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Unit ii 29.02.2016
- 1. UNIT II SOLARENERGY 1 Solar Radiation – Measurements of Solar Radiation - Flat Plate and Concentrating Collectors – Solar direct Thermal Applications – Solar thermal Power Generation - Fundamentals of Solar Photo Voltaic Conversion – Solar Cells – Solar PV Power Generation – Solar PV Applications.
- 2. SOLAR ENERGY Energy fromthe sun. Why is energy from the sun renewable?
- 3. 3 Solar energy Solar energycomes from the light of the sun, which means it is a renewable source of energy. We can use the sun light to create pollution free electricity The solar cell is the system used to convert the sunlight energy into electrical energy
- 4. Disadvantages • Solar panelsare expensive. • When it is cloudy or at night there is not enough light. • Some people don’t like the look of solar panels. What is it? • Solar power uses energy from the Sun. • Solar panels transfer the Suns energy to heat water. Advantages • The energy from the Sun is free. • The sun does not produce greenhouse gases. • The sun will always be there during our lifetime.
- 5. • Solar energyis the most readily available source of energy. • It is free. • It is also the most important of the non- conventional sources of energy because it is non-polluting. Solar Energy
- 7. Energy from thesun • About half the incoming solar energy reaches the Earth's surface. • The Earth receives 174 petawatts (PW) (1015 watts) of incoming solar radiation at the upper atmosphere. Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land masses. • Earth's land surface, oceans and atmosphere absorb solar radiation, and this raises their temperature. 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. 7
- 8. PH 0101 Unit-5Lecture -1 8 Areas of the world with high Solar radiation • The basic resource for all solar energy systems is the sun. • Knowledge of the quantity and quality of solar energy available at a specific location is of prime importance for the design of any solar energy system
- 9. PH 0101 Unit-5Lecture -1 9 • Although the solar radiation is relatively constant outside the earth's atmosphere, local climate influences can cause wide variations in available radiation on the earth’s surface from site to site. • In addition, the relative motion of the sun with respect to the earth will allow surfaces with different orientations to intercept different amounts of solar energy. • It is the primary task of the solar energy system designer to determine the amount, quality and timing of the solar energy available at the site selected for installing a solar energy conversion system.
- 10. Difference between BeamRadiation and diffuse Radiation 10
- 11. Pyranometer – Formeasuring diffuse radiation 11
- 12. Pyrheliometer- for MeasuringBeam radiation 12
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- 14. • Beam radiationenergy (Hb) 14
- 15. Sunshine recorder • Itis used to measure the duration of bright sunshine hours in a day. 15
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- 17. Concentrating ratio ofthe collector 17
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- 19. Thermal Collector Mechanics Solarenergy is absorbed, transformed, and concentrated in a solar thermal collector over a time or spatial gradient to produce usable energy
- 20. Thermal Collector Technologies •Solar Cookers • Parabolic Troughs • Parabolic Dish • Central Receiver System • Solar Chimney • Solar Distillers • Solar Water Heaters
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- 22. Parabolic Trough • Aparabolic trough concentrates sunlight along a spatial gradient into a linear focal point • A fluid acts as a thermal sink as it passes through tubes along the focal point • Parabolic troughs are used to generate electricity but are susceptible to seasonal changes
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- 24. Parabolic Dish • Aparabolic dish or solar furnace is a large reflector that concentrates thermal energy into a single focal point • The focal point can contain a Stirling Engine to generate electricity or the energy can be focused and used in industrial processes • On a small scale, a reactor can be used in the same way a solar oven is used
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- 27. Layout of solarpond electric power plant 27
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- 30. Solar vapour compressionrefrigeration system 30
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- 32. Low temperature solarpower plant 32
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- 35. Solar water heatingsolar air heating
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- 37. Solar Cookers • Solarcookers or ovens are primarily used in developing nations as a primary method for cooking using passive solar heat to cook primary meals • Insulated box that collects solar radiation enhanced by reflectors attached to each side • Helps combat deforestation
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- 39. Solar Distiller • Solarradiation heats up the contaminated water and allows the water to evaporate, leaving the contaminant behind • System design collects distilled water for use • Technology purifies water and can serve from one person to a community depending on the size of system installed
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- 43. Solar Chimney A solarchimney is a technology that can be used to enhance the ventilation of a residential or commercial structure.
- 44. Solar Water Heater- Overview • A solar water heater concentrates solar energy over a time gradient • Common usage ranges from pool heaters to hot water for showering and domestic use • The most popular solar collector • Heavily used in Florida until World War 2 increased the demand for copper
- 45. Solar Water Heater- Components • Conductive thermal collectors (painted black to aide absorption) • Transparent cover to capture solar radiation • Pipes for water flow • Insulation • Water body
- 46. Solar Water Heater- Passive Design • Passive design uses thermal convection to circulate heat in the water system • The water body needs to be above the solar collector • As water heats up it rises into the water body pushing cold water down
- 47. Passive Solar WaterDesign
- 48. Solar Water Heater- Active Design • Uses pumps to circulate hot water • Spends electricity lowering the energy savings
- 49. Applying Solar WaterHeating • The solar collector should be placed facing South and at an angle equal to that of the latitude • For increased efficiency angle should be increase by 15 degrees during the winter season and decreased by 15 degrees in the summer • This makes the angle to the sun closest to 90 degrees during seasonal changes
- 50. 50 What are SolarCells? • Solar cells are devices which convert solar light energy directly into electricity • Sunlight contains packets of energy called photons that can be converted directly into electrical energy. • This is referred to as the photovoltaic effect. • Photo- means light and -voltaic means electrical current; • A solar cell provides direct current (DC) electricity, similar to batteries. • Batteries however use electrochemical reaction.
- 51. 51 Atoms An atom iscomposed of three different particles: • Nucleus- Center of the atom: 1. Protons (P+)-- positively charged. -- equal to the number of electrons. 2 Neutrons -- no charge. 3. Electrons (e-) -- negatively charged. -- orbit the nucleus. The outermost electrons of an atom determine its chemical and electrical properties Protons (P+) Neutrons (e-)
- 52. 52 Semiconductor Doping • Howcan we change the electrical properties of the pure Semiconductor material? • By adding foreign material to it, called dopants. (impurities) • Boron, phosphorus, arsenic are common dopants. • Rate of low :1 every 100,000,000 atoms high: 1 every 10,000 atoms Silicon (Si) with Phosphorus (P2,8,5) dopant : n-type (extra valence electrons are added) Silicon (Si) with Boron (B2,3) dopant = p-type (missing fourth valence electron, holes)
- 53. 53 Photon Hits theAtom of a “Semi” Material . www.altensol.comph/solal-photovoltaic Hole is the “empty space” left behind as a result of the movement of the free electron. Holes have + charge.
- 54. Disadvantages • Solar cellsare expensive. • They take up lots of space. • They only work in Sun light What is it? • Solar cells use energy from the Sun. • Solar panels transfer the Suns energy directly into electricity. Advantages • The energy from the Sun is free. • The sun does not produce greenhouse gases. • The sun will always be there during our lifetime.
- 55. 55 Solar Cell Schematic. . ProtectiveCover-Glass Electrical Contact Antireflective Layer N P-N Junction P Electrical Contact Load current
- 56. 56 . Sunlight ismade of photons, small particles of energy. These photons are absorbed by and pass through the material of a solar cell or solar PV panel. The photons 'agitate' the electrons found in the material of the photovoltaic cell. As they begin to move (or are dislodged), these are 'routed' into a current. This, technically, is electricity - the movement of electrons along a path. www.altensol.com.ph/solar_photovoltaic_philip The Process
- 57. 57 So, How doesit work? • Light breaks silicon bonds and creates “free” electrons and holes, “missing electrons” • Holes are positive charges • Built-in field separates electrons and holes Step 1. Photogeneration of charge carriers, electron (negative) and hole (positive). Step 2. Separation of the charge carriers through the medium.
- 58. Solar Photo voltaic(SPV) 58 • In photovoltaic conversion, Solar radiation falls on semi-conductor devices called solar cells which convert the sunlight directly into electricity. • When a bright light shines on a cell, energy from the light (photons) enables electrons to break free from the junction between them. This is called photo electric effect.
- 59. Solar Photo voltaic(SPV) 59 • N-Type – Excess electrons • N- Type- doping with phosphorous or arsenic • P- Type – Shortage of electrons • P Type – doping silicon with boron • When cell is connected to a load, Electron flow from n-type to p-type • The ratio of the maximum useful power to the ideal power is called fill factor(k). K=0.65 to0.80
- 60. n-type semiconductor p-type semiconductor + + ++ + + + + + + + + + + + - - - - - - - - - - - - - - - - - - Physics of Photovoltaic Generation Depletion Zone
- 61. Solar Photo voltaic(SPV) 61
- 62. Solar thermal powerplant 62
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- 64. Technical Specifications Battery :48 V Motor : 240W Transmission : Automatic Brake : Drum Brake Max.Speed : 25KMPH Mileage : 7 to 10 KM Charging : 3Hours Seat : Single Weight : 40Kg (Approx) Driver Wheels : Rear Front : Caster Wheel Body : Sheet Metal LXBXH : 105X36X80 CM
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