Solar Tracker with MOSFET

In the quest for sustainable and efficient energy solutions, solar power stands at the forefront as a beacon of clean, renewable energy. While the sun’s energy is abundant, optimizing its capture is paramount. This challenge is met head-on by solar trackers, devices which are designed to follow the sun’s path across the sky, maximizing solar panel efficiency. In the heart of these solar trackers,  lie the versatile MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors),  which controls the precise movements that ensure every sunbeam is captured and converted into electricity.  MOSFETs play a key role in making simple projects like Solar Tracker.  This article provides an overview on  how to design a solar tracker circuit with a MOSFET.

Solar Tracker with MOSFET

The main intention of this system is to design a solar tracker circuit with MOSFET for positioning a solar panel according to the position of the Sun. So that more sunlight will hit them by adjusting the solar panel position vertically to the sun.

Required Components

The required components of solar tracker with MOSFET mainly include; 12V DC supply, resistor R1 -10K, potentiometer P1 – 220K, diodes D1 & D2 – 1N4148, D3-1N5402, T1-30V, 10Amp N Channel MOSFET, 555 IC, Capacitors C1-5nF, C2-10nF and C3-100uF/25V.


The connections of the solar tracker with MOSFET follow as;

Solar Tracker Circuit using MOSFET
                                        Solar Tracker Circuit using MOSFET
  • The 12V DC supply is given to 8 & 4 pins of 555 timer IC.
  • The potentiometer P1 is connected to pin7 of the 555 timer IC.
  • The potentiometer VCC and GND pins are connected to one terminal of two diodes D1 & D2 and the other terminals of diodes are grounded through a C1 capacitor.
  • Pins 6 & 2 of the 555 timer IC are connected in between diodes and the C1 capacitor.
  • Pins 5 & 1 of the 555 timer IC are connected to the ground through a C2 capacitor.
  • The resistor R1 is connected to the 12V DC supply and in between pin3 of the 555 timer & gate terminal of MOSFET.
  • The gate pin of the 10Amp MOSFET is connected to pin3 of the 555 timer IC, the source pin of the MOSFET is grounded and the drain pin is connected to the motor negative wire. Here, in N channel MOSFET, it is very common to connect the Source to ground and load to the Drain terminal because, if the load in the circuit is connected to the Source terminal, a higher ‘Vgs’ is necessary for switching this MOSFET transistor, resulting in low current supply in between the two terminals than expected.
  • The motor-positive wire is connected to a 12V DC supply.
  • The D3 diode is connected to two terminals of the motor and capacitor C3 is connected to the drain and source terminals of MOSFET. The motor two terminals are connected to solar panel.


The solar tracker monitors the position of the sun in the sky to provide the commands accordingly to the control circuit as well as the motor so that required adjustments can be made very easily to the solar panel to maintain the necessary accuracy of the solar panel through the sun rays. This solar tracker system needs some significant settings & also adjustments.

This solar tracker system is a single-axis type and it can be designed very quickly, however, you will have to perform some tedious settings in the start & repeat it monthly once. The system efficiency in the early stages is 100% although it will go on fading when weeks progress until you refresh the unique settings. These settings can be changed by changing the positions of the sunrise or sunset of the sun during the year.


The single-axis solar tracker circuit is shown below which is used to implement a type of primitive algorithm within the circuit. This is a very simple concept; we just make a note of the standard time for which the sun stays alive or active over the sky. After that, we change the motor speed such that it turns the solar panel from daylight to dusk less or more facing the sun throughout its revolution.

The motor speed gets adjusted which turns the solar panel at 50 – 60 degrees angle around the set time. The solar tracker circuit used to adjust the speed of the motor is a PWM circuit obviously & the motor utilized in this circuit may be a stepper or an ordinary brush-less motor.

The motor speed adjustment in response to the daytime period should be optimized for several days to make the system very efficient. For records, the date & related speed setting should be noted down so that a similar setting can be provided without checking for the upcoming seasons.

In the above circuit, the solar panel is arranged with the large central rod of gear on the motor whereas the lower frame should be fixed firmly on the ground. The above circuit demonstrates the motor control module for the single-axis solar tracker made with 555 IC & some significant semiconductor parts. Here, potentiometer ‘P1’ must be arranged outside the field where the circuit may be roofed.

The potentiometer is a very important component that may be used to adjust the speed of the motor in all seasons so that the rotation of the solar panel will remain less or more synchronized with the movements of the sun.

The potentiometer ‘P1’ must be very carefully adjusted such that the electric motor used in the circuit will function at some set speed. The arrangement of the gear mechanism can be done in such a way that the diameters of larger & smaller gears generate a stable angular movement to the solar panel to maintain the solar panel faces less or more vertically to the sun during the day. Every time, the P1 setting must be noted down are refreshed equivalent to the several months of the year. After that, this data may be used for the upcoming years.

In the above circuit instead of PWM , LDR can be used as well which will make the entire circuit automatically controlled and no manual engagement is needed.

To make the above circuit LDR dependent go through the below steps.

This circuit is based on a single-axis tracking system, which means it tracks the sun’s east-to-west movement by rotating the solar panel around a single axis (typically the North-South axis). Here’s a basic explanation of how such a circuit can be constructed:

Components you’ll need:

  • 555 Timer IC: The heart of the circuit, which will generate the control signal for motor movement.
  • Light Sensor: A light-dependent resistor (LDR) or a photodiode to detect the sun’s position.
  • MOSFETs: You’ll need two N-channel MOSFETs (e.g., IRF540) to control the direction of the motor.
  • DC Motor: To adjust the solar panel’s position.
  • Power Supply: To provide power to the circuit and motor.
  • Resistors and Capacitors: For configuring the 555 timer in an astable mode.

Here’s a step-by-step explanation of how the solar tracker circuit with a 555 timer and LDR works:

  • 555 Timer Configuration (Astable Mode):
    • Connect pins 4 (RESET) and 8 (VCC) of the 555 timer to the positive power supply voltage (VCC).
    • Connect pin 1 (GND) of the 555 timer to the ground (0V).
    • Connect pin 5 (Control Voltage, CV) to pin 8 (VCC) for a stable operation.
    • Connect pins 2 (Trigger, TRIG) and 6 (Threshold, THRS) together, and connect them to pins 8 (VCC) via a resistor ( say R1).
    • Connect pins 2 (Trigger, TRIG) and 6 (Threshold, THRS) to pin 7 (Discharge, DISCH) via a capacitor (say C1).
    • Connect pin 7 (Discharge, DISCH) to pin 1 (GND) via another resistor (say R2).
    • Connect pins 2 (Trigger, TRIG) and 6 (Threshold, THRS) to the junction of the light sensor and another resistor divider.
  • Light Sensor Setup:
    • Create a voltage divider with two resistors. One resistor is connected to VCC, and the other is connected to GND. The light sensor is connected between these resistors.
    • The resistance of the light sensor changes with the amount of light it receives, which in turn affects the voltage at pins 2 and 6 of the 555 timer.
  • MOSFET Motor Control:
    • Use the 555 timer’s output (pin 3) to drive the gates of two N-channel MOSFETs.
    • Connect the DC motor to the MOSFETs such that it can rotate in both directions.
    • Depending on the voltage at pins 2 and 6 of the 555 timer (controlled by the light sensor), the 555 timer generates a square wave output at pin 3. This output alternates between high and low states, causing the motor to rotate clockwise or counterclockwise.
  • Feedback Loop:
    • As the sun’s position changes, the light sensor’s resistance changes, altering the voltage at pins 2 and 6 of the 555 timer.
    • This, in turn, changes the direction of motor rotation, causing the solar panel to track the sun.

The above two circuits can be tried at home by any electronics enthusiastic.  This would help you to understand the basics of MOSFET better.