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Wednesday, July 12, 2017

Arduino Solar Tracker using LDR and Servo Motor




In this article we are going to make a Solar Panel Tracker using Arduino, in which we will use two LDRs (Light dependent resistor) to sense the light and a servo motor to automatically rotate the solar panel in the direction of the sun light. Advantage of this project is that Solar panel will always follow the sun light will always face towards the sun to get charge all the time and can provide the supply the maximum power. The prototype is very easy to build. Below you will find the complete description of how it works and how the prototype is made.



Required Components:

  • Servo Motor (sg90)
  • Solar panel
  • Arduino Uno
  • LDR’s X 2 (Light Dependent Resistor)
  • 10K resistors X 2
  • Battery (6 to 12V)



How it Works:

In this project, LDR’s are working as light detectors. Before we go into detail, we will have to understand how the LDR’s work. LDR (Light Dependent Resistor) also known as photo resistor is the light sensitive device. Its resistance decrease when the light falls on it and that’s why it is frequently used in Dark or Light Detector Circuit. Check the various circuits based on LDR here.
The two LDR’s are placed at the two sides of solar panel and the Servo Motor is used to rotate the solar panel. The servo will move the solar panel towards the LDR whose resistance will be low, mean towards the LDR on which light is falling, that way it will keep following the light. And if there is same amount of light falling on both the LDR, then servo will not rotate. The servo will try to move the solar panel in the position where both LDR’s will have the same resistance means where same amount of light will fall on both the resistors and if resistance of one of the LDR will change then it rotates towards lower resistance LDR. Check the Demonstration Video at the end of this Article.


Circuit Diagram and Explanation:




In this Arduino Solar Panel Tracker, Arduino is powered by the 9V battery and all the other parts are powered by the Arduino. Arduino recommended input voltage is from 7 to 12 volts but you can power it within the range of 6 to 20 volts which is the limit. Try to power it within the recommended input voltage. So connect the positive wire of the battery to the Vin of the Arduino and the negative wire of the battery to the ground of the Arduino.
Next connect the servo to the Arduino. Connect the positive wire of the servo to the 5V of Arduino and ground wire to the ground of the Arduino and then connect the signal wire of Servo to the digital pin 9 of Arduino. The servo will help in moving the solar panel.
Now connect the LDRs to the Arduino. Connect one end of the LDR to the one end of the 10k resistor and also connect this end to the A0 of the Arduino and connect the other end of that resistor to the ground and connect the other end of LDR to the 5V. Similarly, connect the one end of second LDR to the one end of other 10k resistor and also connect that end to the A1 of Arduino and connect the other end of that resistor to ground and connect the other end of LDR to 5V of Arduino.

Code: 

#include <Servo.h>      //including the library of servo motor 
Servo sg90;             //initializing a variable for servo named sg90
int initial_position = 90;   //Declaring the initial position at 90
int LDR1 = A0;          //Pin at which LDR is connected
int LDR2 = A1;          //Pin at which LDR is connected
int error = 5;          //initializing variable for error
int servopin=9;
void setup() 
  sg90.attach(servopin);  // attaches the servo on pin 9
  pinMode(LDR1, INPUT);   //Making the LDR pin as input
  pinMode(LDR2, INPUT);
  sg90.write(initial_position);   //Move servo at 90 degree
  delay(2000);            // giving a delay of 2 seconds
}  
 
void loop() 

  int R1 = analogRead(LDR1); // reading value from LDR 1
  int R2 = analogRead(LDR2); // reading value from LDR 2
  int diff1= abs(R1 - R2);   // Calculating the difference between the LDR's
  int diff2= abs(R2 - R1);
  
  if((diff1 <= error) || (diff2 <= error)) {
    //if the difference is under the error then do nothing
  } else {    
    if(R1 > R2)
    {
      initial_position = --initial_position;  //Move the servo towards 0 degree
    }
    if(R1 < R2) 
    {
      initial_position = ++initial_position; //Move the servo towards 180 degree
    }
  }
  sg90.write(initial_position); // write the position to servo
  delay(100);
}







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