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www.ccsenet.org/mas Modern Applied Science Vol. 5, No. 6; December 2011

Published by Canadian Center of Science and Education 237

Experimental Investigation and Construction of PV Solar Tracker

Control System Using Image Processing

Morteza Taki

Postgraduate student, Dept. of Agricultural Machinery

University of Tabriz. Iran

Tel: 98-91-3920-4415 E-mail: [email protected]

Yahya Ajabshirchi(Corresponding author)

Associate Prof. Dept. of Agricultural Machinery, Faculty of Agriculture

University of Tabriz, Iran


Hossein BehfarDept. of Agricultural Machinery and Faculty of Agriculture

University of Tabriz, Iran

Tel: 98-91-4300-8753

Mohsen Taki

Dept. of HESA office, Iran


Received: September 5, 2011 Accepted: October 9, 2011 Published: December 1, 2011

doi:10.5539/mas.v5n6p237 URL: http://dx.doi.org/10.5539/mas.v5n6p237

Abstract

Finding energy sources to satisfy the worlds growing demand is one of societys foremost challenges for the

next half-century. The challenge in converting sunlight to electricity via photovoltaic solar cells is dramatically

reducing $/watt of delivered solar electricity. In this context the sun tracking system of a solar panel based on

computer image processing of a shadow is investigated. This is done by using a camera to obtain the picture of a

shadow on a screen by solar panel displacements. This system is independent respect to geographical location of

the solar panel and periodical alignments such as daily or monthly regulations. The collected energy was

measured and compared with that on a fixed surface tilted at towards the South. The results indicate that the

measured collected solar energy on the moving surface was significantly larger (up to 33%) compared with the

fixed surface. The tracking system developed in this study provides easy installation, simple mechanism and lessmaintenance. Furthermore, the operation of the system is independent respect to the initial conFigureuration and

the start time situation.

Keywords: Picture processing, Renewable energy, Solar panel, Two-axis sun tracking

1. Introduction

Finding sufficient supplies of clean energy for the future is one of societys most daunting challenges.

Alternative renewable energy sources such as sun energy can be substituted for exceeding human energy needs.

Covering 0.16% of the land on earth with 10% efficient solar conversion systems would provide 20 TW of

power, nearly twice the worlds consumption rate of fossil energy (Mousazadeh et al, 2009). The solar cells

convert sunlight directly into electricity and are typically combined into modules that hold about 4070 cells. A

number of these modules are mounted in PV (photovoltaic) arrays that can measure up to several meters on a

side. Several connected PV arrays can provide enough power for a household and for large electric utility or

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The system calculates the centroid of the sun and its coordinates S(x, y), then they are forced to match with the

coordinates of the center of the image C(x, y) or the coordinates defined by the user U(x, y), this is achieved by

sending the necessary control commands through the printer port to an electrical motors controller. The control

program can be instructed to fix the coordinates of the sun at any position on the screen. When the position of

the sun changes and either of the two coordinates varies the system sends a digital signal via the printer port to

the motor associated with the respective coordinate. The signal obtained is proportional to the error into the

value of the coordinates. The tracker was implemented on a purpose-built electromechanical system with twodegrees of freedom (Figure 3). A direct current motors controller previously designed was used to convert the

control commands provided by the computer into electrical pulses for the motors.

The software developed in Visual Basic allows the user to see the image of the sun and to set the coordinates in

which the centroid of the sun must be fixed. The system was oriented in the north-south direction, without

attention to exactness. The motors were manually activated from the computer keyboard.

The automatic tracking program starts running. The system was tested working under different weather

conditions and also different north-south and east-west orientations were used.

3. Result and discussion

The performance of the designed Sun's tracking-system has been tested and was found to operate well. The

movement of the PV module following the Sun's incident radiation was smooth and without any time-lag.

A continuous test during 4 days, 4, 5, 6 and 7 July 2011, was done in the yard of the Tabriz University in Iran.

Voltage measurements and solar intensity for the photo-voltaic panel using a fixed load were conducted in clear

and sunny days of the summer season in year 2011. The maximum intensity of global solar radiation noticed

during the experiments was 1320 and measured between 13:3014:00 on 7 July 2011.

Readings were collected from 9:00 o'clock in the morning until 18:00 every day for both modes of operation (i.e.

fixed and tracking). In the fixed position mode, the panel was fixed at each time of measurement facing the south

position with an altitude angle of which is the optimal inclination in Tabriz province of Iran at this time of

the year. Figure 4, 5, 6 and 7 show the solar radiation in measured on 4, 5, 6 and 7 July 2011, for both

modes of operation, respectively.

Table 1 shows the hourly average of daily solar radiation as well as the average of sun radiation for the same

period of time.

Abdalah and Nijmeh (2002, 2004) designed a one and two axis sun tracking system with PLC control where thecollected energy was measured and compared with that on a fixed surface tilted at towards the south. In one

axis, the three tracking modes studied were as follows, rotation about the eastwest, northsouth and vertical

axes. The results indicate that there were increases in daily measured solar energy up to 19.7%, 23.3% and

24.5% for the northsouth, vertical and eastwest tracking as compared with the fixed surface inclined to the

south, and the daily measured solar energy on the two axes tracking was almost 41% increase as compared with

the fixed surface, but the results in Table 1 indicate that the daily measured solar energy on the propose tracker

in this research is more than the types of one axis tracking systems.

4. Conclusion

The first advantage of using the designed Sun-tracker system was the substantial improvement in the output

power from the PV panel. The overall daily output power gain was increased by more than 33% compared to

that for a fixed mounted system. Secondly, the use of a commercial webcam as the sensor element allowed us to

avoid most of the common problems usually presented on the solar trackers currently in use. One of them is thehigh sensitivity of the discrete elements such as photodiodes or phototransistor to weather conditions,

particularly to temperature and humidity. Another important aspect should be considered is the rapid

deterioration that may occur in discrete elements under extreme weather conditions and it can be concluded the

constant maintenance costs.

References

Abdalah, S., & Nijmeh, S. (2002). Design, construction and operation of one axis sun tracking system with PLC

control.Jord J Appl Sci Univer, 4(2), 4553.

Abdalah, S., & Nijmeh, S. (2004). Two axes sun tracking system with PLC control. Energy Conversion and

Management, 45, 1931-1939.http://dx.doi.org/10.1016/j.enconman.2003.10.007Al- Mohamad, A. (2004). Efficiency improvement of photo-voltaic panels using a sun tracking system.Applied

Energy. 79, 345- 354.http://dx.doi.org/10.1016/j.apenergy.2003.12.004

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Table 1. Experimental average daily solar radiation in

Gain %Fixed systemSolar tracker systemDate of day

38.9902125304/07/2011

27.11006127905/07/2011

32.3930123106/07/2011

37.9947130607/07/2011

33.99461267Average

Figure 1. A typical block diagram of the grid connected solar system (Sefa, I. et al., I, 2009)

Figure 2. Block diagram of the solar tracker system

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Figure 5. Experimental result using tracker and fixed system on 5 July 2011


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ISSN 1913-1844 E-ISSN 1913-1852244


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