Solar Circuit Diagrams

Sun Tracking Solar Panel

In this project, we will see a simple Sun Tracking Solar Panel circuit which will track the Sun and position the solar panels accordingly.


  • Introduction
  • Principle of Sun Tracking Solar Panel
  • Sun Tracking Solar Panel Circuit Diagram
    • Components in the Circuit
  • Automated Sun Tracking Solar Panel Circuit Design
    • ATmega328 Microcontroller
    • Solar Panel
    • LDR
    • Servo Motor
  • Code
  • How Sun Tracking Solar Panel Works?
  • Advantages of Sun Tracking Solar Panel
  • Sun Tracking Solar Panel Applications
  • Limitations of Sun Tracking Solar Panel Circuit

With the depletion of nonrenewable energy resources, there is a growing shift towards the utilization of renewable energy sources for electricity generation. Solar panels, in particular, have gained significant popularity. We’ve previously explored an article detailing the installation of solar panels in a home setting. In essence, a solar panel harnesses solar energy, converts it into electrical energy, and then stores it in a battery.

This stored energy can be employed on demand or serve as a direct substitute for electricity supplied by the grid. The following are applications that utilize the energy stored in batteries.

Given the Earth’s rotational nature, the position of the Sun relative to the solar panel is in constant flux. To optimize the utilization of solar energy, it is imperative for solar panels to capture as much sunlight as possible. This can only be achieved if the panels continuously align themselves with the Sun’s position. Consequently, the solar panel must consistently track the Sun’s direction. The circuit responsible for automating the rotation of a solar panel is elucidated in this article.

Sun Tracking Solar Panel

Principle of Sun Tracking Solar Panel

The Sun-tracking solar panel comprises two Light-Dependent Resistors (LDRs), a solar panel, a servo motor, and an ATmega328 Microcontroller.

Positioned along the edges of the solar panel are two LDRs, which function by exhibiting low resistance when exposed to light. A servo motor, affixed to the panel, is responsible for orienting it in the direction of the Sun. The panel is configured in a manner that allows it to compare the light intensities detected by the two LDRs. Subsequently, the panel is rotated toward the LDR registering the highest light intensity, signifying the lowest resistance. The servo motor facilitates precise angle adjustments in the panel’s orientation.

As sunlight conditions change, the panel responds accordingly. If the right LDR detects greater light intensity, the panel gradually shifts to the right, while if the left LDR registers higher intensity, the panel gradually moves to the left. During noon, when the Sun is directly overhead, both LDRs perceive equal light intensities, leading to a stable position for the panel with no rotation.

Sun Tracking Solar Panel Circuit Diagram

Components in the Circuit

  • Solar panel
  • ATmega328 Micro Controller
  • Light Dependent Resistor (LDR) x 2
  • 10KΩ x 3
  • Servo Motor
  • 16MHz Crystal
  • 22pF Ceramic Capacitors x 2
  • Push Button
  • Breadboard
  • Cardboard
  • Connecting Wires

Automated Sun Tracking Solar Panel Circuit Design

The proposed system consists of ATmega328 micro controller, Solar panel, Light Dependent resistors and Servo Motor.

ATmega328 Microcontroller

The ATmega328 belongs to the AVR microcontroller family and is constructed using advanced RISC architecture. It operates as an 8-bit resolution controller with notable specifications, including 32K bytes of Programmable Flash memory, 1K bytes of EEPROM, and 2K bytes of SRAM. This microcontroller boasts 23 programmable I/O pins and provides support for various peripherals such as two 8-bit timers, one 16-bit timer, a 6-channel ADC with 10-bit precision, programmable USART, Serial Peripheral Interface (SPI), 2-wire serial interface (I2C), and other essential functions.

Solar Panel

A solar panel is positioned atop a cardboard surface, primarily for illustrative purposes. The lower portion of the cardboard is linked to a servo motor. The solar panel comprises an arrangement of photovoltaic cells, which are essentially solar cells. These solar cells are constructed from semiconductor material, specifically silicon.

When a sunbeam strikes the solar cell, a portion of its energy is absorbed by the material. This absorbed energy provides sufficient energy for electrons to transition between different orbits within the atom. These cells are equipped with one or more electric fields that guide these electrons, resulting in the generation of current. By introducing metal contacts, we can harness the energy produced by these cells.


LDRs, or Light Dependent Resistors, are resistors whose resistance levels are directly proportional to the intensity of light they are exposed to. As the intensity of light on the LDR increases, its resistance value decreases. LDRs exhibit their highest resistance in darkness. To utilize the LDR’s output effectively, it generates an analog value that needs to be converted into a digital format. This conversion process can be accomplished with the assistance of an Analog-to-Digital Converter (ADC).

The ATmega328 microcontroller is equipped with an internal ADC. Among the available ADC channels (ADC0 to ADC5, corresponding to Pins 23 to 28), we connect the two LDRs to ADC pins 27 and 28 using individual 10K resistors in a voltage divider configuration. The conversion process for ADC is carried out using the successive approximation technique.

Servo Motor

The rotation of the panel is executed by a servo motor. To operate the servo motor, a PWM (Pulse Width Modulation) signal is required to be transmitted to its control pin. Consequently, Pin 17, which supports PWM, is connected to the control pin of the servo motor.

It is possible to store the energy generated by the solar cells by incorporating a battery with the solar panel, allowing for its utilization as required. To ensure effective control and charging of the charge derived from the solar panels, distinct charge controller circuits are employed.


In a previous tutorial, I have shown you “How to Burn Bootloader to ATmega328”. In this tutorial, you can understand how to upload code to the ATmega328 Microcontroller using Arduino IDE.

  #include <Servo.h>
  Servo myservo;
  int ldr1 = 4;
  int ldr2 = 5;
  int val1;
  int val2;
  int pos=90;
  void setup()
  void loop()
  val1 = analogRead(ldr1);
  val2 = analogRead(ldr2);
  val1 = map(val1, 0, 1023, 0, 180);
  val2 = map(val2, 0, 1023, 0, 180);
  if(val1 > (val2+50))
  else if(val2 > (val1+50))

How Sun Tracking Solar Panel Works?

  1. Assemble the circuit as described and upload the code to ATmega328 Microcontroller.
  2. Power on the circuit and place the set up directly under the Sun (on the rooftop).
  3. Based on the light falling on the two LDRs, the ATmega328 Microcontroller changes the position of the Servo Motor which in turn moves in the panel.

Advantages of Sun Tracking Solar Panel

  1. The solar energy can be reused as it is non-renewable resource.
  2. This also saves money as there is no need to pay for energy used (excluding the initial setup cost)
  3. Helps in maximizing the solar energy absorption by continuously tracking the sun.

Sun Tracking Solar Panel Applications

  1. These panels can be used to power the traffic lights and streetlights
  2. These can be used in home to power the appliances using solar power.
  3. These can be used in industries as more energy can be saved by rotating the panel.

Limitations of Sun Tracking Solar Panel Circuit

  1. Though solar energy can be utilized to maximum extent this may create problems in rainy season.
  2. Although solar energy can be saved to batteries, they are heavy and occupy more space and required to change time to time.
  3. They are expensive.

So far, you’ve learned about the operation of a sun-tracking solar panel. If you want to set them up or install them on your house or office rooftops, we recommend the Best Solar Panel Kits for Homes in 2018.

This article will assist you in comprehending the concept of solar panel kits and will instruct you on how to select solar panels (important considerations) when shopping online. Read the entire article and select the one that best meets your needs.


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