Photovoltaic Systems Training Resource Guide Ver. 1.02 January 2011
James Dunlop, PE ÂŠ 2011 Jim Dunlop Solar
Overview f The Photovoltaic Systems Training Resource Guide is a comprehensive set of instructional presentation materials. f This resource is intended to assist faculty and instructors in developing and teaching courses on PV systems technology.
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PV System Training Resources f The Guide is intended to be used in conjunction with the Photovoltaic Systems text and the National Electrical CodeÂŽ.
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Training Needs f The Photovoltaic Systems text and the Photovoltaic Systems Training Resource Guide can be used for training a diversity of target audiences. Product Manufacturers Consumers & Owners
Building Officials
Contractors & Installers
Architects & Engineers
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Marketing & Distribution
Project Developers
Electric Utilities
Financiers & Investors PV Systems TRG Preview  4
Features f Contains Microsoft PowerPoint® presentations for each chapter in the Photovoltaic Systems textbook, plus an additional chapter on PV System Safety. f Includes almost 1000 total slides, and over 200 new illustrations and photographs. f Note pages are provided for every slide with commentary, references and suggested exercises. f Covers new requirements for PV installations in the 2011 National Electrical Code®. © 2011 Jim Dunlop Solar
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Note Pages f Note pages are provided on every slide and contain additional commentary and reference to codes, websites and page numbers in the Photovoltaic Systems text.
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Content f Introduction to PV Systems
f System Sizing
f Solar Radiation
f Mechanical Integration
f Site Surveys and Preplanning
f Electrical Integration
f System Components and Configurations
f Utility Interconnection
f Cells, Modules and Arrays
f Permitting and Inspection
f Batteries
f Commissioning, Maintenance and Troubleshooting
f Charge Controllers
f Economic Analysis
f Inverters
f PV System Safety
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Chapter 1
Introduction to Photovoltaic Systems Solar Technologies ● History and Development ● Markets and Applications ● Industry Sectors
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Advance Organizer f Solar photovoltaic (PV) systems convert solar energy into electrical energy using various components. power conditioning energy source
PV Array
Inverter
power distribution
load
Load Center
energy conversion
energy storage (optional) ÂŠ 2011 Jim Dunlop Solar
Battery
electric utility
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PV System Applications f Spacecraft
f Lighting
f Consumer electronics
Calculators, radios and watches
f Rural development
Health care facilities, schools and community centers
f Offgrid power
Lighting and appliances for remote homes and facilities
f Agricultural uses
Water pumping and irrigation Fence charging
© 2011 Jim Dunlop Solar
Signs, security and parking areas Transportation, navigation and aviation aids
f Specialty applications
Remote monitoring, railway signals, security systems and water treatment
f Telecommunications facilities f Gridconnected systems
Residential, commercial and utilityscale
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Market Drivers f Increasing costs and dependence on imported energy f Environmental impacts from fossil fuel use f Electric utility restructuring f Net metering and interconnection rules f Legislative mandates for renewable generation f Financial incentives f Increasing public awareness and interest
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Quality Measures for PV Systems Equipment Standards Component Testing Performance Ratings Product Certification
Quality Components
Documented Systems Design Review & Approval
Quality System Designs
Education & Training Licensing & Certification System Testing & Inspection
Quality Installations
Warranties & Service Contracts Product Assurance Satisfied Customers Successful Industry
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Chapter 2
Solar Radiation
Terminology & Definitions ● Geometric & Atmospheric Effects ● Solar Power & Energy ● Measurements & Data © 2011 Jim Dunlop Solar
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Wavelength
near ultraviolet
© 2011 Jim Dunlop Solar 0.25 µm
0.3 0.5 Wavelength (µm) 105 m
104 m
103 m
100 m
10 m
1m
100 mm
10 mm
1 mm
100 µm
10 µm
1 µm
0.1 µm
100 Å
10 Å
1Å
Long Radio Waves
AM Radio
Short Radio Waves (FM/TV)
Microwaves
Infrared Radiation
Visible Light
Ultraviolet Radiation
X rays
Gamma rays
Electromagnetic Spectrum
Solar spectrum Visible light 4.5 µm
near infrared
0.7
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Atmospheric Effects Parallel rays from sun
Sun
Reflection Solar Constant = 1366 W/m2
Atmospheric Absorption, Scattering and Reflections
Outer Limits of Atmosphere
Cloud Reflections
Diffuse Radiation Direct Radiation Diffuse Radiation Reflected (Albedo) Radiation Earth’s Surface
TOTAL GLOBAL SOLAR RADIATION  DIRECT + DIFFUSE
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Earth’s Orbit Around the Sun Vernal Equinox: March 20 / 21 Declination = 0° Summer Solstice: June 20 / 21 Declination = +23.5°
Aphelion: July 37
Ecliptic Plane
90 million miles (0.983 AU)
96 million miles (1.017 AU)
Perihelion: January 25
Sun
Winter Solstice: December 21 / 22 Declination = ( 23.5°) Autumnal Equinox: September 22 / 23 Declination = 0°
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Solar Declination Arctic Circle (66.5° N)
North Pole
Tropic of Cancer (23.5° N)
Equator Ecliptic Plane
Sun’s Rays Tropic of Capricorn (23.5° S) 23.5 °
Solar Declination
Antarctic Circle (66.5° S)
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Chapter 3
Site Surveys and Preplanning
Customer Development ● Site Assessment ● Locating PV Arrays ● Shading Analysis ● Project Planning and Preparation © 2011 Jim Dunlop Solar
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Site Survey Equipment
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Array Orientation
Zenith
Surface Normal
Southfacing array Southwestfacing array
East
North
Tilt Angle
West
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Azimuth Angle
South
Surface Direction PV Systems TRG Preview  20
Array Tilt Angle Summer Solstice Latitude+15° tilt maximizes fall and winter performance Close to Latitude tilt maximizes annual performance
Zenith
Equinoxes Winter Solstice East
Latitude15° tilt maximizes spring and summer performance
North South
West
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Solar Shading Calculators f Solar shading calculations are devices used to determine the extent of shading in the solar window. Solmetric SunEye
Solar Pathfinder
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Chapter 4
System Components and Configurations Major Components ● BalanceofSystem ● System Classifications and Designs
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PV System Components
1
2
5
1. PV modules and array 2. Combiner box 6
4
3. DC disconnect 4. Inverter (charger & controller) 5. AC disconnect
3
6. Utility service panel 7
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7. Battery (optional)
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StandAlone PV Systems with AC Loads PV Array
Charge Controller
DC Load
Battery
Inverter/ Charger
AC Load
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AC Source (to Charger Only)
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UtilityInteractive PV System
AC Loads
PV Array
Inverter
Load Center
Electric Utility ÂŠ 2011 Jim Dunlop Solar
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UtilityInteractive PV System with Energy Storage Backup AC Loads
Primary AC Loads
Bypass circuit
Critical Load Sub Panel
Inverter/ Charger
Main Panel
AC Out
AC In DC In/out
PV Array
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Charge Control
Battery
Electric Utility
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Chapter 5
Cells, Modules and Arrays
Principles of Operation ● IV Characteristics ● Response to Irradiance and Temperature ● Series/Parallel Connections ● Specifications and Ratings
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Solar Cells f Solar cells are semiconductor devices that convert sunlight to DC electricity.
() Electrical Load Photovoltaic cell DC current flow
Borondoped silicon (Ptype) wafer < 250 µm
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Phosphorousdoped silicon (Ntype) layer ~ 0.3 µm
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Key IV Parameters f PV device performance is specified by the following IV parameters at a given temperature and solar irradiance condition:
Isc Pmp
Opencircuit voltage (Voc) Shortcircuit current (Isc) Maximum power point (Pmp) Maximum power voltage (Vmp) Maximum power current (Imp)
Current (A)
Imp
Area = Pmp
Voltage (V)
© 2011 Jim Dunlop Solar
Vmp
Voc
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Response to Solar Irradiance
1000 W/m2
Current increases with increasing irradiance
Current
750 W/m2
500 W/m2
Maximum power increases with increasing irradiance Maximum power voltage changes little with irradiance
250 W/m2 Voc changes little with irradiance
Voltage
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Constant Temperature
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Response to Temperature f For crystalline silicon PV devices, increasing cell temperature results in a decrease in voltage and power, and a small increase in current.
Increasing temperature reduces power output
Current
Increasing temperature increases current
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Increasing temperature reduces voltage T = 0°C T = 25°C T = 50°C
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PV Module Rating Conditions f The electrical performance of PV modules is rated at Standard Test Conditions (STC):
Irradiance: 1,000 W/m2 , AM 1.5 Cell temperature: 25°C
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Chapter 6
Batteries Types and Characteristics ● Functions and Features ● Specifications and Ratings
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Battery Cell Design f A cell is the basic electrochemical unit in a battery. +
Positive plate
Electrolyte ÂŠ 2011 Jim Dunlop Solar

Separator
Electrical load
Negative plate
Case
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Types of LeadAcid Batteries Flooded LeadAcid Batteries
ValveRegulated LeadAcid Batteries
Gelled Absorbed Glass Mat
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Chapter 7
Charge Controllers Types and Characteristics ● Functions and Features ● Specifications and Ratings ● Sizing
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PV Systems and Battery Charge Control f A charge controller is required in most PV systems that use battery storage to regulate battery stateofcharge, optimize battery and system performance, and help prevent damage to the batteries or hazardous conditions resulting from the charging process [690.72(A)].
PV Array
Charge Controller
Battery
Charge controller protects battery from overcharge by PV array
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Typical Charge Controllers Morningstar ProStar controller
Outback MPPT controller
Morningstar TriStar controller
Morningstar lighting controller Xantrex Cseries controller
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Chapter 8
Inverters
Definitions and Terminology ● Types and Applications ● Functions and Features ● Selection and Sizing ● Monitoring and Communications © 2011 Jim Dunlop Solar
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StandAlone & Interactive Inverters StandAlone Operation with Battery as DC Power Source
Battery
StandAlone Inverter
Vs.
AC Load AC load is limited by inverter power rating
Interactive Operation with PV Array as DC Power Source
PV Array
Interactive Inverter
Utility Grid
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String Sizing DC Input Operating Range
25°C
Inverter MPPT Range
0°C 25°C 50°C PV Array IV Curves at Different Temperatures
Current
STC
Array voltage decreases with increasing temperature
Voltage © 2011 Jim Dunlop Solar
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Chapter 9
System Sizing
Sizing Principles ● Interactive vs. StandAlone Systems ● Calculations and Software Tools
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Sizing Interactive PV Systems f The sizing of interactive PV systems is centered around the inverter requirements.
Inverter size is determined by the PV array maximum power
PV Array PV array size is limited by available space and budget
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Interactive Inverter
Utility Grid Size of utility service limits maximum system output
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Sizing StandAlone PV Systems f Sizing standalone PV systems begins with determining the electrical load, and then sizing the battery and PV array to meet the average daily load during the critical design month.
Determine Avg. Daily Electrical Load for Each Month
Determine Load and Insolation for Critical Design Month
Size Battery to Meet Load for Desired Days of Autonomy
Size PV Array to Meet Loads for Critical Design Month
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Chapter 10
Mechanical Integration
Design Considerations ● Array Mounting Configurations ● Structural Loads ● Installation
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Types of Mounting Systems f Orientation type
Fixedtilt, adjustable and suntracking arrays
f Groundmounted arrays
Racks, poles and suntracking mounts
f Roofmounted arrays
Racks for flat roofs Standoff mounts for sloped roofs Direct mounts
f Buildingintegrated PV arrays
Replace conventional building material or an architectural feature
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Structural Evaluation
Roof surface Trusses or beams
Module support rails
PV Modules
Point attachments to structure
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Module attachments
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Chapter 11
Electrical Integration
Terminology and Definitions ● Circuit Design Requirements ● Specifying Electrical Components ● CodeCompliant Installation Practices © 2011 Jim Dunlop Solar
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Interactive PV System Components and Circuits Interactive System PV Source Circuits
PV Output Circuit
Inverter Input Circuit
Source Circuit Combiner Box
Inverter Output Circuit AC Fused Disconnect
Ground Fault Protection
Inverter
Utility Disconnect
Main Service Panel
DC Fused Disconnect
PV Array
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Integral components in many small string inverters < 12 kW
Electric Utility
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Chapter 12
Utility Interconnection
Codes and Standards ● Utility Considerations ● Supply and Load Side Connections ● Interconnection Agreements © 2011 Jim Dunlop Solar
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Point of Interconnection f Interactive inverters may be connected to either the load side or the supply side of the service disconnecting means.
To Utility Supply Side Load Side
Distribution Equipment
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Service Disconnect
To Branch Circuits
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Utility Interconnection Agreements f Interactive PV systems require approval from the local electric utility before beginning parallel operations. f Most utilities have standard procedures and agreements for customers to interconnect PV systems, and generally include the following provisions:
Use of listed equipment approved for interactive operation Permitting, inspection and approval by the AHJ Size limits and tiers Location of disconnecting means and labeling Insurance and liabilities Metering and billing Testing and monitoring Maintenance Application and processing fees
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Chapter 13
Permitting and Inspection
Permit Submittal Guidelines ● Plan Review ● System Labels ● Inspection Checklists
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Codes, Standards and Enforcement f The electrical safety system is based on codes, standards and enforcement to help ensure the safety of electrical installations. f Almost every aspect of PV equipment, system designs and installations are governed by the electrical safety system.
Safer Equipment & Systems
Inspection, Code Compliance & Approval (AHJ & Utilities)
Product Standards, Testing & Certification (ANSI, ISO/IEC & NRTLs)
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Worker Safety, Installation & Building Codes (NEC, ICC & OSHA)
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Common Code Violations f Common code compliance problems with PV system designs and installations include the following:
Unsafe wiring methods, insufficient conductor ampacity or insulation type. Lack of or improper placement or ratings of overcurrent protection devices and disconnect means. Use of unlisted equipment or improper application of listed equipment. Improper system grounding. Lack of or improper labeling on systems and components. Insecure attachment or weathersealing of PV arrays to rooftops and other structures.
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Chapter 14
Commissioning, Maintenance and Troubleshooting System Commissioning ● Maintenance Plans ● Diagnostics
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Maintenance Plan f A maintenance plan includes a list and schedule for all required system maintenance and service.
Inspections of components and wiring systems Evaluation of structural attachments and weathersealing Cleaning and removing debris around arrays Performing battery maintenance Conducting electrical tests and verifying performance
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Performance Measurements f Operating parameters in PV systems are measured to verify expected performance. f Most inverters include integral monitoring and displays as standard features. f Measurement on any energized equipment should be performed by qualified persons using appropriate test instruments and PPE.
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Measuring Power f A standard watthour meter can be used to measure average power over brief intervals. f The watthour constant (Kh) indicates the watthours accumulated per revolution of the meter disk. f Multiply Kh by the disk revolution rate to calculate average power through the meter.
© 2011 Jim Dunlop Solar
Pavg = K h × N rev × 3600 where Pavg = average power (W) Wh K h = meter constant ( ) rev rev N rev = disk revolution rate ( ) sec PV Systems TRG Preview  60
Chapter 15
Economic Analysis
Incentives ● Value Assessment ● Life Cycle Costs Analysis ● Financial Tools
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Financial Incentives f Federal tax credits and deductions f Rebate programs f Production incentives f Grants and loans f Sales and property tax exemptions
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LifeCycle Cost Analysis f Lifecycle costs represent the total costs of owning and maintaining an asset over its lifetime, and can be used to compare the costs of PV systems and alternate energy sources. LCC = I + M PV + EPV + RPV âˆ’ S PV where LCC = lifecycle cost ($) I = initial cost ($) M PV = present value of maintenance costs ($) E PV = present value of energy costs ($) R PV = present value of repair and replacements ($) SPV = present value of salvage value ($) ÂŠ 2011 Jim Dunlop Solar
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Chapter 16
PV System Safety Hazards and Avoidance ● Personal Protective Equipment ● Fall Protection ● Electrical Safety
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Fall Protection f Falls are the leading cause of deaths in the construction industry.
Most fatalities occur when employees fall from opensided floors and through floor openings. Many PV arrays are installed on rooftops or elevated structures.
f Each employee on a walking/working surface with an unprotected side or edge 6 feet (1.8 m) or more above a lower level shall be protected from falling by the use of guardrail systems, safety net systems, or personal fall arrest systems.
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Electrical Hazards f Four main types of electrical injuries:
Electrocution or death due to electrical shock Electrical shock Burns Falls (caused by shock)
f Electrical accidents are caused by a combination of three factors:
Unsafe equipment and/or installation, Workplaces made unsafe by the environment, and Unsafe work practices.
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Summary f The Photovoltaic Systems Training Resource Guide is a comprehensive set of instructional presentation materials not found collectively from any other source.
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