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Professor Humayun A Mughal Chairman, Akhter Group PLC

Photovoltaic Technology. The answer to Global Warming?. Professor Humayun A Mughal Chairman, Akhter Group PLC. Key Issues. Global Warming – a Reality Energy Production – major Contributor Growing Demand for Electricity – no Going back Green Energy – is The Only Option

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Professor Humayun A Mughal Chairman, Akhter Group PLC

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  1. Photovoltaic Technology.The answer toGlobal Warming? Professor Humayun A MughalChairman, Akhter Group PLC

  2. Key Issues Global Warming – a Reality Energy Production – major Contributor Growing Demand for Electricity – no Going back Green Energy – is The Only Option The PHOTOVOLTAIC technology – is the Green Option PV is the ANSWER to our needs - Economic,Environmentally friendlyand Renewable

  3. Warming World  At-a-glance: Climate change - evidence and predictions

  4. Long Term High  At-a-glance: Climate change - evidence and predictions

  5. Sea Level Rise  At-a-glance: Climate change - evidence and predictions

  6. Growing Emissions  At-a-glance: Climate change - evidence and predictions

  7. Quick Climate Quiz Cows are guilty of speeding up Global Warming. A - True A - True B - False Methane is the second most significant greenhouse gas and cows are one of the greatest methane emitters. Their grassy diet and multiple stomachs cause them to produce methane, which they exhale with every breath.

  8. Quick Climate Quiz Which country has the highest CO2 emissions per capita? A - Australia B - Canada C - Kuwait D - UAE D - UAE E - USA The Carbon Dioxide Information Analysis Center figures: UAE - 6.17 metric tonnes of carbon per capita Kuwait - 5.97, US - 5.4, Australia - 4.91, UK - 3.87. If total greenhouse gas emissions are compared, some analysts say Australia comes out higher than the US.

  9. The big CO2 emitters

  10. ENERGY USE WorldWide Energy Consumption 1980-2030

  11. Wheredoes ourenergy come from? Share of total Primary Energy Supply in 2002 10,376 Mtoe IEA Energy Statistics

  12. Increasing percentage of Total World Energy used for Electricity Generation Quadrillion BTU 41.6% Electricity is becoming more important 35.6%

  13. Electricity How much do we use? Electricity Use: International Energy Outlook 2002 Population: US Census Bureau

  14. Focus on Electricity World Electricity Generation by Fuel

  15. Coal • Easy to find, cheap, but high emissions • Steps toward increased efficiency: • New Super-critical plant designs • Increase in biomass co-firing • Gas turbine exhausts to heat boiler feedwater • Improvements in thermal efficiency

  16. Hydro Technically exploitablecapability(TWh/yr) Hydropower - Regional Distribution 1999 generation(TWh) • Potential in 150+countries • Proven, advanced technology • Extremely efficient conversion • Low operating costs, long plant life • Often integrated with other developments

  17. Nuclear shares of national electricity generation - 2005 Nuclear • Little pollution • Virtually 0 greenhouse gas • Environmentally benign plants

  18. Natural Gas Air Pollution from the Combustion of Fossil Fuels kg of emission per TJ of energy consumed Sources: U.S. Environmental Protection Agency; American Gas Association • A Low CO2 emitter • Steps toward increased efficiency: • Combined-cycle power plants • Acid gas re-injection • Hydrogen fuel cells

  19. Oil • Electricity generation by: • Conventional Steam • Combustion Turbine • Combined-cycle • Solid waste burden • Air, land and water pollution

  20. Solar Energy The ULTIMATE source. How much is available? The sun’s rays provide enough energy to supply 10,000 timesthe TOTAL energy requirementof mankind. So, howdo we harness it? • Solar Thermal • Photovoltaic

  21. Photovoltaic Possible materials to make PV cells • CdTe Cadmium Telluride • CiGs Copper Indium Gallium Diselenide • Polymers Solar power market share by technology • Silicon Amorphous Thin Film Mono crystallineMulti crystalline

  22. “Sand” Metallurgical Grade Silicon Ingot Electronic Grade Chunks Bars Modules Wafers Strings Cells The Chain

  23. Manufacturing Process Let’s start on the beach! • The starting point is mined quartz sand, SiO2 • Chemical companies produce metallurgical grade (99%) silicon. • It’s not good enough! We need 99.999999% purity.

  24. Manufacturing Process Metallurgical Grade Silicon Silicon Dioxide is mined from the earth's crust, melted, and taken through a complex series of reactions that occur in a furnace with temperatures from 1500 to 2000 oC to produce Metallurgical Grade Silicon (MG-Si). Source - Wacker

  25. Manufacturing Process Hydrochlorination of Silicon MG-Si is reacted with HCl to form trichlorosilane (TCS) in a fluidized-bed reactor. The TCS will later be used as an intermediate compound for polysilicon manufacturing. The TCS is created by heating powdered MG-Si at around 300 oC in the reactor. In the course of converting MG-Si to TCS, impurities such as Fe, Al and B are removed. Si + 3HCl -----> SiHCL3 + H2

  26. Manufacturing Process Distillation of Trichlorosilane The next step is to distill the TCS to attain a high level of purity. At a boiling point of 31.8oC, the TCS is fractionally distilled to result in a level of electrically active impurities of less than 1ppba. The hyper-pure TCS is then vaporized, diluted with high-purity hydrogen, and introduced into a deposition reactor for the polysilicon manufacturing process.

  27. Manufacturing Process Polysilicon Manufacturing Conversion of hyper-pure TCS back tohyper-pure Silicon in poly deposition bells.Thin U-shaped silicon slimrods heated to ~1100 oC.Part of TCS is reduced to Silicon that slowly growsover the slimrods to a final diameter of 20cm or more. Besides the reduction to Silicon, part of the TCS disproportions to the by-product SiCl4.Polysilicon has typical metal contaminationof <1/100ppb and dopant impurities in the rangeof <1ppb. It is now suitable for further processing.

  28. Manufacturing Process Polysilicon Manufacturing The process focusshifts to the silicon’s atomic structure. It must be tranformed into ingots with a singular crystal orientation (this is the primary purpose of Crystal Growing). Before the Polysilicon can be utilized in the Crystal Growing process, it must be first mechanically broken into a chunks of 1 to 3 inches and undergo stringent surface etching and cleaning to maintain a high level of purity. These chunks are then arranged into quartz crucibles which are packed to a specific weight; typically more than 100kg for 200mm crystals to be grown. The next step is the actual crystal growing process.

  29. Manufacturing Process Crystal Growing The crystal growing process simply re-arranges silicon atoms into a specific crystal orientation. The packed crucible is carefully positioned into the lower chamber of a furnace (right). The polysilicon chunks are melted into liquid form, thengrown into an ingot. As the polysilicon chunks reach their melting point of 1420 oC, they change from solid to hot molten liquid. Heat Exchange Method (HEM) is used to form crystalline structure.

  30. Manufacturing Process Crystal Growing Computer Simulation of HEM Process

  31. Manufacturing Process Ingot Sectioning The process in the furnace will see the molten liquid formed into an ingot, using a directional solidification system (DSS), that may be sectioned into silicon bars.

  32. Manufacturing Process Ingot Sectioning The Ingot bricks are cut down …. Bars Ingot sectioning saw Cropping saw

  33. Manufacturing Process Wafer Production …. and sliced to create wafers. Wire Saw Wafers

  34. Manufacturing Process From Wafers Production line designed to produce photovoltaicsolar cells with as-cut p-type wafers for starting material.

  35. 1 2 3 4 7 5 6 Manufacturing Process Cell Production 1. Surface etch …………………... 2. Texturing ………………………. 3. Junction formation ……………. 4. Edge etch ……………………… 5. Oxide Etch ……..……………... 6. Antireflection coating …….…... 7. Metalization ……………..…….. 8. Firing ……..…………………….. 9. Wafer/Cell Characterization

  36. Manufacturing Process –Cell Production Surface Etch Removes saw damage (about 12 m on all sides). Texturing Roughens surface to minimise light reflection .

  37. Manufacturing Process –Cell Production Junction FormationPhosphorous diffused into wafer to form p-n junction Diffusion Furnace .

  38. Manufacturing Process –Cell Production Edge EtchRemoves the junction at the edge of the wafer Wafer Holder . Plasma Etch Station

  39. Manufacturing Process –Cell Production Oxide EtchRemoves oxides from surface formed during diffusion Wafer Etch Station .

  40. Manufacturing Process –Cell Production Anti-Reflection CoatingA silicon nitride layer reduces reflection of sunlight and passivates the cell Plasma PECVD Furnace .

  41. Manufacturing Process –Cell Production MetalisationFront and back contacts as well as the back aluminum layer are printed Screen Printerwith automaticloading and unloadingof cells .

  42. Manufacturing Process –Cell Production FiringThe metal contacts are heat treated (“fired”) to make contact to the silicon. Firing furnace to sinter metal contacts .

  43. Module Production

  44. Price Trend Estimate of global average solar module prices US$/watt

  45. Cost Breakdown Produced in Low labour cost area (Labour cost $2/hour) 8.9% 2.6% 10.5% 78%

  46. The Future Is Bright Example of cost recovery on an installation amortised over 25 years. Assumes an increase in fossil fuel costs of 5% pa. PV generatedper kwh Fossil generatedper kwh

  47. Future Developments R&D is focused on increasing conversion efficiency and reducing cell manufacturing cost, to reduce electricity generation cost. • Improved crystallisation processes for high quality, low-cost silicon wafers • Advanced silicon solar cell device structures and manufacturing processes • Technology transfer of high efficiency solar cell processes from the laboratory to high volume production • Reduction of the silicon wafer thickness to reduce the consumption of silicon • Stable, high efficiency thin-film cells to reduce semiconductor materials costs • Novel organic and polymer solar cells with potentially low manufacturing cost • Solar concentrator systems using lenses or mirrors to focus the sunlight onto small-area, high-efficiency solar cells

  48. AKHTER Improved Cell Efficiency • Laser Grooved Buried Contact Layer • High Efficiency Si Cells • Currently up to 19% Efficiency • Production Efficiencies up to 17%

  49. AKHTER Solar Lens Development • Optical Design • Polarisation effects and the effects of real draught angles and facet sizes. • Lens Zones modelled as a series of annular cones.

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