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Arduino Solar Tracking: How to Create a Solar Tracker using Arduino

Introduction to Arduino Solar Trackers

Solar energy has become increasingly popular as a renewable and sustainable source of power. To maximize the efficiency of solar panels, it is essential to ensure that they are always facing the sun at the optimal angle. This is where solar trackers come into play. Solar trackers are devices that automatically adjust the orientation of solar panels to follow the sun’s movement throughout the day, optimizing their energy output.

Arduino, an open-source electronics platform, has made it easier for enthusiasts and professionals alike to create their own solar tracking systems. In this article, we will guide you through the process of building an Arduino solar tracker, discussing the components required, the circuit diagram, and the programming involved.

Components Required for an Arduino Solar Tracker

To build an Arduino solar tracker, you will need the following components:

Component Quantity
Arduino board (e.g., Uno) 1
Light Dependent Resistor (LDR) 4
Servo motor 2
10kΩ resistor 4
Breadboard 1
Jumper wires As needed
Solar panel 1

Arduino Board

The Arduino board is the brain of the solar tracker. It processes the input from the light sensors and controls the movement of the servo motors. The Arduino Uno is a popular choice for this project due to its ease of use and wide compatibility.

Light Dependent Resistor (LDR)

LDRs are light-sensitive devices whose resistance decreases with increasing light intensity. In this project, we will use four LDRs to detect the position of the sun. The LDRs will be placed in a specific configuration to determine the sun’s location relative to the solar panel.

Servo Motor

Servo motors are used to precisely control the angular position of the solar panel. In this project, we will use two servo motors: one for horizontal (azimuth) movement and another for vertical (altitude) movement. The servo motors will be controlled by the Arduino board based on the input from the LDRs.

Resistors, Breadboard, and Jumper Wires

The 10kΩ resistors are used to create voltage divider circuits with the LDRs. This allows the Arduino to read the light intensity as an analog value. The breadboard and jumper wires are used to connect the components and create the circuit.

Solar Panel

The solar panel is the device that converts sunlight into electrical energy. The size and specifications of the solar panel will depend on your specific application and power requirements.

Circuit Diagram for the Arduino Solar Tracker

The circuit diagram for the Arduino solar tracker is as follows:

     |--- Analog Pin 0

     |--- Analog Pin 1

     |--- Analog Pin 2

     |--- Analog Pin 3

    Servo Motor 1 (Horizontal)
    Brown  --- GND
    Red    --- 5V
    Orange --- Digital Pin 9

    Servo Motor 2 (Vertical)
    Brown  --- GND
    Red    --- 5V
    Orange --- Digital Pin 10

Programming the Arduino Solar Tracker

To program the Arduino solar tracker, you will need to use the Arduino IDE (Integrated Development Environment). The IDE allows you to write, compile, and upload code to the Arduino board.

Here’s a sample code for the Arduino solar tracker:

#include <Servo.h>

Servo servoHorizontal;
Servo servoVertical;

int ldrTL = A0; // LDR Top Left
int ldrTR = A1; // LDR Top Right
int ldrBL = A2; // LDR Bottom Left
int ldrBR = A3; // LDR Bottom Right

int toleranceValue = 50;

void setup() {

void loop() {
  int tl = analogRead(ldrTL);
  int tr = analogRead(ldrTR);
  int bl = analogRead(ldrBL);
  int br = analogRead(ldrBR);

  int averageT = (tl + tr) / 2;
  int averageB = (bl + br) / 2;
  int averageL = (tl + bl) / 2;
  int averageR = (tr + br) / 2;

  int diffHorizontal = averageL - averageR;
  int diffVertical = averageT - averageB;

  if (abs(diffHorizontal) > toleranceValue) {
    if (diffHorizontal > 0) {
      servoHorizontal.write(servoHorizontal.read() + 1);
    } else {
      servoHorizontal.write(servoHorizontal.read() - 1);

  if (abs(diffVertical) > toleranceValue) {
    if (diffVertical > 0) {
      servoVertical.write(servoVertical.read() + 1);
    } else {
      servoVertical.write(servoVertical.read() - 1);


Let’s break down the code:

  1. We include the Servo library to control the servo motors.
  2. We define the servo objects for horizontal and vertical movement.
  3. We declare the analog pins connected to the LDRs.
  4. In the setup() function, we attach the servo motors to their respective digital pins.
  5. In the loop() function, we read the analog values from the LDRs.
  6. We calculate the average values for the top, bottom, left, and right LDRs.
  7. We calculate the difference between the left and right averages (horizontal movement) and the top and bottom averages (vertical movement).
  8. If the absolute difference is greater than the tolerance value, we adjust the servo motors accordingly.
  9. We add a small delay to avoid rapid movements.

Upload this code to your Arduino board, and your solar tracker should start following the sun!

Mounting and Testing the Arduino Solar Tracker

Once you have assembled the circuit and uploaded the code, it’s time to mount the solar tracker and test its functionality. Follow these steps:

  1. Attach the solar panel to the servo motors, ensuring that it is securely fastened.
  2. Mount the entire assembly on a stable surface, such as a tripod or a dedicated stand.
  3. Position the LDRs around the solar panel, ensuring that they are evenly spaced and facing the same direction as the panel.
  4. Power on the Arduino board and observe the movement of the solar panel.
  5. Expose the solar tracker to sunlight and verify that it accurately follows the sun’s position.

If the solar tracker is not moving as expected, double-check your circuit connections and ensure that the code has been uploaded correctly.

Optimizing and Customizing the Arduino Solar Tracker

There are several ways to optimize and customize your Arduino solar tracker:

  1. Adjusting the Tolerance Value: The tolerance value determines how sensitive the tracker is to changes in light intensity. You can experiment with different tolerance values to find the optimal balance between responsiveness and stability.

  2. Adding a Real-Time Clock (RTC): An RTC module allows the solar tracker to keep track of time, enabling more advanced features such as automatic reset to the original position at night or during cloudy conditions.

  3. Implementing Remote Monitoring: You can add a wireless communication module (e.g., Wi-Fi or Bluetooth) to remotely monitor the performance of your solar tracker and receive alerts if any issues arise.

  4. Enhancing the Tracking Algorithm: The sample code provided in this article uses a simple tracking algorithm based on LDR readings. You can explore more advanced algorithms, such as PID (Proportional-Integral-Derivative) control, to improve the tracking accuracy and efficiency.

  5. Upgrading the Hardware: Depending on your application, you may want to use higher-quality components, such as more precise servo motors or higher-resolution LDRs, to enhance the performance of your solar tracker.


  1. Can I use a different Arduino board for this project?
    Yes, you can use any Arduino board that has sufficient analog and digital pins to accommodate the LDRs and servo motors. However, you may need to adjust the pin assignments in the code accordingly.

  2. How do I determine the appropriate size of the solar panel?
    The size of the solar panel depends on your power requirements and the specific application. Consider factors such as the desired output voltage, current, and the available space for mounting the panel.

  3. Can I use this solar tracker for larger solar panels?
    The Arduino solar tracker can be scaled up to accommodate larger solar panels. However, you may need to use stronger servo motors and a more robust mounting structure to handle the increased weight and size.

  4. How do I power the Arduino board and the servo motors?
    You can power the Arduino board using a USB cable connected to a computer or a dedicated power supply. The servo motors can be powered directly from the Arduino board if they require 5V and draw less than 1A of current. For higher power requirements, use a separate power source for the servo motors.

  5. Can I add a battery to store the energy generated by the solar panel?
    Yes, you can add a battery and a charging circuit to store the energy generated by the solar panel. This allows you to use the stored energy even when sunlight is not available. However, this requires additional components and circuitry, which is beyond the scope of this article.


Building an Arduino solar tracker is an excellent way to optimize the performance of your solar panels and explore the world of renewable energy. By following the steps outlined in this article, you can create a functional solar tracker that automatically adjusts the orientation of your solar panel to follow the sun’s movement.

Remember to experiment, optimize, and customize your solar tracker based on your specific requirements and goals. With the power of Arduino and a little creativity, you can take your solar energy projects to the next level!