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.