Embedded Solar Tracking Instrumentation System

Transcription

1 Embedded Solar Tracking Instrumentation System A.H. Yamin, M. N. Ibrahim, M. Idroas and A.R. Zin UniversitiTeknologi Malaysia UTM Johor Bahru, Malaysia Abstract This paper describes the embedded solar tracking instrumentation system by using Atmega32 microcontroller. The system consists of Light Dependent Resistor (LDR) sensor, DC motor and Xbee wireless system. Atmega32 microcontroller is the main component for controlling the system. The solar system will track the location of the sun to ensure the solar panel is always perpendicular with the sun therefore optimizing power output. The operation of the system on sunny and bad weather condition has been presented in this paper. The solar tracking prototype has been stated for future works. Index Terms Embedded, Microcontroller, Wireless, Solar panel, Solar tracking T I. INTRODUCTION he global warming crisis, which is mainly caused by carbon emission is an issue of alarming concern. Immediate, effective and practical actions to eradicate the problem should be taken before it worsens. The emission of carbon as a by-product of electric generation from fossil fuels impacts lives and the Mother Nature. Renewable energy such as solar energy provides a sustainable, safer and much healthier power production, in return safeguarding the earth from the dangers of pollution. To date, solar energy is the best way to replace fossil fuels as the main source for generating electricity. Solar energy uses sun rays that is an unlimited source and available for a long term with zero pollution by-product compared to fossil fuels [1-5]. Besides, the solar energy source is free while the price of fossil fuels had tripled for the last 15 years [3]. The limitation on existing solar energy system is the system is not efficient as it generates low power output and demands high cost. This can be solved by developing an embedded system based on Atmega32 microcontroller and by adding Xbee wireless system for collecting and monitoring data. Nowadays, Atmega32 microcontroller and Xbee wireless system are widely used in the development of an embedded system in many areas. It is because of the reasonable cost, simplicity and ability to connect with a large number of devices [6]. Both Atmega32 and Xbee are easy to install and can be used in any situation. II. SOLAR ENERGY TECHNOLOGY The enhancement of solar energy system has grown from fixed mounted to tracking instrumentation solar panel system and flat to parabolic dish solar panel. The early solar energy technology is based on fixed mounted solar system. The tracking system is added in order to improve the efficiency of the existing system. The purpose of the tracking system is to overcome the limitation of fixed solar panel mountings system. The shading effect is considered in tracking the location of the sun. The sunlight was diffused through the interaction of clouds and dusts [1] [7]. The purpose of parabolic dish solar system is to ensure the sunlight can be focused at one point and it can increase the efficiency of the solar energy system. The improvement of the solar energy system by implementing the tracking system and parabolic dish will gain maximum power output due to the alignment of solar panels towards the sun. The most important aspect in the tracking instrumentation system is to track the location of the sun. The location of the sun depends on the latitude of the site and according to the times of the years [1]. Based on the location of the sun as desired orientation, the tracking device will trigger the motor to operate the solar energy system. The tracking device is used in order to ensure the panel is aligned with the sun. Hence, the maximum output power gain can be achieved. Solar tracking instrumentation is a closed-loop function system. A closed-loop function system is known as feedback system. Feedback system is needed to ensure the solar panel always perpendicular with the sun. Fig. 1 shows the block diagram of solar tracking system. Location of the sun is set as desired input of the system. The sensor is used as the tracking system. The subject of orientation for the system is a condition of the sunlight. It can be either east or west and north or south. Measuring device that used as feedback system is the movement of the motor. Finally, the sun is perpendicular with the solar panel. This work was supported by the Ministry of Higher Education (MOHE) and UniversitiTeknologi Malaysia. Fig. 1: Block diagram of the solar tracking instrumentation system /13/$31.00 IEEE 223

2 III. SOLAR TRACKING INSTRUMENTATION SYSTEM The overall solar tracking system is shown in Fig. 2. The main control system for the solar tracking system is Atmega32 microcontroller. By implementing Atmega32 microcontroller in this project, the microcontroller is used to control the process flow and data transfer and stored the data for further use. The Light Dependent Resistor (LDR) sensor is used and it was attached to the dish parabolic concentrator to ensure the system is always perpendicular with the sun. The sensor will detect the sunlight and transmit the signal to Atmega32 microcontroller. Then, the microcontroller will trigger the motor to move accordingly. The detection of the sun is based on the signal received from the sensor to make sure the panel is always perpendicular with the sun. At the same time, the data received from the sensor will be stored in Atmega32 microcontroller. The information stored in Atmega32 microcontroller will then be sent to the computer by using Xbee wireless system to be analyzed and saved. The sunlight will strike the surface of the dish parabolic reflector. Then, the sunlight is reflected to the solar panel that is placed at the focal length of the dish parabolic system. The light energy will be converted into electrical energy when the light strikes the solar panel. The output from the solar system is Direct Current (DC) which can be stored to the battery or converted to the Alternating Current (AC). The circuit for all solar energy system is designed by using Proteus software. The circuit is separately designed and consists of: Atmega32 microcontroller Light dependent resistor (LDR) sensor DC motor XBEE wireless Fig. 3: Atemega32 microcontroller Atmega32 microcontroller has 40 pins and every pin has their own functions. Some of the features used in this project are programmable I/O line, 8-channel 10-bit analog to digital converter (ADC) at PORTA and universal synchronous asynchronous receiver transmitter at PORTD (Pin 14 and Pin 15). Fig. 4 shows the pin configuration for Atmega32 microcontroller. Fig. 4: Atmega32 layout Fig. 2: Overall solar tracking system A. Atmega32 microcontroller Atmega32 microcontroller is the main part of the system. Atmega32 microcontroller is a high performance with low power microcontroller. The operating voltage for Atmega32 microcontroller is 5V. The speed grades of Atmega32 microcontroller is up to 16MHz [8]. The Atmega32 microcontroller is used for comparing the external comparator output, controlling motor movement for the dual-axis system and to control the Xbee wireless system. Fig. 3 shows the photograph of Atmega32 microcontroller. B. Light Independent Resistor (LDR) sensor By implementing the tracking system in solar energy system, the location of the sun can be determined. The system tracks the sun based on light intensity of the sunlight. In this project, light dependent resistor (LDR) is used as the sensoring device to detect the sunlight. Five LDR sensors are installed in the system. One of the sensors is used as a switch for the system. When this sensor detects sunlight, the system will be enabled. Two other sensors are used to detect the sunlight either north or south along azimuth motion of the system while another two sensors are used to detect the sunlight either east or west along altitude motion of the system. In this project, three comparators have been installed. Each comparator is used to compare the value of two sensors. The value of the sensor is based on the presence of the sunlight. 224

3 The comparator is connected to Atmega32 microcontroller as the input for the tracking system. Furthermore, four LEDs are also used in the system as the indicator for the movement of the motor. For example, two sensors are placed at left and right of the parabolic dish. When the system detects the presence of the sunlight, all the LEDs are switched on. When one side of the sensor is gain more sunlight, one of the LED will be switched on and the DC motor will move anti-clockwise and vice versa. Fig. 5 shows the connection of the sensor. Fig. 7: Xbee wireless module C. DC Motor Fig. 5: Connection of the sensor Two DC motor are required in the solar tracking instrumentation system. The first motor is used to move along azimuth motion which is either north or south. Another motor is used to move along altitude motion which is either east or west. Motor driver is required to drive the motor. The motor driver is connected between Atmega32 microcontroller and DC motor. The 12V DC supply does not give enough torque to move the motor. The power amplifier circuit is needed in order to give enough torque to move the motor. So, Darlington pair circuit is placed in between the motor driver and DC motor [9]. Fig. 6 shows the connection between Atmega32, motor driver and DC motor. Fig. 6: connection between Atmega32, motor driver and DC motor D. XBEE Wireless System Most developers of solar tracking system are not really concerned on collecting the data. There is not much work done on applying wireless network system to collect the data realtime [10] [6]. The data received from the solar tracking system are monitored manually at site. Sometimes, it is hard to collect the data during a bad weather. In this project, Xbee wireless system will be used to collect the data based on real-time. These days, Xbee wireless system is widely used for data transferring. By using XBEE wireless system, data monitoring becomes easier. Besides, it is cheap and compatible to use in most situation. Fig. 7 shows the Xbee wireless system module. The Xbee wireless system has low data transfer rate which is 250kb/s and it has low power consumption [11-14]. The input voltage to the Xbee wireless system is 3.3V. The distance range for indoor is up to 30 meter while for outdoor, it is up to 100 meter [10]. The Xbee wireless system is based on IEEE standard protocols [12]. Fig. 8 shows the connection of Xbee wireless system. Fig. 8: Connection of Xbee wireless system IV. OPERATION OF SOLAR TRACKING SYSTEM Basically, the sensors can detect the exact location of the sun with the presence of sunlight. However, the weather conditions are not sunny all the time. Therefore, the operation of solar tracking system should include the bad weather condition too such as cloudy day and rainy day. The operation is based on presence of the sun throughout the year. The operational flow chart is shown in Fig. 9. This project provides two ways of operation and control mechanism which are: Normal sunny condition Bad weather condition The presence of the sun can be identified by knowing the latitude and longitude of the site. The latitude and longitude of Malaysia is (3º09º36º N) and (101º42º36º E) [15]. So, the sunrise is about 7 a.m. while the dawn about 7 p.m. In this project, the system will be started an hour after the sunrise which is 8 a.m. The system will be stopped an hour before dawn which is 6 p.m. Fig. 10 shows the time of sunrise and dawn in Malaysia. A. Normal Sunny Condition Four sensors are used to detect the presence of the sunlight. The output voltages from two sensors that represent east/west and north/south are compared. The east sensor is compared with the west sensor and the north sensor is compared to the south sensor. Based on the result obtained from the sensor, the solar panel will track the sun. 225

4 B. Bad Weather Condition On bad weather day, the sensor cannot detect the presence of the sunlight because of the interaction of clouds and dusts. The sunlight that strikes the system will lessen and insufficient voltages will be received by the sensor. It can be difficult to the sensor to determine the exact location of the sun. The problem can be solved by implementing the algorithm for the movement of the solar panel. The rotation of the earth towards the sun is 360º in 24 hours. Every hour, the earth rotate about (360º/24=) 15º. So, to collect data every 15 minutes, the rotation of the earth towards the sun is about 3.75º [7]. V. PRELIMINARY RESULT The simulation test has been conducted to verify the interaction between light sensor and motor. Fig. 11 shows the circuit of the interaction between light sensor and motor. This circuit consists of two light sensors to detect the light, two motors and two LED as indicator. The motor rotates either clockwise or anti-clockwise when the sensors detect the presence of the light. Fig. 11: Interaction between light sensor and motor circuit VI. DESIGN OF SOLAR TRACKING SYSTEM The development of the overall solar tracking system has two stages and it is done separately. The first stage is developing a software system that focuses on the operation of the solar embedded system. Meanwhile, the second stage is developing a hardware system which consists of developing on the prototype of solar tracking instrumentation system. Fig. 12 shows the prototype of solar tracking instrumentation system. The prototype is built using polyvinyl chloride (PVC) material because of low cost, flexibility and durability for higher temperature. The idea of prototype platform is based on tripod due to stability of the system. Roller is installed to move easily from one location to others. Fig. 9: Flow chart of the solar tracking system Fig. 10: Sunrise and dawn in Malaysia [15] Fig. 12: Prototype of solar tracking instrumentation system. 226

5 The construction of the prototype will be done based on the operation of the solar that had been developed on software stage. The design of the prototype consists of four sensors that are placed on the north, south, east and west of the parabolic dish. The installation of the sensor is sufficient enough to detect the exact location of the sun and to ensure the solar panel is always facing towards the sun. The system used parabolic dish to reflect the sunlight. Small solar panel is placed at the focal length of the parabolic dish. As a result, the sunlight will be reflected and focused on the solar panel hence maximizing the power output gained. Fig. 13 shows parabolic dish reflector that can be used for developing the prototype of solar tracking system. [7] KHAN, M. T. A., TANZIL, S. M. S., RAHMAN, R. & ALAM, S. M. S. Year. Design and construction of an automatic solar tracking system. In: Electrical and Computer Engineering (ICECE), 2010 International Conference on, Dec [8] [9] LWIN LWIN, O. & HLAING, N. K. Year. Microcontroller-Based Two- Axis Solar Tracking System. In: Computer Research and Development, 2010 Second International Conference on, 7-10 May [10] Zulkifli, N. S. A., F. K. C. Harun, et al. (2012). XBee wireless sensor networks for Heart Rate Monitoring in sport training. International Conference on Biomedical Engineering (ICoBE), [11] [12] Benkic, K., P. Planinsic, et al. (2007). Custom wireless sensor network based on ZigBee. ELMAR, [13] Ping, W. (2008). The Real-Time Monitoring System for In-Patient Based on Zigbee. Second International Symposium on Intelligent Information Technology Application, IITA [14] SeongPeng, L. and Y. Gik Hong (2011). Centralised Smart Home Control System via XBee transceivers. IEEE Colloquium on Humanities, Science and Engineering (CHUSER), [15] Fig. 13: Parabolic dish reflector VII. CONCLUSIONS The paper has presented a method of embedded solar tracking instrumentation system by implementing Atmega32 microcontroller. A solution to maximize the solar panel output is done by positioning the solar panel towards the sun to gain maximum light intensity. A method for tracking the sun on sunny and bad weather condition is also discussed in this paper. The systems also provide more convenient ways on data collection by implementing Xbee wireless system. REFERENCES [1] LYNN, P. A Electricity from Sunlight: An Introduction to Photovoltaics, John Wiley & Sons. [2] HOSSAIN, E., MUHIDA, R. & ALI, A. Year. Efficiency improvement of solar cell using compound parabolic concentrator and sun tracking system. In: Electric Power Conference, EPEC IEEE Canada, 6-7 Oct [3] ALEXANDRU, C. & POZNA, C. Year. Virtual prototype of a dual-axis tracking system used for photovoltaic panels. In: Industrial Electronics, ISIE IEEE International Symposium on, June July [4] ZHOU, Y. & ZHU, J. Year. Application of Fuzzy Logic Control Approach in a Microcontroller-Based Sun Tracking System. In: Information Engineering (ICIE), 2010 WASE International Conference on, Aug [5] KASSEM, A. & HAMAD, M. Year. A microcontroller-based multifunction solar tracking system. In: Systems Conference (SysCon), 2011 IEEE International, 4-7 April [6] Kioumars, A. H. and T. Liqiong (2011). ATmega and XBee-based wireless sensing. 5th International Conference on Automation, Robotics and Applications (ICARA),