PERFORMANCE COMPARISON OF THE SUN TRACKING SYSTEM AND FIXED SYSTEM IN THE APPLICATION OF HEATING AND LIGHTING

PERFORMANCE COMPARISON OF THE SUN TRACKING SYSTEM AND FIXED SYSTEM IN THE APPLICATION OF HEATING AND LIGHTING Sabir Rustemli*¹ Electrical and Electronics Engineering Department, Yuzuncu Yil University, Van, Turkey Ferit Dincadam² Electrical and Electronics Engineering Department, Yuzuncu Yil University, Van, Turkey and Metin Demirtas³ Electrical and Electronics Engineering Department, Balikesir University Balikesir, Turkey الخلاصة : تم - في هذا العمل - تطبيق نظام تتبع شمسي ي ستخدم لتسخين المياه وإنارة الشوارع في مدينة.Van ثم تصميم نظام الطاق ة الشم سية ال ضوي ية للمن زل بقوة 5 آيلو وات و آذلك إعداد تجريبي ل 183 وات. وقد تم اختيار البديل الا مثل بالنسبة لحالات الصلابة والخفة. إن جهاز تتبع الشمس الذي آان يستخدم لتدوير الطاقة الشمسية ما يزال يعمل مع حرآة الشمس. وقد أظهرت المقارنة بين الثابت والتتبع الشمسي أن استخدام تتبع الشمس يزيد الا نتاجية بحولي 29%. ويمكن أن نخلص إل ى أن نظ ام التتب ع الشم سي هو أآثر فاعلية من النظام الثابت وقادر على تعزيز الا نتاجية. *Corresponding Authors: ¹E-mail: sabirrustemli@yyu.edu.tr; Tel: +90 432 2251024, Fax: +90 432 2251730 ²E-mail: fdincadam@hotmail.com; Tel: +90 432 2251024, Fax: +90 432 2251730 ³ E-mail: mdtas@balikesir.edu.tr; Tel: +90 266 6121194, Fax: +90 266 6121257 Paper Received March 24, 2009; Paper Revised May 29, 2009; Paper Accepted June 22, 2009 October 2010 The Arabian Journal for Science and Engineering, Volume 35, Number 2B 171

ABSTRACT In this work, a sun tracking system application is used for water heating and street lighting in Van. The solar photovoltaic system is designed for a house whose power is 5 kilo-watts. An experimental setup is carried out for 183 Watts. An optimal variant is chosen with respect to stiffness and lightness conditions. A sun tracking device was used for rotating the solar still with the movement of the sun. A comparison between fixed and sun tracked solar stills showed that the use of sun tracking increased productivity by around 29%. It can be concluded that the sun tracking system is more effective than the fixed system and is capable of enhancing productivity. Key words: solar energy, sun tracking system, renewable energy 172 The Arabian Journal for Science and Engineering, Volume 35, Number 2B October 2010

PERFORMANCE COMPARISON OF THE SUN TRACKING SYSTEM AND FIXED SYSTEM IN THE APPLICATION OF HEATING AND LIGHTING 1. INTRODUCTION The sun is regarded as a good source of energy for its consistency and cleanliness, unlike other kinds of energy such as coal, oil, and derivations of oil that pollute the atmosphere and the environment. Most scientists, because of the abundance of sunshine capable of satisfying our energy needs in the years ahead, emphasize the importance of solar energy [1]. It is clean, renewable, and plentiful throughout the world. In addition, energy needs and costs have increased in recent years and nature continues to suffer damage during energy production [2]. The amount of power produced by a solar system depends on the amount of sunlight to which it is exposed. As the sun s position changes throughout the day, the solar system must be adjusted so that it is always aimed precisely at the sun and, as a result, produces the maximum possible power. Single-axis-tracking systems are considerably cheaper and easier to construct, but their efficiency is lower than that of two axes sun-tracking systems. In addition, some solar systems have to rely on two axes tracking, such as point focus concentrators [3]. Solar photovoltaic (PV) technology is a very attractive renewable energy option for clean energy generation, but has limited use due to its prohibitively high cost. However, the cost of PV power generation had decreased substantially over the last two decades, and had stabilized. In fact, the cost has slightly increased in recent years to a point that is still quite high compared to the cost of other conventional power generation technologies, as well as non-conventional technology such as wind energy technology [4]. The power generated by a PV system is highly dependent on weather conditions. During cloudy periods and at night, a PV system would not generate any power [5]. Many scientists have studied sun tracking systems with different applications to improve the efficiency of solar systems by adding the tracking equipment to these systems [6 10]. A tracking mechanism must be reliable and able to follow the sun with a certain degree of accuracy, return the collector to its original position at the end of the day or during the night, and also track during periods of cloud cover. Fixed collectors producing heat or electricity throughout the year are usually installed and tilted at an angle equal to the latitude of the installation site facing directly to the sun. In this case, the energy collected by the solar collector during both winter and summer is less due to the sun s changing altitude [11]. Regarding movement capability, three main types of sun trackers exist [12]: fixed surfaces, one axis trackers [13], and two axes trackers [3]. The main difference among them is the ability to reduce the pointing error, increasing the daily irradiation that the solar cells receive and, thus, the electric energy that they produce [14]. Nowadays, street lighting is essential in our society to ensure comfort and security. The installation of street lighting in a city involves complex and expensive work. Moreover, to supply the lights, an electrical network is needed. The problem is the same in remote areas where lighting is needed, for instance, on the sides of roads [15]. There is a clear relationship between poverty and access to electricity. Poverty levels increase the more remote and inaccessible the communities are, while costs for electrification increase due to transport and maintenance costs [16]. In this study, a sun tracking system application is used to meet the energy needs of a house in Van. It is one of the biggest cities in the eastern part of Turkey. The number of members in a family is very high compared to western cities. There are about ten people in a family. Therefore, the poverty level is higher than in western cities of Turkey. The energy demands of a family in this area is also higher than in other areas. A family needs about 5 kw of energy in this area. Hence, a system is designed to generate 5 kw per household by using PV and its cost analysis is investigated. An experimental setup is carried out for 183 Watts. The loads consist of a resistor (132 Watts), a lamp (15 Watts), and a Direct Current (DC) motor (36 Watts). 2. DESIGNING OF 5 KW POWER PRODUCTION FOR A HOUSE BY PV Stand alone (off grid) PV units have been defined as the combination of PV arrays, battery bank, and AC and DC loads. Power generated in the stand alone PV unit can be supplied for a corresponding load [17]. Different sun tracking systems have been studied for applications to improve the efficiency of solar systems by adding tracking equipment to them. Twenty sun stills, a charge regulator, an accumulator group, and an inverter are necessary to supply a house. The electrical block diagram of a house supplied by sun stills is given in Figure 1. The October 2010 The Arabian Journal for Science and Engineering, Volume 35, Number 2B 173

established power is taken as 5 kw. Also, it is thought that the whole system will not be working at the same time. Accumulators are charged when the whole loads are not in use. The loads are supplied PV and accumulators when the whole loads are in use. The design is made taking this condition into account so as to economize the system. Figure 1: The electrical block diagram of a house supplied by sun stills Characteristics and cost of the elements used are given in Table 1. The values of the parameters in Tables are rated values. These values are selected from the catalogs. That is, they are standard values. Table 1. Characteristics and Cost of the Elements Used for 5 kw System Elements Technical Characteristics Used Number Cost ($) Total Cost($) PV 150 W,21.6 V,6.95 A 20 700 14000 Accumulator 12 V, 60 Ah 20 70 1400 Inverter 2000 W 2 900 1800 Inverter 1000 W 1 300 300 Charge regulator 30 A, 12 V 1 220 220 Total 17720 The current for 5 kw is calculated as below [18]: I = P / U *cos ϕ, (cosϕ = 1) (1) where P is power of load, I is current of load, U is the voltage, and cosϕ is the phase angle between I and U (cosϕ = 1 for ohmic load ). The desired current and voltage are obtained by the sun panel connected serially or in parallel. Thus, total power of the sun panel is P = 20*150 = 3000W = 3 kw (2) The current value is The voltage value is I V = 4*6,95= 27,8A. (3) = 5*21,6 = 108V. (4) There area a lot of advantages of this system. Some of them are given below. 174 The Arabian Journal for Science and Engineering, Volume 35, Number 2B October 2010

The daily electrical energy demand of the house can be provided for about 30 years. Electrical energy demand can be provided by means of an accumulator group for 52 hours when there is no sunlight. This process is carried out on the floor about 25 meters square. This system can be started with network coordinated. 2.1. Providing of the Hot Water Demand of a House by Resistance A sun module, charge regulator, accumulator group, inverter, resistance, thermostat, ammeter, and voltmeter are necessary for providing hot water at the house. The hot water demand scheme of the house is given in Figure 2. Figure 2: The hot water demand scheme of the house for 3 kw The current for 3 kw is calculated as below: I = P / U *cosϕ = 3000/ 220 = 13,63 (cosϕ = 1) (5) The power, voltage, and current for one module are 63.855 W, 17.64 V, and 3.69 A, respectively. The demanded current and voltage are obtained from the sun panel connected serially and in parallel. Total power of the sun panel is P = 8*63,855 = 510,84W. (6) The obtained current is The obtained voltage is I V = 4*3,69 = 14,76A. (7) = 2*17,64 = 35,28V. (8) The power, current, voltage, and cost at standard conditions for a house whose hot water demand power is 3 kw are given in Table 2. October 2010 The Arabian Journal for Science and Engineering, Volume 35, Number 2B 175

Table 2. The Characteristics and Cost of the System Elements Used for 3 kw System Elements Technical Characteristics Used Number Unit Cost ($) Total Cost ($) Sun module 63.855 W, 17.64 V, 3.69 A 8 380 3040 Charge regulator 12 V, 20 A 1 220 220 Accumulator 12 V, 60 Ah 12 70 840 Inverter 12/230 V,1500 W 2 700 1400 Resistance 1500 W 2 7 14 Voltmeter (AC) Digital 2 20 40 Ammeter Digital 2 20 40 Voltmeter (DC) Digital 1 20 20 Thermostat Digital 1 35 35 Total - - - 5649 2.2. Street Lighting With 65 W Lamp The sun module, charge regulator, accumulator, inverter, and lamp are used for lighting the street. The block diagram of the lighting system supplied by the sun module is given in Figure 3. Sun module 65 W 17.64 V 3.70 A Charge regulator 12 V, 3A Single Accumulator 12V,60 Ah Inverter 100 W 12/220 V Lamp 65 W 220 V 0.29 A Figure 3: The block diagram of the street lighting system with a lamp The needed power, current, voltage, and cost in standard conditions for the street lighting lamp whose energy is obtained from the sun module are given in Table 3. At the street lighting system: Power of lamp is 65 W and its voltage is 220. Its current is calculated as below: I = P / U * cosϕ = 65/ 220 = 0, 29 A (cosϕ = 1) (9) Table 3. The Needed Power, Current, Voltage, and Cost for 65 W System Elements Technical Characteristics Used Number Unit Cost ($) Total Cost($) Sun module 65 W, 17.64 V, 3.7A 1 400 400 Charge regulator 12 V, 3 A 1 20 20 Accumulator 12 V, 60 Ah 1 70 70 Inverter 12/220 V, 100 W 1 35 35 Lamp 220 V, 65 W 1 7 7 Total - - 532 176 The Arabian Journal for Science and Engineering, Volume 35, Number 2B October 2010

3. APPLICATION CIRCUIT WITH PV The experimental setup is carried out for three different loads whose total power is 183 Watts. They consist of a resistor (132 Watts), a lamp (15 Watts), and a motor (36 Watts). The electrical block diagram of the application circuit for obtaining the hot water and turning on the lamp and tracking system is shown in Figure 4. In this application, the sun panel, charge regulator, inverter, accumulator group, control panel, resistance, drive circuit, and sun tracking system are used. Sun module 63.85 W 17.64 V 3.69 A Charge regulator 12V,20A Acc. group Inverter 300 W 12/220 V Control panel Resistance 132 W 0.6 A 220 V Sun tracking system 36 W 3 A 12 V Street lamp 15 W 220 V 0.06 A Figure 4: The electrical block diagram of the application circuit The hot water is obtained by running the resistance. The lamp is turned on at night and turned off in the daytime by the drive circuit. The sun tracking system is only started in daytime. In the application, the obtained power, current, voltage, and cost in standard conditions are given in Table 4. Table 4. The Need Power, Current, Voltage, and Cost in Standard Conditions for 183 W System Elements Technical Characteristics Used Number Unit Cost ($) Total Cost($) Sun Module 63.855 W, 17.64 V, 3.69 A, 0.4257 m 2 1 375 375 Charge regulator 12 V, 20 A 1 210 210 Accumulator 12 V, 60 Ah 2 70 140 Inverter 12/220 V, 300 W 1 70 70 Resistance 220 V, 132 W 1 4 4 Lamp 220 V, 15 W 1 2 2 Voltmeter (AC) Digital 1 20 20 Ammeter Digital 1 20 20 Voltmeter (DC) Digital 1 20 20 Thermostat Digital 1 35 35 Motor 12 V, 36 W 1 35 35 Total - - - 931 The system used for obtaining the energy of hot water and the lamp is pictured in Figure 5. As shown in Figure 5, the numbers below represent the following: October 2010 The Arabian Journal for Science and Engineering, Volume 35, Number 2B 177

1-The sun tracking system 2-PV 3-Charge regulator 4-Inverter 5-Accumulator 6-Control panel 7-Water tank Figure 5: The system used for obtaining the energy of hot water and the lamp At the standard test conditions, the power of the PV measures 1000 W/m 2 at 25 o C. This value changes between 200 W/m 2 and 800 W/m 2 on cloudy days. It reaches 1200 W/m 2 on sunny days. It is reduced to 50 W/m 2 on rainy days. The PV power is calculated as follows: Power=surface (m 2 )*standard radiation (W/m 2 )*efficiency The module surface = 1,29*0,33=0,4257 m 2 (10) Standard radiation = 1000 W/m 2 Efficiency = 15% Taking into account cloudy and rainy days, efficiency is approximately accepted as 15%. The module power at standard output is P=0,4257*1000*0,15=63,855 W. (11) The rated voltage of the module is V=17,64 V. The rated current of the module is I=3,69 A. While the system is starting, the consumed total power, current, and voltage are calculated as below: 178 The Arabian Journal for Science and Engineering, Volume 35, Number 2B October 2010

The current of resistance 132 W is I = P / U * cosϕ= 132 / 220 = 0, 6 A (cosϕ = 1). (12) The current of lamp 15 W is I = P / U *cosϕ= 15/ 220 = 0,068 A (cosϕ = 1). (13) The current of DC motor 36 W is Total power is given in Equation (15) as I = P / U *cosϕ= 36/12= 3 A (cosϕ 1). (14) P = 132 + 15 + 36 = 183W. (15) Voltage applied to the resistance and lamp is 220 Volt Alternative Current (AC). Motor voltage is 12 Volts DC. 4. DESIGN AND CONTROL OF AUTOMATIC SUN TRACKING SYSTEM As the sun s position changes hourly, the solar power devices should be adjusted to produce the maximum output power. Single-axis-tracking systems are considerably cheaper and easier to construct, but their efficiency is lower than the two axes sun-tracking systems. An early work by Neville [19] presented a theoretical comparative study between the energy available to a two axes tracker, an East West (E W) tracker, and a fixed surface. Hession and Bonwick [20] introduced a sun-tracking system for use with various collectors and platforms [21]. The concept of sun tracking depends on identifying the location of the sun relative to the earth at all times during the day. The rotation of the earth around itself causes the sequence of day and night. Also, its rotation around the sun causes the variation of day and night lengths. Solar time is based on the apparent angular motion of the sun across the sky. At solar noon, the sun crosses the meridian of the observer, and this is used in all the sun-angle relationships, while the local time is determined according to political time zones and other approximations [22 24]. The experimental study was carried out in January in Van. It was designed as a single axis sun tracking system. In this study, the sun tracking system was used to find out the maximum possible gain in output power of the PV system. The studied system started with fixed and sun tracking. The measured average values at the output of PV for the first day of January are given in Table 5. The values measured monthly at the output of PV are given in Table 6. Data is registered hourly by using voltmeter and ammeter measurement devices.. Daily average values were calculated for ten hours. The measurement devices could not read any values when there was no sunlight. Therefore, values for 07:00, 15:00, and 16:00 hours are not given in Table 5. The sun module is rotated 45 o on a single axis. Table 6 is formed using the daily average values in Table 5. The monthly average values are calculated by dividing the total value by 31 for January. The current, voltage, and power gains are calculated to compare the two systems. Those gains are calculated using monthly average values in Table 6. The current gain (G I ) is calculated to compare the two systems as follows: G I % = 100*(1 (0,848935/1,022387)) = 16,97% (16) The current gain 16,97% is obtained on the sun tracking system. The voltage gain (G V ) is calculated as below: G V % = 100 *(1 (11, 23484 /13, 21803)) = 15,00% (17) October 2010 The Arabian Journal for Science and Engineering, Volume 35, Number 2B 179

Table 5. The Measured Average Values at the Output of PV for the First Day of January Hours The Fixed Sun Module Sun System with Single Axis Current(A) Voltage(V) Power(W) Current(A) Voltage(V) Power(W) 07:00 - - - - - - 08:00 - - - 1,40 20,70 28,98 09:00 1,40 18,40 25,76 1,41 19,29 27,19 10:00 1,40 18,48 25,87 1,43 18,80 26,88 11:00 1,45 19,87 28,81 1,50 19,39 29,08 12:00 1,42 18,63 26,26 1,41 18,63 26,26 13:00 1,44 18,48 26,42 1,43 18,48 26,42 14:00 1,42 18,48 26,24 1,48 18,67 27,63 15:00 - - - - - - 16:00 - - - - - - Average 0,851 11,234 9,56 1,006 13,396 13,47 Table 6. The Average Values Measured Monthly at the Output of PV Days The Fixed Sun Module The System with Single Axis Current (A) Voltage (V) Power (W) Current (A) Voltage (V) Power (W) 1 0,851 11,234 9,56013 1,006 13,396 13,476376 2 0,85 11,333 9,63305 1,005 13,295 13,361475 3 0,751 11,234 8,43673 1,007 13,497 13,591479 4 0,852 11,235 9,57222 1,004 13,386 13,439544 5 0,853 11,228 9,57748 1,008 13,406 13,513248 6 0,749 11,237 8,41651 1,003 13,387 13,427161 7 0,951 11,229 10,6788 1,009 13,405 13,525645 8 0,85 11,236 9,5506 1,002 13,388 13,414776 9 0,95 11,229 10,6676 1,002 13,404 13,430808 10 0,86 11,235 9,6621 1,001 13,389 13,402389 11 0,861 11,23 9,66903 1,003 13,403 13,443209 180 The Arabian Journal for Science and Engineering, Volume 35, Number 2B October 2010

12 0,862 11,234 9,68371 1,059 13,189 13,967151 13 0,855 11,231 9,60251 1,058 12,402 13,121316 14 0,857 11,233 9,62668 1,006 13,39 13,47034 15 0,858 11,24 9,64392 1,057 13,101 13,847757 16 0,855 11,221 9,59396 1,062 13,091 13,902642 17 0,75 11,222 8,4165 1,009 13,4 13,5206 18 0,85 11,239 9,55315 1,064 13,072 13,908608 19 0,85 11,223 9,53955 1,018 13,399 13,640182 20 0,849 11,239 9,54191 1,025 13,393 13,727825 21 0,848 11,224 9,51795 1,039 13,398 13,920522 22 0,847 11,238 9,51859 1,066 13,394 14,278004 23 0,846 11,224 9,4955 1,035 13,297 13,762395 24 0,843 11,237 9,47279 1,007 13,395 13,488765 25 0,844 11,225 9,4739 1,004 12,306 12,355224 26 0,852 11,236 9,57307 1,002 13,386 13,412772 27 0,854 11,226 9,587 1,053 12,406 13,063518 28 0,857 11,237 9,63011 1,061 12,194 12,937834 29 0,856 11,227 9,61031 1,004 13,398 13,451592 30 0,851 11,236 9,56184 1,008 13,393 13,500144 31 0,855 11,228 9,59994 1,007 13,399 13,492793 Average Values 0,848935 11,23484 9,53765 1,022387 13,21803 13,5095514 The voltage gain 15.00% is obtained on the sun tracking system. The power of the sun module is calculated as below: P = I * V = 0,8488935*11, 23484 = 9,53718W (The sun module is fixed). (18) P = I * V = 1,022387 *13,21803 = 13,51394W (The sun module is rotated with single axis tracking system). If the powers are compared to each other, the power gain (G P ) is calculated as follows: G P % = 100 *(1 (9.53718/13,51394)) = 29, 42% (20) The power gain of about 29.42% is provided using the single axis tracking system. The motor drive circuit is shown in Figure 6. The sun tracking system circuit consists of two parts. The first part of the circuit is a comparator, which determines whether there is sunlight or not. The Light Diode Resistor (LDR) used in this circuit decides whether the sun tracking process is operational or not. Resistor R3 in the circuit forms the (19) October 2010 The Arabian Journal for Science and Engineering, Volume 35, Number 2B 181

reference voltage of the comparator (Operational Ampflicator-OPAMP) circuit with OPAMP. The light falls on the LDR1 when the sun rises. The value of the resistor LDR1 decreases when the light intensity on the LDR1 increases. The output of the OPAMP-U1 is made active. Thus, OPAMP-U1 drives the transistor Q1. The transistor Q1 driving role RL1 drives the second part of the circuit. That is, the role coil is energized when the transistor Q1 turns on and the second part of the circuit is made active. The sunlight is tracked by LDR2. The value of the resistor LDR2 decreases when light intensity on the LDR2 increases. The output of the OPAMP-U2 is made active (logically 1) when the light drops on the LDR2. The output of the OPAMP-U2 drives the transistor Q2. The role pulls its contacts and stops the DC motor. The DC motor starts running when the light intensity on the LDR2 decreases. The DC motor runs continuously until there is maximum light on the LDR2. Thus, the motor starts when the sun rises and the system tracks the sun until the sun sets. It stops because of decreasing light intensity on the LDR2 when it is night. B1 12V 5K POT R1 100 LDR1 R1 47K R3 47K 3 2 7 1 4 5 U1 6 LM741 R4 22K R5 3K D1 1N4001 RL1 12V Q1 BC546BP 500 POT R6 270 R8 10k LDR2 R9 920K 3 2 7 1 R10 360K 4 5 U2 6 LM741 R11 22K RL2 12V Q2 BC337 DC MOTOR 12V Figure 6: The motor drive circuit The mechanical diagram of the tracking system is shown in Figure 7. The DC motor is started by the DC drive circuit. The speed of the DC motor is reduced by the gear box. The PV module is rotated by the gear box. The DC motor stops when the angle of the sun is about 90 0. PV module stops when DC motor stops. Figure 7: Mechanical diagram of the tracking system 5. CONCLUSION In this study, a design is made for a house whose power is 5 kw. A single axis automatic sun tracker was designed, built, and tested for 183 Watts. It was used to supply three different loads: resistance (132 Watts), lamp (15 Watts), and DC motor (36 Watts). A comparison between fixed and sun tracked solar stills showed that the use of sun tracking increased productivity by around 29.46%. It can be concluded that sun tracking is more effective than the fixed system and is capable of enhancing the productivity. 182 The Arabian Journal for Science and Engineering, Volume 35, Number 2B October 2010

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