Arduino Solar Tracker Gimbal with Sensor Noise Removal

Want to boost your solar panel efficiency without complex mechanics or expensive sensors? This compact Arduino-based solar tracker uses a simple servo gimbal and a pair of light sensors (LDRs) to follow the sun throughout the day. It’s easy to build, affordable, and a great beginner-friendly project for anyone interested in solar technology or Arduino.

How It Works

Two LDRs (Light Dependent Resistors) detect the difference in sunlight from two directions. The Arduino compares the values, calculates the difference, and adjusts a servo motor (acting as a gimbal) to point the panel toward the brighter side—ensuring it always faces the sun directly for maximum energy harvesting.

Circuit Diagram

The two LDRs form a voltage divider with 10k resistors. Their outputs are connected to analog pins A2 and A5 on the Arduino. These represent two opposing directions (left and right or east and west). The servo motor is connected to pin 9.

The Code

int smoothen(int arraySize, int inputPin)
{
  int input = 0;
  double sum = 0;

  for (int i = 0; i < arraySize; i++)
  {
    input = analogRead(inputPin);
    sum += input;
  }

  sum /= arraySize;
  return (int) sum;
}

• smoothen(): Reads the analog pin multiple times and returns the average, filtering out sensor noise.

void loop()
{
  int input = smoothen(20, A2) - smoothen(20, A5);
  input = map(input, -200, 200, 0, 180);
  rotator.write(input);
  Serial.print(input);
  Serial.print(';');
  delay(5);
}

• loop(): Calculates the difference between the two LDR readings, maps that to a servo angle (0–180°), and commands the servo to rotate.
• map(): Converts the sensor difference into a servo-friendly angle range.

How to Test

• Power up your Arduino.
• Shine a flashlight or move the device near a window.
• You’ll see the servo rotate toward the brighter side.
• Open the Serial Monitor to watch the angle value change in real-time.