Basics Of Photovoltaic (PV) Systems For Grid-Tied Applications

Transcription

Basics of Photovoltaic (PV) Systemsfor Grid-Tied ApplicationsPacific Energy CenterEnergy Training Center851 Howard St.1129 Enterprise St.San Francisco, CA 94103Stockton, CA 95204Courtesy of DOE/NRELinstructorPete Shoemaker

Basics of Photovoltaic (PV) Systemsfor Grid-Tied ApplicationsMaterial in this presentation is protected by Copyright law.Reproduction, display, or distribution in print or electronicformats without written permission of rights holders isprohibited.Disclaimer: The information in this document is believed to accuratelydescribe the technologies described herein and are meant to clarify andillustrate typical situations, which must be appropriately adapted toindividual circumstances. These materials were prepared to be used inconjunction with a free, educational program and are not intended toprovide legal advice or establish legal standards of reasonablebehavior. Neither Pacific Gas and Electric Company (PG&E) nor anyof its employees and agents: (1) makes any written or oral warranty,expressed or implied, including, but not limited to, those concerningmerchantability or fitness for a particular purpose; (2) assumes anylegal liability or responsibility for the accuracy or completeness of anyinformation, apparatus, product, process, method, or policy containedherein; or (3) represents that its use would not infringe any privatelyowned rights, including, but not limited to, patents, trademarks, orcopyrights.Some images displayed may not be in the printed booklet because of copyright restrictions.

PG&E Solar Informationwww.pge.com/solarPacific Energy Center (San Francisco)www.pge.com/pecEnergy Training Center shopstraining/stockton

Contact InformationPete ShoemakerPacific Energy Center851 Howard St.San Francisco, CA 94103(415) 973-8850pjsy@pge.comSome images displayed may not be in the printed booklet because of copyright restrictions.

Agenda1.2.3.4.5.6.7.Big picture: Team CaliforniaElectricity FundamentalsPV TechnologyFeasibilityFinancesSales & Installation ProcessJobs Overview and Future Trends5

One Minute SummaryRent a portion of utility grid outputBuy your own power plantSameelectricityCURRENTPOSSIBLERENTCourtesy of DOE/NRELYour home needselectricityPacific Energy CenterSan FranciscoOWNSource: Pete ShoemakerThe basic economics arejust like the “rent vs. buy”of purchasing a home.6

The Big Picture:Team CaliforniaPacific Energy CenterSan Francisco7

The California Regulated UtilityFinancial StructureHow the utilities make money,and why they can support energyefficiency and conservation.

California’s regulated utilities cover mostof the state.PG&ESan Diego Gas &Electric (SDG&E)Southern CaliforniaEdison (SCE)Southern CaliforniaGas (SoCalGas)

They are essentially monopolies in theirrespective territories, and so need to beregulated.CPUCThe California Public Utilities Commission isthe regulatory body.

30 years ago, the utilities made money like mostbusinesses: on profits from sales.ProfitsEnergy SalesThe more energy they sold, the more profitthey made.

Also 30 years ago, California’s powerconsumption was rising rapidly, along with therest of the country.Per-capita powerconsumption.U.S.California

Projecting this into the future made peoplerealize that it was not sustainable, and thatsomething needed to be done.Very high utility billsMany more new power plantsSerious environmental consequences

We needed to lower people’s energy usage,but how?The utility companies had to be involved, buthow could you require them to encourageless energy usage, since their profits andbusiness model depended on more sales?Conclusion:The utility financial structure must change.

DECOUPLINGSeparating profits from sales.ProfitsEnergy SalesEnergy SalesProfits

Since 1978 (gas) and 1982 (electricity)California’s regulated utilities have madeprofits on INVESTMENTS, not SALES.These investments are directed by the CPUCand include energy efficiency andconservation.

Example of EE investment and target:1. The CPUC authorizes PG&E to spend themoney to give away 1,000,000 CFLs.2. The target over 3 years is to reduce electricconsumption [xx] mWh.3. If PG&E makes the target they can set ratesso that they earn [x]% for theirshareholders.4. If they exceed the target they can earnmore, if they miss the target they earn lessor even get penalized.

California utilities have NO incentive toincrease energy usage.They DO have mandates and incentives forenergy efficiency, conservation, andrenewables.The result?California, and PG&E, is the leader inenergy efficiency and renewablegeneration.

Solar Electric Trends

PG&E Electrical Power Mix 2009U.S. Electrical Power Mix June 2011Bioenergy4%Geothermal 4%Other1%Coal1%UnspecifiedWind 3%Small Hydro 3%Solar 1%(market purchases)15%Large Hydro13%Natural Gas35%Source: PG&ENuclear20%Source: U.S. Energy Information Administration,Electric Power Monthly

.Portfolio: Past, Present, and Future2002 Actual10.6% of total bundled retail sales2010 Actual16% of total bundled retail sales2020 Projected33% of total bundled retail sales-- --.,,.11--WSolar Thermal19%Wind24%Solor FV35%Total RPS-Eligible ProcurementTotal RPS-Eligible ProcurementProjected RPS-Bigible Procuren1ent7,504 GWh12,34-0 GWh· 27,000 GWhSource: PG&E' 2002 Corporate Env1roomental Report and PG&E's August 2011 RPS Compliance Report.Note: 2020 delr.eries are based on current and projected future contractual commitments

Solar Thermal TechnologiesUnder ContractI·- IO! t-- -Parabolic TroughDish Engine(SCE/SDG&E). '""'··""··-- --·ICompact Linear FresnelReflectorPower Tower (SCE)Power TowerTrough/B ion1ass HybridCourtesy PG&E

.Solar PV TechnologiesUnder ContractFixed Thin Film (a-Si)Fixed Thin Film (CdTel) (SCE)Unspecified CPV(illustrative)Tracking Crystalline SiliconConcentrating PVCourtesy PG&E

.Other Renewable TechnologiesUnder ContractBiomass EnergyWind EnergyGeothermal EnergySmall Hydropower ( 30MW)BioGasOcean PowerCourtesy PG&E

The Big PictureCalifornia Public Utilities Commission(CPUC) “Loading Order”How we fill in new supply in California1. Energy Efficiency/Demand response2. Renewables3. Distributed Generation (such as CHP)4. Conventional efficient fossil generation

U.S. Electricity Generation 2008Source: Energy Information Administration / Annual Energy Rev iew 2008Total energy consumed 40.67Delivered for end use 13.21 (32%)Over 2/3 of the energy is wasted.

Energy Conservation

Energy Conservation3 times the value!That’s leverage!

PG&E as a Partner and Solutions ProviderPG&E Portfolio Solution1) Reduce consumption asmuch as possible.3) Offset anyremainingcarbonemissions.ReduceEnergyUse2) Get the“greenest”power ewablePowerSupply

Electricity Fundamentals

Electricity psOutputAmount of flowAmount of flowOutput(work done)

Electricity FundamentalsWatt (W) Basic unit of PowerIn generator: Capacity to do workIn appliance (load): Requirement for work to be doneElectrical terms: Amps x Volts Watts 5A x 12V 60 W 0.5A x 120V 60 WKilowatt (kW), Megawatt (MW) 1 kW 1,000 Watts 2.5 kW 2,500 Watts 1 MW 1,000,000 Watts 500 MW 500,000,000 Watts

Electricity FundamentalsPower over time WorkWatts over time Watt-hours (Wh)Power x Time1 sec.1 hourInstantaneouspower: 20 WPower overtime: 20 Wh

Electricity FundamentalsWatt-hour (Wh) x 1000 Kilowatt-hour (kWh)In a generator:How many kWh are produced when a 5 kW PV systemoperates at full power for 6 hours? 30 kWhIn a load:How many kWh are used when a 200 W bulb shines for10 hours? 2000 Wh or 2 kWh

Voltage and CurrentWattsAmpsVoltsVoltsVolts x Amps WattsWattsAmpsArea of rectangle total power (watts)Same area same power, just in different form.

Voltage and Current2 amps20 ampsThe larger the current, the larger the wire needed tomake it flow efficiently (more “pipe”).Copper wire is expensive.Using higher voltage allows the same amount of powerto be transmitted with lower current, saving money.

Types of Electrical CurrentVoltage x Time V1/60 of a second*PV panels produce DC*Batteries only store DC0V-VDC Direct currentAC Alternating current60 Hertz in U.S.(60 cycles / second)*Utility PowerAC power can be stepped up and down in voltage mucheasier than DC power, therefore most power is AC.

The Electric GridSource: PG&E

The Electric GridElectricity can be transported at the speed of light,therefore any point can be said to be connected toall others.This network is called the GRID and is nation-wide.Source: NPRhttp://w w w .npr.org/templates/story/story.php?storyId 110997398Source: NREL

The Electric GridThere are three main components of the grid:Generation: Creating electricity.Transmission: Moving it in bulk fromgenerators to distribution centers.Distribution: Bringing it from centers(sub-stations) to individual homes andbusinesses.Source: NREL

The Electric GridAbove 50,000 V (69 kV up to 765 kV)StepupSub-stationTransmission10,000 V (10 kV)StepdownDistribution120V – 240VGeneration480VHome12,000 V (12 kV)StepdownBusinessSource: NREL

Grid TermsSupply sideGenerationDemand sideUsage (load)Source: NREL

Grid TermsBaseload: Minimum amount of power that isalways neededSeasonal load: Increase in demand inspecific times of the year.Peak load: Maximum amount needed.Capacity: Total power that the system canprovide.

Grid TermsBaseloadPG&E 2006 Annual Usage

Grid TermsSeasonal loadPG&E 2006 Annual Usage

Grid TermsPeak loadPG&E 2006 Annual Usage

Grid TermsHighest demand occurs on only a few hours in the yearThe top “50 Hours”represent 0.6% of thetotal hours in a year20000180001600014000M Ws120001000080006000LoadLoad DuDuration 01Tim e50015501600165017001750180018501

Grid TermsCapacityPG&E 2006 Annual Usage

Grid TermsUnused CapacityPG&E 2006 Annual Usage

Grid TermsSpread out the demand and youcan lower the capacity need.PG&E 2006 Annual Usage

Grid TermsDemand Management orDemand-side ManagementLoad-shifting“How do you get people to use less powerduring peak times and more during off-peak?”

Demand Management Strategies1. Reduce overall load.— Energy efficiency, conservation2. Inform people so they can cooperatevoluntarily.— Publicity, “Flex Your Power” alerts3. Create the ability to remotely turn offcertain appliances.— Smart AC, smart meters, etc.4. Charge more for peak usage.— Time-of-Use rates, Peak-Time pricing and others.

PV Technology

Different types of “Solar”Light energyPhotovoltaic (PV)Electricity produced directly from lightHeat energyConcentrated Solar Power (CSP)Electricity produced by steamWater HeatingSolar Pool HeatingHot water for poolsSolar Water Heating (SWH orSolar Thermal)Hot water for domestic use (DHW)All courtesy of DOE/NREL

Solar Electricity Photovoltaic Effect– photo light;voltaic produces voltage– Photovoltaic (PV) systems convert light directlyinto electricity (using semiconductors)

Electron OrbitsFree electron

How a PV Cell WorksSunlightMetallic Contact Finger(electron pickup)Antireflective coatingElectron flow-N-Layer (Phosphorus)P-N JunctionP-Layer (Boron)Metallic back contact

Solar Cells & the PV Effect Usually produced with semiconductor gradesilicon Dopants create positive and negative regions P/N junction results in .5 volts per cell Sunlight knocks available electrons loose forpotential electrical current Wire grid provides path for current

PV TerminologyCellModuleArrayCourtesy of DOE/NREL

PV System Sizing200 HP engine: means that 200horsepower is the MAXIMUM it willproduce.4 kW PV system: means that 4,000watts (4 kW) is the MAXIMUM it willproduce in full sunlight.

Crystalline Silicon (Mono)Source: DOE National Renew able Energy Laboratory

Crystalline Silicon (Poly)Source: Darren Bouton

Crystalline Silicon PV Products Firm, like crystals Longest track record, over 50 years Most common, over 85% of the market Highest efficiencies: avg. 15%, up to 22% Requires about 100 sf. per kilowattSource: DOE National Renewable Energy Laboratory64

Thin-Film PV ProductsSource: DOE National Renew able Energy Laboratory

Thin-Film PV ProductsSource: DOE National Renewable Energy Laboratory Can be applied on many different materials Longevity still to be proven Production growing at high rate Lower efficiencies: avg. 7%, up to 15% Has potential for big cost reductionPacific EnergyCenter Requiresabout 200 sf. per kilowattSan Francisco66

PV “General Rules” Crystalline PV Products– Efficiencies (rated) range from 12-22%– Space required: 90-150 s.f. per kW Thin-Film PV Products– Efficiencies (rated) range from 5-10%– Space required: 170-300 s.f. per kW

Crystalline vs. Thin-Film1.2 kWCrystallineSiliconThin-film needs about twice as muchspace for the same-size system, butthe total cost is about the same.1.2 kWThin-FilmSource: DOE National Renew able Energy Laboratory

Efficiency vs. Capacity1.2 kW (1,200w)75 square feet16w per sq.ft.Capacity totalpowerEfficiency power per sq.ft.1.2 kW (1,200w)150 square feet8w per sq.ft.Courtesy of DOE/NREL

Heat effectAir temperature70 FRoof surface100 FUnder modules120 FCourtesy: Schott Solar

Crystalline vs. Thin-Film: Heat response Heat increases electrical resistance, whichlowers power output. Output begins dropping at 20 C (68 F). Percentage of drop is called TemperatureCoefficient of Power. It is measured in % per degree Centigrade,i.e. -0.35%/ C Thin film degrades less than crystalline.

Crystalline vs. Thin-Film: Heat responseSample data from spec sheetsCrystalline -0.478%Thin film -0.19%

Crystalline vs. Thin-Film: Heat response100% of Degrees Centigrade(Fahrenheit)Thin FilmCrystalline60(140)6570

PV Panel Technology Laboratory)Sample nCrystalline SiliconT he orignal approach; grow silicon crystal structures in a variety of ways. Represents almost 90%of total market. Appearance dark blue to black but other colors possible with changes to antireflective coatings.Single CrystalGrown in Cylinders and wire- orlaser-sliced into circular wafers asthin as 200 microns. Cells arecircular and modules are inherentlyflat black or charcoal.14 - 15%25%BP ineCast in blocks or drawn through adie to create a "ribbon" and wiresliced or cut into rectangularwafers. Cells are typically vibrantblue.12 - 14%19%BP SolarEvergreen SolarKyocera SolarSchott SolarSharpSunWorldThin-Film MaterialsNear single-atom vapor or electro-deposition on low-cost materials (glass, stainless steel, orplastic). Modules can be flexible. Appearance dark charcoal to near black; can also be semitransparent.Amorphous Silicon(a-Si)Cell and module production part ofsame process. Widely used inconsumer products and on flexiblesubstrates.5 - 7%13%BP SolarKaneka SolarT erraSolarUnited Solar OvonicCopper Indium Diselenide(CIS)Alternative semiconductor materialunder commercialization.8 - 10%19%Global SolarShell SolarCadmium Telluride(CdTe)Alternative semiconductor materialunder commercialization.7 - 9%17%BP SolarFirst Solar

Growth Forecast?Source: Renew able Energy World.com

InvertersInverterDCACChanges Direct Current (DC) toAlternating Current (AC)Pacific Energy CenterSan Francisco76

Inverters Range in size from 1 Kw to 500 Kw Can easily be connected together,even different models Best to locate in cooler areaSource: Darren BoutonPacific Energy CenterSan Francisco77

InvertersTypical system layoutPanel &meterInverter“Strings” of modulesStrings must be of specific length and number,of equal size, and on the same plane.Power production is very sensitive to shading.Pacific Energy CenterSan Francisco78

System Inverters: Online string sizing toolLimited configurations, cannot deviate.Pacific Energy CenterSan Francisco79

InvertersMicro-inverterOne per moduleInverts DC to AC right thereSystem layoutPanel &Combiner box &meter Energy CentercommunicatorPacificSan Francisco80

ReliabilitySource: NASAPacific Energy CenterSan Francisco81

Reliability Mature technology—over 50 years old Essential to the space program Millions in use Products tested and approved by CEC Long warranties backed by large,stable companies— 20 to 25 years on panels— 10 to 25 years on inverters— 10 year labor warrantyPacific Energy CenterSan Francisco82

It works during the day, but what about at night?Previously, there wasonly one solution:Courtesy of DOE/NRELStore the excess inbatteries during the day,then draw off thebatteries at night, orwhen it’s cloudy.But now?83

Net MeteringThe utility grid is a twoway street!Electricity can be “sentback” to the grid by thecustomer.Source Andy Black 2006 All rights reserved.Source: Andy Black Eliminates the need for batteries. Reduces cost and maintenance.X Ensures a constant supply of electricity.Source: DOE NREL

Typical System ComponentsArrayInverterMeterPanelBalance of System(BOS)Source: Darren BoutonLoads

Typical System Components1. Solar array2. Inverter3. House electricalpanelSource: PG&E86

Monitoring Extra hardware sends inverter data to internetInverter company or 3rd party hosts websiteCustomer can view system from home or remotelyCurrent and historical data can be displayedCan cost extra but somecompanies are offering it asstandard package.Courtesy SMA unny-beam-with-bluetoothr.html

MonitoringTotal system history.Real-time, per panel.Courtesy Enphase LWtm4844

Feasibility89

Solar Geometry90

Solar GeometryPlane of the Ecliptic91

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Solar GeometryACTUAL:The sun radiates in alldirections.EXPERIENTIAL:On Earth all radiation from thesun is parallel to one another.93

Horizonin winterHorizon insummer94Source: Wikipedia

This ray strikes parallel to the surface.This ray strikes 45 degree angle to the surface.This ray strikes perpendicular to the surface.95

Latitude and Longitude96

Sun PathSpring/Fall Noon:90o – Latitude52.5o in SFSummer Noon:90o – Latitude 23.576o in SFWinter Noon:90o – Latitude – 23.529o in SFWSWinter: Rises 30o south ofENESummer: Rises 30o north ofESource: PG&E97

Sun Path Overhead Projection98

Sun Path Overhead Projection99

Summer sunWinter sunSource: NASA100

Sun Path Horizon ProjectionEdward Mazria. Passive Solar Energy Book, Expanded101Professional EditionRodale Press, 1979, Pg. 311

Sun Chart: San FranciscoSource: University of Oregon, Solar Radiation Monitoring ram.html

Does the site havean appropriate southern exposure?Use a compass to identify north (and thus south),a first step in assessing solar access at a site.103

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San Francisco: declination 14ºTrue south reads as 166ºtrueIn west:True azimuth Compass azimuth Declination109

trueIn east:True azimuth Compass azimuth - Declination110

Magnetic South vs. True SouthMagnetic South Compass South A compass aligns with the earth’s magnetic field, which is notexactly aligned with the earth’s rotational axis. Magnetic Declination the number of degrees that true south iseast or west from magnetic south. True south 15 east of magnetic south(SF, SJ, Stockton)True South Solar SouthNOTE: go to National Geophysical Data Center (NGDC) ion.jspto determine your site’s magnetic declination111

Describing Location of the SunFirst understand where it is! Azimuth - horizontalangle of sun east or westof due south Altitude - angle of sunabove the horizon Azimuth and altitudedescribe the location ofthe sun in the sky at agiven time.90180450270Illustration from Environmental Control Systems byFuller Moore, McGraw-Hill, Inc., 1993, p. 76.

PV Siting Issues to Consider1. Sun energy potential (insolation)2. Space3. Shading4. Orientation (N – S)5. Tilt angle6. Aesthetics113

Peak Sun Hours Equivalent1000w/m²“Digital” sunlight114

Peak Sun Hours Equivalent3500Kwh 3Hours of the DayTypical daily pattern115

Peak Sun Hours Equivalent3500Kwh 3Hours of the DayEqual areas116

What is the solar resource potential?Peak Sun-hours Measured in kWh/m2/daySource: DOE National Renewable Energy Laboratory (NREL) Resource Assessment Programhttp://rredc.nrel.gov/solar/old data/nsrdb/redbook/atlas/serve.cgi117

What is the solar resource potential?Peak Sun-hours Measured in kWh/m2/day118

Monthly PercentagesSource: morehead.unc.eduPercentage of yearly insolation per monthCityJanFebMarAprMayJunJulAugSan Francisco4.0%5.7%7.5% 10.1% 11.5% 12.16.% 12. 11.1%Los cg.8%fi.1%4 5,3'3.5%11.3·% 11.8% 11.5% 10.4% g 437.16 .16 1J0.0% ll.1!Ji% 13.3% 14.5% 12.16% 10.5%b.8%5.3%4.1%6.1%3.1%2.4%1JO. Ratio of sunniest six months to least sunny (“summer to winter”) ''CitySunniestSan FranciscoLos AngelesLeast sunnyRatio08.1%31.!Jr%2.14to 164.5%35.5%1.82to 11 Portland-12.1%'273%1192.fi7to 1'

Weather/Sun Potential Summary California climate ideal for solar Panels produce in all light Fog has cooling effect, which raisesefficiency Microclimates likely less than 15%loss from normal120

Space RequirementsRoof / Ground Area: Crystalline Silicon90-150 square feet per kW Thin-Film170-250 square feet per kWFor a 4 kW residential system:Crystalline: 360 to 600 sf.Thin film: 650 to 1000 sf.Note: Consideration should also be given for accessto the system (can add up to 20% of needed area)121

Space Requirements: Overhead Photos47 x 13 611 sf.122

PV OrientationFor tilted roof:NorthNotgoodWestEastGoodVerygoodOKSouth123

PV OrientationNWESOverheadmaps: true N-S124

TiltTilt Angle at which the collectors aremounted relative to 0º (flat horizontal surface)Ex. 30ºtilt angleº125

Tilt12 ft.4 ft.18 deg.Typical roof in this area is 4:12.For every 12 feet horizontal, it drops 4 feet.This equals 18 degrees up from horizontal.Normal roof pitch is a very good mounting angle.126

Orientation / Degrees from SouthTilt Angle vs. Building Orientation0 23 45 68 90 (South)(SSE, SSW)(SE, SW)(ESE, WSW)(E, W)0 Flat0.890.890.890.890.8918 30 4:12 7:120.97 1.000.97 0.990.95 0.960.92 0.910.88 0.8445 12:120.970.960.930.870.7860 21:120.890.880.850.790.7090 Vertical0.580.590.600.570.52Source: “A Guide to Photov oltaic (PV) System Design and Installation” -- CEC, June 2001Bottom line: Tilt is a factor, but not a major one.127

TrackingCourtesy of DOE/NRELFor most home systems, the extra expense and maintenance oftracking motors is not worth the efficiency gain. Better to buy a fewextra panels.For large commercial systems it may be worth it.128

Will the PV system be free from shade?Source: DOE National Renew able Energy Laboratory129

72-cell PV module Copyright Solmetric 2010

72-cell PV module with bypass diodes Copyright Solmetric 2010

Module I-V curve with shaded cell stringsCellICell stringCopyright Solmetric 2010V

Shade one cell of one cell stringOne bypass diode turns onIVCopyright Solmetric 2010

Shade one cell in each of two cell stringsTwo bypass diodes turn onIVCopyright Solmetric 2010

Monocrystalline Shading EffectPartial Module Shading Effect3Unshaded ModuleThe Extreme Effects of Shading2.51 cell 25%shadedAmps2% of One Cell Shaded0%0%25 %25 %1 cell 75%shaded50 %50 %75 %66 %1 cell 100%shadedl00 %75 %w ith 3 cells shaded93 %1 cell 50%shaded1.510.5% Loss of Module Power00510152025VoltsCourtesy: Solar Energy International135

Per-Module DevicesSolar MagicNational SemiconductorEnphase MicroinverterEnphase EnergyModule MaximizerTigo EnergyDirect Grid MicroinverterDirect Grid TechnologiesPV AC ModuleEXELTECHSunMizerXandexPowerBoxSolar EdgeParallux vBoosteIQ Energy

Per-Module Devices: Two Basic TypesEnphase MicroinverterEnphase EnergyModule MaximizerTigo EnergyMicroinverterChanges DC to ACNeeds no other inverterMaximizerAdjusts DC voltage: DC to DCNeeds system inverter

Solar AccessPV Requirements Solar Window 9 am - 3 pm (ideal)8 am - 4 pm (possible) Need minimum of 4 hours during solarwindow with no shade (prefer 5 hours) Summer more important than winter138

ShadingSunsetSunriseSolar Window“Shade-free from 9 to 3”Good chance for PV139

ShadingBad chance for PV140

Planning for ShadeSource: PEC Staff141

Planning for ShadeS2 to 1 ratiorecommended1 ft.2 ft.No goodSource: PEC Staff142

Solar PathfinderUsed to gain a quick and approximate understandingof solar access and objects on the horizon that shade agiven location. Latitude specific sun path diagram isplaced in the pathfinder.The transparent, convex plastic domereflects objects on the horizon, enablingthe user to see the relationship betweenthese objects and the path of the sun.Obstructions can be traced onto sunpathdiagram.143

Courtesy of Andy Black144

Solmetric SunEyeTM110210145Courtesy: Solmetric, Corp.

Sunpath View Visuallydemonstratesseasonal sunpath andshading effectsof obstructions Summarytabular dataCourtesy: Solmetric, Corp.146

Detailed View Chart showsproportion of totalsolar energyavailable at thissite each monthCourtesy: Solmetric, Corp.147

Where to Go for Tools Pacific Energy Center: Tool Lending LibraryPhone: 415-973-9945Email: pectools@pge.com Pacific Energy Center Web Site:www.pge.com/pec/tll148

How will PV affect site aesthetics?Source: Darren Bouton149

How will PV affect site aesthetics?Source: Darren Bouton150

Roof IssuesDon’t put a new PV system on an old roof! Minimum roof life should be 5 – 7 years. Good idea to do PV and roof at same time Estimate for panel removal/replacement is 1,000 perKw of system size.Courtesy London Flat Roofing, pairs/asphalt-flat-roofs/

Online Production Calculatorwww.csi-epbb.com Official program for CSI rebate, everyone mustuse. Buyers don’t have to “trust the salesperson”. Takes all relevant factors as input and givesestimated annual production and rebateamount.

Online Production Calculator

Online Production Calculator

Online Production Calculator

Online Production Calculator: Shading

Online Production Calculator: ShadingNo shadeWith shade

Finances158

Net MeteringSell Power to theUtility by DaySource Andy Black 2006 All rights reserved.Buy Power at Nightand Winter. Exchange at Retail Annual CycleSource Andy Black 2006 All rights reserved.159

Net Metering – No Blackout ProtectionUnsafe to send livepower into grid whileworkers repairingdowned linesXSource Andy Black 2006 All rights reserved.No “voltage reservoir”means house currentcould fluctuate anddamage appliancesXSource Andy Black 2006 All rights reserved.160

Reduce Your Energy Bills!Spin Your Meter Slower Use the electricity you generatefirst to reduce electricity youwould normally buy from theutility or electric service providerSpin Your Meter BackwardsSource: Darren Bouton Excess electricity generatedgoes through your meter andinto the grid Spins your meter backwards! Get credit for “stored” electricityon the grid

Net MeteringMeterCustomer sideUtility side

Net MeteringGeneration: 3 kWhSurplus: 2 kWhMeterLoad: 1 kWhCustomer sideCash credit: .602 kWh @ (going rate)Utility side

Net MeteringGeneration: 1 kWhSurplus: 0 kWhMeterLoad: 1 kWhCustomer sideCash credit: .00Utility side

Net MeteringGeneration: 0 kWhNeed: 1 kWhMeterLoad: 1 kWhCustomer sideCash debit: .091 kWh @ (going rate)Utility side

Net MeteringWhat do you get paid if your system over-produces?Cost of power at .16/KwhWholesale cost: .10/kwhMarkup to cover gridmaintenance: .06/kwh CPUC rule—PG&E must comply The “full retail” rate that PV owners get paid for theirpower includes a subsidy (markup) that comes fromall rate payers. The CPUC determined that this full subsidy wouldonly be allowed to cover your usage, not for you to gointo the power-generation business. For over-production, compensation will be at a lowerrate, to be determined.166

Net MeteringAverage monthly usagePV system productionkWh/moRoll il167

Net MeteringAverage monthly usagePV system productionkWh/moThe surplus covers the shortfall,and your yearly bill is �April168

Net MeteringAverage monthly usagePV system productionkWh/moPV system produces less thanyour yearly usage.750500You pay this 9

Net MeteringAverage monthly usagePV system productionkWh/moPV system produces morethan your yearly usage.750You are paid a different rate for this amount – around 4 per 70

Methods of PaymentTwo fundamentally different concepts:Net MeteringServes the onsite load FIRST, theninteracts with the utility grid.One meterFeed-in TariffDoes not serve the onsite load andONLY interacts with the utility grid.Two meters171

Feed-in TariffGeneration trackFeed-in (credit)MeterUsage (debit)MeterUsage track172

Net Metering vs. Feed-in TariffNet Metering:For PV systems from 1 kW to 1 mWFeed-in Tariff:For PV systems from 1 mW to 20 mW.See www.pge.com/feedintariffs173

PG&E Renewable Energy ProgramsCalifornia Solar InitiativeSolar Water Heating (CSI Thermal)AvailablePG&EProgramsSelf Generation Incentive

Solar 1% PG&E Electrical Power Mix 2009 U.S. Electrical Power Mix June 2011 Bioenergy4% Small Hydro3% Other 1% Coal 1% Geothermal 4% Wind3% Unspecified (market purchases) . Total power that the system can provide. Grid Terms Baseload PG&E 2006 A nnual Usage. Grid Te