Sun always craves its path across the sky. So the radiation beam angle will change continuously throughout its path. So if we try to design a solar powered device, Sun Tracker - DIY solar project is a good recommendation for utilizing the maximum power from the sun. Normally the solar panels are oriented perpendicular to the sun to receive maximum radiations. This simple low cost Diy solar project-Sun Tracker will help us to achieve maximum power at all the time from the solar panels automatically by moving the solar panel according to the direction of sun, i.e. tracking the sun. That is, tracking the sun means, to rotate the position of solar panels according to the position of sun. Here we are trying to design a simple sun tracker - DIY solar project, which will fulfill these conditions. 

How Do Solar Panels Works?

solar panels

A solar cell which is also known as photovoltaic cell, is an electrical device, which convert light energy directly in to electrical energy or electricity. The amount of electrical energy depends up on the amount of light energy falling on the solar panels.  Actually, solar cell is a form of photoelectric cell with current, voltage and resistance varying when exposed to sun light. When sun light strikes these solar panels or cells, electrons in the cells become loose from their atoms and start moving. Generally, the solar cell is made up of with two different layers, which stuck together. When sun light strikes on the cells, the electrons starts moving according to the intensities of light and if we attach an electrical conductor to the positive and negative sides of the panel, the electrons starts moving through this electrical circuit path (through conductors) and we can produce an electrical energy that is electricity. 

 Working of Sun Tracker - DIY Solar Project:  

This sun tracker circuit controls the movement of solar panels to achieve maximum radiation from the sun. The solar panels are normally oriented perpendicular to the sun for getting the optimal parameters. This Sun Tracker - DIY Solar Project will help us to achieve maximum power transfer at all times from the solar panels automatically by tracking the sun.  

In this Sun Tracker circuit, two LDRs are used to detect the direction of sun. The LDRs are arranged on the solar panel in such a way to strike the radiation on LDRs, directly from the sun. The intensity of light falling on these LDRs is varied in accordance with movement of the sun’s direction.  

DIY sun Tracking Circuit

Fig : DIY Sun Tracking Circuit Diagram

The main element in this Sun Tracker - DIY Solar Project circuit is the two voltage comparators using LM358 dual Op-Amp. We all know that, when light falling on LDRs, its resistance decreases with the increase in light intensity. Two resistors R3 and R4 are connected in series with these LDRs. Hence, when light intensity falling on the LDR increases, voltage across the corresponding resistors also increases. The voltage comparator produces a high output, when the voltage at the non-inverting (+) terminal is higher than the voltage at the inverting terminal (-). The inverting terminals (-) of both the comparators are shorted together and connected to RV1, which is a variable resistor and is used to set the reference voltage. This 10K pot (RV1) can be varied to adjust the sensitivity of both the LDRs. The motor used in the DIY solar tracking circuit is connected to an H-Bridge formed by the complimentary symmetry transistors BC547 & BC557. This H-Bridge circuit element controls the direction of motor rotation. The various modes of the motor rotation are listed in the table given below.

solar tracker     









Anti-Clock Wise



Clock Wise




Table: Various Modes of Motor Rotation

The comparator output depends on the inverting and non-inverting terminal voltage. Consider a situation, where, more light falls on LDR1, then the voltage at the non-inverting terminal of comparator (A1) start increasing and its output goes high and the output of the other comparator (A2) is low. In this case, the transistors Q1& Q4 will turn on and the motor starts to rotate in clock wise direction as a result of the current flow. Now the second case, when the output of the second comparator (A2) is high and the output of comparator (A1) goes in to low state, then the transistors Q2 and Q3 will turn on and the resulting current flow will rotate the motor in anti-clock wise direction. If the outputs of both comparators (A1 & A2) are low, then the transistors (Q3 & Q4) will be in on state but the motor will not run, since there is no current flow through the motor. Similarly, if the outputs of both comparators (A1 & A2) are high, then the transistors (Q1 & Q2) will be in on state but here also, no current flow occurs through the motor so the motor will not rotate. Thus, according to the intensities of light falling on the two LDRs, comparators rotates the motor either clock wise or in anti-clock wise direction. Care should be taken that the DC Motor should be connected to the solar panel in such a way that, it will rotate the panel according to the movement of sun.

Electronic Components:

  • Op-Amp, A1&A2: LM 358 (2No.s)
  • LDR: 2No.s
  • POT, RV1: 10K
  • DC Motor: M
  • Diode: 1N 4001(4No.s)
  • Solar Panel


  • R1: 1K
  • R2: 1K
  • R3: 10K
  • R4: 10K


  • Q1, Q2: BC 547
  • Q3, Q4: BC 557
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