn't be required for a deployment scenario. It is fun to see that something that normally one would think would be so complicated to solve is actually in fact so simple.