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1. Solar Tracker Using LDR
Sensor
BY
T.SELVALAKSHMI,B.E.,
DR.G.U.POPE COLLEGE OF ENGINEERING,
SAWYARPURAM

2. CONTENTS
 ABSTRACT
 INTRODUCTION
 PROBLEM WITH SOLAR
 What is a Solar Tracker ?
 Need For A Sun Tracking System
 Conditions For Maximum Output
 REQURED COMPONENTS
 BLOCK DIAGRAM
 CIRCUIT DIAGRAM
 WORKING
 Description of components
 Advantages
 Disadvantages
 Applications
 RESULT AND DISCUSSION
 CONCLUSIONS

3. ABSTRACT
 The aim of this project is to consume the maximum solar energy through solar panel. A Solar
Tracker is a device onto which solar panels are built-in which tracks the motion of the sun
ensuring that maximum amount of sunlight strikes the panels all over the day. Power output from
a solar cell will be maximum when it is facing the sun i.e. the angle between its surface and sun
rays is 90 degree. Solar tracking allows more energy to be produced because the solar array is
able to remain aligned to the sun. For rotation part, one standard servo motor has been selected. In
software part, the code is constructed in C programming and inserted in Arduino.

4. INTRODUCTION
 Extracting usable electricity from the sun was made possible by the discovery of
the photoelectric effect.
 Subsequent development of the solar cell, which is a semi-conductive material
that converts visible light into a direct current.
 Solar arrays, a series of solar cells electrically connected, generates a DC voltage
which can be used on a load.

5. Cont.…
 For further optimization of these panels solar trackers are being
implemented, which enhances the efficiency of panels by 30-35 %.
 Solar energy is a very large, inexhaustible source of energy. The power from
the sun intercepted by the earth is approximate 1.8*1011 MW. Solar energy
could supply all the present and future energy needs of the world on a
continuing basis. This makes it one of the most promising of the
unconventional energy sources.

6. PROBLEM WITH SOLAR
 Problem associated with the use of solar energy is that its availability varies
widely with time.
 The variation in availability occurs daily because of the day night cycle and
also seasonally because of the earth’s orbit around the sun.
 To rectify these above problems the solar panel should be such that it
always receive maximum intensity of light.

7. What is a Solar Tracker ?
 A solar tracker is a generic term used to describe devices that orient or
align various payloads toward the sun.
 Example for payloads are photovoltaic panels, reflectors, Collectors,
lenses or other optical devices.
 The system focuses on the optimization of the electric energy produced
by photovoltaic cells through the development of a sun-tracking system.

8. Need For A Sun Tracking System
 From dawn to dusk the sun keeps changing the angle from 0-90 rising
and 90-180 declining.
 In a year of 365 days the sun moves approximately 22.5 degrees north to
22.5 degrees south of the equator.
 We get maximum energy from the sun when - The angle of the sun is
degrees - The sun’s position is 0 +/- 5 degrees of the equator

9. Cont.…
 For the fluctuation factors mentioned previously, fixed solar panels does
not give higher efficiencies.
 A tracking system helps the solar panels keep oriented to the sun at the
optimum possible angle.
 The tracking system improves the efficiency of solar panels by 30% for
single axis and an additional 6% for dual axis.

10. REQURED COMPONENTS
1. LDR Sensor Module
2. LEDs or DC Motor
3. Resisters
4. 9 V Battery
5. PCB Board
6. BC 547 Transistor
7. Connecting Wires

11. BLOCK DIAGRAM

12. CIRCUIT DIAGRAM

13. CIRCUIT EXPLANATON
 In the circuit two LDR (Light Dependent Resistors) sensors are used to sense the
light. Since LDR is an analogue sensor they are connected to the analog pins A0
and A1 of Arduino. The sensors are connected in series with 10 k ohm resistors.
 A servomotor is also connected to the digital pin D10. D10 is a PWM (pulse width
modulation) pin. A momentary switch is also connected to digital pin D2, mainly
for calibration purposes. When the switch is pressed D2 pin will act as the ground
(GND). A 12-volt adapter or 9 volt battery, can be used to power this whole circuit.
RAW pin in Arduino Nano is the power pin.

14. WORKING
 In this project an Arduino Nano is used, which works as a controlling unit.
Two LDR’s (Light Dependent Resistor) are also connected to analog pins
of the Arduino. A dummy solar plate is attached in parallel to the axis of
servo motor and both the sensors are kept on the dummy solar plate as
shown in the figure below.
 The arrangement is made in such a way that the movement of sun is from
sensor 1 to sensor 2, as shown in the mage below.

15. WORKING

16. Conditions to be followed:-
Condition 1:
 Sun is in left side – Light on sensor1 is high because shadow of
barrier falls on sensor 2 so solar plate moves clockwise.
Condition 2:
 Sun is in right Side – Light on sensor2 is high because shadow of
barrier falls on sensor1 so solar plate movie anticlockwise.

17. Conditions to be followed:-
Condition 3:
 Sun is in the middle – Light on both sensors are equal so, plate will not rotate in
any direction.
 Output is shown in the demo video below. You can see that the plate moves in
the direction of light, but some fluctuation is visible in video because light is
coming from multiple sources. Fluctuation is automatically removed when
system is placed in direct sunlight.

18. Description of components

19. Light Dependent Resistor (LDR)
 An LDR or light dependent resistor is also known as photo resistor, photocell, and photo
conductor.
 It is a one type of resistor whose resistance varies depending on the amount of light falling on its
surface. When the light falls on the resistor, then the resistance changes. These resistors are often
used in many circuits where it is required to sense the presence of light.
 For instance, when the LDR is in darkness, then it can be used to turn ON a light or to turn OFF a
light when it is in the light.
 A typical light dependent resistor has a resistance in the darkness of 1MOhm, and in the
brightness a resistance of a couple of k Ohm.

20. Light Dependent Resistor (LDR)

21. Light Emitting Diode
 A light-emitting diode (LED) is a two-lead semiconductor light source. It is p-n
junction diode that emits light when activated.
 The long terminal is positive and the short terminal is negative. When a
suitable current is applied to the leads, electrons are able to recombine with
electron holes within the device, releasing energy in the form of photons.
 This effect is called electroluminescence, and the color of the light
(corresponding to the energy of the photon) is determined by the energy band
gap of the semiconductor.

22. Light Emitting Diode
 LEDs are typically small (less than
1 mm2) and integrated optical
components may be used to shape
the radiation pattern.
 In this project the LED is used as
output.

23. Battery
 A 9V battery is required to
supply the dc power to drive
the LDR Sensor Module and
other components connected
to it.

24. Advantages
 Solar tracking systems continually orient photovoltaic panels towards the sun and
can help maximize your investment in your PV system.
 One time investment, which provides higher efficiency & flexibility on
dependency over other sources.
 Tracking systems can help reducing emissions and can contribute against global
warming.
 Bulk implementations of tracking systems help reduced consumption of power by
other sources.
 It enhances the clean and emission free power production.

25. Disadvantages
 Initial investment is high on solar panels.
 It’s a bit of difficult for servicing, as the tracking systems are not
quite popular regionally.
 Moving parts and gears which will require regular maintenance.
 May require repair or replacement of broken parts over a long
run.

26. Applications
 Can be used for small & medium scale power
generations.
 For power generation at remote places where power
lines are not accessible.
 For domestic backup power systems.

27. CONCLUSIONS
 An Arduino solar tracker was designed and constructed in the current work. LDR light sensors
were used to sense the intensity of the solar light occurrence on the photo-voltaic cells panel.
Conclusions of this project is summarized as ,The existing tracking system successfully sketched
the light source even it is a small torch light, in a dark room, or it is the sun light rays. The
Arduino solar tracker with servo motor is employed by means of Arduino ATmega328p
microcontroller. The essential software is developed via Arduino Uno. The cost and reliability of
this solar tracker creates it suitable for the rural usage. The purpose of renewable energy from this
paper offered new and advanced idea to help the people.

29. Any
QUERIES??...