A Study on the Development of High Accuracy Solar Tracking Systems

A Study on the Development of High Accuracy Solar Tracking Systems Department of Nuclear & Energy Engineering, Jeju National University OH, SEUNG JIN SET2009 - 8 th International Conference on Sustainable Energy Technologies Aachen, Germany. August 31 st to 3 rd September 2009 Jeju Nat’l Univ. SET2009

1. INTRODUCTION 2. CALCULATION OF SOLAR POSITION 3. COMPONENTS & FABRICATION 4. MOTION APPLICATION 5. RESULT Contents Jeju Nat’l Univ. SET2009

Kyoto is intended to cut global emissions of greenhouse gases INTRODUCTION

Solar energy
reliable and cost-effective , no pollutant into environment
systems without a solar tracking system -> lower output
Solar tracking system
orienting a day-lighting reflector, solar photovoltaic panel or concentrating solar reflector or lens toward the sun.
works best when pointed directly at the sun, increasing the effectiveness over the non-tracking systems.
The accuracy of the solar trackers depends on the types of application:
Concentrators for solar cells and day-lighting systems would require higher degree of accuracy, ensuring the concentrated sun rays are directed at the focal point.
Systems are either a single-axis or two-axes devices.
Large power plants or high temperature facilities may employ multiple ground-mounted mirrors and an absorber target with or without secondary concentration.
INTRODUCTION

INTRODUCTION Solar Energy Uses

Existing program
C-language and Visual Basic are often used
Manufacturers have supplied their systems
with libraries for these algorithms.
The problem is that it is difficult for a user
to integrate such codes into the one main program.
LabVIEW (Laboratory Virtual Instrumentation Engineering Workbench)
a platform and development environment for a visual programming language from National Instruments.
The graphical language is named "G“.
Block diagram, Front panel
Easy-to-use, high-performance,
extensive application
INTRODUCTION Motion Control by LabVIEW

INTRODUCTION
Optical method :
“ closed loop system”
it uses several feedback sensors ; a photo-sensor and a position sensor and a comparator.
Drawback in a cloudy day without an extensive algorithm.
Astronomical method :
employs the longitude and latitude data of a location
simple programming
high degree accuracy and less error
starting position of tracker to be always same from day to day
operating motors are easily subject to the “backlash”
Method of Solar Tracking Systems

The tracker device must be positioned horizontally to implement the altitude and azimuth angles along with the hour angle
the Solar altitude(h) : the angle between a line that points from the site towards the centre of the sun, and the horizon
The solar azimuth(A) : the angle between the line from the observer to the sun projected on the ground and the line from the observer due south.
The declination(δ) : The declination(δ) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle
The hour angle(H) : the angle between the half plane determined by the Earth axis and the zenith (half of the meridian plane) and the half plane determined by the Earth axis and the given point.
CALCULATION OF SOLAR POSITION Calculations of Solar Altitude and Azimuth

Block diagram for calculating solar altitude and azimuth CALCULATION OF SOLAR POSITION Calculations of Solar Altitude and Azimuth

The solar tracking system must be returned to the initial position after the sun disappears below the horizon, otherwise it must be started to track the sun after the sun appears above the horizon.
Why is “sunrise and sunset time” necessary? For Sunrise, For Sunset, Time of Sunrise or Sunset Hour angle Right ascension (Longitude)/15 CALCULATION OF SOLAR POSITION Calculations of Sunrise and Sunset Time

Block diagram for calculating the time of sunrise and sunset CALCULATION OF SOLAR POSITION Calculations of Sunrise and Sunset Time

Application Software
Motion Controller
Amplifier or Drive
Mechanical Elements
Feedback device or Position sensor
COMPONENTS & FABRICATION

COMPONENTS & FABRICATION Performance of step-motor and gear ratio • Step- motor step angle : 0.0144˚ • Step- resolution : 25,000 • X-axis gear ratio 2:1 -> Azimuth • Y-axis gear ratio 2:1 -> Altitude

COMPONENTS & FABRICATION Amount of Clouds 1 2 4 3 Cover for making shadow CdS Sensor ⅹ4ea 5 Working principal of system by feedback sensors Sensor(1) > Sensor(2) : Rotate down Sensor(2) < Sensor(2) : Rotate up Sensor(3) >Sensor(4) : Rotate left Sensor(3) < Sensor(4) : Rotate right Sensor(1) = Sensor(2) or/and Sensor(3)= Sensor(4) : Stop Sensor(5) lower than a specific value : transfer to open loop

COMPONENTS & FABRICATION

COMPONENTS & FABRICATION Motion Application

RESULTS c Calculation KASI c Calculation KASI

Conditions value Location Jeju city, Jeju do, Koea Longitude Long. 126˚15 ΄60˝ E Latitude 33˚ 30΄ 30˝ N. Lat. Date 1 st of January, 2009 Time 00:01~24:00 Error Altitude Azimuth Maximum[°] 0.0371 at 4am 0.0823 at 1 am Minimum[°] 0.0006 at 10am 0.00012 at 5pm

RESULTS Closed loop system

RESULTS Open loop system

In this study, the solar tracking system was fabricated and has achieved high accuracy for the tracking of the sun rays. Our tracker system is cost effective and the algorithm is relatively simple , combining the advantages of both the optical and the astronomical methods. A series of studies with the solar tracker yield the following results. 1)The calculated solar altitude and azimuth for the 1st of January, 2009 were compared with those of KASI, and the average errors are less than 0.018 degrees during the day . 2)The calculated sunrise and sunset times for the month of January, 2009 were compared with those of KASI, and the average errors are found to be less than 1 second. 3)The solar tracking system is found to be accurate and cost-effective and it can be used in many fields such as data-processing, concentrated PV, the photocatalyst generation of hydrogen , and contributing to the harnessing of the solar energy . CONCULSION

This work is supported by the grant (No.R33-2008-000-10166-00) of the World Class University (WCU) programme of the Korea Science & Engineering Foundation.

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A Study on the Development of High Accuracy Solar Tracking Systems

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A Study on the Development of High Accuracy Solar Tracking Systems — Presentation Transcript