Submitted By
Patil Uday T.
Shingare Ashish M.
Zarekar Nilesh B.
Pukale Rahul S.
Pharne Indrajit D.

---

[attachment=12746]
1. INTRODUCTION
1.1 Introduction
In today’s climate growing energy needs and increasing environmental concern, alternatives to the use of non¬¬-renewable and polluting fossil fuels have to be investigated. One such alternative is solar energy. Solar energy is quite simply the energy produced by directly by the sun and collected elsewhere, normally the earth. The sun creates its energy throw a thermonuclear process that converts about 650, 000,000 tons of hydrogen to helium every second process creates heat and electromagnetic radiation. The heat remains in sun and is instrumental in maintaining the thermonuclear reaction. the electromagnetic radiation (including visible light, infrared-red light and ultraviolet radiation) streams out in to space in all directions. Only a very small fraction of the total radiation produced reaches the earth. The radiation that does reach the earth is the indirect source of nearly every type of 0energy used today. The exceptions are geothermal energy, and nuclear fission and fusion. Even fossil fuels owe their origins to the sun; they were once living plants and animals whose life was dependant up on the sun. Much of worlds required energy can be supplied directly by solar power. More still can be provided indirectly. The practicality of doing so will be examined as well as the benefits and drawbacks. In addition, the uses solar energy is currently applied to will be noted.
Due to the nature of solar energy, two components are required to haw a fictional solar energy generator. These two components are collector and storage unit. The collector simply collects radiation that falls on it and converts fraction of it in to other forms of energy (either electricity and heat or heat alone). The storage unit is required because of the non-constant nature of solar energy; at a certain times only a very small amount of radiation will be received. At a night or during heavy cloud cover eg, the amount energy produced by the collector will be quite small. The storage unit can hold the excess energy produced during the period of maximum productivity, and reels it when the productivity drops. In practice, backup power supply is usually added, too, for the situation when the amount of energy required is greater than both what is being produced and what is soared in the container. Methods of collecting and solar energy vary depending on the uses planed for the solar generator.
In general, there are three types of collectors and many forms of storage units. The three types of collectors are flat plate, focusing and passive collectors. Flat plate collectors are more commonly used type of collector today. They are arrays of solar panels arranged in simple plane. They can be of nearly any size, and have output that is directly related to a few variables including size, facing and cleanliness. These variables all affect the amount of radiation that falls on the collector. Often these collector panels have automated machinery that keeps the facing the sun. The additional energy they take in due to the correction of facing more than compensates for the energy needed to drive the extra machinery. Focusing collectors are essentially flat-plate collectors with optical devices arranged to maximize the radiation falling on focus of the collector. These are currently used only in a few scattered areas. Solar furnaces are examples of this types of collector.
Although they can produce far greater amounts of energy at single point than the flat-plane collectors can, they lose some of the radiation that the flat plane panels do not. Radiation reflected off the ground will be used by flat-plane panels but usually will be ignored by focusing collectors (in snow covered regions, this reflected radiation can be significant). One other problem with focusing collectors in general is due to temperature. The fragile silicon components that absorb the incoming radiation lose efficiency at high temperatures, and if they get too hot they can even be permanently damaged. The focusing collectors by their very nature can create much higher temperatures and need more safe guards to protect their silicon components. Passive collectors are completely different from the other two types of collectors.
The passive collectors absorb radiation and convert it to heat naturally, without being designed and built to do so. All objects have this property to some extent, but only some objects (like walls) will be able to produce enough heat to make it worthwhile. Often their natural ability to convert radiation to heat enhanced in some way or another (by being painted black, for example) and a system for transferring the heat to a different location is generally added.
1.1.2 Earth-Sun Geometry
Our project is based on microcontroller system for solar tracking system. The major disadvantages of solar energy are the amount of sun light that arrives at the earth surface is not constant. It depends on location, time of day, time of year, and weather conditions. Because the sun does not deliver that much energy to any one place at any one time, a large surface area is required to collect the energy at a useful rate. We use solar panels to track the power from sun rays. Maximum power can get when sun is at 90 to panel. But this is not always possible because of earth rotation. The term earth rotation refers to the spinning of our planet on its axis. Because of rotation the earth’s surface moves at the equator at a seed of about 467m per second.
The ecliptic plane can be defined as two-dimensional flat surface that geometrically intersects the earth’s orbital path around the sun. On this plane, the earth’s axis is not right angles to this surface, but inclined at an angle of about 23.5 from the perpendicular.
1.1.2 Energy from the Sun
The sun has produced energy for billions of years. Solar energy is the sun’s rays (solar radiation) that reach the earth. Solar energy can be converted into other forms of energy, such as heat and electricity. In 1830s, the British astronomer John Herschel used a solar thermal collector box (a device that absorbs the sunlight to collect heat) to cook food during an expedition to Africa. Today, people use the sun energy for lost things. Solar energy can be converted in to thermal (or heat) energy and used to.
1) Heat water –for use in home, buildings, swimming pools.
2) Heat space- inside greenhouses, homes, and other buildings.
Solar energy can be converted to electrical in two ways:
Photovoltaic (PV device) or solar cells change sunlight directly in to electricity. PV systems are often used in remote locations that are not connected to the electric grid. they are also used to power watches, calculator, and lighted road solar power plant indirectly generate electricity when the heat from solar thermal collector s is used to heat a fluid which produces steam that is used to power generator. Out of the 15 known solar electric generating units operating in the United States at the end of 2006, 10 of these are in California and 5 in Arizona. No statistics are being collector on solar plants that produce less than 1 megawatt of electricity, so there may be smaller solar plants in a number of other states.
1.1.3 Photovoltaic energy
Photovoltaic energy is the conservation of sunlight into electricity. A photovoltaic cell, commonly called a solar cell or PV cell, is the technology used to convert solar energy directly into electrical energy. A photovoltaic cell is non-mechanical device usually made from silicon alloys. Sunlight is composed of photons, or particles of solar energy. These photon contain various amount of energy corresponding to the different wave length of the solar spectrum. When photons strike a photovoltaic cell, they may be reflected, pass right through, or be absorbed. Only the absorbed photons provide energy to generate electricity. When enough sunlight (energy) is absorbed by the material (a semiconductor), electrons are dislodged from materials atoms. Special treatment of the material surface during manufacturing make the front surface of the cell more respective to free electrons, so the electrons naturally migrate to the surface.
Structure of photovoltaic frame electron leave their positions, holes are formed. When many electrons each carrying a negative charge, travel towards the surface of the cell, the resulting imbalance of charge between the cells front and back surface create a voltage potential like negative and positive terminals of a battery. When the two surfaces are connected through an external load, electricity flows. The photovoltaic cell is the basic building block of a photovoltaic system. Individual cell can vary in size from about 1 centimetre (1/2 inches) to about 10 centimetres (4 inches) across. However, one cell only
produces 1 or 2 watts which isn’t enough power for most applications. To increase power output, cells are electrically connected into a package weather-tight module. Modules can be further connected to from an array. The term array refers to the entire generating plant, whether it is made up of one or several thousand modules. The number of modules connected together in an array depends on the amount of power output needed.
The performance of a photovoltaic array is dependent upon sunlight. Climate condition (e.g. could, 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 percent efficient in converting sunlight. Further research is being conducted to raise this efficiency to 20 percent. The photovoltaic effect is the electrical potential developed between two dissimilar materials when their common junction is illuminated with radiation of photons. The photovoltaic cell, thus, converts light directly into electricity. The PV effect was discovered in 1839 by French physicist Becquerel. It remained in the laboratory until 1954, when Bell Laboratories produced the first silicon solar cell. It soon found application in the U.S. space programs for its high power capacity per unit weight. Since then it has been an important source of power for satellites. Having developed maturity in the space applications, the PV technology is now spreading into the terrestrial applications ranging from powering remote sites to feeding the utility lines.
Some advantages of photovoltaic system are:
1) Conversion of sunlight to electricity is direct, so bulky mechanical generator systems are unnecessary.
2) PV array environmental impact is minimal, requiring no water for system cooling and generating no by-products.
Photovoltaic cell, like batteries, generates direct current (DC) which is generally used for small loads (electronic equipment). When DC from photovoltaic cells is used for commercial applications or sold to electric using the electric grid, it must be converted to alternating current (AC) using inverters, solid state devices that convert DC power in to AC. Historically; PV has been used at remote sites to provide electricity. In the future PV arrays may be located at sites that are also connected to the electrical grid enhancing the efficiency of photovoltaic (PV) arrays, and are essential for concentration PV system. The project discusses a light tracking servo model which has been built to simulate the movement of a pv array 
1.2 Necessity
In today's climate of growing energy needs and increasing environmental concern, alternatives to the use of non-renewable and polluting fossil fuels is solar energy Solar energy is quite simply the energy produced directly by the sun and collected elsewhere, normally the Earth. The sun creates its energy through a thermonuclear process that converts about 650,000,000 tons of hydrogen to helium every second.
The process creates heat and electromagnetic radiation. The heat remains in the sun and is instrumental in maintaining the thermonuclear reaction.
The electromagnetic radiation (including visible light, infra-red light, and ultra-violet radiation) streams out into space in all directions.
Only a very small fraction of the total radiation produced reaches the Earth. The radiation that does reach the Earth is the indirect source of nearly every type of energy used today.
1.3 About the project
This project is designed to improve existing solar collection system to provide higher efficiency for lower cost. The existing system receives sun energy only for new hours, which is really not economical when compare the cost, which we are spending.
Here the proposed system is designed to observe the sun light for the available maximum hours, for example – 12 hours a day. This project operates a solar panel to constantly face sun at 90 degrees to produce maximum voltage. It will move the solar panel from east to west to correct for the durational movement of the Sun in the sky. The set of Light Intensify Sensors give the input to the and it operates Stepper motors with mechanism
1.4 Objectives
This project operates a solar panel to constantly face sun at 90 degrees to produce maximum voltage. It can move the solar panel from east to west also to correct for the durational movement of the Sun in the sky. The microcontroller give the input to the Stepper motor and operate with gear mechanism.
1.5 About the solar tracking
The solar tracker is a device, which points a solar panel at the brightest part of the sky in order to achieve maximum power output from the solar panel. The solar panel will move as per the sun movement to collect maximum possible light energy from Morning 6.00 AM to Evening 6.00 PM
3. LITERATURE SURVEY
2.1 Global Energy resources
Current global energy consumption is 4.1*1020J annually, which is equivalent to an instantaneous yearly-averaged consumption rate of 13*1012 W (13 trillion watts, or 13 terawatts TW). Projected population and economic growth will more than double this global energy consumption rate by the mid -21st century and more than triple rate by 2100, even with aggressive conservation efforts. Hence to contribute significantly to global primary energy supply, a prospective resource has to be capable of providing at least 1-10TW of power for an extended period of time. The threat of climate change imposes a second requirement on prospective energy resource. They must produce energy without the emission of additional greenhouse gases. Stabilization of atmospheric CO2 level at even twice their preanthropogenic value will require amounts of carbon-neutral energy by mid-century. The needed levels are in excess of 10 TW, increasing after 2050 to support economic growth for an expanding population.
The three prominent options to meet this demand for carbon-neutral energy are fossil fuel use in conjunction with carbon sequestration, nuclear power, and solar power. The challenge for carbon sequestration is finding secure storage for the 25 billion metric tons of CO2 produced annually on earth. At atmospheric pressure, this yearly global emission of CO2 would occupy 12500 km3, equal to the volume of lake superior, it is 600 times the amount of CO2 injected every year into oil wells to super productions, 100 times amount of natural gas the industry draws in and out of geologic storage in the united states each year to smooth seasonal demand, and 20,000 times the amount of CO2 stored annually in Norway‘s sleipner reservoir. Beyond finding storage volume carbon sequestration also must prevent leakage. A 1%leak rate would nullified the sequestration effort in a century, far too short a time to have lasting impact on climate change. Although many scientists are optimistic, the success of carbon sequestration on the required scale for sufficiently long time has not yet been demonstrated. Nuclear power is a second conceptually viable option. Producing 10TW of nuclear power would required construction of a new 1 giga-watt-electric nuclear fission plant somewhere in the world every other day for the next 50 year. Once that level of deployment was reached, the terrestrial uranium resource base would be exhausted in 10 years. The required fuel would the have to be mined from sea water or else breeder reactor technology would have to be developed and disseminated to countries wishing to meet their additional demand in this way. The third option is to exploit renewable energy sources, of which solar energy is by far the most prominent. The remaining global practically exploitable hydroelectric sources is less than 0.5TW. the cumulative energy in all the tides and ocean current in the world amounts to less than 2TW. The total geothermal energy at the surface of earth, integrated over all the land area of the continents, is 12TW, of which only a small fraction could be practically extracted. the amount of globally extractable wind power has been estimated by the IPCC and others to be 2-4TWe.for comparison the solar constant at the top of the atmosphere is 170,000TW, of which on average, 120,000TW strikes the earth. It is clear that solar energy can be exploited on the needed scale to meet global energy demand in a carbon- neutral fashion without significantly affecting the solar resource.
Solar energy storage and distribution are critical to match demand. The amount of produced by covering 0.16% of the earth’s land area with 10% efficient solar cell is equal to that produced by 20000 1-GWe nuclear fission plants.
2.2 Sun as the source of radiation
The sun is a sphere of intensely hot gaseous matter with a diameter of 1.39*109 m & is about 1.5*1011 m away from the earth. As seen from the earth the sun rotate on its axis once about every four weeks . However it does not rotate as a solid body, the equator takes about 27 days & the polar regions takes about 30 days for each rotation. The sun has an effective black body temperature of 5762 K. the temperature of innermost region, the core estimated between 8*106 to 40*106 K & the density about 100 times of that of water. The sun, in effect is a continuous fusion reactor with its constituents gases as the –containing vessel retained by the gravitational forces.
several fusion reactor have been suggested to be source of energy radiated by the sun, the one to be considered the most important is the process in which four hydrogen atoms combined to form one helium atom, the mass of the helium nucleus is less than that of the four protons, some mass have been lost in the reaction & converted in to energy this energy is produced in the interior of the solar sphere, at the temperature of many million degrees.
A schematic representation of the structure of sun is shown in figure. It is estimated that 90% of the energy is generated in the region 0 to 0.23R (where R is the radius of the sun), which contains 40% of the mass of the sun. At a distance 0.7R from the centre, the temperature drops to about 130000K & the density to 70 kg /m3, here convection process begin to become important. The zone from 0.7 to 1.0R is known as convective zone. Within this zone the temperature drops to about 5000K & the density to about 10-5 kg/m3