光伏发电设计与安装 113p

Photovoltaic Design and Installation,Bucknell University Solar Scholars Program,Presenters: Colin Davies 08Eric Fournier 08,Outline,Why Renewable Energy?The Science of PhotovoltaicsSystem ConfigurationsPrinciple Design Elements The Solar Scholars program at Bucknell (walking tour),Whats wrong with this 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 plants.,40%,85% of our energy consumption is from fossil fuels!,Why Sustainable Energy Matters,The 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 (which can lead to political and economic instability),Why Sustainable Energy Matters,Detrimental 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 ecosystems),A Sustainable Energy Future,Develop and deploy renewable energy sources on a much wider scaleBring down cost of renewable energyMake improvements in the efficiency of energy conversion, distribution, and use,Three Methods:- Incentives- Economy of scale- Regulation,Making the Change to Renewable Energy,Solar Geothermal Wind Hydroelectric,Todays Solar Picture,Germany 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 is 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 Pennsylvania,Pennsylvania is in fact a leader in renewable energyIncentivesLocal & state grant and loan programsTax deductionsRECs (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 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.,Electricity,Part 2: Learning Objectives,Compare AC and DC electrical current and understand their 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 energy 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 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 Terminology,Watt (W) are a measure of Power Unit rate of electrical energyAmps x Volts = Watts 1 Kilowatt (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 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 Electrical Current,DC = Direct Current PV panels produce DCBatteries store DC AC = Alternating Current Utility power Most consumer appliances use AC,Meters and Testing,Clamp on meter Digital multimeter Never test battery current using a multimeter!,System Types,Part 1: Learning Objectives,Understand the functions of PV componentsIdentify different system types,Photovoltaic (PV) Terminology,Cell Module Panel Negative to groundAC side of system = Neutral to ground,Batteries,Part 4: Learning Objectives,Battery basicsBattery functionsTypes of batteries Charging/dischargingDepth of dischargeBattery safety,Batteries in Series and Parallel,Series connectionsBuilds voltageParallel connections Builds amp-hour capacity,Battery Basics,BatteryA device that stores electrical energy (chemical energy to electrical energy and vice-versa)CapacityAmount of electrical energy the battery will containState of Charge (SOC)Available battery capacityDepth of Discharge (DOD)Energy taken out of the batteryEfficiencyEnergy out/Energy in (typically 80-85%),The Terms:,Functions of a Battery,Storage for the nightStorage during cloudy weatherPortable powerSurge for starting motors,*Due to the expense and inherit inefficiencies of 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 Details,Primary (single use)Secondary (recharged)Shallow Cycle (20% DOD)Deep Cycle (50-80% DOD),Types:,Unless lead-acid batteries are charged up to 100%, they will loose capacity over timeBatteries should be equalized on a regular basis,Charging/Discharging:,Battery Capacity,Amps x Hours = Amp-hours (Ah),Capacity:,100 amps for 1 hour1 amp for 100 hours20 amps for 5 hours,Capacity changes with Discharge RateThe higher the discharge rate the lower the capacity and vice versaThe higher the temperature the higher the percent of rated capacity,100 Amp-hours =,Rate of Charge or Discharge,Rate = C/TC = Batterys rated capacity (Amp-hours)T = The cycle time period (hours),Maximum recommend charge/discharge rate = C/3 to C/5,Cycle Life vs. Depth of Discharge,Depth Of Discharge (DOD) %,# of Cycles,Battery Safety,Batteries 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 new)Always disconnect batteries, and make sure tools have insulated handles to prevent short circuiting,Battery Wiring Considerations,Battery wiring leads should leave the battery bank from opposite cornersEnsures equal charging and discharging; prolongs battery lifeMake sure configuration of battery bank allows for proper connections to be easily made,Controllers & Inverters,Part 5: Learning Objectives,Controller basicsController featuresInverter basicsSpecifying an inverter,Controller Basics,To protect batteries from being overcharged,Function:,Maximum Power Point TrackingTracks the peak power point of the array (can improve power production by 20%)!,Features:,Additional Controller Features,Voltage 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 batteriesTemperature Compensation: adjusts the charging of batteries according to ambient temperature,Other Controller Considerations,When specifying a controller you must consider:DC input and output voltageInput and output currentAny optional features you needController redundancy: On a stand-alone system it might be desirable to have more then one controller per array in the event of a failure,Inverter Basics,An electronic device used to convert direct current (DC) electricity into alternating current (AC) electricity,Function:,Efficiency penaltyComplexity (read: a component which can fail)Cost!,Drawbacks:,Specifying an Inverter,What 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 current (based on modules and wiring)Surge CapacityEfficiencyWeather protectionMetering/programming,Solar Site,Part 6: Learning Objectives,Understand azimuth and altitudeExplain magnetic declinationDescribe proper orientation and tilt angle for solar collectionDescribe the concept of “solar window”,Site Selection Panel Direction,Face southCorrect for magnetic declination,Orientation and Tilt Angle,Sun Chart for 40 degrees N Latitude,Site Selection Tilt Angle,Year round tilt = latitudeWinter + 15 lat.Summer 15 lat.,Max performance isachieved when panelsare perpendicular to thesuns rays,Solar Access,Optimum Solar Window 9 am 3 pmArray should have NO SHADING in this window (or longer if possible),Solar Pathfinder,An essential tool in finding a good site for solar is the Solar PathfinderProvides daily, monthly, and yearly solar hours estimates,Practical Determinants for Site Analysis,Loads and time of useLocal climate characteristicsDistance from power conditioning equipment Accessibility for maintenanceAesthetics,Energy Efficiency,Part 7: Learning Objectives,Identify cost effective electrical load reduction strategies List problematic loads for PV systemsDescribe penalties of PV system components Explain phantom loadsEvaluate types of lighting; efficiency comparison,Practical Efficiency Recommendations,For 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 shines,Typical Wattage Requirements,Appliances to Avoid,Electric oven or stoveElectric space heaterDishwasher with heatersElectric water heaterElectric clothes dryer,Improving Energy Efficiency in the Home,Space Heating:Super insulationPassive solar design Wood stovesPropaneSolar hot waterRadiant Floor/ baseboardEfficient windows,Domestic hot water heatingSolar thermal Propane/natural gasNo electric heatersOn demand hot water,Improving Energy Efficiency in the Home,Kitchen 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 Loads,Cost 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 electricity,Lighting Efficiency,Factors effecting light efficiencyType