Presentation R Castro

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Presentation R Castro

  1. 1. 1 A LOOK AT PHOTOVOLTAICS Rui Castro, rcastro@ist.utl.pt IST – Technical University of Lisbon, Power Systems Group
  2. 2. The sun 2  Passive heat  This is heat which we receive from the sun naturally; this can be taken into account in the design of buildings so that less additional heating is required  Solar thermal  Uses the sun’s heat to provide hot water for buildings  Photovoltaic (PV) energy  Converts energy from the sun into electricity
  3. 3. Some figures 3 Renewables
  4. 4. Some figures 4 Wind
  5. 5. Some figures 5 PV
  6. 6. Some figures 6 PV annual increase Source: IEA Trends in Photovoltaic Applications
  7. 7. Europe: Global PV market leader 7 Source: Global Market Outlook for PV until 2013
  8. 8. How does PV work 8 Photovoltaic effect  Phenomenon that certain materials produce electric current when they are exposed to light  Discovered in 1839 by 19 year old Alexandre Edmond Becquerel French physicist  1873: Willoughby Smith discovered the photoconductivity of selenium  1923: Albert Einstein received the Nobel Prize for his theories explaining the photoelectric effect  1954: The PV effect in Cadmium was reported; primary work was performed by Rappaport, Loferski and Jenny
  9. 9. How does PV work 9 PN Junction and Semiconductors  One pure silicon crystal is doped with two different dopants (e.g. arsenic, gallium, aluminum, phosphorus)  One half of the crystal is left electron deficient: p-type layer and the other half has an excess of electrons: n-type layer  There is an electric field across the junction between the two halves  Electrons in the crystal can only travel in one direction - from the electron rich half to the electron poor half  Where the two halves of the crystal meet is called a PN junction, and this doped crystal is a semiconductor
  10. 10. How does PV work 10 Energy from sunlight  The light from the sun is made up of packets of energy called Photons  When a visible light photon strikes a solar cell it can pass straight through, be reflected, or be absorbed  If the photon is absorbed its energy is absorbed by an electron enabling it to cross the junction and fill a hole  Electrons are physically moving across the PN junction and the holes are moving in the opposite direction  DC current is established around the load circuit
  11. 11. PV power 11  The power that a PV produces depends on  The amount of incident sunlight (irradiance)  The efficiency of the PV at converting this light to electricity  Peak power (Wp)  Output power at Standard Test Conditions (STC)  STC: teta=25ºC; G=1000W/m2
  12. 12. PV electricity potential in Europe 12
  13. 13. Annual frequency of hourly irradiation 13 Lisboa 5000 4170 4000 Frequência de ocorrência (h) 3000 2000 1093 1000 598 568 484 523 322 332 275 235 159 0 0 0-100 100-200 200-300 300-400 400-500 500-600 600-700 700-800 800-900 900-1000 Radiação (W/m2)
  14. 14. Average monthly irradiation 14 400 307,0 300,2 300 Radiação solar incidente G (W/m2) 273,9 262,9 217,2 209,6 200 177,2 135,5 111,9 100 87,8 77,0 63,6 0 Jan Fev Mar Abr Mai Jun Jul Ago Set Out Nov Dez
  15. 15. Some simple technical calculations 15  Global yearly irradiation @ Lisbon:  H=1600kWh/m2  Sample PV module:  Pp=200Wp, A=1,5m2  Average efficiency:  Ef=12%  Yearly PV energy production:  Ea=12%*1600*1,5=288kWh  Yearly utilization factor (equivalent hours @ peak power)  ha=Ea/Pp=1440h
  16. 16. Renewables utilization factor 16 Large Hydro Portugal Wind PV
  17. 17. PV technologies 17 Crystalline silicon technology  Efficiency ranges between 12% and 17%  This is the most common technology representing about 90% of the market today  Types of crystalline cells  Monocrystalline (Mono c-Si)  Polycrystalline (or Multicrystalline) (multi c-Si)  Ribbon sheets (ribbon-sheet c-Si)
  18. 18. PV technologies 18 Thin film technology  Depositing extremely thin layers of photosensitive materials onto a low-cost backing such as glass, stainless steel or plastic  Lower production costs compared to the more material- intensive crystalline technology  Price advantage is currently counterbalanced by lower efficiency (5% to 13%)  Types of thin film modules depend on the active material  Amorphous silicon (a-Si)  Cadmium telluride (CdTe)  Copper Indium/gallium Diselenide/disulphide (CIS, CIGS)  Multi junction cells (a-Si/m-Si)
  19. 19. Thin films 19
  20. 20. PV technologies 20 Other cell types  Concentrated photovoltaic (CPV)  Designed to operate with concentrated sunlight  Built into concentrating collectors that use a lens to focus the sunlight onto the cells  Use very little of the expensive semiconducting PV material while collecting as much sunlight as possible  Efficiencies are in the range of 20 to 30%  Flexible cells  Based on a similar production process to thin film cells, when the active material is deposited in a thin plastic, the cell can be flexible  This opens the range of applications, especially for Building integration (roofs-tiles)
  21. 21. 21 CPV MST Ltd. (Israel) is developing a novel concentrating PV (CPV) technology. The basic unit is the solar tracker, with an output power of about 50 kWp. The system's lenses concentrate sunlight to 500 suns on multi-junction highly-efficient (37 %) solar cells.
  22. 22. Flexible cells 22
  23. 23. PV applications 23 Grid-connected domestic systems  Most popular type for homes and businesses in developed areas  Connection to the local electricity network  An inverter is used to convert the DC power to AC
  24. 24. London City Hall, 67 kWp PV system 24
  25. 25. Woking Station (UK), 73 kWp PV 25
  26. 26. Chicken farm, 160 kWp solar tiles, 26 Switzerland
  27. 27. PV housing community, Malaysia 27
  28. 28. PV applications 28 Grid-Connected power plants  Production of a large quantity of photovoltaic electricity in a single point  The size ranges from several hundred kilowatts to several megawatts
  29. 29. Solar farm, 23 MW PV, Spain 29
  30. 30. Solar farm, 20 MW PV, Spain 30
  31. 31. PV applications 31 Off-grid for rural electrification  Where no mains electricity is available  The system is connected to a battery via a charge controller  An inverter can be used to provide AC power  Use of normal electrical appliances
  32. 32. PV applications 32 Off-grid industrial applications  Repeater stations for mobile telephones  Traffic signals  Marine navigation aids  Security phones  Remote lighting  Highway signs  Waste water treatment plants
  33. 33. PV in Portugal 33 Source: IEA Report 2008 - Portugal
  34. 34. Moura PV Power Plant 34  One of the world largest centralized PV plants, with 45,6 MWp installed power  Located @ Amareleja, east Alentejo and owned and operated by Acciona Energy  Built in about 13 months  262 080 PV modules  2520 solar trackers (azimuthal)  Area occupied 250 ha  The estimated annual output is 93 GWh  Final yield slightly over 2000 kWh/kWp Source: IEA Report 2008 - Portugal
  35. 35. Moura power plant 35 Aerial view
  36. 36. Moura power plant 36 Sun tracking system
  37. 37. 37 Double sun (Portugal) WS Energia developed and patented the DoubleSun® Technology which duplicates the annual energy yield of commercial PV modules by combining extremely light flat mirrors with easy-to- mount, quick-to-install tracking systems.
  38. 38. Costs 38 Feed-in tariff vs market prices Renewables feed-in tariff Market price Source: Energy Services Regulatory Authority
  39. 39. Costs 39 Renewables feed-in tariff PV Wind Source: Energy Services Regulatory Authority
  40. 40. Some simple economic calculations 40 PV Wind • Investment=5€/Wp • Investment=1€/W • Utilization =1500h • Utilization=2200h • Cost=370€/MWh • Cost=70€/MWh Energy cost Energy cost Utilization Investment

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