DESIGN AND DEVELOPMENT OF SOLAR CHARGE CONTROLLER WITH SUN TRACKING

DESIGN AND DEVELOPMENT OF SOLAR CHARGE
CONTROLLER WITH SUN TRACKING
A project report
Submitted in partial fulfillment of requirements for the award of Degree of
BACHELOR OF TECHNOLOGY
in
ELECTRICAL AND ELECTRONICS ENGINEERING
by
CH. NIKHIL CHAKRAVARTHY
(14501A0221)
G. RAJA SEKHAR B.K.S.K.A RAMLAL
(14501A0236) (14501A0220)
B. SIVA DURGA PRASAD B.SREENU
(14501A0212) (14501A0211)
UNDER THE GUIDANCE
OF
Dr. K. LENIN, M.E, Ph.D.
Professor
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
PRASAD V. POTLURI SIDDHARTHA INSTITUTE OF TECHNOLOGY
Autonomous & Permanent Affiliation to JNTUK, Kakinada
AICTE approved, NBA & NAAC accredited and ISO 9001: 2008 certified Institution
KANURU, VIJAYAWADA – 520007
MARCH-2018

PRASAD V. POTLURI SIDDHARTHA INSTITUTE OF TECHNOLOGY
Autonomous & Permanent Affiliation to JNTUK, Kakinada
AICTE approved, NBA & NAAC accredited and ISO 9001: 2008 certified Institution
KANURU, VIJAYAWADA – 520007
DEPARTMENT OF ELECTRICAL AND ELECTRONICS
ENGINEERING
CERTIFICATE
This is to certify that the project work entitled “DESIGN AND DEVELOPMENT
OF SOLAR CHARGE CONTROLLER WITH SUN TRACKING” is being
submitted by “CH. NIKHIL CHAKRAVARTHY (14501A0221)” in partial
fulfillment of the requirements for the award of BACHELOR OF TECHNOLOGY in
ELECTRICAL & ELECTRONICS ENGINEERING by Jawaharlal Nehru
Technological University Kakinada, Kakinada is a record of bonafide work carried
out by them under our guidance and supervision.
The results embodied in this report have not been submitted to any other University or
Institute for the award of any degree or diploma.
Internal Guide Head of the Department
Dr. K. LENIN, Ph.D. Dr. M. VENU GOPALA RAO, Ph.D.
Professor Professor & HoD.
External Examiner

ACKNOWLEDGEMENT
We sincerely express our deep sense of gratitude to our beloved guide Dr. K.
LENIN, M.E, Ph.D., Professor, Department of ELECTRICAL &
ELECTRONICS ENGINEERING for his immense interest with wholehearted
involvement in the project and for his valuable guidance at each and every phase
of the work. We particularly express our heart full thanks for his supervision and
inspiration in completion of the project.
We are grateful to Head of the Department of Electrical & Electronics
Engineering Dr. M. VENUGOPALA RAO, M.E, Ph.D., for providing
necessary Facilities to carry out this project.
We wish to express our profound sense of gratitude to our beloved Principal
Dr. K. SIVAJI BABU, M.TECH, Ph.D. for extending his Official support for
the progress of this project.
We would like to express our thanks to all teaching and non-teaching staff
members of Electrical & Electronics department for their encouragement and
support in successful completion of this project.
Project Associates
Ch. Nikhil Chakravarthy (14501A0221)
G. Raja Sekhar (14501A0236)
B. S. K. S. K Ramlal (14501A0220)
B. Siva Durga Prasad (14501A0212)
B. Sreenu (14501A0211)

INDEX
CONTENTS PAGENO
ABSTRACT i
LIST OF FIGURES
LIST OF TABLES
CHAPTER-1 1
INTRODUCTION 2
LITERATURE SURVEY 3
BLOCK DIAGRAM 4
CHAPTER 2: ARDUINO NANO 6
2.1 General 7
2.2 Technical Specifications 8
2.3 Power 8
2.4 Memory 9
2.5 Input and Output 9
2.6 Communication 10
2.7 Programming 11
2.8 Automatic Reset 11
2.9 ATmega328P Microcontroller 12
2.9.1 Features 12
2.9.2 Pin configuration 14
2.9.3 Pin Description of ATmega328P 15
CHAPTER 3: PHOTOVOLTAIC CELL 18
3.1 General 19
3.2 Types of Photovoltaic cells 20
3.2.1 Single crystal silicon 20
3.2.2 Polycrystalline silicon 21
3.2.3 Ribbon silicon 22
3.2.4 Amorphous silicon 23
3.3 Working of PV cell 24
3.3.1 Charge carrier separation 25

3.3.2 The P-N junction 26
3.4 PV array 26
3.4.1 Portable arrays 27
3.4.2 Tracking arrays 28
3.5 Photovoltaic module performance 29
3.6 PV panel specifications 34
CHAPTER 4: SOLAR TRACKER 35
4.1 General 36
4.2 Evolution of solar tracker 36
4.3 Solar Irradiation: Sunlight and solar constant 37
4.4 Sunlight 38
4.5 Types of solar trackers 41
4.5.1 Single axis tracker 41
4.5.1.1 Horizontal single axis tracker 41
4.5.1.2 Horizontal single axis tracker with tilted modules 41
4.5.1.3 Vertical single axis tracker 42
4.5.1.4 Tilted single axis tracker 42
4.5.2 Dual axis tracker 42
4.5.2.1 Tip-tilt 43
4.5.2.2 Azimuth-altitude 43
4.6 Types of drives 44
4.6.1 Active tracker 44
4.6.2 Passive tracker 44
4.6.3 Manual tracking 44
CHAPTER 5: LEAD-ACID BATTERY 45
5.1 Chemical changes during discharging 46
5.2 Chemical changes during charging 47
5.3 Characteristics of Lead-acid cell 48
5.4 Indications of fully charged cell 49
5.5 Maintenance procedures 49
5.6 Specifications 50
CHAPTER 6: SERVO MOTOR AND VOLTAGE REGULATOR 51
6.1 Servo motor 52
6.1.1 Servo mechanism 53

6.1.2 Working principle of servo motor 53
6.1.3 Controlling of servo motor 54
6.1.4 Specifications 55
6.2 Voltage regulator 55
6.2.1 LM7805 series voltage regulator 55
6.2.2 Features of voltage regulator 56
CHAPTER 7: SOFTWARE DESIGN AND DUMPING 57
7.1 Software used 58
7.2 Software design 58
7.2.1 Flowchart for solar charge controller 58
7.2.2 Flowchart for sun tracker 59
7.3 Software dumping procedure 59
CHAPTER 8: PROPOSED HARDWARE 60
8.1 Hardware used in circuit construction 61
8.2 Working operation of circuit 62
CHAPTER 9: EXPERIMENTAL RESULTS 63
9.1 Pictorial view of experimental setup 64
9.1 Charging test 64
9.2 Discharging test 65
CONCLUSION 66
FUTURE SCOPE 67
REFERENCES 68
PUBLICATION DETAILS
International Journal for Research in Applied Science and
Engineering Technology
ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 6.887
Volume 6 Issue III, March 2018

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ABSTRACT
Solar Energy- the ultimate & future source of energy for mankind in the near future.
This project work proposes the design and development of Arduino based solar charge
controller with sun tracking using PWM (Pulse Width Modulation) technique. Solar
Charge controller which is part of the design which enhances the recharging capacity of
the battery in a quick mode. Once the battery reaches fully charged condition, a logic
system in the controller will keep the battery on trickle charge. The charge controller will
also take care of the deep discharge protection and cut off the load when the battery
reaches a certain level when discharged. The main feature of this charge controller is to
control the load. During day time when the load is not connected the battery gets charged
from solar panel. When the battery voltage reaches peak value, Arduino interrupts further
charging. An inbuilt analog to digital converter is used to determine voltage of the
battery, solar panel and current drawn by the load. The solar tracking system is
implemented in this project, such that panel is always kept at right angle to incident
radiation. This project has been experimentally verified by a hardware setup.

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LIST OF FIGURES
Fig no TITLE OF THE FIGURE Page no
1.1 Block diagram of the proposed system 4
2.1 Components on Arduino Nano board 7
2.2 Pin configuration of ATmega328P 14
2.3 ATmega328P 15
3.1 PV cell 19
3.2 PV cell working 24
3.3 Parallel connection of PV panel 27
3.4 Portable arrays 28
3.5 Tracking arrays 29
3.6 Photovoltaic module performance 30
3.7 Current-Voltage curves of PV panel 31
3.8 Current-Voltage characteristics when module is
shades and unshaded 32
3.9 Current-Voltage characteristics at different
temperatures
32
3.10 PV module performance under battery charging 33
4.1 Sun’s apparent motion 37
4.2 Angle of elevation and zenith angle 40
5.1 Lead-Acid battery 46
5.2 Discharging of lead-acid battery 47
5.3 Charging of lead-acid battery 48
6.1 Servo motor 52
6.2 Pulse width control of servo motor 54
6.3 LM7805 Voltage regulator 55
7.1 Flowchart of solar charge controller 58
7.2 Flowchart of sun tracking system 59
8.1 Circuit diagram of proposed system 62
9.1 Pictorial view of experimental setup 64

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LIST OF TABLES
Table no TITLE OF TABLES Page no
4.1 Range of the brightness of sunlight (lux) 39
9.1 Charging test results 65
9.2 Discharging test results 65

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CHAPTER- 1
INTRODUCTION
One of the most promising renewable energy sources characterized by a huge
potential of conversion into electrical power is the solar energy. The conversion of solar
radiation into electrical energy by Photo-Voltaic (PV) effect is very promising
technology, being clean, silent, reliable, with very small maintenance costs and small
ecological impact. The interest in the Photo Voltaic conversion systems is visibly
reflected by the exponential increase of sales in this market segment with a strong growth
projection for the next decades.
The continuous evolution of the technology determined a sustained increase of the
conversion efficiency of PV panels, but nonetheless the most part of the commercial
panels have efficiencies no more than 20%. A constant research preoccupation of the
technical community involved in the solar energy harnessing technology refers to various
solutions to increase the PV panel’s conversion efficiency. Among PV efficiency
improving solutions we can mention: solar tracking, solar charge controller, optimization
of solar cells geometry, enhancement of light trapping capability, use of new materials,
etc. Efficiency of the system can be drastically increase by using Arduino for PWM
(Pulse Width Modulation) control and solar tracker.
The solar charge controller described here has the following features:
 Overcharge protection
 System status display
 Built-in digital voltmeter (0V-20V range)
 Single axis solar tracking
The major components of this system are as follows
 Arduino
 Solar panel
 Rechargeable battery
 Light dependent resistor
 Servo motor

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 Charge control
 Load control
LITERATURE SURVEY
Photovoltaic (PV) is the field of technology and research related to the application of
solar cells for energy by converting sun energy (sunlight or sun 5 ultra violet radiation)
directly into electricity [1-4]. Due to the growing demand for clean sources of energy, the
manufacture of solar cells and PV arrays has expanded dramatically in recent years [5].
PV production has been doubling every two years, increasing by an average of 48 percent
each year since 2002, making it the world’s fastest-growing energy technology [6]. At the
end of 2008, according to preliminary data, cumulative global installations reached
15,200 megawatts [7]. PV is best known as a method for generating electric power by
using solar cells packaged in PV modules, often electrically connected in multiples as
solar PV arrays to convert energy from the sun into electricity. The term PV denotes the
unbiased operating mode of a photodiode in which current through the device is entirely
due to the transduced light energy. Virtually all PV devices are some type of photodiode.
Solar cells produce direct current electricity from light, which can be used to power
equipment or to recharge a battery. The first practical application of PV was to power
orbiting satellites and other spacecraft, but today the majority of PV modules are used for
grid connected power generation. Cells require protection from the environment and are
usually packaged tightly behind a glass sheet. When more power is required than a single
cell can deliver, cells are electrically connected together to form photovoltaic modules, or
solar panels. A single module is enough to power an emergency telephone, but for a
house or a power plant the modules must be arranged in arrays. Although the selling price
of modules is still too high to compete with grid electricity in most places, significant
financial incentives in Japan and then Germany and Italy triggered a huge growth in
demand, followed quickly by production. Perhaps not unexpectedly, a significant market
has emerged in off-grid locations for solar-power-charged storage-battery based solutions
[8]. These often provide the only electricity available. The EPIA (European Photovoltaic
Industry Association) /Greenpeace Advanced Scenario shows that by the year 2030, PV
systems could be generating approximately 1,864 GW of electricity around the world [9].

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This means that, assuming a serious commitment is made to energy efficiency, enough
solar power would be produced globally in twenty-five years’ time to satisfy the
electricity needs of almost 14% of the world’s population [10].
BLOCK DIAGRAM:
Fig1.1 Block diagram of the proposed design

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PV Panel:
Photovoltaic (PV) is a method of generating electrical power by converting solar
radiation into direct current electricity using semiconductors that exhibits the
photovoltaic effect. Photovoltaic power generation employs solar panels comprised of an
array of cells containing a photovoltaic material. The PV generator is formed by the
combination of many PV cells connected in series and parallel to provide the desired
value of the output voltage and current.
Arduino Nano:
Arduino Nano, which employs ATmega328 as a microcontroller, is used in this
project for many purposes.
1. To read input data such as voltage, current, temperature etc.
2. To generate PWM signal for switching purposes.
3. To control battery charging voltage.
4. To implement load control.
5. To give control to servomotor for sun tracking.
Battery:
The solar energy is converted into electrical energy and stored in a 12V battery. The
efficiency of battery charging system is to store the energy from solar panel. Lead-acid
battery is used in this system because it is inexpensive and high capacitated. The 12V of
lead-acid battery has six cells. Overcharging battery can cause reduce life span of battery.
Switching Circuit:
MOSFET is used as a switching device because it has fast switching speed and low
voltage drop. MOSFET is a voltage-controlled device. It operates in two modes-enhanced
mode and depletion mode. In the hardware circuit transistor is used to switch the
MOSFET from microcontroller. A MOSFET and transistor combination is used for the
switching purpose between solar panel and battery.

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CHAPTER 2
ARDUINO NANO
2.1 GENERAL
Arduino is an open-source platform used for building electronics projects. Arduino
consists of both a physical programmable circuit board (often referred to as
a microcontroller) and a piece of software, or IDE (Integrated Development
Environment) that runs on your computer, used to write and upload computer code to the
physical board.
The Arduino does not need a separate piece of hardware (called a programmer) in order
to load new code onto the board – you can simply use a USB cable. Additionally, the
Arduino IDE uses a simplified version of C++, making it easier to learn to program.
Finally, Arduino provides a standard form factor that breaks out the functions of the
micro-controller into a more accessible package. The parts of Arduino Nano is shown in
fig 2.1.
Fig2.1 Components on Arduino Nano board

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2.2 TECHNICAL SPECIFICATIONS
Microcontroller ATmega328
Architecture AVR
Operating Voltage 5 V
Flash Memory 32 KB of which 2 KB used by bootloader
SRAM 2 KB
Clock Speed 16 MHz
Analog IN Pins 8
EEPROM 1 KB
DC Current per I/O Pins 40 mA (I/O Pins)
Input Voltage 7-12 V
Digital I/O Pins 22 (6 of which are PWM)
PWM Output 6
Power Consumption 19 mA
2.3 POWER
The Arduino Uno can be powered via the Mini-B USB connection or with an
external power supply. The power source is selected automatically.
External (non-USB) power can come from either an AC-to-DC adapter or battery. The
adapter can be connected by plugging a 2.1mm center-positive plug into the board's
power jack. Leads from a battery can be inserted in the Gnd and Vin pin headers of the
POWER connector.
The board can operate on an external supply of 6 to 20 volts. If supplied with less than
7V, however, the 5V pin may supply less than five volts and the board may be unstable.
If using more than 12V, the voltage regulator may overheat and damage the board. The
recommended range is 7 to 12 volts. The power pins are as follows:
 VIN: The input voltage to the Arduino board when it's using an external power source (as
opposed to 5 volts from the USB connection or other regulated power source). You can

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supply voltage through this pin, or, if supplying voltage via the power jack, access it
through this pin.
 5V: This pin outputs a regulated 5V from the regulator on the board. The board can be
supplied with power either from the DC power jack (7 - 12V), the USB connector (5V),
or the VIN pin of the board (7-12V).
 3V3: A 3.3 volt supply generated by the on-board regulator.
 GND: Ground pins.
2.4 MEMORY
The ATmega328 has 32 KB (with 0.5 KB used for the bootloader). It also has 2 KB of
SRAM (Static random-access memory) and 1 KB of EEPRO
(Electrically erasable programmable read-only memory).
2.5 INPUT AND OUTPUT
Each of the 14 digital pins on the Nano can be used as an input or output,
using pinMode(), digitalWrite(), and digitalRead() functions. They operate at 5
volts. Each pin can provide or receive a maximum of 40 mA and has an internal
pull-up resistor (disconnected by default) of 20-50 kOhms. In addition, some
pins have specialized functions:
 Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL
serial(transistor-transistor logic) data. These pins are connected to the
corresponding pins of the FTDI USB-to-TTL Serial chip.
 External Interrupts: 2 and 3. These pins can be configured to trigger an interrupt
on a low value, a rising or falling edge, or a change in value.
 PWM: 3, 5, 6, 9, 10, and 11. Provide 8-bit PWM output with the analogWrite()
function.
 SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK). These pins support SPI (Serial

10
Peripheral Interface) communication, which, although provided by the underlying
hardware, is not currently included in the Arduino language.
 LED: 13. There is a built-in LED (Light emitting diode) connected to digital pin
13. When the pin is HIGH value, the LED is on, when the pin is LOW, it's off.
The Nano has 8 analog inputs, each of which provide 10 bits of resolution
(i.e. 1024 different values). By default they measure from ground to 5 volts,
though is it possible to change the upper end of their range using the
analogReference() function. Analog pins 6 and 7 cannot be used as digital pins.
Additionally, some pins have specialized functionality:
 I2C: 4 (SDA) and 5 (SCL). Support I2C (TWI) communication using the Wire
library.
There are a couple of other pins on the board:
 AREF: Reference voltage for the analog inputs. Used with analogReference().
 Reset: Bring this line LOW to reset the microcontroller. Typically used to add a
reset button to shields which block the one on the board.
2.6 COMMUNICATION
The Arduino Nano has a number of facilities for communicating with a
computer, another Arduino, or other microcontrollers. The ATmega328P
provide UART TTL (Universal asynchronous receiver-transmitter transistor-transistor
logic) (5V) serial communication, which is available on digital pins 0 (RX) and 1
(TX). An FTDI FT232RL on the board channels this serial communication over
USB and the FTDI drivers (included with the Arduino software) provide a
virtual com port to software on the computer. The Arduino software includes a
serial monitor which allows simple textual data to be sent to and from the
Arduino board. The RX and TX LEDs on the board will flash when data is being
transmitted via the FTDI chip and USB connection to the computer (but not for

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serial communication on pins 0 and 1). A SoftwareSerial library allows for
serial communication on any of the Nano's digital pins. The ATmega328P also
support I2C (TWI) and SPI communication. The Arduino software includes a
Wire library to simplify use of the I2C bus.
2.7 PROGRAMMING
The Arduino Nano can be programmed with the Arduino software. Select
"Arduino Duemilanove or Nano w/ ATmega328P" from the Tools > Board menu
(according to the microcontroller on your board). The ATmega328P on the
Arduino Nano comes pre-burned with a bootloader that allows you to upload
new code to it without the use of an external hardware programmer. It
communicates using the original STK500 protocol. You can also bypass the
bootloader and program the microcontroller through the ICSP (In-Circuit Serial
Programming) header using Arduino ISP (In-circuit Serial Programmer) or similar.
2.8 AUTOMATIC RESET
Rather than requiring a physical press of the reset button before an upload,
the Arduino Nano is designed in a way that allows it to be reset by software
running on a connected computer. One of the hardware flow control lines (DTR)
of the FT232RL is connected to the reset line of the ATmega328P via a 100
Nano farad capacitor. When this line is asserted (taken low), the reset line drops
long enough to reset the chip. The Arduino software uses this capability to allow
you to upload code by simply pressing the upload button in the Arduino
environment. This means that the bootloader can have a shorter timeout, as the
lowering of DTR can be well-coordinated with the start of the upload. This
setup has other implications. When the Nano is connected to either a computer
running Mac OS X or Linux, it resets each time a connection is made to it from
software (via USB). For the following half-second or so, the bootloader is
running on the Nano. While it is programmed to ignore malformed data (i.e.
anything besides an upload of new code), it will intercept the first few bytes of

12
data sent to the board after a connection is opened. If a sketch running on the
board receives one-time configuration or other data when it first starts, make
sure that the software with which it communicates waits a second after opening
the connection and before sending this data.
2.9 ATmega328P MICROCONTROLLER
The Atmel picoPower ATmega328/P is a low-power CMOS (Complementary Metal-
Oxide Semiconductor) 8-bit microcontroller based on the AVR enhanced RISC (Reduced
instruction set computer) architecture. By executing powerful instructions in a single
clock cycle, the ATmega328/P achieves throughputs close to 1MIPS (Microprocessor
without Interlocked Pipeline Stages) per MHz. This empowers system designer to
optimize the device for power consumption versus processing speed.
The device is manufactured using Atmel’s high density non-volatile memory
technology. The On-chip ISP Flash allows the program memory to be reprogrammed In-
System through an SPI (Serial Peripheral Interface), by a conventional nonvolatile
memory programmer, or by an On-chip Boot program running on the AVR core. The
Boot program can use any interface to download the application program in the
Application Flash memory. Software in the Boot Flash section will continue to run while
the Application Flash section is updated, providing true Read-While-Write operation. By
combining an 8-bit RISC CPU with In-System Self-Programmable Flash on a monolithic
chip, the Atmel ATmega328/P is a powerful microcontroller that provides a highly
flexible and cost effective solution to many embedded control applications.
2.9.1 FEATURES
 High Performance, Low Power Atmel AVR 8-Bit Microcontroller Family
 131 Powerful Instructions
 32 x 8 General Purpose Working Registers
 32KBytes of In-System Self-Programmable Flash program Memory, 1KBytes EEPROM
and 2KBytes Internal SRAM.
 Write/Erase Cycles: 10,000 Flash/100,000 EEPROM

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 Data Retention: 20 years at 85°C/100 years at 25°C
 23 Programmable I/O Lines
 28-pin PDIP, 32-lead TQFP (Thin Quad Flat Package), 28-pad QFN (quad-flat no-
leads)/MLF (micro leadframe) and 32-pad QFN/MLF
 Two 8-bit Timer/Counters with Separate Prescaler and Compare Mode
 One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture Mode
 8-channel 10-bit ADC in TQFP and QFN/MLF package
 Six Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, Standby, and
Extended Standby
 Speed Grade: 0-20MHz
 Operating Voltage: 1.8 - 5.5V
 Temperature Range: -40°C to 105°C

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2.9.2 PIN CONFIGURATION
The pin configuration of ATmega328/P is shown in fig 2.2.
Fig2.2 Pin configuration of ATmega328P

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Fig2.3 ATmega328P
2.9.3 PIN DESCRIPTION OF ATmega328P
VCC
Digital supply voltage.
GND
Ground.
Port B (PB[7:0]) XTAL1/XTAL2/TOSC1/TOSC2
Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for
each bit). The Port B output buffers have symmetrical drive characteristics with both high
sink and source capability. As inputs, Port B pins that are externally pulled low will
source current if the pull-up resistors are activated. The Port B pins are tri-stated when a
reset condition becomes active, even if the clock is not running. Depending on the clock
selection fuse settings, PB6 can be used as input to the inverting Oscillator amplifier and
input of internal clock operating circuit.

16
Depending on the clock selection fuse settings, PB7 can be used as output from the
inverting Oscillator amplifier. If the Internal Calibrated RC Oscillator is used as chip
clock source, PB[7:6] is used as TOSC[2:1] input for the Asynchronous Timer/Counter2
if the AS2 bit in ASSR is set.
Port C (PC[5:0])
Port C is a 7-bit bi-directional I/O port with internal pull-up resistors (selected for
each bit). The PC[5:0] output buffers have symmetrical drive characteristics with both
high sink and source capability. As inputs, Port C pins that are externally pulled low will
source current if the pull-up resistors are activated. The Port C pins are tri-stated when a
reset condition becomes active, even if the clock is not running.
PC6/RESET
If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that the
electrical characteristics of PC6 differ from those of the other pins of Port C. If the
RSTDISBL Fuse is un-programmed, PC6 is used as a Reset input. A low level on this pin
for longer than the minimum pulse length will generate a Reset, even if the clock is not
running. Shorter pulses are not guaranteed to generate a Reset.
Port D (PD[7:0])
Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for
each bit). The Port D output buffers have symmetrical drive characteristics with both high
sink and source capability. As inputs, Port D pins that are externally pulled low will
source current if the pull-up resistors are activated. The Port D pins are tri-stated when a
reset condition becomes active, even if the clock is not running.
AVCC
AVCC is the supply voltage pin for the A/D Converter, PC[3:0], and PE[3:2]. It
should be externally connected to VCC, even if the ADC is not used. If the ADC is used,
it should be connected to VCC through a low-pass filter. Note that PC[6:4] use digital
supply voltage, VCC.

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AREF
AREF is the analog reference pin for the A/D Converter.
ADC[7:6]
In the TQFP and VFQFN package, ADC[7:6] serve as analog inputs to the A/D
converter. These pins are powered from the analog supply and serve as 10-bit ADC
channels.

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CHAPTER -3
PHOTOVOLTAIC CELL

19
CHAPTER -3
PHOTOVOLTAIC CELL
3.1 GENERAL
A solar cell, or photovoltaic cell, is an electrical device that converts the energy
of light directly into electricity by the photovoltaic effect, which is
a physical and chemical phenomenon. It is a form of photoelectric cell, defined as a
device whose electrical characteristics, such as current, voltage, or resistance, vary when
exposed to light. Individual solar cell devices can be combined to form modules,
otherwise known as solar panels. In basic terms a single junction silicon solar cell can
produce a maximum open-circuit voltage of approximately 0.5 to 0.6 volts.
Solar cells are described as being photovoltaic, irrespective of whether the source
is sunlight or an artificial light. They are used as a photodetector detecting light or
other electromagnetic radiation near the visible range, or measuring light intensity. Fig
3.1 shows layout of PV cell
Fig 3.1 PV cell

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3.2 TYPES OF PHOTOVOLTAIC CELLS
Now, most commercial photovoltaic cells are manufactured from silicon, the same
material from which sand is made. In this case, however, the silicon is extremely pure.
Other, more exotic materials such as gallium arsenide are just beginning to make their
way into the field.
The four general types of silicon photovoltaic cells are:
 Single-crystal silicon.
 Polycrystalline silicon (Also known as multi-crystal silicon).
 Ribbon silicon.
 Amorphous silicon (Also known as thin film silicon).
3.2.1 Single-crystal silicon
Monocrystalline silicon (also called "single-crystal silicon", "single-crystal Si", "mono
c-Si", or mono-Si) is the base material for silicon chips used in virtually all electronic
equipment today. Mono-Si also serves as a photovoltaic, light-absorbing material in the
manufacture of solar cells.
It consists of silicon in which the crystal lattice of the entire solid is continuous, unbroken
to its edges, and free of any grain boundaries. Mono-Si can be prepared as an intrinsic
semiconductor that consists only of exceedingly pure silicon, or it can be doped by the
addition of other elements such as boron or phosphorus to make p-type or n-type silicon.
Due to its semiconducting properties, single-crystal silicon is perhaps the most important
technological material of the last few decades—the "silicon era", because its availability
at an affordable cost has been essential for the development of the electronic devices on
which the present-day electronics.
Monocrystalline silicon is generally created by one of several methods that involve
melting high-purity, semiconductor-grade silicon (only a few parts per million of
impurities) and the use of a seed to initiate the formation of a continuous single crystal.
This process is normally performed in an inert atmosphere such as argon, and in an inert
crucible such as quartz to avoid impurities that would affect the crystal uniformity.

21
The most common production method is the Czochralski process, which dips a precisely
oriented rod-mounted seed crystal into the molten silicon. The rod is then slowly pulled
upwards and rotated simultaneously, allowing the pulled material to solidify into a
monocrystalline cylindrical ingot up to 2 meters in length and weighing several hundred
kilograms. Magnetic fields may also be applied to control and suppress turbulent flow,
further improving the uniformity of the crystallization. Other methods are float-zone
growth, which passes a polycrystalline silicon rod through a radiofrequency-heating coil
that creates a localized molten zone from which a seed crystal ingot grows, and Bridgman
techniques, which move the crucible through a temperature gradient to cool it from the
end of the container containing the seed. The solidified ingots are then sliced into
thin wafers for further processing.
Compared to the casting of polycrystalline ingots, the production of monocrystalline
silicon is very slow and expensive. However, the demand for mono-Si continues to rise
due to the superior electronic properties—the lack of grain boundaries allows for better
charge carrier flow and prevents electron recombination—allowing for improved
performance of integrated circuits and photovoltaics.
Monocrystalline silicon is also used for high-performance photovoltaic (PV) devices.
Since there are less stringent demands on structural imperfections compared to
microelectronics applications, lower quality solar grade silicon (Sog-Si) is often used for
solar cells. Monocrystalline silicon has the highest efficiency of 26.7%.
3.2.2 Polycrystalline silicon
Polycrystalline silicon, also called polysilicon or poly-Si, is a high
purity, polycrystalline form of silicon, used as a raw material by the
solar photovoltaic and electronics industry.
Polysilicon is produced from metallurgical grade silicon by a chemical purification
process, called the Siemens process. This process involves distillation of volatile silicon
compounds, and their decomposition into silicon at high temperatures. An emerging,
alternative process of refinement uses a fluidized bed reactor. The photovoltaic industry
also produces upgraded metallurgical-grade silicon (UMG-Si), using metallurgical
instead of chemical purification processes. When produced for the electronics industry,

22
polysilicon contains impurity levels of less than one part per billion (ppb), while
polycrystalline solar grade silicon (SoG-Si) is generally less pure.
The polysilicon feedstock – large rods, usually broken into chunks of specific sizes
and packaged in clean rooms before shipment – is directly cast into multi-
crystalline ingots or submitted to a recrystallization process to grow single crystal boules.
The products are then sliced into thin silicon wafers and used for the production of solar
cells, integrated circuits and other semiconductor devices.
Polysilicon consists of small crystals, also known as crystallites, giving the material its
typical metal flake effect. While polysilicon and multi-silicon are often used as
synonyms, multi-crystalline usually refers to crystals larger than 1 mm. Multi-crystalline
solar cells are the most common type of solar cells in the fast-growing PV market and
consume most of the worldwide produced polysilicon. About 5 tons of polysilicon is
required to manufacture 1 megawatt (MW) of conventional solar modules. Polysilicon is
distinct from monocrystalline silicon and amorphous silicon.
Polycrystalline cells can be recognized by a visible grain, a "metal flake effect".
Semiconductor grade (also solar grade) polycrystalline silicon is converted to "single
crystal" silicon – meaning that the randomly associated crystallites of silicon in
"polycrystalline silicon" are converted to a large "single" crystal. Single crystal silicon is
used to manufacture most Si-based microelectronic devices. Polycrystalline silicon can
be as much as 99.9999% pure.
3.2.3 Ribbon silicon
The name describes the manufacturing process, where a sheet of silicon the ribbon is
pulled vertically from a bath of molten silicon to form a multi-crystalline silicon crystals.
The ribbon is then cut into lengths which are treated with traditional processes to
form solar cells. Mobil-Tyco, Solar Energy Corp., Energy Materials, Corp., Motorola and
IBM developed the process in the 1970s.
Ribbon growth has the capability of using less silicon compared to
other wafer production methods as wafers are manufactured to the approximately correct
specification avoiding the need for sawing of silicon blocks. Silicon accounts for more

23
than 50% of manufacturing costs in producing first generation solar cells, where much of
the silicon is discarded as waste at the sawing stage of manufacture. Employing the string
ribbon process allows the manufacture of PV grade silicon wafers to the approximate
dimensions while avoiding the waste encountered when sawing wafers from ingots. This
manufacturing process uses about half the amount of input silicon required by traditional
processes.
String Ribbon technology is a technique where the ribbon is pulled from the silicon
melt between two wires, it is not capable of achieving the same electrical performance as
conventional wafer technology. Typically a cut wafer will convert 18-20% of the
incoming light into electricity where String Ribbon Solar Cells are capable of converting
13-14%. In research laboratories the technology has reached as high as 18.3%, however it
cannot be produced commercially to this specification. Wafer technologies have reached
as high as 25% in laboratory conditions.
While String Ribbon technology has certain advantages as to the shape of the crystals,
the overall thickness varies enough so that not every 'silicon strip' can be processed
directly into a solar cell. In addition to this drawback, the growth process is thermally
very inefficient. The radiating area/gram of crystal is extremely high, leading to very high
energy expenses which offset the reduced silicon use/expense.
3.2.4 Amorphous silicon
Amorphous silicon (a-Si) is the non-crystalline form of silicon used for solar cells
and thin-film transistors in LCDs. It is used as semiconductor material for a-Si solar cells,
or thin-film silicon solar cells, it is deposited in thin films onto a variety of flexible
substrates, such as glass, metal and plastic. Amorphous silicon cells generally feature low
efficiency, but are one of the most environmentally friendly photovoltaic technologies,
since they do not use any toxic heavy metals such as cadmium or lead.
In amorphous silicon this long range order is not present. Rather, the atoms form a
continuous random network. Moreover, not all the atoms within amorphous silicon are
fourfold coordinated. Due to the disordered nature of the material some atoms have
a dangling bond. Physically, these dangling bonds represent defects in the continuous
random network and may cause anomalous electrical behaviour. The material can

24
be passivated by hydrogen, which bonds to the dangling bonds and can reduce the
dangling bond density by several orders of magnitude. Hydrogenated amorphous silicon
(a-Si:H) has a sufficiently low amount of defects to be used within devices such as
solar photovoltaic cells, particularly in the proto-crystalline growth regime. However,
hydrogenation is associated with light-induced degradation of the material, termed
the Staebler–Wronski effect.
Amorphous silicon (a-Si) has been used as a photovoltaic solar cell material for
devices, which require very little power, such as pocket calculators, because their lower
performance compared to conventional crystalline silicon (c-Si) solar cells is more than
offset, by their simplified and lower cost of deposition onto a substrate.
3.3 WORKING OF PV CELL
Fig 3.2 PV cell working
When a photon hits a piece of silicon, one of three things can happen as shown in fig
3.2.
1. The photon can pass straight through the silicon — this (generally) happens for lower
energy photons,
2. The photon can reflect off the surface.

25
3. The photon can be absorbed by the silicon, if the photon energy is higher than the
silicon band gap value. This generates an electron-hole pair and sometimes heat,
depending on the band structure.
When a photon is absorbed, its energy is given to an electron in the crystal lattice.
Usually this electron is in the valence band, and is tightly bound in covalent bonds
between neighbouring atoms, and hence unable to move far. The energy given to it by the
photon "excites" it into the conduction band, where it is free to move around within the
semiconductor. The covalent bond that the electron was previously a part of now has one
fewer electron — this is known as a hole. The presence of a missing covalent bond
allows the bonded electrons of neighbouring atoms to move into the "hole," leaving
another hole behind, and in this way a hole can move through the lattice. Thus, it can be
said that photons absorbed in the semiconductor create mobile electron-hole pairs.
A photon need only have greater energy than that of the band gap in order to excite an
electron from the valence band into the conduction band. However, the solar frequency
spectrum approximates a black body spectrum at ~6000 K, and as such, much of the solar
radiation reaching the Earth is composed of photons with energies greater than the band
gap of silicon. The solar cell will absorb these higher energy photons, but the difference
in energy between these photons and the silicon band gap is converted into heat (via
lattice vibrations — called phonons) rather than into usable electrical energy.
3.3.1 Charge carrier separation
There are two main modes for charge carrier separation in a solar cell:
1. Drift of carriers, driven by an electrostatic field established across the device.
2. Diffusion of carriers from zones of high carrier concentration to zones of low
carrier concentration.
In the widely used p-n junction solar cells, the dominant mode of charge carrier
separation is by drift. However, in non-p-n-junction solar cells (typical of the third
generation solar cell research such as dye and polymer solar cells), a general electrostatic

26
field has been confirmed to be absent, and the dominant mode of separation is via charge
carrier diffusion.
3.3.2 The P-N junction
The most commonly known solar cell is configured as a large-area p-n junction made
from silicon. As a simplification, one can imagine bringing a layer of n-type silicon into
direct contact with a layer of p-type silicon. In practice, p-n junctions of silicon solar cells
are not made in this way, but rather by diffusing an n-type dopant into one side of a p-
type wafer (or vice versa).
If a piece of p-type silicon is placed in intimate contact with a piece of n-type silicon,
then a diffusion of electrons occurs from the region of high electron concentration (the n-
type side of the junction) into the region of low electron concentration (p-type side of the
junction). When the electrons diffuse across the p-n junction, they recombine with holes
on the p-type side. The diffusion of carriers does not happen indefinitely, however,
because charges build up on either side of the junction and create an electric field. The
electric field creates a diode that promotes charge flow, known as drift current that
opposes and eventually balances out the diffusion of electron and holes. This region
where electrons and holes have diffused across the junction is called the depletion region
because it no longer contains any mobile charge carriers. It is also known as the space
charge region.
3.4 PV ARRAY
For almost all applications, the one-half volt produced by a single cell is inadequate.
Therefore, cells are connected together in series to increase the voltage. Several of these
series strings of cells may be connected together in parallel to increase the current as
well.
These interconnected cells and their electrical connections are then sandwiched
between a top layer of glass or clear plastic and a lower level of plastic or plastic and
metal. An outer frame is attached to increase mechanical strength, and to provide a way
to mount the unit. This package is called a "module” or "panel". Typically, a module is
the basic building block of photovoltaic systems.

27
In many applications the power available from one module is inadequate for the load.
Individual modules can be connected in series, parallel, or both to increase either output
voltage or current. This also increases the output power.
It is important to note that photovoltaic panels or modules from different
manufacturers should not be mixed together in a single array, even if their power, voltage
or current outputs are nominally similar. This is because differences in the I-V
characteristic curves of the panels as well as their spectral response are likely to cause
extra mismatch losses in the array reducing its efficiency.
Fig 3.3 Parallel connections of PV panels
3.4.1 Portable arrays
A portable array may be as small as a one square foot module easily carried by one
person to recharge batteries for communications or flashlights. They can be mounted on
vehicles to maintain the engine battery during long periods of inactivity. Larger ones can

28
be installed on trailers or truck beds to provide a portable power supply for field
operations as shown in fig 3.4.
Fig 3.4 Portable arrays
3.4.2 Tracking arrays
Arrays that track, or follow the sun across the sky, can follow the sun in one axis or in
two. Tracking arrays perform best in areas with very clear climates. This is because
following the sun yields significantly greater amounts of energy when the sun's energy is
predominantly direct. Direct radiation comes straight from the sun, rather than the entire
sky.
Normally, one axis trackers follow the sun from the east to the west throughout the
day. The angle between the modules and the ground does not change. The modules face
in the "compass" direction of the sun, but may not point exactly up at the sun at all times.
Two axis trackers change both their east-west direction and the angle from the ground
during the day. The modules face straight at the sun all through the day. Two axis
trackers are considerably more complicated than one axis types. Fig 3.5 shows describes
about single axis and dual axis tracking.

29
Fig 3.5 Tracking arrays
3.5 PHOTOVOLTAIC MODULE PERFORMANCE
To insure compatibility with storage batteries or loads, it is necessary to know the
electrical characteristics of photovoltaic modules. As here, "I" is the abbreviation for
current, expressed in amps. "V" is used for voltage in volts, and "R" is used for resistance
in ohms.
A photovoltaic module will produce its maximum current when there is essentially no
resistance in the circuit. This would be a short circuit between its positive and negative
terminals. This maximum current is called the short circuit current, abbreviated I(sc).
When the module is shorted, the voltage in the circuit is zero.
Conversely, the maximum voltage is produced when there is a break in the circuit.
This is called the open circuit voltage, abbreviated V(oc). Under this condition the
resistance is infinitely high and there is no current, since the circuit is incomplete. These
two extremes in load resistance, and the whole range of conditions in between them, are
depicted on a graph called a I-V (current-voltage) curve. Current, expressed in amps, is
on the vertical Y-axis. Voltage, in volts, is on the horizontal X-axis. The short circuit
current occurs on a point on the curve where the voltage is zero. The open circuit voltage
occurs where the current is zero.

30
The power available from a photovoltaic module at any point along curve is expressed
in watts. Watts are calculated by multiplying the voltage times the current (watts = volts x
amps, or W = VA).
At the short circuit current point, the power output is zero, since the voltage is zero. At
the open circuit voltage point, the power output is also zero, but this time it is because the
current is zero. The PV module performance is shown in fig 3.6.
Fig 3.6 Photovoltaic module performance
There is a point on the "knee" of the curve where the maximum power output is
located. This point on our example curve is where the voltage is 15 volts, and the current
is 2.5 amps. Therefore the maximum power in watts is 15 volts times 2.5 amps, equalling
37.5 watts.
The power, expressed in watts, at the maximum power point is described as peak,
maximum, or ideal, among other terms. Maximum power is generally abbreviated as
"I(mp)." Various manufacturers call it maximum output power, output, peak power, rated
power, or other terms.
The current-voltage (I-V) curve is based on the module being under standard
conditions of sunlight and module temperature. It assumes there is no shading on the
module. Standard sunlight conditions on a clear day are assumed to be 1000 watts of

31
solar energy per square meter (1000 W/m2
or l KW/m2
). This is sometimes called "one
sun," or a "peak sun." Less than one sun will reduce the current output of the module by a
proportional amount. For example, if only one-half sun (500 W/m2) is available, the
amount of output current is roughly cut in half as shown in fig 3.7.
Fig 3.7 Current-Voltage curves of PV panel
For maximum output, the face of the photovoltaic modules should be pointed as
straight toward the sun as possible because photovoltaic cells are electrical
semiconductors, partial shading of the module will cause the shaded cells to heat up.
They would be acting as inefficient conductors instead of electrical generators. Partial
shading may ruin shaded cells.
Partial module shading has a serious effect on module power output. For a typical
module, completely shading only one cell can reduce the module output by as much as
80%. One or more damaged cells in a module can have the same effect as shading as
shown in fig 3.8.

32
Fig 3.8 Current- Voltage characteristics when module is shaded and unshaded
This is why modules should be completely unshaded during operation. A shadow
across a module can almost stop electricity production. Thin film modules are not as
affected by this problem, but they should still be unshaded. Module temperature affects
the output voltage inversely. Higher module temperatures will reduce the voltage by 0.04
to 0.1 volts for every one Celsius degree risen in temperature (0.04V/0C to 0.1V/0C). In
Fahrenheit degrees, the voltage loss is from 0.022 to 0.056 volts per degree of
temperature rise. This is why modules should not be installed flush against a surface. Air
should be allowed to circulate behind the back of each module so its temperature does not
rise and reducing its output. An air space of 4-6 inches is usually required to provide
proper ventilation. The I-V characteristics of PV panel at different temperatures is shown
in fig 3.9.
Fig 3.9 Current- Voltage characteristics at different temperatures

33
The last significant factor, which determines the power output of a module, is the
resistance of the system to which it is connected. If the module is charging a battery, it
must supply a higher voltage than that of the battery. If the battery is deeply discharged,
the battery voltage is fairly low. The photovoltaic module can charge the battery with a
low voltage, shown as point 1 in Figure 3.10. As the battery reaches a full charge, the
module is forced to deliver a higher voltage, shown as point 2. The battery voltage drives
module voltage.
Fig 3.10 PV module performance under battery charging
Eventually, the required voltage is higher than the voltage at the module's maximum
power point. At this operating point, the current production is lower than the current at
the maximum power point. The module's power output is also lower. To a lesser degree,
when the operating voltage is lower than that of the maximum power point, the output
power is lower than the maximum. Since the ability of the module to produce electricity
is not being completely used whenever it is operating at a point fairly far from the
maximum power point, photovoltaic modules should be carefully matched to the system
load and storage. Using a module with a maximum voltage that is too high should be
avoided nearly as much as using one with a maximum voltage that is too low.
The output voltage of a module depends on the number of cells connected in series.
Typical modules use any of 30, 32, 33, 36, or 44 cells wired in series. The modules with

34
30- 32 cells are considered self-regulating modules. 36 cell modules are the most
common in the photovoltaic industry. Their slightly higher voltage rating, 16.7 volts,
allows the modules to overcome the reduction in output voltage when the modules are
operating at high temperatures. Modules with 33 - 36 cells also have enough surplus
voltage to effectively charge high antimony content deep cycle batteries. However, since
these modules can overcharge batteries, they usually require a charge controller.
Nowadays 44 cell modules are available with a rated output voltage of 20.3 volts. These
modules are typically used only when a substantially higher voltage is required. Another
application for 44 cell modules is a system with an extremely long wire run between the
modules and the batteries or load. If the wire is not large enough, it will cause a
significant voltage drop. Higher module voltage can overcome this problem.
3.6 PV PANEL SPECIFICATIONS
General Specifications
 Manufacturer: Oswal Electrical Company Delhi
 Model: OECOGSEPL 10WP/12V
 Solar cell: Poly crystalline
 Solar cell shape: Rectangle
Electrical Specifications
 Open circuit voltage: Voc= 21.07 V
 Short circuit current: Isc= 0.61 A
 Maximum voltage: Vmp= 17.00 V
 Maximum current: Imp= 0.59 A
 Tolerance Pmax: ± 3%
 Maximum system voltage: 1000V

35
CAPTER -4
SOLAR TRACKER
CHAPTER -4

36
SOLAR TRACKER
4.1 GENERAL
A solar tracker is a device that orients a payload toward the Sun. Payloads are
usually solar panels, parabolic troughs, Fresnel reflectors, lenses or the mirrors of
a heliostat. For flat-panel photovoltaic systems, trackers are used to minimize the angle of
incidence between the incoming sunlight and a photovoltaic panel. This increases the
amount of energy produced from a fixed amount of installed power generating capacity.
In concentrator photovoltaics (CPV) and concentrated solar power (CSP) applications,
trackers are used to enable the optical components in the CPV and CSP systems. The
optics in concentrated solar applications accept the direct component of sunlight light and
therefore must be oriented appropriately to collect energy. Tracking systems are found in
all concentrator applications because such systems collect the sun's energy with
maximum efficiency when the optical axis is aligned with incident solar radiation.
4.2 EVOLUTION OF SOLAR TRACKER
Since the sun moves across the sky throughout the day, in order to receive the best
angle of exposure to sunlight for collection energy. A tracking mechanism is often
incorporated into the solar arrays to keep the array pointed towards the sun. A solar
tracker is a device onto which solar panels are fitted which tracks the motion of the sun
across the sky ensuring that the maximum amount of sunlight strikes the panels
throughout the day. When compare to the price of the PV solar panels, the cost of a solar
tracker is relatively low. Most photovoltaic solar panels are fitted in a fixed location- for
example on the sloping roof of a house, or on framework fixed to the ground. Since the
sun moves across the sky though the day, this is far from an ideal solution. Solar panels
are usually set up to be in full direct sunshine at the middle of the day facing South in the
Northern Hemisphere, or North in the Southern Hemisphere. Therefore morning and
evening sunlight hits the panels at an acute angle reducing the total amount of electricity
which can be generated each day. Fig 4.1 shows the sun’s apparent motion.
.

37
Fig 4.1 Sun’s apparent motion
During the day the sun appears to move across the sky from left to right and up and
down above the horizon from sunrise to noon to sunset. Figure 4.1 shows the schematic
above of the Sun's apparent motion as seen from the Northern Hemisphere. To keep up
with other green energies, the solar cell market has to be as efficient as possible in order
not to lose market shares on the global energy marketplace. The end-user will prefer the
tracking solution rather than a fixed ground system to increase their earnings because:
 The efficiency increases by 30-40%.
 The space requirement for a solar park is reduced, and they keep the same output
 In terms of cost per Watt of the completed solar system, it is usually cheaper to use a
solar tracker and less solar panels where space and planning permit.
 A good solar tracker can typically lead to an increase in electricity generation capacity of
30-50%.
4.3 SOLAR IRRADIATION: SUNLIGHT AND SOLAR CONSTANT
The sun delivers energy by means of electromagnetic radiation. There is solar fusion
that results from the intense temperature and pressure at the core of the sun. Protons get
converted into helium atoms at 600 million tons per second. Because the output of the

38
process has lower energy than the protons which began, fusion gives rise to lots of energy
in form of gamma rays that are absorbed by particles in the sun and re-emitted. The total
power of the sun can be estimated by the law of Stefan and Boltzmann.
P=4πr2 σϵT 4 W
T is the temperature that is about 5800K, r is the radius of the sun which is 695800 km
and σ is the Boltzmann constant which is 1.3806488 × 10-23
m 2
kg s-2
K -1
. The
emissivity of the surface is denoted by ϵ. Because of Einstein’s famous law E=mc2
about
millions of tons of matter are converted to energy each second. The solar energy that is
irradiated to the earth is 5.1024
Joules per year. This is 10000 times the present worldwide
energy consumption per year. Solar radiation from the sun is received in three ways:
direct, diffuse and reflected.
Direct radiation: is also referred to as beam radiation and is the solar radiation which
travels on a straight line from the sun to the surface of the earth.
Diffuse radiation: is the description of the sunlight which has been scattered by
particles and molecules in the atmosphere but still manage to reach the earth’s surface.
Diffuse radiation has no definite direction, unlike direct versions.
Reflected radiation: describes sunlight which has been reflected off from non-
atmospheric surfaces like the ground.
4.4 SUNLIGHT
Photometry enables us to determine the amount of light given off by the Sun in terms
of brightness perceived by the human eye. In photometry, a luminosity function is used
for the radiant power at each wavelength to give a different weight to a particular
wavelength that models human brightness sensitivity. Photometric measurements began
as early as the end of the 18th
century resulting in many different units of measurement,
some of which cannot even be converted owing to the relative meaning of brightness.
However, the luminous flux (or lux) is commonly used and is the measure of the
perceived power of light. Its unit, the lumen, is concisely defined as the luminous flux of
light produced by a light source that emits one candela of luminous intensity over a solid
angle of one steradian. The candela is the SI unit of luminous intensity and it is the power

39
emitted by a light source in a particular direction, weighted by a luminosity function
whereas a steradian is the SI unit for a solid angle; the two-dimensional angle in three-
dimensional space that an object subtends at a point.
One lux is equivalent to one lumen per square metre;
1 lx = 1lm ∙ m-2
= 1 cd ∙ sr ∙ m-2
I.e. a flux of 10 lumen, concentrated over an area of 1 square metre, lights up that area
with illuminance of 10 lux.
Sunlight ranges between 400 lux and approximately 130000 lux, as summarized in the
table below. Table 4.1 shows the various luminous flux at different times of a day.
Time of day Luminous flux (lux)
Sunrise or sunset on a clear day 400
Overcast day 1000
Full day (not direct sun) 10000 – 25000
Direct sunlight 32000 – 130000
Table 4.1: Range of the brightness of sunlight (lux)
Elevation angle
The elevation angle is used interchangeably with altitude angle and is the angular
height of the sun in the sky measured from the horizontal. Both altitude and elevation are
used for description of the height in meters above the sea level. The elevation is 0 degrees
at sunrise and 90 degrees when the sun is directly overhead. The angle of elevation varies
throughout the day and also depends on latitude of the particular location and the day of
the year.

40
Zenith angle
This is the angle between the sun and the vertical. It is similar to the angle of elevation
but is measured from the vertical rather than from the horizontal. Therefore, the zenith
angle = 90 degrees – elevation angle.
Fig 4.2 Angle of elevation and Zenith angle
Azimuth angle
This is the compass direction from which the sunlight is coming. At solar noon, the
sun is directly south in the northern hemisphere and directly north in the southern
hemisphere. The azimuth angle varies throughout the day. At the equinoxes, the sun rises
directly east and sets directly west regardless of the latitude. Therefore, the azimuth
angles are 90 degrees at sunrise and 270 degrees at sunset.

41
4.5 TYPES OF SOLAR TRACKERS
4.5.1 Single axis tracker
Single axis trackers have one degree of freedom that act as the axis of rotation. The
axis of rotation of single axis trackers is aligned along the meridian of the true North.
With advanced tracking algorithms, it is possible to align them in any cardinal direction.
Common implementations of single axis trackers include horizontal single axis trackers
(HSAT), horizontal single axis tracker with tilted modules (HTSAT), vertical single axis
trackers (VSAT), tilted single axis trackers (TSAT) and polar aligned single axis trackers
(PSAT). The orientation of the module with respect to the tracker axis is important when
modelling performance.
4.5.1.1 Horizontal single axis tracker (HSAT)
The axis of rotation for horizontal single axis tracker is horizontal with respect to the
ground. The posts at either end of the axis of rotation of a horizontal single axis tracker
can be shared between trackers to lower the installation cost. Field layouts with
horizontal single axis trackers are very flexible. The simple geometry means that keeping
all of the axes of rotation parallel to one another is all that is required for appropriately
positioning the trackers with respect to one another. Appropriate spacing can maximize
the ratio of energy production to cost, this being dependent upon local terrain and shading
conditions and the time-of-day value of the energy produced. Horizontal trackers
typically have the face of the module oriented parallel to the axis of rotation. As a module
tracks, it sweeps a cylinder that is rotationally symmetric around the axis of rotation. In
single axis horizontal trackers, a long horizontal tube is supported on bearings mounted
upon pylons or frames. The axis of the tube is on a north–south line. Panels are mounted
upon the tube, and the tube will rotate on its axis to track the apparent motion of the Sun
through the day.
4.5.1.2 Horizontal single axis tracker with tilted modules (HTSAT)
In HSAT, the modules are mounted flat at 0 degrees, while in HTSAT, the modules
are installed at a certain tilt. It works on same principle as HSAT, keeping the axis of
tube horizontal in north–south line and rotates the solar modules east to west throughout

42
the day. These trackers are usually suitable in high latitude locations but does not take as
much land space as consumed by Vertical single axis tracker (VSAT). Therefore, it
brings the advantages of VSAT in a horizontal tracker and minimizes the overall cost of
solar project.
4.5.1.3 Vertical single axis tracker (VSAT)
The axis of rotation for vertical single axis trackers is vertical with respect to the
ground. These trackers rotate from East to West over the course of the day. Such trackers
are more effective at high latitudes than are horizontal axis trackers. Field layouts must
consider shading to avoid unnecessary energy losses and to optimize land utilization.
Also optimization for dense packing is limited due to the nature of the shading over the
course of a year. Vertical single axis trackers typically have the face of the module
oriented at an angle with respect to the axis of rotation. As a module tracks, it sweeps a
cone that is rotationally symmetric around the axis of rotation.
4.5.1.4 Tilted single axis tracker (TSAT)
All trackers with axes of rotation between horizontal and vertical are considered tilted
single axis trackers. Tracker tilt angles are often limited to reduce the wind profile and
decrease the elevated end height. With backtracking, they can be packed without shading
perpendicular to their axis of rotation at any density. However, the tilt angle and the
latitude limit the packing parallel to their axes of rotation. Tilted single axis trackers
typically have the face of the module oriented parallel to the axis of rotation. As a module
tracks, it sweeps a cylinder that is rotationally symmetric around the axis of rotation.
4.5.2 Dual axis tracker
Dual axis trackers have two degrees of freedom that act as axes of rotation. These axes
are typically normal to one another. The axis that is fixed with respect to the ground can
be considered a primary axis. The axis that is referenced to the primary axis can be
considered a secondary axis. There are several common implementations of dual axis
trackers. They are classified by the orientation of their primary axes with respect to the
ground. Two common implementations are tip-tilt dual axis trackers (TTDAT) and
azimuth-altitude dual axis trackers (AADAT). The orientation of the module with respect

43
to the tracker axis is important when modelling performance. Dual axis trackers typically
have modules oriented parallel to the secondary axis of rotation. Dual axis trackers allow
for optimum solar energy levels due to their ability to follow the Sun vertically and
horizontally. No matter where the Sun is in the sky, dual axis trackers are able to angle
themselves to be in direct contact with the Sun.
4.5.2.1 Tip–tilt
A tip–tilt dual axis tracker (TTDAT) is so-named because the panel array is mounted
on the top of a pole. Normally the east–west movement is driven by rotating the array
around the top of the pole. On top of the rotating bearing is a T- or H-shaped mechanism
that provides vertical rotation of the panels and provides the main mounting points for the
array. The posts at either end of the primary axis of rotation of a tip–tilt dual axis tracker
can be shared between trackers to lower installation costs.
Other such TTDAT trackers have a horizontal primary axis and a dependent
orthogonal axis. The vertical azimuthal axis is fixed. This allows for great flexibility of
the payload connection to the ground mounted equipment because there is no twisting of
the cabling around the pole.
Field layouts with tip–tilt dual axis trackers are very flexible. The simple geometry
means that keeping the axes of rotation parallel to one another is all that is required for
appropriately positioning the trackers with respect to one another. Normally the trackers
would have to be positioned at fairly low density in order to avoid one tracker casting a
shadow on others when the Sun is low in the sky. Tip-tilt trackers can make up for this by
tilting closer to horizontal to minimize up-Sun shading and therefore maximize the total
power being collected. The axes of rotation of many tip–tilt dual axis trackers are
typically aligned either along a true north meridian or along an east–west line of latitude.
4.5.2.2 Azimuth-altitude
An azimuth–altitude dual axis tracker (AADAT) has its primary axis (the azimuth
axis) vertical to the ground. The secondary axis, often called elevation axis, is then
typically normal to the primary axis. They are similar to tip-tilt systems in operation, but
they differ in the way the array is rotated for daily tracking. Instead of rotating the array

44
around the top of the pole AADAT systems can use a large ring mounted on the ground
with the array mounted on a series of rollers. The main advantage of this arrangement is
the weight of the array is distributed over a portion of the ring, as opposed to the single
loading point of the pole in the TTDAT. This allows AADAT to support much larger
arrays. Unlike the TTDAT, however, the AADAT system cannot be placed closer
together than the diameter of the ring, which may reduce the system density, especially
considering inter-tracker shading.
4.6 TYPES OF DRIVES
4.6.1 Active tracker
Active trackers make use of motors and gear trains for direction of the tracker as
commanded by the controller responding to the solar direction. The position of the sun is
monitored throughout the day. When the tracker is subjected to darkness, it either sleeps
or stops depending on the design. This is done using sensors that are sensitive to light
such as LDRs. Their voltage output is put into a microcontroller that then drives actuators
to adjust the position of the solar panel.
4.6.2 Passive tracker
Passive trackers use a low boiling point compressed gas fluid driven to one side or the
other to cause the tracker to move in response to an imbalance. Because it is a non-
precision orientation it is not suitable for some types of concentrating photovoltaic
collectors but works just fine for common PV panel types. These have viscous dampers
that prevent excessive motion in response to gusts of wind.
4.6.3 Manual tracking
In some developing nations, drives have been replaced by operators who adjust the
trackers. This has the benefits of robustness, having staff available for maintenance and
creating employment for the population in the vicinity of the site.

45
CHAPTER -5
LEAD-ACID BATTERY

46
CHAPTER -5
LEAD-ACID BATTERY
The most inexpensive secondary cell is the lead acid cell and is widely used for
commercial purposes. A lead-acid cell when ready to use contains two cells immersed in
a dilute sulphuric acid of specific gravity of about 1.28. The positive plate is of lead-
peroxide and negative plate is lead.
Fig 5.1 Lead-Acid battery
5.1 CHEMICAL CHANGES DURING DISCHARGING
In the discharged state both the positive and negative plates become lead
sulfate (PbSO4) and the electrolyte loses much of its dissolved sulfuric acid and becomes
primarily water. The discharge process is driven by the conduction of electrons from the
negative plate back into the cell at the positive plate in the external circuit as shown in fig
5.2.
At cathode
Pb(s) + HSO−
4(aq) → PbSO4(s) + H+
(aq) + 2e−

47
Release of two conducting electrons gives lead electrode a net negative charge as
electrons accumulate they create an electric field which attracts hydrogen ions and repels
sulphate ions, leading to a double-layer near the surface. The hydrogen ions screen the
charged electrode from the solution which limits further reactions unless charge is
allowed to flow out of electrode.
At anode
PbO2(s) + HSO−
4(aq) + 3H+
(aq) + 2e−
→ PbSO4(s) + 2H2O(l)
The total reaction can be written as
Pb(s) + PbO2(s) + 2H2SO4(aq) → 2PbSO4(s) + 2H2O(l)
The sum of the molecular masses of the reactants is 642.6 g/mol, so theoretically a cell
can produce two faradays of charge from 642.6 g of reactants, or 83.4 ampere-hours per
kilogram. For a 2 volts cell, this comes to 167 watt-hours per kilogram of reactants, but a
lead–acid cell in practice gives only 30–40 watt-hours per kilogram of battery, due to the
mass of the water and other constituent parts.
Fig 5.2 Discharging of a lead acid battery
5.2 CHEMICAL CHANGES DURING CHARGING
As a lead-acid battery is charged in the reverse direction, the action described in the
discharge is reversed. The lead sulphate (PbSO4) is driven out and back into the

48
electrolyte (H2SO4). The return of acid to the electrolyte will reduce the sulphate in the
plates and increase the specific gravity. This will continue to happen until all of the acid
is driven from the plates and back into the electrolyte as shown in fig 5.3.
2PbSO4(s) + 2H2O(l) → Pb(s) + PbO2(s) + 2H2SO4(aq)
Fig 5.3 Charging of a lead acid battery
5.3 CHARACTERISTICS OF LEAD-ACID CELL
 Terminal Voltage - When the battery delivers current, the voltage terminal voltage is
less than its EMF due to its internal resistance. Lead acid cell has less lead sulphate that
will clogged the pores of the battery once there is continuous flow of current.
 EMF- The EMF of a fully charged L-A cell is relatively higher, its open circuit voltage
will reach as high as 2.2 Volts while other has 1.2 Volts only.
 Capacity - The capacity of the cell is defined as the quantity of electricity which it can
give out during single discharge until its terminal voltage falls to 1.8 V. Battery capacity
is measured by Ampere-hours and the capacity of lead-acid cell is not permitted to
discharged beyond 1.8 V, thus it has high capacity.
 Efficiency - There are two ways which we can measure the efficiency of the lead-acid
cell that is ampere-hour efficiency and watt-hour efficiency. The L-A cell has 90%
Ampere-hour efficiency and 75% Watt-hour efficiency. These data is relatively higher
compare to other secondary cells.

49
Ampere-hour efficiency= (Amp-hr provided on discharge/ Amp-hr on charge) x 100
Watt-hour efficiency= (Energy given on discharge/ Energy input of charge) x 100
5.4 INDICATIONS OF FULLY CHARGED CELL
The indications of a fully charged battery are:
 Voltage- During charging, the terminal potential of a cell increases and provides an
indication to its state of charge. A fully charged lead-acid cell has a terminal voltage of
about 2 volts.
 Specific gravity- When the battery is fully charged the specific gravity increases up to
1.28. This can be measured by means of a hydrometer.
 Gassing- When the battery is fully charged, the charging current starts electrolysis of
water. The result is that hydrogen is given off at cathode and oxygen at anode; this
process is known as gassing. Gassing indicates that charging current is not doing useful
work and hence should be stopped.
 Colour of plates- The visual examination of colour of the plates of lead-acid cell
provides another important indication of state of charge. When the cell is fully charged,
the positive plate gets converted into Pbo2 which is brown in colour and negative plate to
spongy lead which is grey in colour
5.5 MAINTENANCE PROCEDURES
The average life of secondary battery can be increased by taking proper care of
batteries. Some of the important battery precautions that should be taken for healthy
maintenance of battery are the following:
 The battery should be recharged immediately after the discharge according the rates of
charge and discharge specified by manufacturer.
 The top of battery should be kept clean and dry.
 The level of electrolytes in the battery should always be kept above the top of the
electrode plates. The loss of water due to evaporation and decomposition during charging
should be compensated by adding pure distilled water.

50
 The temperature of the battery should not exceed 40 o
C. At higher temperatures, the
electrode plate deteriorate very rapidly.
 If the white lead sulphate is accumulated on the electrode plates, it should be removed by
overcharging the battery by passing a current which is about 150% of the normal current.
 The battery should never be short circuited.
 The battery should not be left in a discharge condition for a long time.
 When not in use, the battery must be fully charged and kept in a cool and dry place.
5.5 SPECIFICATIONS
Type : Sealed lead-acid battery
Nominal Voltage : 12V
Rated Capacity : 1.3AH
Approx. Weight : 0.57Kg
Maximum discharge current : 19.5A
Case material : Acrylonitrile butadiene styrene
(A.B.S)
Initial resistance (Fully charged battery) : 78mOhms
Operating temperature : -20 o
C to 50 o
C
Specific Energy : 26 Watt-Hour/Kg

51
CHAPTER -6
SERVO MOTOR AND VOLTAGE RGULATOR

52
CHAPTER -6
SERVO MOTOR AND VOLTAGE RGULATOR
6.1 SERVO MOTOR
A servo motor is an electrical device which can push or rotate an object with great
precision. If you want to rotate and object at some specific angles or distance, then you
use servo motor. It is just made up of simple motor which run through servo mechanism.
If motor is used is DC powered then it is called DC servo motor, and if it is AC powered
motor then it is called AC servo motor. We can get a very high torque servo motor in a
small and light weight packages. Doe to these features they are being used in many
applications like toy car, RC helicopters and planes, Robotics, Machine etc.
Servo motors are rated in kg/cm. his kg/cm tells you how much weight your servo
motor can lift at a particular distance. For example: A 6kg/cm Servo motor should be
able to lift 6kg if the load is suspended 1cm away from the motors shaft, the greater the
distance the lesser the weight carrying capacity.
Fig 6.1 Servo motor

53
6.1.1 Servo mechanism
It consists of three parts:
1. Controlled device
2. Output sensor
3. Feedback system
It is a closed loop system where it uses positive feedback system to control motion
and final position of the shaft. Here the device is controlled by a feedback signal
generated by comparing output signal and reference input signal.
Here reference input signal is compared to reference output signal and the third signal
is produces by feedback system. And this third signal acts as input signal to control
device. This signal is present as long as feedback signal is generated or there is
difference between reference input signal and reference output signal. So the main task
of servomechanism is to maintain output of a system at desired value at presence of
noises.
6.1.2 Working principle of servo motor
A servo consists of a Motor (DC or AC), a potentiometer, gear assembly and a
controlling circuit. First of all we use gear assembly to reduce RPM and to increase
torque of motor. Say at initial position of servo motor shaft, the position of the
potentiometer knob is such that there is no electrical signal generated at the output port of
the potentiometer. Now an electrical signal is given to another input terminal of the error
detector amplifier. Now difference between these two signals, one comes from
potentiometer and another comes from other source, will be processed in feedback
mechanism and output will be provided in term of error signal. This error signal acts as
the input for motor and motor starts rotating. Now motor shaft is connected with
potentiometer and as motor rotates so the potentiometer and it will generate a signal. So
as the potentiometer’s angular position changes, its output feedback signal changes. After
sometime the position of potentiometer reaches at a position that the output of
potentiometer is same as external signal provided. At this condition, there will be no

54
output signal from the amplifier to the motor input as there is no difference between
external applied signal and the signal generated at potentiometer, and in this situation
motor stops rotating.
6.1.3 Controlling of servo motor
All motors have three wires coming out of them. Out of which two will be used for
Supply (positive and negative) and one will be used for the signal that is to be sent from
the MCU. Servo motor is controlled by PWM (Pulse with Modulation) which is
provided by the control wires. There is a minimum pulse, a maximum pulse and a
repetition rate. Servo motor can turn 90 degree from either direction form its neutral
position. The servo motor expects to see a pulse every 20 milliseconds (ms) and the
length of the pulse will determine how far the motor turns.
Fig 6.2 Pulse width control of servo motor
Servo motor works on PWM (Pulse width modulation) principle, means its angle of
rotation is controlled by the duration of applied pulse to its Control PIN. Basically servo
motor is made up of DC motor which is controlled by a variable resistor (potentiometer)
and some gears. High speed force of DC motor is converted into torque by Gears. We
know that WORK= FORCE X DISTANCE, in DC motor force is less and distance
(speed) is high and in Servo, force is High and distance is less. Potentiometer is
connected to the output shaft of the Servo, to calculate the angle and stop the DC motor
on required angle.

55
6.1.4 Specifications
 Manufacturer : Vega Robo Kit
 Model : V3006
 Operating Voltage : 4.8-6.0V
 PWM Input Range : Pulse Cycle 20±2ms, Positive Pulse 1~2ms
 STD Direction : Counter Clockwise / Pulse Traveling 1500 to 1900µsec
 Stall Torque : 6 kg-cm at 4.8V, 7.1 Kg-cm at 6V
 Operating Speed : 0.18 sec/ 60° at 4.8V, 0.16 sec/ 60° at 6V at no load
 Weight : 40g (1.41 oz)
 Special Feature : Heavy Duty Plastic Gears, Economy Servo
6.2 VOLTAGE REGULATOR
6.2.1 LM 7805 SERIES VOLTAGE REGULATOR
This series of fixed-voltage integrated-circuit voltage regulators is designed for a wide
range of applications. These applications include on-card regulation for elimination of
noise and distribution problems associated with single-point regulation. Each of these
regulators can deliver up to 1.5 A of output current. The internal current-limiting and
thermal-shutdown features of these regulators essentially make them immune to
overload.
Fig 6.3 LM7805 Voltage Regulator

56
6.2.2 FEATURES OF VOLTAGE REGULATOR
 Output Current up to 1.5A
 Internal Thermal-Overload Protect
 High Power-Dissipation Capability
 Internal Short-Circuit Current Limiting
 Output Transistor Safe-Area Compensation
 3-Terminal Regulators

57
CHAPTER -7
SOFTWARE DESIGN AND DUMPING

58
CHAPTER -7
SOFTWARE DESIGN AND DUMPING
7.1 SOFTWARES USED
1. Arduino IDE 1.8.5
2. EasyEDA for drawing circuit diagram
7.2 SOFTWARE DESIGN
7.2.1 Flowchart for Solar Charge Controller
Fig 7.1 Flowchart for solar charge controller

59
7.2.2 Flowchart for Sun Tracker
Fig 7.2 Flowchart of sun tracking system
7.3 SOFTWARE DUMPING PROCEDURE
1. The assembly language Instructions typed in dos editor or notepad with an extension of
.INO.
2. Compile the above .INO file with Arduino IDE software.
3. Before uploading your sketch, you need to select the correct items from the Tools >
Board and Tools > Port menus.
4. Once you've selected the correct serial port and board, press the upload button in the
toolbar or select the Upload item from the Sketch menu. Current Arduino boards will
reset automatically and begin the upload.
5. The Arduino Software (IDE) will display a message when the upload is complete, or
show an error.

60
CHAPTER -8
PROPOSED HARDWARE

61
CHAPTER -8
PROPOSED HARDWARE
8.1 HARDWARE USED IN CIRCUIT CONSTRUCTION
Following components used in the circuit construction
 MOSFET
It is switching device which can operates whenever we are giving gate pulses on it. It has
three terminal devices.
 Arduino Nano
The Arduino Nano employs ATmega328 microcontroller which can operated as per
programmed written. The execution will be done by this microcontroller.
 Solar panel
Solar panels absorb sunlight as a source of energy to generate electricity.
 Servo motor
Servo motor is used to align the solar panel perpendicular to sun rays according to the
PWM signals generated by Arduino.
 Current sensor
The current sensor is used to measure the amount of current drawn by load.
 Temperature sensor
Temperature sensor is used to monitor room temperature since the battery chemical
reaction varies with temperature.
 LDR
An LDR is a component that has a (variable) resistance that changes with the light
intensity that falls upon it. This allows them to be used in light sensing circuits.
 LED

62
Here LEDs Are used to indicate battery and load status. These LEDs are turned on with
the help of Arduino.
8.2 WORKING OPERATION OF THE CIRCUIT
Whenever the solar panel output voltage is greater than battery voltage, the Arduino turns
on switching circuit 1 and the battery gets charged. When the battery is fully charged the
Arduino turns off switching circuit 1 thereby protecting the battery from getting
overcharged. During night times the solar panel voltage is less than battery voltage so the
Arduino turns on switching circuit 2 thereby connecting the load. When the battery
voltage is low the Arduino disconnects load thereby protecting the battery from deep
discharge. During daytime a pair of LDR’s are used to track the sun and tilt the solar
panel such that maximum amount of sunlight is incident on it.
Fig 8.1 Circuit diagram of the proposed system

63
CHAPTER -9
EXPERIMENTAL RESULTS

64
CHAPTER -9
EXPERIMENTAL RESULTS
9.1 PICTORIAL VIEW OF EXPERIMENTAL SETUP
9.1 Pictorial view of experimental setup
9.2 CHARGING TEST
The test was conducted on March 10, 2018 from 10:00AM to 12:00PM. A 10W solar
panel was used to provide charging voltage. A voltage sensor was used to measure
voltage of solar panel and battery. Solar panel voltage and battery voltage was noted and
recorded at the beginning of the charging experiment. All the values are tabulated until
the battery is fully charged.
The results obtained was tabulated in Table 9.1. The measured parameters include
solar panel voltage (V1), battery voltage (V2), load status and battery status.

65
Time Solar Panel
voltage
Battery
voltage
Load
status
Battery status
10:00 AM 14.4V 11.9V Off Bulk Charging
11:30 AM 14.73V 13.4V Off Float Charging
12:00 PM 14.83V 13.7V Off Charged
Table 9.1: Charging test result
9.3 DISCHARGING TEST
The voltages for discharging test was recorded for an interval of an hour. The
parameters recorded are battery voltage and load status. The results are tabulated in Table
9.2.
Time Battery voltage Load status
7:00 PM 13.7V On
8:00 PM 13.2V On
9:00 PM 12.7V On
10:00 PM 12.3V On
11:00 PM 11.93V On
12:00 AM 11.6V Off
Table 9.2: Discharging test result

66
CONCLUSION
In this project, Solar charge controller with sun tracking has been implemented to
enhance battery life. Here PWM (Pulse width modulation) technique is utilized to charge
battery and control load variations. Here Arduino control is implemented to prevent
overcharging and undercharging of the battery. Also, solar tracker is implemented to
derive maximum efficiency of PV panel.

67
FUTURE SCOPE
In future PWM (Pulse width modulation) technique can be replaced by Maximum power
point tracking algorithm (MPPT) to enhance the efficiency of the Photovoltaic Panel.

68
REFERENCES
[1] Akarsh Sinha, M. Pavithra, K.R. Sutharshan,Sarat Kumar Sahoo, "Arduino Based
Pulse Width Modulated Output Voltage Control of a dc-dc Boost Converter Using
Proportional ,Integral and Derivative Control Strategy," Australian Journal of Basic and
Applied Sciences, vol.7, pp.l04-108, Sept 2013.
[2] Md. Ashiquzzaman, Nadia Afroze, Md. Jabed Hossain, Umama Zobayer, and Md.
Mottaleb Hossain, “Cost Effective Solar Charge Controller Using Microcontroller ”,
Canadian Journal on Electrical and Electronics Engineering vol. 2, no. 12, pp. 571-576,
2011.
[3] M.K.A1am,F.H.Khan and A.S.Imtiaz, "An efficient power electronics solution for
lateral multi-junction solar cell systems," in Proc.IEEE IECON,pp.4373-4378,2011 .
[4] Gazi, S.M., Muhaiminul, and Salim, K.M “Design and Construction of
Microcontroller Based Maximum Power Point PWM Charge Controller for Photovoltaic
Application”. Development in Renewable Energy Technology (2009) 1st International
Conference, Pp. 1-4, 2009.
[5] Robert Weissbach and Isaac Aunkst “A MICROCONTROLLER-BASED SOLAR
PANEL TRACKING SYSTEM”, American Society for Engineering Education, 2007.
[6] Frede Blaabjerg,Florin Iov, Remus Teodorescue, Zhe Chen,„‟Power Electronics in
Renewable Energy Systems‟‟, Aalborg University, Institute of Energy, IEEE
transaction, 2006.
[7] E. Koutroulis and K. Kalaitzakis, "Novel battery charging regulation system for
photovoltaic applications", IEE Proceedings, 2004.
[8] K.Ktse. S.H Chung “ A Novel Maximum Power Point Tracker For PV panels using
Switching frequency Modulation” IEEE Trans on power electronics vol 17, 6 Nov 2002.
[9] Sanidad, L, Parsons, R, Baghzouz, Y, and Boehm, R “Effect of ON/OFF charge
controllers on stand-alone PV system performance”. Energy Conversion Engineering
Conference and Exhibit, (IECEC) 35th Intersociety, Las Vegas, NV, 1497-1501, 2000.
[10] C Hua, J Lin and C Shen “Implementation of a DSP- Controlled Photovoltaic
System with Peak Power Tracking” IEEE Trans on ind electronics vol,45 no 1,jan1998.

It is here by certified that the paper ID : IJRASET14282, entitled
Design and Development of Solar Charge Controller with Sun Tracking
by
Ch. Nikhil Chakravarthy
after review is found suitable and has been published in
Volume 6, Issue III, March 2018
in
International Journal for Research in Applied Science &
Good luck for your future endeavors

by
G. Raja Sekhar
in

by
B. K. S. A Ramlal
in

by
B. Sreenu
in

by
B. Siva Durga Prasad
in

International Journal for Research in Applied Science & Engineering Technology (IJRASET)
Volume 6 Issue III, March 2018- Available at www.ijraset.com
729©IJRASET (UGC Approved Journal): All Rights are Reserved
Design and Development of Solar Charge
Controller with Sun Tracking
Ch. Nikhil Chakravarthy1
, G. Raja Sekjar2
, B. K. S. A Ramlal3
, B. Sreenu4
, B. Siva Durga Prasad5
1, 2, 3, 4, 5
Department of Electrical and Electronics Engineering, PVP Siddhartha Institute of Technology, Vijayawada, India
Abstract: This paper proposes the design and development of Arduino based solar charge controller with sun tracking using
PWM technique. This PWM technique is employed using ATmega328P on Arduino board. The Arduino is used to charge a 12V
battery using 10W solar panel. The main feature of this charge controller is to control the load. During day time when load is
not connected the battery gets charged from solar panel. When battery reaches peak value of 14.7V charging current & further
charging is interrupted by Arduino. An inbuilt analogue to digital converter is used to determine voltage of battery, solar panel
and current drawn by the load. A solar tracking system is also implemented such that panel is always kept at right angle to
incident radiation.
Keywords: photovoltaic (PV), Arduino Nano, LDR, Battery, Light Emitting Diode.
I. INTRODUCTION
As the conventional are depleted day by day the world is moving towards alternative sources, energy like solar energy, wind energy
etc. Solar energy can be used to generate power in two-ways; solar thermal conversion and solar electrical conversion. Solar thermal
is employed to heat fluids in order to produce steam to derive turbines while solar electric (photovoltaic) is the direct conversion of
sunlight into electricity through photocells. Photovoltaic (PV) production becomes double every two years [2]. For this reason, it has
become the world’s fastest growing energy technology all around the world [4-10].
A charge controller is an essential part of nearly all power systems in which batteries are used to store generated power, whether the
power source is PV, wind e.tc [3]. A PV system consists a number of solar cells which converts sunlight directly into electrical
energy. A charge controller is one of the important components of PV system. The main function of a charge controller in a PV
system is to keep batteries properly charged and safe for the long term, and to protect it from deep discharging [3], without which
the battery will overcharge. Absence of charge controller in PV system results in high maintenance cost and frequent battery
replacement. Hence, a charge controller is important to prevent battery overcharging excessively, over discharging, reverse current
flow at night and to prolong the life of the batteries in a PV system [3]. Voltage change in LDR where combination of voltage and
tracking position is implemented with the use of artificial intelligence algorithm which results in a single axis tracking strategy
along with charge controller
When a lead acid battery is charged, its voltage rises. When the charge current is first turned on, the internal resistance of the
battery resists the current, and the voltage immediately rises above the open circuit voltage. Towards the end of charge, the voltage
rises sharply as the battery begins to “gas”. “Gassing” is the decomposition of the liquid water into hydrogen and oxygen gasses
which is also known as “electrolysis” [1]. If gassing is left to continue for a long period of time, the battery is overcharged, resulting
in accelerated corrosion of the battery plates, loss of electrolyte, and physical damage of the plates.
The aim of this paper is to design and construct an Arduino based charge controller for PV application along with sun tracking
system, capable of charging a 12V battery using 10W solar panel. The hardware design is adopted.
II. MATERIALS AND METHODS
A. Hardware design
The system design is based on the block diagram shown in figure 1. The LDR sensors provide analog data as an output. This analog
data is given to analog pins ATMega328P microcontroller which can work on voltage up to 5V, so using an ATMega328P is an
added advantage since reduces the cost of separate A/D converters IC. The analog output of sensors is connected to ADC pins of
ATMega328P microcontroller and the A/D conversion is completed by using software program.

Figure 1: Block diagram of the system
B. Voltage sensing section
Voltage divider network is used as voltage sensor for the controller. The resistance values chosen are 20KΩ and 100KΩ such that
maximum input voltage to A/D converter is 5V.
C. Current sensor
The current sensor is used for measuring load current. Here in this project we used Hall-effect sensor as a current sensor.
D. Switching Circuit
MOSFET is used as a switching device because it has fast switching speed and low voltage drop. MOSFET is a voltage-controlled
device. It operates in two modes-enhanced mode and depletion mode. IRF9540 MOSFET is used as a switch because it is easy to
use and has faster switching speed. In the hardware circuit transistor is used to switch the mosfet from microcontroller. A MOSFET
and transistor combination is used for the switching purpose between solar panel and battery.
E. Battery
Battery capacity is expressed in Amp-hours or mA-hours. Battery charge and discharge currents are expressed in terms of “C-Rate”.
The solar energy is converted into electrical energy and stored in a 12V battery. The efficiency of battery charging system is to store
the energy from solar panel. The main two types of batteries are rechargeable and disposable. The most popular types of
rechargeable batteries in use today are the Sealed-Lead-Acid (SLA), Nickel-Cadmium (NiCd), Nickel-Metal-Hydride (NiMH), and
Lithium-Ion (Li-Ion). Weight, capacity, and cost are the primary consideration in battery equipment. Lead-acid battery is used in
this system because it is inexpensive and high capacitated. The 12V of lead-acid battery has 6 cells. It is safe to charge most of lead-
acid batteries by current up to 0.1C rate, where C is the battery capacity in Ah. Overcharging battery can cause reduce life span of
battery.
F. PV panel
The solar panel is used to convert solar energy to electrical energy. Solar energy is being used around the world. Solar panel is
connected in either series or parallel to achieve the desire output voltage and current. Three types of solar panels are
Monocrystalline (single silicon), Polycrystalline (Multi-silicon), and amorphous thin-film. Crystalline solar cells are wired in series
to produce solar panels. Monocrystalline solar panels are more efficient than polycrystalline but also the most expensive. The

efficiency of amorphous solar panel is not as high as crystalline solar panel. The solar panel is used to charge a 12V battery. The
peak output voltage of solar panel is 20V. A typical 12V panel will contain 36 cells. Photovoltaic cells combine to make solar panel,
solar module or PV array. Photovoltaic solar panel is used to absorb current and voltage depends on light intensity.
G. Software design
The Arduino is operated according to the program written inside its memory. The main objective of this program is to control,
coordinate and to execute various task such as to control battery voltage, controlling of load and to track position of sun. The
program has been developed according to the flow chart shown in figure 2 and figure 3.Based on these flowcharts the program was
written in Arduino IDE, debugged and then loaded into Arduino nano board.
Figure 2: Charge controller program flow chart
Figure 3: Sun tracking system program flow chart

DESIGN AND DEVELOPMENT OF SOLAR CHARGE CONTROLLER WITH SUN TRACKING

DESIGN AND DEVELOPMENT OF SOLAR CHARGE CONTROLLER WITH SUN TRACKING

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DESIGN AND DEVELOPMENT OF SOLAR CHARGE CONTROLLER WITH SUN TRACKING