6545(Print), ISSN (Online) Volume 4, Issue 1, January- February (2013), IAEME & TECHNOLOGY (IJEET)

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1 INTERNATIONAL International Journal of JOURNAL Electrical Engineering OF ELECTRICAL and Technology (IJEET), ENGINEERING ISSN 0976 & TECHNOLOGY (IJEET) ISSN (Print) ISSN (Online) Volume 4, Issue 1, January- February (2013), pp IAEME: Journal Impact Factor (2012): (Calculated by GISI) IJEET I A E M E MICROCONTROLLER BASED AUTOMATIC SOLAR POWER TRACKING SYSTEM 1 Hemlata B. Nirmal, 2 Syed A. Naveed 1 P.G. Student, Electronics and Telecommunication Dept. Jawaharlal Nehru Engineering College, Aurangabad, (M.S.) INDIA. 2 Electronics and Telecommunication Dept. Jawaharlal Nehru Engineering College, Aurangabad, (M.S.) INDIA. hemlatanirmal@rediffmail.com, sa_naveed01@rediffmail.com ABSTRACT Renewable energy resources are getting priorities in the whole world in order to provide a sustainable power production and safe world to the future generation. Solar energy is rapidly gaining the focus as an important means of expanding renewable energy uses. Solar trackers are the most appropriate and proven technology to increase the efficiency of solar panels through keeping the panels aligned with suns position. A microcontroller based design methodology of an automatic solar tracker is presented in this paper. The unit controls the movement of solar panel always aligned towards the direction of the sun, due to this maximum thermal energy would be culminated from solar panel. Sun always moves from east to west direction independent of weather condition, so with this concept without using sensors movement of the solar panel from east to west direction is done with the help of programme loaded into the microcontroller. This prototype is designed for single axis as well as for double axis to solve solstice problem. From hardware testing we come to know that solar tracking system tracks the sun precisely and provides more power at the output as compared to that static solar panel. Keywords: Solar panel, solar tracking, microcontroller, stepper motor, liquid crystal display. 109

2 I. INTRODUCTION Energy is essential factor for the development of any nation. Most of the energy production depends on fossil fuels. The resources of the fossil fuels are limited, so that there is growing demand for energy from renewable resources like solar, geothermal and ocean tidal wave. Among all renewable systems photovoltaic system is the one which has great chance to replace the conventional energy resources. Solar panel directly converts solar radiation into electrical energy. Solar panel is mainly made from semiconductor materials. To enhance the performance of solar panel the only way is to increase the intensity of light falling on it. Solar tracker is the best technology to increase the efficiency of solar panel by keeping panel aligned with the suns position. In this paper a microcontroller based simple and easily programmed automatic solar tracker is presented. II. TECHNOLOGY TO ENHANCE POWER OUTPUT FROM SOLAR PANEL In order to increase the efficiency of photovoltaic system there are three methods. First is increasing the efficiency of solar cell, second is maximizing the power output and third is employing a tracking system. Improvement of solar cell efficiency is an ongoing research work and people throughout the world are actively doing research on this. Maximum power point tracking is the process to maximize the output power from solar panel by keeping the solar panels operation on the knee point of photovoltaic characteristics. A number of maximum power point tracking algorithms have been developed and employed around the world [1]. At particular time, maximum power can be received from a stationary array of solar panel in case of maximum power point tracking technology. However, it cannot increase the power generation when the sun is not aligned with the system. Automatic solar tracker increases the efficiency of the solar panel by keeping the solar panel aligned with the rotating sun. Solar tracking is a basically electromechanical system to track the suns position that increases power output of solar panel 30% to 60% than the stationary system [2]. A few design methodology of solar tracking system has been proposed in recent days [3]-[4]. Maximum rays from the sun reach on the earth s surface through interaction of clouds, dusts and water. These rays are called as diffused rays which reduces the output of solar cell. If these rays reflected on the panel through the reflectors it will increase the overall output of the panel [5]. III. PHOTOVOLTAIC TECHNOLOGY Solar energy is most abundant and convenient source of renewable energy. Photovoltaic cells are the basic of solar system. In the word photovoltaic photo means light and voltaic means producing electricity. Therefore the photovoltaic process is producing electricity directly from sunlight. The output power of a photovoltaic cell depends on the amount of light projected on the cell. The output power also depends on the time of day, season, panel position and orientation. 110

3 IV. AUTOMATIC SOLAR TRACKING SYSTEM The sun moves across the sky during the day, it is advantageous to have the solar panels track the location of the sun such that the panels are always perpendicular with the position of the sun. But available solar trackers in the market are much more costly to integrate with solar panel system [6]. Solar tracking presented in this paper can provide an effective solution to such problem. The major components those are used in the system are given below.. Microcontroller. Stepper motor. L293D.Liquid crystal display Fig. 1 shows the schematic diagram of automatic solar power tracking system. Fig.1 Schematic of solar tracker circuitry A. Microcontroller The PIC18F452 microcontroller has been used in the system. Microcontroller is the heart of overall system. PIC 18F452 has some features such as analog comparator(ac), analog to digital converter (ADC), universal synchronous asynchronous receiver transmitter (USART), timers and parallel slave port (PSP). 111

4 B. Stepper motor Stepper motors are commonly used in precision positioning control applications. Five characteristics of stepper motor have been considered while choosing stepper motor for solar tracker. Stepper motor is brushless, load independent, has open loop positioning capability, good holding torque and excellent response characteristics. The stepper motor that has been used in the system has the specifications of 4.4volts, 4Ω resistance, 1.8º per step, 2 phases, bipolar. C. L293D L293D is quadruple high-current half-h driver. All inputs are TTL compatible. Each output is a complete totem-pole drive circuit with a Darlington transistor sink and a pseudo- Darlington source. The L293D has some features such as wide supply voltage range 4.5V to 36V, separate input logic supply, thermal shutdown, high noise immunity inputs, output current 600mA per channel, peak output current 1.2mA per channel and output clamp diodes for inductive transient suppression. D. Liquid crystal display 16X2 character Liquid crystal display is used in this system to display solar panel voltage and number of cycles completed. V. OPERATION OF THE SOLAR TRACKER Solar tracker provides three ways of operation and control mechanism through the programme written in the microcontroller. The three ways of operation includes normal day light condition, bad weather condition and bidirectional rotation. Whether there is normal day light or bad weather sun always present in the sky. With this programme loaded into the microcontroller to move the panel from east to west direction automatically. Once the day of 24 hours completed panel brought to initial position to start the new day. The entire day is divided into 24x6=144 parts of 10 minute each. The day light is assumed to be present for 10 hours that is 60 parts of 10 minutes. Stepper motor has resolution of 1.8ºper step. The worm gear ratio that has been used is 30:1. With this the number of steps required by the stepper motor to move the panel through 2.4º is 40. With beginning of the daylight from a reference point the system starts counting the stepping cycles each of 40 steps. Three counters used counter1 for day light, counter2 for whole day and conuter3 for season correction. After every one month the light emitting diode will turned ON to indicate there is need to do correction to solve elevation problem. For this purpose a separate mechanism of fine pitch of lead screw is used for compensating the elevation of the sun. Once the counter1 reaches 60 counts there will be no further movement of the stepper motor. But the counting of the cycles continues up to 144 in counter2. This completes the day of 24 hours. The numbers of days are calculated in counter3. As number of days is not equal to 365 then panel is brought to initial position by counting 60 cycles backward. Then start the new day. But whenever number of days is equal to 365 then resetting of all counters is required. A 6volt lead acid rechargeable cell is used as storage element for the motor drive as well as the power supply for the other circuits. Operational flow of the solar tracker is given in fig.2 112

5 Fig.2 Operational flow chart of solar tracker VI. HARDWARE TESTING OF SOLAR PANEL Table I shows the data of voltage, current and power received from solar tracking system and static solar panel for a day. Fig. 3 shows the comparison of electric power characteristic curves from solar tracking system and static solar panel. It shows that solar tracking system is able to receive more Sunlight and consequently generate more power as compared to static solar panel. TABLE I Observations of solar panel during hardware testing 113

6 Fig. 3 Electric Power vs. Hours characteristic curve VII. CONCLUSION The proposed sun tracker automatically tracks the sun capturing maximum solar power with help of microcontroller. The system tracks the sun both in normal and bad weather condition. The tracker can initialize the starting position itself which reduce the need of any more photo resistor. Summer solstice and winter solstice problem is solved manually by tilting the panel with the help of fine screw arrangement. REFERENCES [1] C. Hua and C. Shen (1998) Comparative study of peak power tracking techniques for solar storage system, Applied Power Electronics Conference and Exposition, vol. 2, pp [2] A. K. Saxena and V. Dutta (1990), A versatile microprocessor based controller for solar tracking, Photovoltaic Specialists Conference, vol. 2, pp [3] B. Koyuncu and K. Balasubramanian (1991), A microprocessor controlled automatic sun tracker, IEEE Transactions on Consumer Electronics, vol. 37, no. 4, pp [4] Md. Tanvir Arafat Khan, S. M. Shahrear Tanzil, Rifat Rahman, S M Shafiul Alam (2010) Design and construction of an automatic solar tracking system, international conference on electrical and computer engineering, Dhaka, Bangladesh. [5] R. U. Rahman, D. I. Ahmed, M. A. Fahmi, T. Tasnuva M. F. Khan (2009), Performance Enhancement of PV solar system by diffused refection, Intl. Conf. on the Developments in Renewable Energy Technology, PP [6] WATTSON SOLAR TRACKER RETAIL PRICE AND DATA SHEET. [Online].Available: [7] Microcontroller datasheet. [Online] Available: c.pdf. [8] L293D datasheet. [Online]. Available: [9] LM317 datasheet. [Online]. Available: [10] Neeraj Tiwari, D. Bhagwan Das and Prabal Pratap Singh, Design, Development And Hardware Realization Of X-Beebased Single Axis Solar Tracking System International Journal of Electrical Engineering & Technology (IJEET), Volume 3, Issue 3, 2012, pp. 8-20, Published by IAEME 114