This document provides information on how a sun tracking solar panel works including its components and circuit design. It contains a circuit diagram and descriptions of the key components including a solar panel, microcontroller, light dependent resistors, servo motor, resistors, capacitors, and other parts. The system uses two LDRs to sense light intensity and a servo motor connected to the solar panel to rotate it toward the direction of the sun for maximum efficiency.

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TABLE OF CONTENTS
1. Introduction……………………………………………………………...2
2. Principle of Sun Tracking Solar Panel………………………………......3
3. Sun Tracking Solar Panel Circuit Diagram……………………………..4
4. Components in the Circuit………………………………………………5
5. Solar Panel……………………………………………………………...6
6. ATmega328 Microcontroller…………………………………………...8
7. LDR…………………………………………………………………….9
8. Servo Motor……………………………………………………………11
9. Code…………………………………………………………………...18
10. Automated Sun Tracking Solar Panel Circuit Design…………………19
11. How Sun Tracking Solar Panel Works?.................................................19
12. Advantages of Sun Tracking Solar Panel………………………………20
13. Sun Tracking Solar Panel Applications………………………………...20
14. Limitations of Sun Tracking Solar Panel Circuit……………………….20
15. Conclusion………………………………………………………………21
16. References……………………………………………………………….21

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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.
1. INTRODUCTION
As the non renewable energy resources are decreasing, use of renewable resources for
producing electricity is increasing. Solar panels are becoming more popular day by day. We
have already read a post about how to install solar panel for home. Solar panel absorbs the
energy from the Sun, converts it into electrical energy and stores the energy in a battery.
This energy can be utilized when required or can be used as a direct alternative to the grid
supply. Utilization of the energy stored in batteries is mentioned in below given applications.
The position of the Sun with respect to the solar panel is not fixed due to the rotation of the
Earth. For an efficient usage of the solar energy, the Solar panels should absorb energy to a
maximum extent.
This can be done only if the panels are continuously placed towards the direction of the Sun.
So, solar panel should continuously rotate in the direction of Sun. This article describes about
circuit that rotates solar panel.

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2. Principle of Sun Tracking Solar Panel
The Sun tracking solar panel consists of two LDRs, solar panel and a servo motor and
ATmega328 Micro controller.
Two light dependent resistors are arranged on the edges of the solar panel. Light dependent
resistors produce low resistance when light falls on them. The servo motor connected to the
panel rotates the panel in the direction of Sun. Panel is arranged in such a way that light on two
LDRs is compared and panel is rotated towards LDR which have high intensity i.e. low
resistance compared to other. Servo motor rotates the panel at certain angle.
When the intensity of the light falling on right LDR is more, panel slowly moves towards right
and if intensity on the left LDR is more, panel slowly moves towards left. In the noon time,
Sun is ahead and intensity of light on both the panels is same. In such cases, panel is constant
and there is no rotation

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3. Sun Tracking Solar Panel Circuit Diagram

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4. 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

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5. SOLAR PANEL
Photovoltaic solar panels absorb sunlight as a source of energy to generate electricity.
A photovoltaic (PV) module is a packaged, connected assembly of typically 6x10
photovoltaic solar cells. Photovoltaic modules constitute the photovoltaic array of
a photovoltaic system that generates and supplies solar electricity in commercial and residential
applications.
Each module is rated by its DC output power under standard test conditions (STC), and
typically ranges from 100 to 365 Watts (W). The efficiency of a module determines the area of
a module given the same rated output – an 8% efficient 230 W module will have twice the area
of a 16% efficient 230 W module. There are a few commercially available solar modules that
exceed efficiency of 24%.
A single solar module can produce only a limited amount of power; most installations contain
multiple modules. A photovoltaic system typically includes an array of photovoltaic modules,
an inverter, a battery pack for storage, interconnection wiring, and optionally a solar
tracking mechanism.
The most common application of solar energy collection outside agriculture is solar water
heating systems.
The price of solar electrical power has continued to fall so that in many countries it has become
cheaper than ordinary fossil fuel electricity from the electricity grid since 2012, a phenomenon
known as grid parity.
THEORY AND CONSTRUCTION
Photo voltaic modules use light energy (photons) from the Sun to generate electricity through
the photovoltaic effect. The majority of modules use wafer-based crystalline silicon cells
or thin-film cells. The structural (load carrying) member of a module can either be the top layer
or the back layer. Cells must also be protected from mechanical damage and moisture. Most
modules are rigid, but semi-flexible ones based on thin-film cells are also available. The cells
must be connected electrically in series, one to another.
A PV junction box is attached to the back of the solar panel and it is its output interface
Externally, most of photovoltaic modules use MC4 connectors type to facilitate easy
weatherproof connections to the rest of the system. Also, USB power interface can be used.
Module electrical connections are made in series to achieve a desired output voltage or in
parallel to provide a desired current capability (amperes). The conducting wires that take the
current off the modules may contain silver, copper or other non-magnetic conductive transition
metals. Bypass diodes may be incorporated or used externally, in case of partial module
shading, to maximize the output of module sections still illuminated.
Some special solar PV modules include concentrators in which light is focused by lenses or
mirrors onto smaller cells. This enables the use of cells with a high cost per unit area (such
as gallium arsenide) in a cost-effective way.

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Solar panels also use metal frames consisting of racking components, brackets, reflector
shapes, and troughs to better support the panel structure
Figure. PV System

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6. ATMEGA328 MICROCONTROLLER
ATmega328 is an AVR family micro controller. It is based on advanced RISC architecture. It
is an 8-bit controller. It has 32K Bytes of Programmable Flash memory, 1K Bytes of EEPROM
and 2K Bytes of SRAM. It has 23 programmable I/O pins. It supports peripheral features like
two 8-bit timers, one 16-bit timer, 6 channel ADC with 10-bit resolution, programmable
USART, Serial Peripheral Interface, 2 wire serial interface (I2C), etc.
Figure: Pin Diagram

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7. Light Dependent Resistor (LDR)
Light Dependent Resistors or LDRs are the resistors whose resistance values depend on
intensity of the light. As the intensity of light falling on the LDR increases, resistance value
decreases. In dark, LDR will have maximum resistance. LDR will output an analog value which
should be converted to digital. This can be done using analog to digital converter.
ATmega328 has analog to digital converter internally. It has six ADC channels from ADC0 to
ADC5 (Pins 23 – 28). The two LDRs are connected to ADC pins i.e. 27 and 28 in a voltage
divider fashion with the help of individual 10KΩ Resistors. ADC conversion is done using
successive approximation method.
A Typical LDR
LDR Symbol

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The most common type of LDR has a resistance that falls with an increase in the light intensity
falling upon the device (as shown in the image above). The resistance of an LDR may typically
have the following resistances:
Daylight = 5000Ω
Dark = 20000000Ω
You can therefore see that there is a large variation between these figures. If you plotted this
variation on a graph you would get something similar to that shown by the graph shown above.
Applications of LDRs
There are many applications for Light Dependent Resistors. These include:
Lighting switch
The most obvious application for an LDR is to automatically turn on a light at a certain light
level. An example of this could be a street light or a garden light.
Camera shutter control
LDRs can be used to control the shutter speed on a camera. The LDR would be used to measure
the light intensity which then adjusts the camera shutter speed to the appropriate level.

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Example - LDR controlled Transistor circuit
The circuit shown above shows a simple way of constructing a circuit that turns on when it
goes dark. In this circuit the LDR and the other Resistor form a simple 'Potential Divider'
circuit, where the centre point of the Potential Divider is fed to the Base of the NPN Transistor.
When the light level decreases, the resistance of the LDR increases. As this resistance increases
in relation to the other Resistor, which has a fixed resistance, it causes the voltage dropped
across the LDR to also increase. When this voltage is large enough (0.7V for a typical NPN
Transistor), it will cause the Transistor to turn on.
The value of the fixed resistor will depend on the LDR used, the transistor used and the supply
voltage.
8. SERVO MOTOR
A servomotor is a rotary actuator or linear actuator that allows for precise control of angular or
linear position, velocity and acceleration. It consists of a suitable motor coupled to a sensor for
position feedback. It also requires a relatively sophisticated controller, often a dedicated
module designed specifically for use with servomotors.
Servomotors are not a specific class of motor although the term servomotor is often used to
refer to a motor suitable for use in a closed-loop control system.
Servomotors are used in applications such as robotics, CNC machinery or automated
manufacturing
A servomotor is a closed-loop servomechanism that uses position feedback to control its
motion and final position. The input to its control is a signal (either analogue or digital)
representing the position commanded for the output shaft.
The motor is paired with some type of encoder to provide position and speed feedback. In the
simplest case, only the position is measured. The measured position of the output is compared
to the command position, the external input to the controller. If the output position differs from
that required, an error signal is generated which then causes the motor to rotate in either

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direction, as needed to bring the output shaft to the appropriate position. As the positions
approach, the error signal reduces to zero and the motor stops.
The very simplest servomotors use position-only sensing via a potentiometer and bang-bang
control of their motor; the motor always rotates at full speed (or is stopped). This type of
servomotor is not widely used in industrial motion control, but it forms the basis of the simple
and cheap servos used for radio-controlled models.
More sophisticated servomotors use optical rotary encoders to measure the speed of the output
shaft and a variable-speed drive to control the motor speed. Both of these enhancements,
usually in combination with a PID control algorithm, allow the servomotor to be brought to its
commanded position more quickly and more precisely, with less overshooting.
Figure: Servo Motor

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CRYSTAL OSCILLATOR
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a
vibrating crystal of piezoelectric material to create an electrical signal with a
precise frequency. This frequency is often used to keep track of time, as in quartz wristwatches,
to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies
for radio transmitters and receivers. The most common type of piezoelectric resonator used is
the quartz crystal, so oscillator circuits incorporating them became known as crystal
oscillators, but other piezoelectric materials including polycrystalline ceramics are used in
similar circuits.
A crystal oscillator, particularly one made of quartz crystal, works by being distorted by
an electric field when voltage is applied to an electrode near or on the crystal. This property is
known as electrostriction or inverse piezoelectricity. When the field is removed, the quartz -
which oscillates in a precise frequency - generates an electric field as it returns to its previous
shape, and this can generate a voltage. The result is that a quartz crystal behaves like an RLC
circuit.
Quartz crystals are manufactured for frequencies from a few tens of kilohertz to hundreds of
megahertz. More than two billion crystals are manufactured annually. Most are used for
consumer devices such as wristwatches, clocks, radios, computers, and cell phones. Quartz
crystals are also found inside test and measurement equipment, such as counters, signal
generators, and oscilloscopes.

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BREADBOARD
A breadboard is a solderless device for temporary prototype with electronics and test circuit
designs. Most electronic components in electronic circuits can be interconnected by inserting
their leads or terminals into the holes and then making connections through wires where
appropriate. The breadboard has strips of metal underneath the board and connect the holes on
the top of the board. The metal strips are laid out as shown below. Note that the top and bottom
rows of holes are connected horizontally and split in the middle while the remaining holes are
connected vertically.
In the early days of radio, amateurs nailed bare copper wires or terminal strips to a wooden
board (often literally a board to slice bread on) and soldered electronic components to
them. Sometimes a paper schematic diagram was first glued to the board as a guide to placing
terminals, then components and wires were installed over their symbols on the schematic.
Using thumbtacks or small nails as mounting posts was also common.
Breadboards have evolved over time, with the term now being used for all kinds of prototype
electronic devices. For example, US Patent 3,145,483, was filed in 1961 and describes a
wooden plate breadboard with mounted springs and other facilities. US Patent 3,496,419, was
filed in 1967 and refers to a particular printed circuit board layout as a Printed Circuit
Breadboard. Both examples refer to and describe other types of breadboards as prior art.
The breadboard most commonly used today is usually made of white plastic and is a pluggable
(solderless) breadboard. It was designed by Ronald J. Portugal in 1971.

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CARDBOARD
Cardboard is a generic term for heavy-duty paper-based products having greater thickness and
superior durability or other specific mechanical attributes to paper; such as foldability, rigidity
and impact resistance. The construction can range from a thick sheet known
as paperboard to corrugated fiberboard which is made of multiple corrugated and flat layers.
Despite widespread general use in English and French, the term cardboard is deprecated in
commerce and industry as not adequately defining a specific product. Material producers,
container manufacturers, packaging engineers, and standards organizations, use more specific
terminology

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RESISTORS AND CAPACITORS
A resistor is a passive two-terminal electrical component that implements electrical
resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow,
adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines,
among other uses. High-power resistors that can dissipate many watts of electrical power as
heat, may be used as part of motor controls, in power distribution systems, or as test loads
for generators. Fixed resistors have resistances that only change slightly with temperature, time
or operating voltage. Variable resistors can be used to adjust circuit elements (such as a volume
control or a lamp dimmer), or as sensing devices for heat, light, humidity, force, or chemical
activity.
Resistors are common elements of electrical networks and electronic circuits and are ubiquitous
in electronic equipment. Practical resistors as discrete components can be composed of various
compounds and forms. Resistors are also implemented within integrated circuits.
The electrical function of a resistor is specified by its resistance: common commercial resistors
are manufactured over a range of more than nine orders of magnitude. The nominal value of
the resistance falls within the manufacturing tolerance, indicated on the component.

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A capacitor is a passive two-terminal electronic component that stores electrical energy in
an electric field. The effect of a capacitor is known as capacitance. While some capacitance
exists between any two electrical conductors in proximity in a circuit, a capacitor is a
component designed to add capacitance to a circuit. The capacitor was originally known as
a condenser or condensator. The original name is still widely used in many languages, but not
commonly in English.
The physical form and construction of practical capacitors vary widely and many capacitor
types are in common use. Most capacitors contain at least two electrical conductors often in
the form of metallic plates or surfaces separated by a dielectric medium. A conductor may be
a foil, thin film, sintered bead of metal, or an electrolyte. The nonconducting dielectric acts to
increase the capacitor's charge capacity. Materials commonly used as dielectrics
include glass, ceramic, plastic film, paper, mica, and oxide layers. Capacitors are widely used
as parts of electrical circuits in many common electrical devices. Unlike a resistor, an ideal
capacitor does not dissipate energy.
When two conductors experience a potential difference, for example, when a capacitor is
attached across a battery, an electric field develops across the dielectric, causing a net
positive charge to collect on one plate and net negative charge to collect on the other plate. No
current actually flows through the dielectric, however, there is a flow of charge through the
source circuit. If the condition is maintained sufficiently long, the current through the source
circuit ceases. However, if a time-varying voltage is applied across the leads of the capacitor,
the source experiences an ongoing current due to the charging and discharging cycles of the
capacitor.
Capacitance is defined as the ratio of the electric charge on each conductor to the potential
difference between them. The unit of capacitance in the International System of Units (SI) is
the farad (F), defined as one coulomb per volt (1 C/V). Capacitance values of typical capacitors
for use in general electronics range from about 1 picofarad (pF) (10−12 F) to about 1 millifarad
(mF) (10−3 F).

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9. CODE
#include <Servo.h>
Servo myservo;
int ldr1 = 4;
int ldr2 = 5;
int val1;
int val2;
int pos=90;
void setup()
{
myservo.attach(11);
Serial.begin(9600);
myservo.write(pos);
}
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))
{
if(pos<180)
pos=pos+1;
myservo.write(pos);
Serial.println("backward");
delay(10);
}
else if(val2 > (val1+50))
if(pos>0)
pos=pos-1;

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10. AUTOMATED SUN TRACKING SOLAR PANEL
CIRCUIT DESIGN
The proposed system consists of ATmega328 micro controller, Solar panel, Light
Dependent resistors and Servo Motor.
myservo.write(pos);
Serial.println("forward");
delay(10);
}
}

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11. HOW SUN TRACKING SOLAR PANEL WORKS?
 Assemble the circuit as described and upload the code to ATmega328 Microcontroller.
 Power on the circuit and place the set up directly under the Sun (on the rooftop).
 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.
12. ADVANTAGES OF SUN TRACKING SOLAR PANEL
 The solar energy can be reused as it is non-renewable resource.
 This also saves money as there is no need to pay for energy used (excluding the initial
setup cost)
 Helps in maximizing the solar energy absorption by continuously tracking the sun.
13. SUN TRACKING SOLAR PANEL APPLICATIONS
 These panels can be used to power the traffic lights and streetlights
 The se can be used in home to power the appliances using solar power.
 These can be used in industries as more energy can be saved by rotating the panel.
14. 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 came to know about the working principle of a sun-tracking solar panel. If you want
to set up or install them on your home or office rooftops then we would like to share with you
about Best Solar Panel Kits for Homes In 2018.
This article will help you in understanding the concept of solar panel kits and guides you how
to choose solar panels (vital considerations) when purchasing online. Read the complete article
and choose the one that best matches your requirements.

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15. CONCLUSION
[1] The invention of Solar Tracking System helps us improve the performance of PV solar
system in a simple way.
[2] Used relative method of sunlight strength.
[3] Established a model of automatic tracking system to keep vertical contact between solar
panels and sunlight.
[4] Improved the utilization rate of solar energy and efficiency of photovoltaic power
generation system.
16. REFERENCES
[1] electrical machines – m.v.deshpande – jain book agency.
[2] electrical machines ( ac & dc machines ) – j.b.gupta – jain book agency.
[3] digital electronics and logic design – b. somanathan nair – phi learning pvt. ltd.
[4] digital electronics and microprocessors – r.p.jain – mc. graw hill education.
[5] digital and microprocessor fundamentals: theory and applications – william kleitz –
prentice hall.
[6] www.electronicshub.org/sun-tracking-solar-panel