Multi-axes sun-tracking system with PLC control for photovoltaic
panels in Turkey
Cemil Sungur
*
Selcuk University, Technical Science College, Electrical and Electronics Science, Alaeddin Keykubat Campus, 42075 Konya, Turkey
article info
Article history:
Received 9 January 2008
Accepted 25 June 2008
Available online 9 August 2008
Keywords:
Azimuth
PLC
Solar cells
Solar angles
Sun tracking
abstract
In the present study, the azimuth and solar altitude angles of the sun were calculated for a period of 1
year at 37.6
latitude in the Northern hemisphere, where Turkey is located, and according to these angles,
an electromechanical system which tracks the sun on both axes and which is controlled via
a programmable logic control (PLC) and an analog module was designed and implemented.
After the mechan ical control unit of the designed system was started, the performance measurements of
the solar panel were carried out first when the solar panel was in a fixed position and then the solar
panel was controlled while tracking the sun on azimuth and solar altitude angles and the necessary
measurements were performed. It was observed that the control system operated without a problem.
Besides, when the data obtained from the measurements were compared, it was seen that 42.6% more
energy was obtained in the two-axes sun-tracking system when compared to the fixed system.
Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction
Solar energy is clean, renewable and abundant in every part of
our world; the energy needs and costs have increased in recent
years and the nature is damaged during the process of energy
production. These aspects have made environment-friendly and
clean sources of energy, particularly solar energy, more important.
In the present study, a method was developed in order to effectively
utilize solar cells, which is one of the efficient means of using solar
energy.
Solar cells are systems which are composed of semiconductor
materials and which convert solar energy directly into direct
current electrical energy. The amount of electrical energy which
will be obtained from PV systems is directly proportional to the
intensity of the sun light which falls on the panel. However, the
change observed in sun light does not occur linearly, for this reason
it is desired that the solar panels be fixed in a way that they face the
sun or that they have a system which tracks the sun. Sun-tracking
systems are designed in a way to track the sun on a single axis
(according to the azimuth angle) or in a way to track the sun on
both axes (according to the azimuth and solar altitude angles).
Various studies were conducted on sun-tracking systems by using
a number of different methods.
Abdallah and Nijmeh designed and constructed an electrome-
chanical, two-axes sun-tracking system. The programming method
of control with an open loop system is employed where the
programmable logic controller is used to control the motion of the
sun-tracking surface [1]. Barakat et al. designed a two-axes sun-
tracking system with closed loop system and with complicated
typical electronic control circuits. They found that the energy
available to the two-axes tracker is higher by 20% [2]. Ali presented
a sun-tracking design, whereby the movement of a photovoltaic
module was controlled to follow the sun’s radiation using
a programmable logic controller (PLC) unit. All electronic circuits
and the necessary software have been designed and developed to
perform the technical tasks [3]. Neville presented a theoretical
comparative study between the energy available to a two-axes
tracker, an east–west tracker and a fixed surface. It was found that
the energy available to the ideal tracker is higher by 5–10% and 50%
than the east–west tracker and the fixed surface, respectively [4].
Khalifa performed an experimental study to investigate the effect of
using a two-axes sun-tracking system on the thermal performance
of compound parabolic concentrators (CPCs). The tracking CPC
collector showed a better performance with an increase in the
collected energy of up to 75% compared with an identical fixed
collector [5]. Hession introduced a sun-tracking system for use with
various collectors or platforms. The system used both analog and
digital techniques with sun sensing phototransistors that enabled
the sun’s position to be resolved to a precision of better than 0.1
[6]. Baltas conducted a comparative study between continuous and
stepwise tracking. They showed that unlike concentrating systems,
flat plate photovoltaic (FPPV) arrays yielded almost the same
energy when tracking in a stepwise fashion. Tracking motors could
be idle for 1 h or 2 h and yet obtain more than 98% of the energy
*
Tel.: þ90 332 2232378; fax: þ90 332 2410185.
E-mail address: csungur@selcuk.edu.tr
Contents lists available at ScienceDirect
Renewable Energy
journal homepage: www.elsevier.com/locate/renene
0960-1481/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.renene.2008.06.020
Renewable Energy 34 (2009) 1119–1125