光伏發(fā)電設(shè)計與安裝 113p

1、Photovoltaic Design and Installation Bucknell University Solar Scholars Program Presenters: Colin Davies 08Eric Fournier 08OutlineWhy Renewable Energy?The Science of PhotovoltaicsSystem ConfigurationsPrinciple Design Elements The Solar Scholars program at Bucknell (walking tour)Whats wrong with this

2、 picture? Pollution from burning fossil fuels leads to an increase in greenhouse gases, acid rain, and the degradation of public health.In 2005, the U.S. emitted 2,513,609 metric tons of carbon dioxide, 10,340 metric tons of sulfur dioxide, and 3,961 metric tons of nitrogen oxides from its power pla

3、nts.40%85% of our energy consumption is from fossil fuels!Why Sustainable Energy MattersThe worlds current energy system is built around fossil fuelsProblems:Fossil fuel reserves are ultimately finiteTwo-thirds of the world s proven oil reserves are locating in the Middle-East and North Africa (whic

4、h can lead to political and economic instability)Why Sustainable Energy MattersDetrimental environmental impactsExtraction (mining operations)CombustionGlobal warming? (could lead to significant changes in the world s climate system, leading to a rise in sea level and disruption of agriculture and e

5、cosystems)A Sustainable Energy FutureDevelop and deploy renewable energy sources on a much wider scaleBring down cost of renewable energyMake improvements in the efficiency of energy conversion, distribution, and useThree Methods:- Incentives- Economy of scale- RegulationMaking the Change to Renewab

6、le Energy Solar Geothermal Wind Hydroelectric Todays Solar PictureGermany leads solar production (over 4.5 times more then US production) Japan is 2nd (nearly 3 times more then US production) this is mainly due to incentivesFinancial IncentivesInvestment subsidies: cost of installation of a system i

7、s subsidized Net metering: the electricity utility buys PV electricity from the producer under a multiyear contract at a guaranteed rateRenewable Energy Certificates (RECs)Solar in PennsylvaniaPennsylvania is in fact a leader in renewable energyIncentivesLocal & state grant and loan programsTax dedu

8、ctionsRECs (in 2006: varied from $5 to $90 per MWh, median about $20)Harnessing the Sun Commonly known as solar cells, photovoltaic (PV) devices convert light energy into electrical energyPV cells are constructed with semiconductor materials, usually silicon-basedThe photovoltaic effect is the basic

9、 physical process by which a PV cell converts sunlight into electricityWhen light shines on a PV cell, it may be reflected, absorbed, or pass right through. But only the absorbed light generates electricity.ElectricityPart 2: Learning Objectives Compare AC and DC electrical current and understand th

10、eir important differences Explain the relationship between volts, amps, amp-hours, watts, watt-hours, and kilowatt-hours Learn about using electrical meters Electricity Terminology Electricity = Flowing electrons Differences in electrical potential create electron flow Loads harness the kinetic ener

11、gy of these flowing electrons to do work Flowing water is a good conceptual tool for understanding Electricity Terminology Voltage (E or V) Unit of electromotive force Can be thought of as electrical pressureAmps (I or A)Rate of electron flow Electrical current 1 Amp = 1 coulomb/second = 6.3 x 1018

12、electrons/second Electricity Terminology Resistance (R or ) The opposition of a material to the flow of an electrical current Depends onMaterial Cross sectional areaLength Temperature Electricity TerminologyWatt (W) are a measure of Power Unit rate of electrical energyAmps x Volts = Watts 1 Kilowatt

13、 (kW) = 1000 watts Electricity Terminology Watt-hour (Wh) is a measure of energy Unit quantity of electrical energy (consumption and production) Watts x hours = Watt-hours 1 Kilowatt-hour (kWh) = 1000 Wh Power and Energy Calculation Draw a PV array composed of four 75 watt modules. What size is the

14、system in watts ?Electricity Terminology Amp-hour (Ah) Quantity of electron flow Used for battery sizing Amps x hours = Amp-hours Amp-hours x Volts = Watt-hours A 200 Ah Battery delivering 1A will last _ hours 200 Ah Battery delivering10 A will last _ hours 100 Ah Battery x 12 V = _ Wh Types of Elec

15、trical Current DC = Direct Current PV panels produce DCBatteries store DC AC = Alternating Current Utility power Most consumer appliances use ACMeters and TestingClamp on meter Digital multimeter Never test battery current using a multimeter!System TypesPart 1: Learning Objectives Understand the fun

16、ctions of PV componentsIdentify different system typesPhotovoltaic (PV) Terminology Cell Module Panel Negative to groundAC side of system = Neutral to groundBatteriesPart 4: Learning ObjectivesBattery basicsBattery functionsTypes of batteries Charging/dischargingDepth of dischargeBattery safetyBatte

17、ries in Series and Parallel Series connectionsBuilds voltageParallel connections Builds amp-hour capacityBattery BasicsBatteryA device that stores electrical energy (chemical energy to electrical energy and vice-versa)CapacityAmount of electrical energy the battery will containState of Charge (SOC)A

18、vailable battery capacityDepth of Discharge (DOD)Energy taken out of the batteryEfficiencyEnergy out/Energy in (typically 80-85%)The Terms:Functions of a BatteryStorage for the nightStorage during cloudy weatherPortable powerSurge for starting motors*Due to the expense and inherit inefficiencies of

19、batteries it is recommended that they only be used when absolutely necessary (i.e. in remote locations or as battery backup for grid-tied applications if power failures are common/lengthy)Batteries: The DetailsPrimary (single use)Secondary (recharged)Shallow Cycle (20% DOD)Deep Cycle (50-80% DOD)Typ

20、es:Unless lead-acid batteries are charged up to 100%, they will loose capacity over timeBatteries should be equalized on a regular basisCharging/Discharging:Battery CapacityAmps x Hours = Amp-hours (Ah)Capacity:100 amps for 1 hour1 amp for 100 hours20 amps for 5 hoursCapacity changes with Discharge

21、RateThe higher the discharge rate the lower the capacity and vice versaThe higher the temperature the higher the percent of rated capacity100 Amp-hours =Rate of Charge or DischargeRate = C/TC = Batterys rated capacity (Amp-hours)T = The cycle time period (hours)Maximum recommend charge/discharge rat

22、e = C/3 to C/5Cycle Life vs. Depth of DischargeDepth Of Discharge (DOD) % # of CyclesBattery SafetyBatteries are EXTREMELY DANGEROUS; handle with care!Keep batteries out of living space, and vent battery box to the outsideUse a spill containment vesselDont mix batteries (different types or old with

23、new)Always disconnect batteries, and make sure tools have insulated handles to prevent short circuitingBattery Wiring ConsiderationsBattery wiring leads should leave the battery bank from opposite cornersEnsures equal charging and discharging; prolongs battery lifeMake sure configuration of battery

24、bank allows for proper connections to be easily madeControllers & InvertersPart 5: Learning ObjectivesController basicsController featuresInverter basicsSpecifying an inverterController BasicsTo protect batteries from being overchargedFunction:Maximum Power Point TrackingTracks the peak power point

25、of the array (can improve power production by 20%)!Features:Additional Controller FeaturesVoltage Stepdown Controller: compensates for differing voltages between array and batteries (ex. 48V array charging 12V battery)By using a higher voltage array, smaller wire can be used from the array to the ba

26、tteriesTemperature Compensation: adjusts the charging of batteries according to ambient temperatureOther Controller ConsiderationsWhen specifying a controller you must consider:DC input and output voltageInput and output currentAny optional features you needController redundancy: On a stand-alone sy

27、stem it might be desirable to have more then one controller per array in the event of a failure Inverter BasicsAn electronic device used to convert direct current (DC) electricity into alternating current (AC) electricityFunction:Efficiency penaltyComplexity (read: a component which can fail)Cost!Dr

28、awbacks:Specifying an InverterWhat type of system are you designing?Stand-aloneStand-alone with back-up source (generator)Grid-Tied (without batteries)Grid-Tied (with battery back-up)Specifics:AC Output (watts)Input voltage (based on modules and wiring)Output voltage (120V/240V residential)Input cur

29、rent (based on modules and wiring)Surge CapacityEfficiencyWeather protectionMetering/programmingSolar SitePart 6: Learning Objectives Understand azimuth and altitudeExplain magnetic declinationDescribe proper orientation and tilt angle for solar collectionDescribe the concept of “solar windowSite Se

30、lection Panel DirectionFace southCorrect for magnetic declinationOrientation and Tilt AngleSun Chart for 40 degrees N LatitudeSite Selection Tilt AngleYear round tilt = latitudeWinter + 15 lat.Summer 15 lat.Max performance isachieved when panelsare perpendicular to thesuns raysSolar AccessOptimum So

31、lar Window 9 am 3 pmArray should have NO SHADING in this window (or longer if possible)Solar PathfinderAn essential tool in finding a good site for solar is the Solar PathfinderProvides daily, monthly, and yearly solar hours estimatesPractical Determinants for Site AnalysisLoads and time of useLocal

32、 climate characteristicsDistance from power conditioning equipment Accessibility for maintenanceAestheticsEnergy EfficiencyPart 7: Learning Objectives Identify cost effective electrical load reduction strategies List problematic loads for PV systemsDescribe penalties of PV system components Explain

33、phantom loadsEvaluate types of lighting; efficiency comparisonPractical Efficiency RecommendationsFor every $1 spent on energy efficiency, you save $3-$5 on system costAdopt a load dominated approach Do it efficiently Do it another wayDo with lessDo without Do it using DC powerDo it while the sun sh

34、ines Typical Wattage Requirements ApplianceWattageBlender350TV (25 inch)130Washer1450Sunfrost Refrigerator (7 hours a day)refrigerator/freezer (13 hours a day)112475Hair Dryer1000Microwave (.5 sq-ft)Microwave (.8 1 sq-ft)7501400Appliances to AvoidElectric oven or stoveElectric space heaterDishwasher

35、 with heatersElectric water heaterElectric clothes dryerImproving Energy Efficiency in the HomeSpace Heating:Super insulationPassive solar design Wood stovesPropaneSolar hot waterRadiant Floor/ baseboardEfficient windowsDomestic hot water heatingSolar thermal Propane/natural gasNo electric heatersOn

36、 demand hot water Improving Energy Efficiency in the HomeKitchen StovesSolar cookers Gas burners- no glow bar ignition MicrowavesWashing machinesHigh efficiency horizontal axis Cooling Ceiling fans Window shadesEvaporative cooling InsulationTreesReflective attic coverAttic fan Phantom Loads Phantom

37、LoadsCost the United States:$3 Billion / year10 power plants 18 million tons of CO2More pollution than 6 million cars TVs and VCRs alone cost the US $1 Billion/year in lost electricityLighting EfficiencyFactors effecting light efficiencyType of lightPositioning of lightsFixture designColor of ceilin

38、gs and wallsPlacement of switchesIncandescent LampsAdvantages Most commonLeast expensivePleasing lightDisadvantages Low efficiency Short life 750 hoursElectricity is conducted through a filament which resists the flow of electricity, heats up, and glowsEfficiency increases as lamp wattage increasesF

39、ROM THE POWER PLANT TO YOUR HOME INCANDESCENT BULBS ARE LESS THAN 2% EFFICIENCTFluorescent BulbsLes wattage, same amount of lumens Longer life (10,000 hours)May have difficulty starting in cold environmentsNot good for lights that are repeatedly turned on and offContain a small amount of mercury Lig

40、ht Emitting Diode (LED) LightsAdvantages Extremely efficient Long life (100,000 hours)Rugged No radio frequency interferenceDisadvantagesExpensive (although prices are decreasing steadily)A relatively new technology MountingPart 8: Learning ObjectivesEvaluate structural considerations List hardware requirementsPros and cons of different mounting techniquesGeneral ConsiderationsWeather characteristicsWind intensityEstimated snowfallSite characteristics Corrosive salt waterAnimal interferenceHuman factorsVandalism Theft protectionAestheticsBasic Mounting OptionsFixedRoof, groun