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Course tcd 08electric

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  • 1. Solar Electric Fundamentals
  • 2. Photovoltaics (PV) or Solar Electric• Direct conversion of sunlight into dc electricity.• Solid-state electronics, no-moving parts.• High reliability, warranties of 20 years or more.• PV modules are series- and parallel- interconnected to meet the voltage and current requirements.• Energy storage (battery) is needed for nighttime operation.
  • 3. Basic Electricity Terms• Ampere (Amp, A) – Basic unit of electric current, like the flow of water in a pipe.• Volt (V) – Basic unit of electric voltage (potential), like the pressure of water in a pipe.• Watt (W) – Basic unit of electric power. 1 Volt X 1 Amp = 1 Watt• Watt-Hour – Basic unit of electric energy. 1 Watt for 1 hour = 1 Watt-hour (Wh) 100 Watts for 10 hours = 1 kiloWatt-hour (kWh)
  • 4. Outline• Solar Industry Status• Solar Electric – Systems View• Solar PV Technology• Stand-alone Off-grid Applications• Grid-connected Applications• Intro to Hybrid Systems• Solar System Analysis Tools
  • 5. Outline• Solar Industry Status• Solar Electric – Systems View• Solar PV Technology• Stand-alone Off-grid Applications• Grid-connected Applications• Intro to Hybrid Systems• Solar System Analysis Tools
  • 6. A typical solar cell (10cm x 10cm)generates about 1W at about 0.5V.
  • 7. Individual cells are connected inseries (increases the voltage) and in parallel (increases the current) into a module.
  • 8. World PV Cell/Module Production (MW) 1194.71200 Rest of world1000 Europe Japan800 744.1 U.S.600 561.8 Average annual growth rate of 43% over last 5 390.5400 years; 57% in 2004 287.7 201.3200 154.9 125.8 77.6 88.6 40.2 46.5 55.4 57.9 60.1 69.4 0 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Source: Paul Maycock, PV News, February 2005 026587210
  • 9. PV Markets Government Other Utility Industrial • Most Cost Effective: Transportation – Small Loads • Emergency Call Commercial Boxes Residential • Irrigation Controls Other • Sign lighting Health – Avoided Line Grid Interactive Extensions ($20k to Cells/Modules $100k/mile) To OEM • Water Pumping Water Pumping • Residential – Remote Diesel Remote Generators ($0.19 Transportation to $1.68/kWh) Consumer Communications Goods2001 EIA data
  • 10. Outline• Solar Industry Status• Solar Electric – Systems View• Solar PV Technology• Stand-alone Off-grid Applications• Grid-connected Applications• Intro to Hybrid Systems• Solar System Analysis Tools
  • 11. Simple Direct Drive PV System What determines the system design? The amount of sun? The size of the solar array? The characteristics of the pump? Evaporation from the tank? The cow?
  • 12. Simple Direct Drive PV System Where do you start in a system design? With the Load Evaporation from the tank And the cow.
  • 13. Simple Direct Drive PV System Simplified Design Process The sun & weather determine the energy available The Load determines the size of the pump (power & flow)The solar array is sized todeliver the needed energyin the time available.
  • 14. Simple Direct Drive PV System What is the PV array size? 1000 W/m2 for 6 hours 1200 gal/day = 200 gal/hour 6 hours/day 1200 gal/day10% array efficiency= 100W/m2 200 gal/hr, from 50ft, for 100W
  • 15. Load Determination 1st Step in Dedicated System Design• Identify all energy • Use maximum power to needs, then diversify size wire, switchgear, &• Chose high efficiency inverter appliances • Use energy• Add up all power and requirements and calculate energy environment to size needed per day batteries• Determine what loads • Use distances & are right for Solar specific appliances to• Chose structures and determine phase & enclosures voltage
  • 16. Design Basics• dc motors make simplest systems; PV modules heart of the system.• Non-grid remote systems like lights, communications, etc. require energy storage (batteries); batteries are the heart of the system.• Complex loads like remote homes may require other generators and inverter; inverter is the heart of the system.• All designs start with the electrical (load) requirements.
  • 17. Design Basics• Total daily (use cycle) energy must be known or best estimate in kWh/cycle.• Largest power level must be known to determine wire size, safety gear, inverter specifications, etc.• Required system availability must be established.• Site specific resources must be determined.......resource maps and the like are not usable for design.
  • 18. Design Procedure• Determine loads—both kWh and ac or dc kW• Determine energy storage requirements• Set System availability• Size PV and other generation to meet load directly or charge the energy storage subsystem• Chose voltage, wiring, inverter, controls to match ampacity (Max current plus)
  • 19. Outline• Solar Industry Status• Solar Electric – Systems View• Solar PV Technology• Stand-alone Off-grid Applications• Grid-connected Applications• Intro to Hybrid Systems• Solar System Analysis Tools
  • 20. The Photovoltaic EffectPhosphorous: 5 valenceelectrons P Silicon: 4 valence electrons P-N Si Junction Boron: 3 valence electrons BNo material is consumed and the process could continue indefinitely
  • 21. “Czochralski” Technology
  • 22. Cast Polycrystalline Technology
  • 23. “Sheet” Technologies “Thin film” SiliconEdge-defined Film-fed Growth (EFG)
  • 24. PV CellsPV Cells are wired in and in parallel to increaseseries to increase voltage... current
  • 25. PV is ModularCells are assembled into modules, and modules into arrays.
  • 26. Thin Film Technologies On Glass
  • 27. Thin Film TechnologiesOn Flexible Substrates
  • 28. Building-Integrated PV (BIPV)
  • 29. Concentrating PV Systems Line Point Focus Focus 30-50X 100-1000X
  • 30. 36 cells in Series About 18 Volts
  • 31. Series connection increases voltage Parallel connection increases current
  • 32. Modules are connected in series andparallel to achieve the voltage and current needed for the system
  • 33. Collector Technology Considerations• Flat plate, single crystal and polycrystalline Si most common and high acceptance• Higher efficiencies usually mean less cost for wiring and structure• Tracking can provide more power and energy in less space but fixed costs must be compared• Long term performance essential.
  • 34. Outline• Solar Industry Status• Solar Electric – Systems View• Solar PV Technology• Stand-alone Off-grid Applications• Grid-connected Applications• Intro to Hybrid Systems• Solar System Analysis Tools
  • 35. Simple Direct Drive PV System
  • 36. WaterPumpingDesigns
  • 37. Rural Electrification: ClassicsHistorically, the primary means ofproviding power have been through gridextension and diesel generators. – Grid Extension: Very high initial cost, poor cost recovery, time intensive (generation, transmission, distribution) and usually must be subsidized. Most often used. – Diesel Generators: Inexpensive installation but expensive to operate, environmental damage/pollution, and subject to volatile fuel costs and availability.
  • 38. Solar Water Pumping Ute Mt. Ute Tribe , COInadequate Wind & High Maintenance Costs
  • 39. Simple DC PV System with Battery Storage
  • 40. Charge Controllerprotects the Batteries From: Overcharge, Over-Discharge
  • 41. Energy Storage• Deep cycle storage batteries are common• Batteries require a temperature moderated enclosure and maintenance• Storage size tied to electrical usage• Technical issues are temperature, temperature, and temperature-I’ll explain• Most systems with batteries use a charge control device
  • 42. Just like solar cells, batteries are connected in series and parallel to achieve the storage requirements
  • 43. 12 volt PV-Battery System
  • 44. Typical PV - Battery Systems
  • 45. DC PV System Example:PJKK Federal Building, HI • 2 solar panels per lamp with peak output of 96 watts • 39 Watt fluorescent lamps, 2500 lumens • 90 amp-hour battery powers 12 hours per night • ~$2500 per light
  • 46. Department of InteriorNational Park Service
  • 47. Military FieldApplications
  • 48. USDA Forest Service
  • 49. Wedding Day!!!In Xinjiang, China, the groombought 2-40 watt PV panels forthe bride as a wedding present.
  • 50. AC PV System with Inverter
  • 51. Inverter 5kWConverts Direct Current (DC) to Alternating Current (AC)
  • 52. 50 kW Inverter
  • 53. AC System Controls• Inverters convert dc to ac• Inverters require an enclosure and may be placed with switchgear and controllers• Inverters are matched to system voltage and maximum aggregate load• System controls represent the least reliable components in a PV system
  • 54. System Efficiency Efficiency = power out / power in Battery 80% Array 10% Round-trip Inverter 90% Efficiency Efficiency Efficiency100 Watts from sun > 10 Watts >8 Watts > 7.2 AC Watts to loadOverall system efficiency is product of component efficiencies.Example 0.10*0.80*0.90=0.072...exacerbated by “mismatch” losses, typical system efficiency = 0.06
  • 55. Outline• Solar Industry Status• Solar Electric – Systems View• Solar PV Technology• Stand-alone Off-grid Applications• Grid-connected Applications• Intro to Hybrid Systems• Solar System Analysis Tools
  • 56. Utility-Connected (Line-Tie) PV System
  • 57. Grid-connected Metering Requirements Depend on the Local Electric Utility
  • 58. Jicarilla, Apache, AZ2.4 kW Grid Connected Dulce High School
  • 59. Building-Integrated PV (BIPV)
  • 60. Utility-Connected PV Example: Presidio Thoreau Center • Building-Integrated Photovoltaics • 1.25 kW PV Array • Spacing between cells admits daylight into entry atrium below
  • 61. Outline• Solar Industry Status• Solar Electric – Systems View• Solar PV Technology• Stand-alone Off-grid Applications• Grid-connected Applications• Intro to Hybrid Systems• Solar System Analysis Tools
  • 62. Hybrid PV/Generator System
  • 63. Hybrid Power System Examples: “Communications” Carol Spring Mtn., AZ Mt. Home AFB, IDTest Ban Treaty Monitoring, Antarctica McMurdo Station, Antarctica
  • 64. Village Power Hybrids Simulation Models for Options Analysis Wind PV Inverter Diesel losses Fuel Cell RectifierBio-Power DC Bus AC Bus Wind lossesµ-Hydro µ-Turbines losses Dump Battery Load Load Bank losses Rate Structure
  • 65. Outline• Solar Industry Status• Solar Electric – Systems View• Solar PV Technology• Stand-alone Off-grid Applications• Grid-connected Applications• Intro to Hybrid Systems• Solar System Analysis Tools
  • 66. PV Design ToolsSystem Sizing Available SoftwareSystem Configuration – PVSYSTOn grid vs. Off grid – PV DESIGN PROEst. Power OutputBuilding Simulations – WATSUN PVShading – PV CADTemperature & Thermal – PV FORMPerformance – BLCCEconomic AnalysisAvoided Emissions – HOMERBuilding Energy Load Analysis – ENERGY-10Meteorological Data – AWNSHADELibrary of Modules, Batteries& Inverters
  • 67. PV Design Tools• PV Watts http://rredc.nrel.gov/solar/codes_algs/PVWATTS/ – Google: PVWATTS• RETScreen – PV – Google: RETScreen• HOMER Distributed System Hybrid Optimization Model – www.nrel.gov/homer