DUAL AXIS SOLAR TRACKING SYSTEM

Abstract:            Solar panel has been used increasingly in recent years to convert solar energy to electrical energy. The solar panel can be used either as a stand-alone system or as a large solar system that is connected to the electricity grids. The earth receives 84 Terawatts of power and our world consumes about 12 Terawatts of power per day. We are trying to consume more energy from the sun using solar panel. In order to maximize the conversion from solar to electrical energy, the solar panels have to be positioned perpendicular to the sun. Thus the tracking of the sun’s location and positioning of the solar panel are important. The goal of this project is to design an automatic tracking system, which can locate position of the sun. The tracking system will move the solar panel so that it is positioned perpendicular to the sun for maximum energy conversion at all time. Photoresistors will be used as sensors in this system. The system will consist of light sensing system, microcontroller, gear motor system, and a solar panel. Our system will output up to 40% more energy than solar panels without tracking systems.

Generally, solar panels are stationary and do not follow the movement of the sun. Here is a solar tracker system that tracks the sun’s movement across the sky and tries to maintain the solar panel perpendicular to the sun’s rays, ensuring that the maximum amount of sunlight is incident on the panel throughout the day. The solar tracker starts following the sun right from dawn, throughout the day till evening, and starts all over again from the dawn next day.

Fig. 1: Circuit of solar tracking systemFig. 1 shows the circuit of the solar tracking system. The solar tracker comprises comparator IC LM339, H-bridge motor driver IC L293D (IC2) and a few discrete components. Light-dependent resistors LDR1 through LDR4 are used as sensors to detect the panel’s position relative to the sun. These provide the signal to motor

driver IC2 to move the solar panel in the sun’s direction. LDR1 and LDR2 are fixed at the edges of the solar panel along the X axis, and connected to comparators A1 and A2, respectively. Presets VR1 and VR2 are set to get low comparator output at pins 2 and 1 of comparators A1 and A2, respectively, so as to stop motor M1 when the sun’s rays are perpendicular to the solar panel. 

When LDR2 receives more light than LDR1, it offers lower resistance than LDR1, providing a high input to comparators A1 and A2 at pins 4 and 7, respectively. As a result, output pin 1 of comparator A2 goes high to rotate motor M1 in one direction (say, anti-clockwise) and turn the solar panel. 

When LDR1 receives more light than LDR2, it offers lower resistance than LDR2, giving a low input to comparators A1 and A2 at pins 4 and 7, respectively. As the voltage at pin 5 of comparator A1 is now higher than the voltage at its pin 4, its output pin 2 goes high. As a result, motor M1 rotates in the opposite direction (say, clock-wise) and the solar panel turns. 

Fig. 2 Proposed assembly for the solar tracking systemSimilarly, LDR3 and LDR4 track the sun along Y axis. Fig. 2 shows the proposed assembly for the solar tracking system. ABOUT INTEGRATED CIRCUITS:LM339 is a comparator IC with four inbuilt comparators. A comparator is a simple circuit that moves signals between the

analog and digital worlds. It compares two input voltage levels and gives digital output to indicate the larger one. The two input pins are termed as inverting (V-) and non-inverting (V+). The output pin goes high when voltage at V+ is greater than that at V-, and vice versa. In common applications, one of the pins is provided with a reference voltage and the other one receives analog input from a sensor or any external device. If inverting pin (V-) is set as reference, then V+ must exceed this reference to result in high output. For inverted logic, the reference is set at V+ pin.

Pin Diagram: 

Pin Description: 

Pin No Function Name1 Output of 2nd comparator Output 22 Output of 1st comparator Output 13 Supply voltage; 5V (+36 or ±18V) Vcc4 Inverting input of 1st comparator Input 1-5 Non-inverting input of 1st comparator Input 1+6 Inverting input of 1st comparator Input 2-7 Non-inverting input of 2nd comparator Input 2+8 Inverting input of 3rd comparator Input 3-9 Non-inverting input of 3rd comparator Input 3+10 Inverting input of 4th comparator Input 4-11 Non-inverting input of 4th comparator Input 4+12 Ground (0V) Ground13 Output of 4th comparator Output 414 Output of 3rd comparator Output 3

 

L293D is a dual H-bridge motor driver integrated circuit (IC). Motor drivers act as current amplifiers since they take a low-current control signal and provide a higher-current signal. This higher current signal is used to drive the motors.

L293D contains two inbuilt H-bridge driver circuits. In its common mode of operation, two DC motors can be driven simultaneously, both in forward and reverse direction. The motor operations of two motors can be controlled by input logic at pins 2 & 7 and 10 & 15. Input logic 00 or 11 will stop the corresponding motor. Logic 01 and 10 will rotate it in clockwise and anticlockwise directions, respectively.

Enable pins 1 and 9 (corresponding to the two motors) must be high for motors to start operating. When an enable input is high, the associated driver gets enabled.

As a result, the outputs become active and work in phase with their inputs. Similarly, when the enable input is low, that driver is disabled, and their outputs are off and in the high-impedance state. 

Pin Diagram: 

Pin Description: 

 Pin No

 Function  Name

1 Enable pin for Motor 1; active high Enable 1,22 Input 1 for Motor 1 Input 13 Output 1 for Motor 1 Output 14 Ground (0V) Ground5 Ground (0V) Ground6 Output 2 for Motor 1 Output 27 Input 2 for Motor 1 Input 28 Supply voltage for Motors; 9-12V (up to 36V)  Vcc 2

9 Enable pin for Motor 2; active high Enable 3,410 Input 1 for Motor 1 Input 311 Output 1 for Motor 1 Output 312 Ground (0V) Ground13 Ground (0V) Ground14 Output 2 for Motor 1 Output 415 Input2 for Motor 1 Input 416 Supply voltage; 5V (up to 36V) Vcc 1

EXPERIMENTAL SETUP:

 RESULTS AND CONCLUSIONS:

From the design of experimental set up with IC’s based solar tracking system using stepper motor. If we compare with fixed solar panel system we found that efficiency of IC based solar tracking system is improved by 30- 45% and it was found that all parts of experimental set up are giving good results. Moreover this tracking system tracks the sun continuous manner. And this system is more effective and efficient in long run. The solar tracking system can be still enhanced additional features like rain protection and wind protection which can be done as future work.