SUN TRACKER Report
SrMANF
Sun Tracker
Introduction
A Solar tracker is a device for orienting a solar photovoltaic panel
towards the sun. In solar tracking systems the surface of the
module tracks the sun automatically throughout the day. Tracking
system increases the efficiency of the system considerably there
by reducing the cost per unit of output energy.
Why to Use Solar Tracking System?
The problem here is that the sun’s position is not constant
throughout the day. The output from the solar system depends on
the intensity of sunlight and the angle at which radiation is being
incident. Hence there is a need to track the sun in order to produce
maximum output throughout the day. The solution to the problem
is our project “SOLAR TRACKING SYSTEM”.
Types of tracking systems
There are two main types of solar trackers, single-axis and two-
axis.
Single-axis
Single-axis solar: trackers follow the sun from sunrise to sunset as
it moves in the sky through the day from east to west. They are
called a single-axis trackers as the mechanism only rotates in one
plane around a single axis. The axis can be oriented so that the cells
stand up at a tilt (called a polar axis) or lie flat (called a horizontal
axis). Horizontal axes are more suitable for small latitudes whilst
polar axis are more suitable for larger latitudes.
Polar type single-axis tracker
Horizontal type single-axis trackers
The advantages of single-axis trackers are that they are less
complicated, and thus less expensive.
Single-axis horizontal trackers are also structurally more rigid and
stable, and hence less likely to be damaged during storms.
Dual-axis
Dual-axis, or two-axis, trackers follow the sun completely. The two
axes of rotation allow the tracker to position the solar cells directly
perpendicular to the sun’s ray all the time. As they are able to
adjust for the sun’s height as well east to west rotation dual-axis
trackers fully adjust for seasons as well as adjusting to face the sun
as it sits low in the horizon at sunrise and sunset, and high in the
sky in the middle of the day.
Dual-axis solar tracker
Disadvantages of solar trackers:
An added upfront cost to your solar installation
Generally require some maintenance
Moving parts and added complexity come with the usual
pitfalls of risk of breakdown
Structurally less rigid then permanent mounts and hence can
be vulnerable to storm damage
objective of the project
The main aim of our project is to make the panel to rotate
according to the sun’s direction from morning to evening
automatically so that the panel grabs the solar enenrgy
tomaximum extent possible throughout the day.
To fabricate a motor control interfaced with driver circuit.
To construct a model prototype solar cell movement system
with a mechanical assemble to move the panel from 180⁰ E
to W.
To design an electronic circuit to sense the intensity of light
and to control motor driver for the panel movement.
To construct an emergency light inverter circuit i.e. to operate
tube light with the help of charged battery from the solar
panel
Light Sensor
Light sensors are among the most common sensor type. The sun
tracker uses a cadmium sulfide (CdS) photocell for light sensing.
This is the least expensive and least complex type of light sensor.
The CdS photocell is a passive component whose resistance in
inversely proportional to the amount of light intensity directed
toward it.
Photo-Resistor Sensor (LDR or Photo-cell) SEN-LHT01 is selected
this sensor is more cheaper and smaller in size than another
light sensor
Datasheet is attached
http://kennarar.vma.is/thor/v2011/vgr402/ldr.pdf
Microcontroller
Since the project’s focus is on embedded software control, the
microcontroller is the heart of the system. The microcontroller
selected for this project had to be able to convert the analog
photocell voltage into digital values and also provide four output
channels to control motor rotation.
Why Arduino Over PIC?
The Microchip PIC is a family of microcontrollers, while an Arduino
is a development platform, The Arduino is a complete
development platform with its own standards, integrated
development environment (IDE) and programming interface (API).
If you are new to microcontrollers, the Arduino platform is
certainly worth considering for educational purposes.
Arduino is easier in its programming (C or assembly) than PIC ...
altough its not cheaper but easier
The LCD is used to show functions result.
ATMega328 - Microcontroller with Bootloader for UNO is slected
This arduino satisfy our requirements and more cheaper
than other ones
Datasheet is attached
http://www.atmel.com/images/atmel-8271-8-bit-avr-
microcontroller-atmega48a-48pa-88a-88pa-168a-168pa-328-
328p_datasheet_summary.pdf
Microcontroller ATmega328
Operating Voltage 5V
Input Voltage (recommended) 7-12V
Input Voltage (limits) 6-20V
Digital I/O Pins 14 (of which 6 provide PWM output)
Analog Input Pins 6
DC Current per I/O Pin 40 mA
DC Current for 3.3V Pin 50 mA
Flash Memory 32 KB (ATmega328) of which 0.5 KB used by bootloader
SRAM 2 KB (ATmega328)
EEPROM 1 KB (ATmega328)
Clock Speed 16 MHz
Character LCD Module 20 Char. x 2 Line is selected
Character LCD module is one of the display device that well used
for electornics equipments. Its ability to dislpaly alpha-numeric
characters has contributed the improvement of function of the
electronics devices. Especially its very low power consumption is
suitable for battery powered devices.
Motor Driver and Stepper Motor
A single unipolar stepper motor was chosen to position the
tracking sensor. A stepper motor was selected because of the
precision it offers in positioning applications such as this.
The rotation angle of the motor is proportional to the input
pulse.
Precision positioning and repeatability of movement since
good stepper motors havean accuracy of 3-5% of a step and
this error is non cumulative from one step to thenext.
Excellent response to starting/stopping/reversing.
Very reliable since they are no contact brushes in the motor.
Therefore the life of themotor is simply dependent on the
life of the bearing.
The motors response to the digital input pulses provides
open-loop control, makingthe motor simpler and less costly
to control.
It is possible to achieve very slow speed synchronous
rotation with a load that isdirectly coupled to the shaft.
A wide range of rotational speeds can be realized as the speed
is proportional to thefrequency of the input pulses.
High Quality Unipolar Stepper Motor is selcted
provide sufficient torque
Stepper Motor Parameters
Rated voltage : 12VDC
Number of Phase : 2
Stride Angle : 5.625° /64 Frequency : 100Hz
DC resistance : 50Ω±7%(25℃) In-traction Torque >34.3mN.m(120Hz) Self-positioning Torque >34.3mN.m Friction torque : 600-1200 gf.cm Pull in torque : 300 gf.cm Insulated resistance >10MΩ(500V)
Insulated electricity power :600VAC/1mA/1s
Lists the major components utilized in the project.
Item Size or Part No. Quantity
Microcontroller
Oscillator
Voltage regulator
Photocell
Step motor
Capacitor
Resistor
Diode
Transistor
Switch
Software/System Operation
Software operation can be divided into three main parts. The first
part is initial positioning. Prior to powering up the system, the
photocell must be manually set to a starting point (east).
The second part of the system code deals with light tracking. This
is the heart of the program. Once the tracker has set its initial
position to a bright source of light (sun), it is ready to align itself
more precisely and continue tracking the light .The tracker first
measures light intensity at its present location.
The last portion of the software routine allows the tracker to reset
itself at the end of a day.
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