OPTIMUM UTILISATION OF SOLAR ENERGY full report
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24-01-2011, 09:02 PM
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Solar panel converts the light energy from the sun into electrical energy. In ordinary solar panel systems, the solar panel is fixed in a particular direction. The solar panel delivers maximum energy only when it faces directly towards the sun. Since the sun is moving continuously, the solar panel cannot deliver maximum energy when the solar panel fixed at one direction.
The goal of the project and implimentation is to control the solar panel continuously, according to the movement of the sun. This is done by controlling the mechanical movement of solar panel. The mechanical movement of solar panel is controlled through the stepper motor using Microcontroller. The sun’s movement from east to west is divided into segments keeping a fixed time frame for each segment with the use of Real Time Clock (RTC).
1.1Software/ hardware tools used
1.2 Project cycle
2. Circuit description
3. Storage device
3.1Types of batteries
3.2Lead acid battery
4.1Brief introduction to microcontroller
5. Solar panel
5.1. Different types of solar panel
5.1.1Monocrystal solar panel
5.1.3. Thin film panel
6. Lightning systems
6.1. Light emitting diodes
6.1.1Efficiency and operational parameters
6.1.3Advantages and disadvantage
6.2Light dependent resistor
7. Stepper motor
7.1When to use stepper motor
7.2Two phase stepper motor winding
7.4Advantages and disadvantages of stepper motor
8. Driver ULN2803A
9. Real time clock (RTC)
10. Mechanical design considerations
11. Liquid crystal display
11.1 Interfacing a LCD with microcontroller
12. Embedded development software tools
13. Flow chart
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 and implimentation 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 in the 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.
1.1. SOFTWARE/HARDWARE TOOLS USED:
• Microcontroller kit or Atmel AT89C51 microcontroller.
• Keil Micro Vision Integrated Development Environment.
• C51 C Compiler, A51 Assembler.
1.2. PROJECT CYCLE:
• Specification of the project and implimentation
• Circuit designing.
• PCB Layout.
• Device test
• Writing code.
2.0 CIRCUIT DESCRIPTION:
Fig 1: Block Diagram
2.3 COMPONENTS USED:
1) Microcontroller (AT89C51)
2) Real Time Clock (RT 1307)
3) Stepper motor.
4) Lead acid battery (9AH, 12V DC)
6) Solar panel
3.0. POWER SUPPLY:
Power supply is a reference to a source of electrical energy. A device or system that supplies electrical or other types of energy to an output load or group of loads is called a power supply unit or PSU. The term is most commonly applied to electrical energy supplies, less often to mechanical ones, and rarely to others.
3.1. DUAL SUPPLIES:
There are many types of power supply. Most are designed to convert high voltage AC mains electricity to a suitable low voltage supply for electronic circuits and other devices. A power supply can by broken down into a series of blocks, each of which performs a particular function.
For example a 5V regulated supply:
Some electronic circuits require a power supply with positive and negative outputs as well as zero volts (0V). This is called a 'dual supply' because it is like two ordinary supplies connected together as shown in the diagram.
Dual supplies have three outputs, for example a ±9V supply has +9V, 0V and -9V outputs. A power supply may include a power distribution system as well as primary or secondary sources of energy such as:
• Conversion of one form of electrical power to another desired form and voltage, typically involving converting AC line voltage to a well-regulated lower-voltage DC for electronic devices. Low voltage, low power DC power supply units are commonly integrated with the devices they supply, such as computers and household electronics; for other examples, see switched-mode power supply, linear regulator, rectifier and inverter (electrical).
• Chemical fuel cells and other forms of energy storage systems
• Solar power
• Generators or alternators
Constraints that commonly affect power supplies are the amount of power they can supply, how long they can supply it without needing some kind of refueling or recharging, how stable their output voltage or current is under varying load conditions, and whether they provide continuous power or pulses.
A regulated power supply or stabilized power supply is one that includes circuitry to tightly control the output voltage and/or current to a specific value. The specific value is closely maintained despite variations in the load presented to the power supply's output, or any reasonable voltage variation at the power supply's input
3.2. Types of Power Supply:
Power supplies for electronic devices can be broadly divided into linear and switching power supplies. The linear supply is a relatively simple design that becomes increasingly bulky and heavy for high current devices; voltage regulation in a linear supply can result in low efficiency. A switched-mode supply of the same rating as a linear supply will be smaller, is usually more efficient, but will be more complex.
3.2.1. electrical power storage device (Battery):
A battery is a type of linear power supply that offers benefits that traditional line-operated power supplies lack: mobility, portability and reliability. A battery consists of multiple electrochemical cells connected to provide the voltage desired.
3.3. TYPES OF BATTERYS:
The most commonly used dry-cell battery is the carbon-zinc dry cell battery. Dry-cell batteries are made by stacking a carbon plate, a layer of electrolyte paste, and a zinc plate alternately until the desired total voltage is achieved. The most common dry-cell batteries have one of the following voltages: 1.5, 3, 6, 9, 22.5, 45, and 90. During the discharge of a carbon-zinc battery, the zinc metal is converted to a zinc salt in the electrolyte, and magnesium dioxide is reduced at the carbon electrode. These actions establish a voltage of approximately 1.5 V.
3.3.1. LEAD ACID BATTERY:
The lead-acid storage battery may be used. This battery is rechargeable; it consists of lead and lead/dioxide electrodes which are immersed in sulfuric acid. When fully charged, this type of battery has a 2.06-2.14 V potential. During discharge, the lead is converted to lead sulfate and the sulfuric acid is converted to water. When the battery is charging, the lead sulfate is converted back to lead and lead dioxide.
4.1. A BRIEF INTRODUCTION TO MICROCONTROLLER:
When we have to learn about a new computer we have to familiarize about the machine capability we are using, and we can do it by studying the internal hardware design (devices architecture), and also to know about the size, number and the size of the registers.
A microcontroller is a single chip that contains the processor (the CPU), non-volatile memory for the program (ROM or flash), volatile memory for input and output (RAM), a clock and an I/O control unit. Also called a "computer on a chip," billions of microcontroller units (MCUs) are embedded each year in a myriad of products from toys to appliances to automobiles. For example, a single vehicle can use 70 or more microcontrollers. The following picture describes a general block diagram of microcontroller.
The hardware is driven by a set of program instructions, or software. Once familiar with hardware and software, the user can then apply the microcontroller to the problems easily.
4.2 PIN CONFIGURATION:
The pin diagram of the 8051 shows all of the input/output pins unique to microcontrollers:
The following are some of the capabilities of 8051 microcontroller.
• Internal ROM and RAM
• I/O ports with programmable pins
• Timers and counters
• Serial data communication
• The 8051 architecture consists of these specific features:
• 16 bit PC &data pointer (DPTR)
• 8 bit program status word (PSW)
• 8 bit stack pointer (SP)
• Internal ROM 4k
• Internal RAM of 128 bytes.
• 4 register banks, each containing 8 registers
• 80 bits of general purpose data memory
• 32 input/output pins arranged as four 8 bit ports: P0-P3
• Two 16 bit timer/counters: T0-T1
• Two external and three internal interrupt sources Oscillator and clock circuits.
Fig 2: Pin diagram of AT89C51
(A)T89C51xx Memory Mapping:
T89C51RD2 T89C51RD2 has the following memory areas:
• User memory area 64 KB size where the upper 1 KB is used for bootloader
• A hardware security byte for configuration information and security levels.
• XAF area for ISP:
– Boot Status Byte (BSB)
– Software Boot Vector (SBV)
– Software Security Byte (SSB)
5.0. SOLAR PANEL:
The solar panel is what's at the heart of a photovoltaic system. Photovoltaic is where sunlight is converted into usable electricity. Most solar panels are not one large cell but are made up of a string of silicon cells wired in series to produce the desired output.
Currently there are three types of solar panels commonly available. Two of these, the monocrystalline and polycrystalline, are designed to be supported by a rigid aluminum frame and covered with glass. The third type is a thin film and may be in a rigid or a flexible frame. The panels we most commonly see in use today are the rigid mono and poly crystalline panels that can be mounted either on a roof or ground rack.
Thin film panels can be adhered straight onto a metal roof or incorporated into a roof shingle. The mono and poly crystalline panels are the most durable and have the longest project and implimentationed life, typically 20 years. Most of the panels warranties covering power output are based on this 20 year life span. The thin film products, while said to be cheaper to produce over the crystalline silicon panels, are questionable in terms of efficiency and longevity. There seem to be new developments in the thin film industry so we will follow it and make updates when substantial improvements are made.
5.1. Different Types Of Solar Panels:
5.1.1. Monocrystal solar panels
Monocrystalline panels use crystalline silicon produced in a large sheet which has been cut to the size of the panel, thus making one large single cell. Metal strips are laid over the entire cell and act as a conductor that captures electrons. Mono panels are slightly more efficient than Polycrystalline panels but they don't usually cost more than Poly Panels.
5.1.2. Polycrystal panels:
Polycrystalline panels use a bunch of small cells put together instead of one large cell. Poly panels are slightly less efficient than mono panels. They are also claimed to be cheaper to manufacturer than mono panels although we have noticed them to be very similarlypriced.
There are a couple different ways a polycrystalline silicon cell can be made:
In this process, molten silicon is cast in a large block which, when cooled, can be cut into thin wafers to be used in photovoltaic cells. These cells are then assembled in a panel. Conducting metal strips are then laid over the cells, connecting them to each other and forming a continuous electrical current throughout the panel.
String ribbon uses a variation of the polycrystalline production process, using the same molten silicon but slowly drawing a thin strip of crystalline silicon out of the molten form. These strips of photovoltaic material are then assembled in a panel with the same metal conductor strips attaching each strip to the electrical current.
It is also said that string ribbon solar panels are even cheaper to manufacturer than the cast polysilicon method. If this were the case then why are String Ribbon Panels the most costly? This technology saves on costs over standard polycrystalline panels as it eliminates the sawing process for producing wafers. Some string ribbon technologies also have higher efficiency levels than other polycrystalline technologies.
5.1.3. Thin Film Panels:
Thin film panels are produced very differently from crystalline panels. Instead of molding, drawing or slicing crystalline silicon, the silicon material in these panels have no crystalline structure and can be applied as a film directly on various materials. Variations on this technology use other semiconductor materials like copper indium diselenide (CIS) and cadmium telluride (CdTe).
These materials are then connected to the same metal conductor strips used in the other processes, but do not necessarily use the other components typical in photovoltaic panels as they do not require the same level of protection needed for more fragile crystalline cells.
The primary advantages of thin film panels lie in their low manufacturing costs and versatility. Because amorphous silicon and similar semiconductors do not depend on the long, expensive process of creating silicon crystals, they can be produced much more quickly. Because they can be applied in thin layers to different materials, it is also possible tomakeflexiblesolarcells.
Thin film panels do have several significant drawbacks. They are the least efficient type of solar panel currently available. Thin-film technology also uses silicon with high levels of impurities. This can cause a drop in efficiency within a short period of time.
6.0 LIGHTNING SYSTEMS:
6.1 LIGHT EMITTING DIODES:
Like a normal diode, the LED consists of a chip of semiconducting material doped with impurities to create a p-n junction. As in other diodes, current flows easily from the p-side, or anode, to the n-side, or cathode, but not in the reverse direction. Charge-carriers—electrons and holes—flow into the junction from electrodes with different voltages. When an electron meets a hole, it falls into a lower energy level, and releases energy in the form of a photon.
The wavelength of the light emitted, and therefore its color, depends on the band gap energy of the materials forming the p-n junction. In silicon or germanium diodes, the electrons and holes recombine by a non-radiative transition which produces no optical emission, because these are indirect band gap materials. The materials used for the LED have a direct band gap with energies corresponding to near-infrared, visible or near-ultraviolet light.
6.1.2. Lifetime and failure:
Solid state devices such as LEDs are subject to very limited wear and tear if operated at low currents and at low temperatures. The most common symptom of LED (and diode laser) failure is the gradual lowering of light output and loss of efficiency. Sudden failures, although rare, can occur as well.
The main types of LEDs are miniature, high power devices and custom designs such as alphanumeric or multi-color.
6.1.4. Miniature LEDs:
Different sized LEDs. 8 mm, 5 mm and 3 mm, with a wooden match-stick for scale.These are mostly single-die LEDs used as indicators, and they come in various-sizes from 2 mm to 8 mm, through-hole and surface mount packages. They are usually simple in design, not requiring any separate cooling body. Typical current ratings ranges from around 1 mA to above 20 mA. The small scale sets a natural upper boundary on power consumption due to heat caused by the high current density and need for heat sinking.
6.1.5. ADVANTAGES AND DISADVANTAGES:
• Efficiency: LEDs produce more light per watt than incandescent bulbs.
• Color: LEDs can emit light of an intended color without the use of color filters that traditional lighting methods require. This is more efficient and can lower initial costs.
• Size: LEDs can be very small (smaller than 2 mm2) and are easily populated onto printed circuit boards.
• On/Off time: LEDs light up very quickly. A typical red indicator LED will achieve full brightness in microseconds. LEDs used in communications devices can have even faster response times.
• Cycling: LEDs are ideal for use in applications that are subject to frequent on-off cycling, unlike fluorescent lamps that burn out more quickly when cycled frequently, or HID lamps that require a long time before restarting.
• Dimming: LEDs can very easily be dimmed either by pulse-width modulation or lowering the forward current.
• Cool light: In contrast to most light sources, LEDs radiate very little heat in the form of IR that can cause damage to sensitive objects or fabrics. Wasted energy is dispersed as heat through the base of the LED.
• Slow failure: LEDs mostly fail by dimming over time, rather than the abrupt burn-out of incandescent bulbs.
• Lifetime: LEDs can have a relatively long useful life. One report estimates 35,000 to 50,000 hours of useful life, though time to complete failure may be longer. Fluorescent tubes typically are rated at about 10,000 to 15,000 hours, depending partly on the conditions of use, and incandescent light bulbs at 1,000–2,000 hours.
• Shock resistance: LEDs, being solid state components, are difficult to damage with external shock, unlike fluorescent and incandescent bulbs which are fragile.
• Focus: The solid package of the LED can be designed to focus its light. Incandescent and fluorescent sources often require an external reflector to collect light and direct it in a usable manner.
• High initial price: LEDs are currently more expensive, price per lumen, on an initial capital cost basis, than most conventional lighting technologies. The additional expense partially stems from the relatively low lumen output and the drive circuitry and power supplies needed.
• Temperature dependence: LED performance largely depends on the ambient temperature of the operating environment. Over-driving the LED in high ambient temperatures may result in overheating of the LED package, eventually leading to device failure. Adequate heat-sinking is required to maintain long life. This is especially important when considering automotive, medical, and military applications where the device must operate over a large range of temperatures, and is required to have a low failure rate.
• Voltage sensitivity: LEDs must be supplied with the voltage above the threshold and a current below the rating. This can involve series resistors or current-regulated power supplies.
• Light quality: Most cool-white LEDs have spectra that differ significantly from a black body radiator like the sun or an incandescent light. The spike at 460 nm and dip at 500 nm can cause the color of objects to be perceived differently under cool-white LED illumination than sunlight or incandescent sources, due to metamerism, red surfaces being rendered particularly badly by typical phosphor based cool-white LEDs. However, the color rendering properties of common fluorescent lamps are often inferior to what is now available in state-of-art white LEDs.
• Area light source: LEDs do not approximate a “point source” of light, but rather a lambertian distribution. So LEDs are difficult to use in applications requiring a spherical light field. LEDs are not capable of providing divergence below a few degrees. This is contrasted with lasers, which can produce beams with divergences of 0.2 degrees or less.
An LDR is an input transducer (sensor) which converts brightness (light) to resistance. It is made from cadmium sulphide (CdS) and the resistance decreases as the brightness of light falling on the LDR increases.
A multimeter can be used to find the resistance in darkness and bright light, these are the typical results for a standard LDR:
• Darkness: maximum resistance, about 1M .
• Very bright light: minimum resistance, about 100 .
For many years the standard LDR has been the ORP12, now the NORPS12, which is about 13mm diameter. Miniature LDRs are also available and their diameter is about 5mm.
An LDR may be connected either way round and no special precautions are required when soldering.
7.0. STEPPER MOTOR:
A stepper motor is an electromechanical device which converts electrical pulses into discrete mechanical movements. The shaft or spindle of a stepper motor rotates in discrete step increments when electrical command pulses are applied to it in the proper sequence. The motors rotation has several direct relationships to these applied input pulses. The sequence of the applied pulses is directly related to the direction of motor shafts rotation. The speed of the motor shafts rotation is directly related to the frequency of the input pulses and the length of rotation is directly related to the number of input pulses applied.
7.1. When to Use a Stepper Motor:
A stepper motor can be a good choice whenever controlled movement is required. They can be used to advantage in applications where you need to control rotation angle, speed, position and synchronism. Because of the inherent advantages listed previously, stepper motors have found their place in many different applications. Some of these include printers, plotters, high end office equipment, hard disk drives, medical equipment, fax machines, automotive and many more.
7.2. TWO PHASE STEPPER MOTOR WIRING:
The above motor is a two phase motor. This is sometimes called Unipolar. The two phase coils are center tapped and this case the center taps are connected to ground. These coils are wound so that it is reversed when the drive signal is applied to either coil at a time. The N and S of the stator phase are reversed depending upon whether the drive signal is applied to coil 1 as opposed to coil 2.
Fig: Two phase stepper motor wiring
7.4. Torque Generation:
The torque produced by a stepper motor depends on several factors.
• The step rate
• The drive current in the windings
• The drive design or type
In a stepper motor a torque is developed when the magnetic fluxes of the rotor and stator are displaced from each other. The stator is made up of a high permeability magnetic material. The presence of this high permeability material causes the magnetic flux to be confined for the most part to the paths defined by the stator structure in the same fashion that currents are confined to the conductors of an electronic circuit. This serves to concentrate the flux at the stator poles. The torque output produced by the motor is proportional to the intensity of the magnetic flux generated when the winding is energized. The basic relationship which defines the intensity of the magnetic flux is defined by:
H = (N ´ i) ¸ l where:
N = The number of winding turns
i = current
H = Magnetic field intensity
l = Magnetic flux path length
This relationship shows that the magnetic flux intensity and consequently the torque is proportional to the number of winding turns and the current and inversely proportional to the length of the magnetic flux path. From this basic relationship one can see that the same frame size stepper motor could have very different torque output capabilities simply by changing the winding parameters. More detailed information on how the winding parameters affect the output capability of the motor can be found in the application note entitled “Drive Circuit Basics”.
7.4.3. Step Angle Accuracy
One reason why the stepper motor has achieved such popularity as a positioning device is its accuracy and repeatability. Typically stepper motors will have a step angle accuracy of 3 – 5% of one step. This error is also noncumulative from step to step. The accuracy of the stepper motor is mainly a function of the mechanical
precision of its parts and assembly. Figure 9 shows a typical plot of the positional accuracy of a stepper motor.
7.5. Stepper Motor Advantages and Disadvantages:
1. The rotation angle of the motor is proportional to the input pulse.
2. The motor has full torque at standstill (if the windings are energized)
3. Precise positioning and repeatability of movement since good stepper motors have an accuracy of 3 – 5% of a step and this error is non cumulative from one step to the next.
4. Excellent response to starting/ stopping/reversing.
5. Very reliable since there are no contact brushes in the motor. Therefore the life of the motor is simply dependant on the life of the bearing.
6. The motors response to digital input pulses provides open-loop control, making the motor simpler and less costly to control.
7. It is possible to achieve very low speed synchronous rotation with a load that is directly coupled to the shaft.
8. A wide range of rotational speeds can be realized as the speed is proportional to the frequency of the input pulses.
1. Resonances can occur if not properly controlled.
2. Not easy to operate at extremely high speeds.
Open Loop Operation:
One of the most significant advantages of a stepper motor is its ability to be accurately controlled in an open loop system. Open loop control means no feedback information about position is needed. This type of control eliminates the need for expensive sensing and feedback devices such as optical encoders. Your position is known simply by keeping track of the input step pulses.
8.0. DRIVER (ULN2803A):
• Eight darlingtons with common emitters.
• Output current to 500mA
• Output voltage to 50v
• Integral suppression diodes versions for all popular logic families
• Output can be paralleled inputs pinned opposite outputs to simplify board layout
The ULN2801A-ULN2805Aeach contain eight darlington transistors with common emitters and integral suppression diodes for inductive loads. Each darlington features a peak load current rating of 600mA (500mA continuous) and can withstand at least50V in the off state. Outputs may be paralleled for higher current capability. Five versions are available to simplify interfacing to standard logic families : the ULN2801Ais designed for general purpose application swith a current limit resistor ; theULN2802Ahas a 10.5kW input resistor and zener for 14-25VPMOS; theULN2803Ahas a 2.7kW input resistor for 5V TTL and CMOS ; the ULN2804A has a 10.5kW input resistor for 6-15V CMOS and the ULN2805A is designed to sink a minimum of 350mA for standard and Schottky TTL where higher output current is required. All types are supplied in a 18-lead plastic DIP with a copper lead from and feature the convenient input opposite-output pin out to simplify board layout.
For ULN2803A (each driver for 5 V, TTL/CMOS)
9.0. REAL TIME CLOCK:
A real-time clock (RTC) is a battery-powered clock that is included in a microchip in a computer motherboard. This microchip is usually separate from the microprocessor and other chips and is often referred to simply as "the CMOS" (complementary metal-oxide semiconductor). A small memory on this microchip stores system description or setup values - including current time values stored by the real-time clock. The time values are for the year, month, date, hours, minutes, and seconds. When the computer is turned on, the Basic Input-Output Operating System (BIOS) that is stored in the computer's read-only memory (ROM) microchip reads the current time from the memory in the chip with the real-time clock.
The DS1307 serial real-time clock (RTC) is a low-power, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV SRAM. Address and data are transferred serially through an I²C, bidirectional bus. 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. The DS1307 has a built-in power-sense circuit that detects power failures and automatically switches to the backup supply. Timekeeping operation continues while the part operates from the backup supply.
9.1. KEY FEATURES:
Real-Time Clock (RTC) Counts Seconds, Minutes, Hours, Date of the Month, Month, Day of the week, and Year with Leap-Year a Compensation Valid Up to 2100
56-Byte, Battery-Backed, General-Purpose RAM with Unlimited Writes
I²C Serial Interface
Programmable Square-Wave Output Signal
Automatic Power-Fail Detect and Switch Circuitry
Consumes Less than 500nA in Battery-Backup Mode with Oscillator Running
Optional Industrial Temperature Range: -40°C to +85°C
Available in 8-Pin Plastic DIP or SO
10.0 MECHANICAL DESIGN CONSIDERATIONS:
A CAM changes the input motion, which is usually rotary motion (a rotating motion), to a reciprocating motion of the follower. They are found in many machines and toys. CAM has two parts, the FOLLOWER and the CAM PROFILE.
11.0. LIQUID CRYSTAL DISPLAY:
Advances in the features, miniaturization and cost of LCD (Liquid Crystal Displays) controller chips have made LCDs usable not only in commercial products but also in hobbyist project and implimentations. By themselves, Liquid Crystal Displays can be difficult to drive because they require multiplexing, AC drive waveforms and special voltages. LCD modules make this driving simpler by attaching hardware to the raw glass LCD.
LCD modules can be split into to groups: those that have built-in controller and driver chips, and those that have only driver chips. The category of display modules that have built-in controllers can be split again into character LCD m
odules and graphic LCD modules. Character module can display only text and perhaps some special symbols, while graphic modules can display lines, circles, squares and patterns in addition to text this project and implimentation is primarily concerned with character LCD modules that have the Hitachi HD44780 controller built-in.
11.1. INTERFACING A LCD WITH A MICROCONTROLLER:
This is an example how to interface to the standard Hitachi-44780 using an 8051 microcontroller. It is standard 16-character by 2-line LCD module, see schematic below. It uses 4-bit interfacing.
EMBEDDED DEVELOPMENT SOFTWARE TOOLS
In this project and implimentation a solar panel tracker has been developed to increase the amount of power generated by solar panel as the sun traverse across the sky. An 8051 microcontroller was used to control the movement of solar panel. The system was designed to be autonomous, such that energy generated by solar panel would be used to charge a lead battery, which in turn acts as a supply to glow the lamp at night. Overall, the system was a positive learning experience for the student, which allows maximizing his creative potential as well as utilizing many technologies in Electrical Engineering Technology discipline.
1. Heating the water
2. Electric fence
3. Battery charger
4. Emergency battery backup
5. Solar cooker
Without using RTC we can control the solar panel by considering intensity of the sun rays received.
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07-01-2012, 04:07 PM
The Solar Powered Aircraft an unmanned flying wing, controlled remotely from the ground that is designed to run on solar power and flying at an altitude 1,00,000fts.
The 'first successful craft made from spruce wood, was flown by brothers Robert and Roland Boucher as an experimental spy plane for the American aiir force in 1974.
Gossamer- penguin significant as the first sustained flight of an air craft relying solely on direct solar power rather than batteries. A later model Solar Challenger, crossed the English Channel in 1981 attaining a height of about 11 ,000 ft but could not stay aloft for long periods.
Pathfinder is a proof-of-concept vehicle for two prototype solar-powered aircraft—Helios and Centurion—which currently are under development at AeroVironment. Both vehicles have a wingspan of about 200 feet. Helios, an ultra long-duration vehicle, would use an energy storage system to power the aircraft at night. The solar cells would power the vehicle during the day and recharge the energy storage system. Duration of such a flight could be several weeks to months. Centurion, an ultrahigh-altitude vehicle that could reach altitudes of 100,000 feet or higher, does not have an energy storage system, and thus would operate only during the day. Hope it will become a cheap substitute for satellite for gathering scientific data and carrying communication equipments.
ENERGY FROM THE SUN?
Solar panels have the ability to meet all of our energy needs, but at present we only use a tiny fraction of the energy that the sun has to offer. How much energy does the sun produce? How is it produced? And how much of the sun's energy can be theoretically harvested via solar cells?
Energy from the sun is caused from thermonuclear explosions deep within the sun. These explosions fuse atoms of hydrogen into atoms of helium. A tremendous amount of energy is released during the thermonuclear reaction and the sun releases that energy as radiation. This radiation travels through space at the speed of light, and solar panels can make practical use of it. Our sun generates an enormous amount of energy, and potentially, had we the technology to harvest that sunlight with solar arrays across the solar system, we could harvest huge amounts of energy.
According to our friends at Astronomy Cafe, we calculate the amount of energy given off the sun every hour as:
"3.8 x 10^33 ergs/sec or 3.8 x 10^26 watts of power, an amount of energy each second equal to 3.8 x 10^26 joules. In one hour, or 3600 seconds, [the Sun] produces 1.4 x 10^31 Joules of energy or 3.8 x 10^23 kilowatt-hours."
The sun produces more energy every hour than the entire energy needs of human civilization from the beginning of time. Solar panels will help us harvest increasing amounts of this abundance of energy to meet our energy needs in the future.
HOW DO SOLAR PANEL WORKS?
Learn how solar panels convert sunlight into electricity Solar panels collect solar radiation from the sun and actively convert that energy to electricity. Solar panels are comprised of several individual solar cells. These solar cell function similarly to large semiconductors and utilize a large-area p-n junction diode. When the solar cells are exposed to sunlight, the p-n junction diodes convert the energy from sunlight into usable electrical energy. The energy generated from photons striking the surface of the solar panel allows electrons to be knocked out of their orbits and released, and electric fields in the solar cells pull these free electrons in a directional current, from which metal contacts in the solar cell can generate electricity. The more solar cells in a solar panel and the higher the quality of the solar cells, the more total electrical output the solar panel can produce. The conversion of sunlight to usable electrical energy has been dubbed the Photovoltaic Effect.
The photovoltaic effect arises from the properties of the p-n junction diode; as such there are no moving parts in a solar panel.
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17-01-2012, 06:45 AM
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17-01-2012, 09:32 AM
to get information about OPTIMUM UTILISATION OF SOLAR ENERGY full report ,ppt and related topic link bellow page
to get information about OPTIMUM UTILISATION OF SOLAR ENERGY full report ,ppt and related topic link bellow page