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Solartracking system


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documentation on solar tracking system

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Solartracking system

  1. 1. 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. SKTRMCE,DEPT. OF ECE Page 1
  3. 3. INTRODUCTION: Commercial made solar trackers are a nice addition to any solar panel array. They help increase the time that panels directly face the sun and allow them to produce their maximum power. Unfortunately they can be expensive to buy. We decided to make our own solar tracker to see if we could reduce the cost. We did not want to reinvent the wheel but wanted to make it more affordable. We started out small and came up with the idea of solar tracking using time instead of using a device that would sense where the sun is and move the panels toward it. The objective of this project is to control the position of a solar panel in accordance with the motion of sun. Brief Methodology: This project is designed with solar panels, RTC, Microcontroller, Stepper Motor and its driving circuit. In this project RTC is used to find or the location of Sun. It’s a open loop system. Renewable energy is rapidly gaining importance as an energy resource as fossil fuel prices fluctuate. At the educational level, it is therefore critical for engineering and technology students to have an understanding and appreciation of the technologies associated with renewable energy. One of the most popular renewable energy sources is solar energy. Many researches were conducted to develop some methods to increase the efficiency of Photo Voltaic systems (solar panels). One such method is to employ a solar panel tracking system. This project deals with a RTC based solar panel tracking system. Solar tracking enables more energy to be generated because the solar panel is always able to maintain a perpendicular profile to the sun’s rays. Development of solar panel tracking systems has been ongoing for several years now. As 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 to the solar energy radiated by the sun. This will tend to maximize the amount of power absorbed by PV systems. It has been estimated that the use of a tracking system, over a fixed system, can increase the power output by 30% - 60%. The increase is significant enough to make tracking a viable preposition despite of the enhancement in system cost. It is possible to align the tracking heliostat normal to sun using electronic control by a micro controller. Design requirements are: 1) during the time that the sun is up, the system must follow the sun’s position inthe sky. 2) This must be done with an active control, timed movements are useful. It should be totally automatic and simple to operate. The operator interference should be minimal and restricted to only when it is actually required SKTRMCE,DEPT. OF ECE Page 3
  5. 5. LIST OF COMPONENTS:  Power supply  Microcontroller(AT89C51)  Solar panel  DC motor  LCD(Liquid crystal Display)  RTC(Real Time Clock-DS1307)  L293D Driver  keypad POWER SUPPLY: In this project power supplies with +5V & -5V option normally +5V is enough for total circuit. Another supply is used in case of OP amp circuit .Transformer primary side has 230/50HZ AC voltage whereas at the secondary winding the voltage is step downed to 12/50hz and this voltage is rectified using two full wave rectifiers .The rectified output is given to a filter circuit to filter the unwanted ac in the signal After that the output is again applied to SKTRMCE,DEPT. OF ECE Page 5
  6. 6. a regulator LM7805(to provide +5v) regulator. WhereasLM7805 is for providing 5V regulation. CIRCUIT FEATURES: Brief description of operation: Gives out well regulated +5V output, output current capability of 1A Circuit complexity: Very simple and easy to build Circuit performance: Very stable +5V output voltage, reliable operation Power supply voltage: 230V AC Power supply current: 1A MICROCONTROLLER:(AT89C51) AT89C51 MICROCONTROLLER FEATURES 89C51 based architecture 8 -Kbytes of on-chip Reprogrammable Flash Memory  128 x 8 RAM  Two 16 Timer/Counters -bit  Full duplex serial channel  Boolean processor  Four 8 I/O ports, 32 I/O lines -bit  Memory addressing capability – 64K ROM and 64K RAM  Power save modes: – Idle and power-down  Six interrupt sources  Most instructions execute in 0.3 us  CMOS and TTL compatible Maximum speed: 40 MHz @ Vcc = 5V  Industrial temperature available  Packages available: – 40-pin DIP – 44-pin PLCC SKTRMCE,DEPT. OF ECE Page 6
  7. 7. – 44-pin PQFP SOLAR PANEL: Photovoltaic energy is the conversion of sunlight into electricity. A photovoltaic cell, commonly called a solar cell or PV, is the technology used to convert solar energy directly into electrical power. A photovoltaic cell is a non mechanical device usually made from silicon alloy The photovoltaic cell is the basic building block of a photovoltaic system. Individual cells can vary in size from about 0.5 inches to about 4 inches across. However, one cell only produces 1 or 2 watts, which isn't enough power for most applications. The performance of a photovoltaic array is dependent upon the sunlight .Climatic conditions (eg., clouds, fog) have a significant effect on the amount of solar energy received by a photovoltaic array and, in turn, its performance. Most current technology photovoltaic modules are about 10% efficient in converting solar radiation. Further research is being conducted to raise this efficiency to 20%. BRUSHLESS DC GEAR MOTOR : Conventional DC motors use a stationary magnet with a rotating armature combining the commutation segments and brushes to provide automatic commutation. In comparison, the brushless DC motor is a reversed design: the permanent magnet is rotating whereas the windings are part of the stator and can be energized without requiring a commutator-and-brush system. SPECIFICATION:  INPUT VOLTAGE-15V  INPUT CURRENT- 0.6A  R.P.M -10:1 SKTRMCE,DEPT. OF ECE Page 7
  8. 8. Fig. Brushless Dc Motor LCD (LIQUID CRYSTAL DISPLAY) : The Liquid Crystal Display (LCD) is a low power device (microwatts). Now a days in most applications LCDs are using rather using of LED displays because of its specifications like low power consumption, ability to display numbers and special characters which are difficult to display with other displaying circuits and easy to program. An LCD requires an external or internal light source. Temperature range of LCD is 0ºC to 60ºC and lifetime is an area of concern, because LCDs can chemically degrade these are manufactured with liquid crystal material (normally organic for LCDs) that will flow like a liquid but whose molecular structure has some properties normally associated with solids . FIELD EFFECT LCD: Field-effect LCDs are normally used in such applications where source of energy is a prime factor (e.g., watches, portable instrumentation etc.).They absorb considerably less power than the light-scattering type. However, the cost for field-effect units is typically higher, and their height is limited to 2 inches. On the other hand, light-scattering units are available up to 8 inches in height. Field-effect LCD is used in the project for displaying the appropriate information Fig.Liquid Crystal Display SKTRMCE,DEPT. OF ECE Page 8
  9. 9. DS 1307(RTC) Real-Time Clock (RTC) Counts Seconds, Minutes, Hours, Date of the Month, Month, Day of the Week, and Year with Leap-Year Fig.DS1307 pin and Pin configuration The DS1307 serial alarm real-time clock provides a full binary coded decimal (BCD) clock calendar that is accessed by a simple serial interface. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. The end of the month date is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour format with AM/PM indicator. In addition, 96 bytes of NV RAM are provided for data storage. The DS1307 will maintain the time and date, provided the oscillator is enabled, as long as at least one supply is at a valid level An interface logic power-supply input pin (VCCIF) allows the DS1307 to drive SDA and SCL pins to a level that is compatible with the interface logic. This allows an easy interface to 3V logic in mixed supply systems. The DS1307 offers dual-power supplies as well as a battery input pin. The dual power supplies support a programmable trickle charge circuit that allows a rechargeable energy source (such as a super cap or rechargeable battery) to be used for a backup supply. The VBAT pin allows the device to be backed up by a non-rechargeable battery. The DS1307 is fully operational from 2.0V to 5.5V. Two programmable time-of-day alarms are provided by the DS1307. Each alarm can generate an interrupt on a programmable combination of seconds, minutes, hours, and day. “Don’t care” states can be inserted into one or more fields if it is desired for them to be ignored for the alarm condition. The time-of-day alarms can be programmed to assert two different interrupt outputs or to assert one common interrupt output. Both interrupt outputs operate when the device is powered by VCC1, VCC2, or VBAT. The DS1307 supports a direct interface to SPI serial data ports or standard 3-wire interface. A straightforward address and data format is implemented in which data transfers can occur 1 byte at a time or in multiple-byte-burst mode. SKTRMCE,DEPT. OF ECE Page 9
  10. 10. L293D DRIVER: The L293D is a monolithic integrated high voltage, high current four channel driver designed to accept standard DTL or TTL logic levels and drive inductive loads (such as relays solenoids, DC and stepping motors) and switching power transistors. To simplify use as two bridges is pair of channels is equipped with an enable input. A separate supply input is provided form the logic, allowing operational at a low voltage and internal clamp diodes are included. This device is suitable for use in switching applications at frequencies up to 5 KHz. The L293D is assembled in a 16 lead plastic package which has 4 center pins connected together and used for heat sinking. Fig.L293D pin configuration FEATURES:  600ma. output current capability perchannel  1.2a pe ak o utput current (nonrepetitive) per channel  enable facility  overtemperature protection  logical ”0” input voltage up to 15v  internal clamps diodes KEYPAD: Keypads are a part of HMI or Human Machine Interface and play really important role in a small embedded system where human interaction or human input is needed. Matrix keypads are well known for their simple architecture and ease of interfacingwith any microcontroller. Scanning a matrix keypad: There are many methods depending on how the keypadis connected with the controller, but the basic logic is same. The columns as i/p and rows making them o/p, this whole procedure of reading the keyboard is called scanning. SKTRMCE,DEPT. OF ECE Page 10
  11. 11. Fig. Matrix Keypad CRYSTAL OSCILLATOR: crystal oscillator is an electronic circuit that produces electrical oscillations at a particular designed frequency determined by the physical characteristics of one or more crystals, generally of quartz, positioned in the circuit feedback loop. A piezoelectric effect causes a crystal such as quartz to vibrate and resonate at a particular frequency. The quartz crystal naturally oscillates at a particular frequency, its fundamental frequency that can be hundreds of megahertz. The crystal oscillator is generally used in various forms such as a frequency generator, a frequency modulator and a frequency converter. Fig. CRYSTAL OSCILLATOR SKTRMCE,DEPT. OF ECE Page 11
  12. 12. INTERFACING OF COMPONENTS WITH MICROCONTROLLER AT89C51: Interfacing Lcd With Microcontroller Fig. Interfacing of DS1307 with Fig. Interfacing of L293D with DC Motor microcontroller SKTRMCE,DEPT. OF ECE Page 12
  13. 13. WORKING OF SOLAR TRACKING SYSTEM: The system contains two modules, one is tracking and the other is controlling module. Tracking module which will take angular rotation with the help of DC gear motor in synchronous with the starting position of the sun. As sun rises from East, it will also take the angle according to the angle of raising sun. So it will continuously track the sun till the sun sets in the West. Initially when the supply from the power kit was drawn and given to all the components of the control circuit and keyboard. When the power supply is switched ON the panel comes to the original position and by the keypad switches the clock time in the LCD screen can be setted by the keypad switches. K1, K2 and K3 are the switches of keypad. K1 represents Increment switch, K2 represents Decrement switch and K3 represents Enable switch. Initially the panel stands at reference position 8:00AM and according to the setting time the panel rotates with the help of brushless DC Gear Motor. Module is designed with efficient Microcontroller from ATMEL 89C51 which helps to drive the tracking module at different instants. The keypad switches was connected to the microcontroller through latch to the port2(Pins 2.6, 2.7,2.8) and microcontroller was connected to the LCD screen through the pins(P1.4 to P1.7) and the LCD displays the preset time. DS1307 is the RTC(Real Time Clock) used to produce clock pulses through microcontroller which connects the LCD display, displays the time. L293D driver was connected to the DC Motor, microcontroller and 9V battery. The pulses that was produced by the microcontroller helps to connect the DC supply to the DC brushless motor. The DC brushless motor was mounted on a separate stand and connected to a shaft which rotates the solar panel given from the microcontroller based upon this gear motor operates. When the supply was given to the dc gear motor, according to the setting from keypad, the solar panel reaches the set state from the initial position with one degree as one second and after reaching the set position it covers every degree by one degree. 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 SKTRMCE,DEPT. OF ECE Page 13
  14. 14. beginning of the daylight from a reference point the system starts counting the stepping cycles each of 40 steps. ADVANTAGES: 1. Solar power is pollution free during use. Production end wastes and emissions are manageable using existing pollution controls. End-of-use recycling technologies are under development. 2. Facilities can operate with little maintenance after initial setup. 3. Solar electric generation is economically superior where grid connection or fuel transport is difficult, costly or impossible. 4. When grid-connected, solar electric generation can displace the highest cost electricity during times of peak demand can reduce grid loading. 5. Grid-connected solar electricity can be used locally thus reducing transmission/distribution losses. 6. Once the initial capital cost of building a solar power plant has been spent, operating costs are extremely low compared to existing power technologies. 7. The power obtained by solar tracking is almost constant over a period of time when compared with the output obtained by a panel without tracking. DISADVANTAGES: 1. Solar electricity is almost more expensive than electricity generated by other sources. 2. Solar electricity is not available at night and is less available in cloudy weather conditions. Therefore, a storage or complimentary power system is required. 3. Limited power density. 4. Solar cells produce DC which must be converted to ACwhen used in currently existing distribution grids SKTRMCE,DEPT. OF ECE Page 14
  15. 15. Fig. Overview Of Simple Solar Tracker SKTRMCE,DEPT. OF ECE Page 15
  16. 16. CONCLUSION: In recent years, the generation of electricity using solar technology has seen a tremendous growth, in particular because of the economic considerations and smooth operation of the solar panels. Even though the initial costs are high, but operation costs and maintenance costs are low. Solar tracking system today offer an innovative method to track the solar insolation and provide economic compatibility of the generation of electric power where grid connections are difficult to setup and costly. Here the tracking system is based on microcontroller with effective systematic operation and the solar panel is rotated by the dc gear motor effectively. SKTRMCE,DEPT. OF ECE Page 16