Things You Need

Hardware Components:

1. DFRduino UNO R3
2. DFRobot I/O Expansion Shield
3. DF05BB Tilt/Pan Kit(5Kg)
4. DFRobot Photocell x 4
5. Resistor 10kOhm x 4
6. DFRobot Solar Panel

Software:

1. Arduino IDE

Tools:

1. Solder Iron

In modern solar tracking systems, the solar panels are fixed on a structure that moves according to the position of the sun.

Let us design a solar tracker using two servo motors, a light sensor consisting of four mini photocells and Arduino UNO board.

Assembly of the Pan Tilt

Follow the steps in the images above and assemble the parts.

Remember: Use rubber spacers when using the M1x6.

Connections

Stack the I/O Expansion Shield on the Arduino.

• Connect lower servo with D9 in shield.
• Connect upper servo with D10 in shield.
• Take +5V and GND to power rails in breadboard.
• Connect +5V in breadboard to each photocell.
• Connect upper left photocell to A0.
• Connect upper right photocell to A1.
• Connect lower right photocell to A2.
• Connect lower left photocell to A3.
• Connect GND terminal of each photocell to GND with 10k Ohm resistor in series.

Fixing and Testing

• Fix the Solar Panel on a cardboard and paste it on the face of upper servo.

• Take out all the wires and give them a play so as to move about 180 degrees.

• Put the system on a stable platform.

• Upload the code and test it with a bright LED or a bulb.

Schematics

Image source : Electronics Hub

CODE

#include<Servo.h>

Servo servohori;
int servoh = 0;
int servohlimithigh = 180;
int servohlimitlow = 0;

Servo servoverti;
int servov = 0;
int servovlimithigh = 180;
int servovlimitlow = 0;

//Assigning LDRs variables
int ldrtopl = 0;
int ldrtopr = 1;
int ldrbotr = 2;
int ldrbotl = 3;

void setup() {
  servohori.attach(10);
  servohori.write(0);
  servoverti.attach(9);
  servoverti.write(0);
}

void loop() {
  /* code */
  servoh = servohori.read();
  servov = servoverti.read();

  //capturing analog values of each LDR
int topl = analogRead(ldrtopl);
int topr = analogRead(ldrtopr);
int botl = analogRead(ldrbotl);
int botr = analogRead(ldrbotr);
// calculating average
int avgtop = (topl + topr) / 2; //average of top LDRs
int avgbot = (botl + botr) / 2; //average of bottom LDRs
int avgleft = (topl + botl) / 2; //average of left LDRs
int avgright = (topr + botr) / 2; //average of right LDRs

if (avgtop < avgbot)
{
  servoverti.write(servov +1);
  if (servov > servovLimitHigh)
   {
    servov = servovLimitHigh;
   }
  delay(10);
}
else if (avgbot < avgtop)
{
  servoverti.write(servov -1);
  if (servov < servovLimitLow)
{
  servov = servovLimitLow;
}
  delay(10);
}
else
{
  servoverti.write(servov);
}

if (avgleft > avgright)
{
  servohori.write(servoh +1);
  if (servoh > servohLimitHigh)
  {
  servoh = servohLimitHigh;
  }
  delay(10);
}
else if (avgright > avgleft)
{
  servohori.write(servoh -1);
  if (servoh < servohLimitLow)
   {
   servoh = servohLimitLow;
   }
  delay(10);
}
else
{
  servohori.write(servoh);
}
delay(50)
}