INDEX 7 ENERGY ARCHITECTURE & 8 URBAN PLANNING AGRICULTURE & 9 HORTICULTURE! SOLAR LIGHTING 10 ' 13 METHOD DEVELOPMENT 14 "*

Transcription

1 INDEX LIST OF FIGURE I SOLAR ENERGY INTRODUCTION APPLICATION OF SOLAR 7 ENERGY ARCHITECTURE & 8 URBAN PLANNING AGRICULTURE & 9 HORTICULTURE! SOLAR LIGHTING 10 ' WATER HEATING SOLAR COOKER ENERGY STORAGE 13 METHOD DEVELOPMENT 14 "* SOLAR TRACKER HISTORY TYPES QF SOLAR TRACKER HORIZONTAL AXLE VERTICAL AXLE ALTITUDE-AZIMUTH TWO-AXIS MOUNT MULTI-MIRROR REFLECTIVE 22 UNIT 2.3 DRIVE TYPES ACTIVE TRACKER PASSIVE TRACKER CHRONOLOGICAL TRACKER THIN-FILM SOLAR TRACKER 26 & SOLAR CELL

2 1. INTRODUCTION TYPES OF SOLAR CELL HIGH-EFFICIENCY CELLS MULTIPLE-JUNCTION SOLAR CELLS THIN-FILM SOLAR CELLS CRYSTALLINE SILICON APPLICATION SOLAR CELL EFFICIENCY FACTOR MATERIAL USED FOR SOLAR CELL 40 DESIGN AND DEVELOPMENT OF SOLAR TRACKER METHOD OF POWER GENERATION 43

3 2. SELECTION OF MATERIAL DETAIL OF EACH COMPONENT ASSEMBLY OF SOLAR TRACKER WORKING OF SOLAR TRACKER COST OF SOLAR TRACKER FUTURE ASCPECT FUTURE ASCPECT CONCLUSION REFERANCES LIST OF FIGURES Fig No. Title 1.1 Use of different energy in the word 1.2 Use of solar energy in the world 1.3 Architecture Building 1.4 Farm house 1.5 Solar lighting 1.6 Water heating 1.7 Solar cooker 2.1 Horizontal Axle 2.2 Vertical Axle 2.3 Two Axis Mount 2.4 Multi mirror reflective unit 2.5 Thin-film solar tracker 3.1 Types of solar cells & its efficiency 4.1 Assembly of base stand 4.2 Gear box

4 4.3 Solar Plate 4.4 Battery Assembly 4.5 Assembly of solar tracker Page No. SOLAR ENERGY CONTENTS: 1. INTRODUCTION 2. APPLICATION OF SOLAR ENERGY ARCHITECTURE & URBAN PLANNING 2. AGRICULTURE & HORTICULTURE 3. SOLAR LIGHTING 1. WATER HEATING 2. SOLAR COOKER 3.

5 1. [ ~-

6 1. ENERGY STORAGE METHOD 2. DEVELOPMENT INTRODUCTION In today's climate of 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 directly by the sun and collected elsewhere, normally the Earth. Solar energy is the radiant light and heat from the Sun that has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation along with secondary solar resources such as wind and wave power, hydroelectricity and biomass account for most of the available renewable energy on Earth. Only a minuscule fraction of the available solar energy is used. Solar power provides electrical generation by means of heat engines or photovoltaic. Once converted its uses are only limited by human ingenuity. A partial list of solar applications includes space heating and cooling through solar architecture, potable water via distillation and disinfection, daylighting, hot water, thermal energy for cooking, and high temperature process heat for industrial purposes. Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute sunlight. Active solar techniques include the use of photovoltaic panels, solar thermal collectors, with electrical or mechanical equipment, to convert sunlight into useful outputs. Passive solar techniques include orienting a building to the Sun, selecting materials with

7 favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air. The Earth receives 174 peta watts (PW) of incoming solar radiation (insulation) at the upper atmosphere. Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land masses. The spectrum of solar light at the Earth's surface is mostly spread across the visible and near-infrared ranges with a small part in the near-ultraviolet. Earth's land surface, oceans and atmosphere absorb solar radiation, and this raises their temperature. Warm air containing evaporated water from the oceans rises, causing atmospheric circulation or convection. When the air reaches a high altitude, where the temperature is low, water vapor condenses into clouds, which rain onto the Earth's surface, completing the water cycle. The latent heat of water condensation amplifies convection, producing atmospheric phenomena such as wind, cyclones and anti-cyclones. Sunlight absorbed by the oceans and land masses keeps the surface at an average temperature of 14 C. By photosynthesis green plants convert solar energy into chemical energy, which produces food, wood and the biomass from which fossil fuels are derived.

8 ~.s ~ > ' I ) > ) ) )

9 i Coal 2 5% Gas 2 3% I

10 Biomass 4% uclear > A> Hydro f N

11 ir r olar heat 0.5% Wind 0.3% * Geothermal 0.2% B i o f u e l s

12 0. 2 % S o l a r p h o t o v o l

13 t a i c % 1.1 Use of Different Energy in the World ~ 4 As we seen from the above graph solar energy is most wildly use as a nonconversional energy in the world. Renewable energy sources are even larger than the traditional fossil fuels and in theory can easily supply the world's energy needs. 89 PW of solar power falls on the planet's surface. While it is not possible to capture all, or even most, of this energy, capturing less than 0.02% would be enough to meet the current energy needs. Barriers to further solar generation include the high price

14 of making solar cells and reliance on weather patterns to generate electricity. Also, solar generation does not produce electricity at night, which is a particular problem in high northern and southern latitude countries; energy demand is highest in winter, while availability of solar energy is lowest. This could be overcome by buying power from countries closer to the equator during winter months. Globally, solar generation is the fastest growing source of energy, seeing an annual average growth of 35% over the past few years. Japan, Europe, China, U.S. and India are the major growing investors in solar energy. Advances in technology and economies of scale, along with demand for solutions to global warming, have led photovoltaic to become the most likely candidate to replace nuclear and fossil fuels. ~5~

15 7.2 TW 32 TW 86,000 TW Hydro Geothermal

16 870 TW 15 TW Glob al Solar Wind Consumption 1.2 Use of Solar Energy in the World

17 1.2 APPLICATIONS OF SOLAR ENERGY ARCHITECTURE AND URBAN PLANNING AGRICULTURE AND HORTICULTURE SOLAR LIGHTING SOLAR THERMAL WATER HEATING HEATING, COOLING AND VENTILATION WATER TREATMENT COOKING PROCESS HEAT ELECTRICAL GENERATION EXPERIMENTAL SOLAR POWER SOLAR CHEMICAL SOLAR VEHICLES

18 ARCHITETURE AND URBAN PLANNING Darmstadt University of Technology in Germany won the 2007 Solar Decathlon in Washington, D.C. with this passive house

19 designed specifically for the humid and hot subtropical climate. Sunlight has influenced 1.3 Architecture Building building design since the beginning of architectural history. Advanced solar architecture and urban planning methods were first employed by the Greeks and Chinese, who oriented their buildings toward the south to provide light and warmth. The common features of passive solar architecture are orientation relative to the Sun, compact proportion (a low surface area to volume ratio), selective shading (overhangs) and thermal mass. When these features are tailored to the local climate and environment they can produce well-lit spaces that stay in a comfortable temperature range. Socrates' Megaron House is a classic example of passive solar design. The most recent approaches to solar design use computer modeling tying together solar lighting, heating and ventilation systems in an integrated solar design package. Active solar equipment such as pumps, fans and switchable windows can complement passive design and improve system performance. ~ 8 ~

20 1.2.2 AGRICULTURE AND HORTICULTURE 1.4 Farm house Agriculture and horticulture seek to optimize the capture of solar energy in order to optimize the productivity of plants. Techniques such as timed planting cycles, tailored row orientation, staggered heights between rows and the mixing of plant varieties can improve crop yields. While sunlight is generally considered a plentiful resource, the exceptions highlight the importance of solar energy to agriculture. During the short growing seasons of the Little Ice Age, French and English farmers employed fruit walls to maximize the collection of solar energy. These walls acted as thermal masses and accelerated ripening by keeping plants warm. Early fruit walls were built perpendicular to the ground and facing south, but over time, sloping walls were developed to make better use of sunlight. In 1699, Nicolas Fatio de Duillier even suggested using a tracking mechanism which could pivot to follow the Sun. [26] Applications of solar energy in agriculture aside from growing crops include pumping water, drying crops, brooding chicks and drying chicken manure. More recently the technology has been embraced by vinters, who use the energy generated by solar panels to power grape presses.

21 ~9~ SOLAR LIGHTING Daylighting features such as this oculus at the top of the Pantheon, in Rome, Italy have been in use since antiquity. The history of lighting is dominated by the use of natural light. The Romans recognized a right to light as early as the 6th century and 1.5 Solar Lighting English law echoed these judgments with the Prescription Act of In the 20th century artificial lighting

22 became the main source of interior illumination but daylighting techniques and hybrid solar lighting solutions are ways to reduce energy consumption. Daylighting systems collect and distribute sunlight to provide interior illumination. This passive technology directly offsets energy use by replacing artificial lighting, and indirectly offsets non-solar energy use by reducing the need for airconditioning. [34] Although difficult to quantify, the use of natural lighting also offers physiological and psychological benefits compared to artificial lighting. Hybrid solar lighting is an active solar method of providing interior illumination. HSL systems collect sunlight using focusing mirrors that track the Sun and use optical fibers to transmit it inside the building to supplement conventional lighting. ~ 10 ~

23 1.2.4 WATER HEATING Solar hot water systems use sunlight to heat water. In low geographical latitudes (below 40 degrees) from 60 to 70% of the domestic hot water use with temperatures up to 60 C can be provided by solar heating systems. The most common types of solar water heaters are evacuated tube collectors (44%) and glazed flat plate collectors (34%) generally used for 1.6 water heating domestic hot water; and unglazed plastic collectors (21%) used mainly to heat swimming pools. As of 2007, the total installed capacity of solar hot water systems is approximately 154 GW. China is the world leader in their deployment with 70 GW installed as of 2006 and a long term goal of 210 GW by Israel and Cyprus are the per capita leaders in the use of solar hot water systems with over 90% of homes using them. In the United States, Canada and Australia heating swimming pools is the dominant application of solar hot water with an installed capacity of 18 GW as of 2005.

24 ~ 11 ~ SOLAR COOKER The Solar Bowl in Auroville, India, concentrates sunlight on a movable receiver to produce steam for cooking. Solar cookers use sunlight for cooking, drying and pasteurization. They can be grouped into three 1.7 solar cooker broad categories: box cookers, panel cookers and reflector cookers. The simplest solar cooker is the box

25 cooker first built by Horace de Saussure in A basic box cooker consists of an insulated container with a transparent lid. It can be used effectively with partially overcast skies and will typically reach temperatures of C.[58] Panel cookers use a reflective panel to direct sunlight onto an insulated container and reach temperatures comparable to box cookers. Reflector cookers use various concentrating geometries (dish, trough, Fresnel mirrors) to focus light on a cooking container. These cookers reach temperatures of 315 C and above but require direct light to function properly and must be repositioned to track the Sun. The solar bowl is a concentrating technology employed by the Solar Kitchen in Auroville, Pondicherry, India, where a stationary spherical reflector focuses light along a line perpendicular to the sphere's interior surface, and a computer control system moves the receiver to intersect this line. Steam is produced in the receiver at temperatures reaching 150 C and then used for process heat in the kitchen. ~12~

26 1.3 ENERGY STORAGE METHODS Solar Two's thermal storage system generated electricity during cloudy weather and at night. Solar energy is not available at night, and energy storage is an important issue because modern energy systems usually assume continuous availability of energy. Thermal mass systems can store solar energy in the form of heat at domestically useful temperatures for daily or seasonal durations. Thermal storage systems generally use readily available materials with high specific heat capacities such as water, earth and stone. Well-designed systems can lower peak demand, shift timeof-use to off-peak hours and reduce overall heating and cooling requirements. Phase change materials such as paraffin wax and Glauber's salt are another thermal storage media. These materials are inexpensive, readily available, and can deliver domestically useful temperatures (approximately 64 C). The "Dover House" (in Dover, Massachusetts) was the first to use a Glauber's salt heating system, in Solar energy can be stored at high temperatures using molten salts. Salts are an effective storage medium because they are low-cost, have a high specific heat capacity and can deliver heat at temperatures compatible with conventional power systems. The Solar Two used this method of energy storage, allowing it to store 1.44 TJ in its 68 m 3 storage tank with an annual storage efficiency of about 99%. Off-grid PV systems have traditionally used rechargeable batteries to store excess electricity. With grid-tied systems, excess electricity can be sent to the transmission grid. Net metering programs give these systems a credit for the electricity they

27 deliver to the grid. This credit offsets electricity provided from the grid when the system cannot meet demand, effectively using the grid as a storage mechanism. ~ 13 ~ 1.4 DEVELOPMENT Nellis Solar Power Plant in the United States, the largest photovoltaic power plant in North America. Beginning with the surge in coal use which accompanied the Industrial Revolution, energy consumption has steadily transitioned from wood and biomass to fossil fuels. The early development of solar technologies starting in the 1860s was driven by an expectation that coal would soon become scarce. However development of solar technologies stagnated in the early 20th century in the face of the increasing availability, economy, and utility of coal and petroleum. The 1973 oil embargo and 1979 energy crisis caused a reorganization of energy policies around the world and brought renewed attention to developing solar technologies.[104] [105] Deployment strategies focused on incentive programs such as the Federal Photovoltaic Utilization Program in the US and the Sunshine Program in Japan. Other efforts included the formation of research facilities in the

28 US (SERI, now NREL), Japan (NEDO), and Germany (Fraunhofer Institute for Solar Energy Systems ISE). ~ 14-

29 SOLAR TRACKER CONTENTS: 1. HISTORY 2. TYPES OF SOLAR TRACKER 1. HORIZONTAL AXLE 2. VERTICAL AXLE 3. ALTITUDE-AZIMUTH 4. TWO-AXIS MOUNT 5. MULTI-MIRROR REFLECTIVE UNIT 2.3 DRIVE TYPES 1. ACTIVE TRACKER 2. PASSIVE TRACKER 3. CHRONOLOGICAL TRACKER

30 4. THIN-FILM SOLAR TRACKER HISTORY A solar tracker is a device for orienting a daylighting reflector, solar photovoltaic panel or concentrating solar reflector or lens toward the sun. The sun's position in the sky varies both with the seasons and time of day as the sun moves across the sky. Solar powered equipment works best when pointed at or near the sun, so a solar tracker can increase the effectiveness of such equipment over any

31 fixed position, at the cost of additional system complexity. There are many types of solar trackers, of varying costs, sophistication, and performance. One well-known type of solar tracker is the heliostat, a movable mirror that reflects the moving sun to a fixed location, but many other approaches are used as well. The required accuracy of the solar tracker depends on the application. Concentrators, especially in solar cell applications, require a high degree of accuracy to ensure that the concentrated sunlight is directed precisely to the powered device, which is at (or near) the focal point of the reflector or lens. Typically concentrator systems will not work at all without tracking, so at least single-axis tracking is mandatory. Very large power plants or high temperature materials research facilities using multiple ground-mounted mirrors and an absorber target require very high precision similar to that used for solar telescopes. Non-concentrating applications require less accuracy, and many work without any tracking at all. However, tracking can substantially improve both the amount of total power produced by a system and that produced during critical system demand periods (typically late afternoon in hot climates) The use of trackers in nonconcentrating applications is usually an engineering decision based on economics. Compared to photovoltaics, trackers can be inexpensive. This makes them especially effective for photovoltaic systems using high-efficiency (and thus expensive) panels. For low-temperature solar thermal applications, trackers are not usually used, owing to the high expense of trackers compared to adding more collector area and the more restricted solar angles required for Winter performance, which influence the average year-round system capacity.

32 ~ 16 ~ ~ 2.2 TYPES OF SOLAR TRACKER Solar trackers may be active or passive and may be single axis or dual axis. Single axis trackers usually use a polar mount for maximum solar efficiency. Single axis trackers will usually have a manual elevation (axis tilt) adjustment on a second axis which is adjusted on regular intervals throughout the year. Compared to a fixed mount, a single axis tracker increases annual output by approximately 30%, and a dual axis tracker an additional 6%. There are two types of dual axis trackers, polar and altitude-azimuth.

33 2.2.1 HORIZONTAL AXLE ~ 17 ~

34 2.1 Horizontal Axle Several manufacturers can deliver single axis horizontal trackers which may be oriented by either passive or active mechanisms, depending upon manufacturer. In these, a long horizontal tube is supported on bearings mounted upon pylons or frames. The axis of the tube is on a North-South line. Panels are mounted upon the tube, and the tube will rotate on its axis to track the apparent motion of the sun through the day. Since these do not tilt toward the equator they are not especially effective during winter mid day (unless located near the equator), but add a substantial amount of productivity during the spring and summer seasons when the solar path is high in the sky. These devices are less effective at higher latitudes. The principal advantage is the inherent robustness of the supporting structure and the simplicity of the mechanism. Since the panels are horizontal, they can be compactly placed on the axle tube without danger of self-shading and are also readily accessible for cleaning. For active mechanisms, a single control and motor may be used to actuate multiple rows of panels. Manufacturers include Array Technologies, Inc. Wattsun Solar Trackers (gear driven active), Zomeworks (passive) and Power light (active).

35 ~ 18-