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Photovoltaic Systems Training Resource Guide Ver. 1.02 January 2011

James Dunlop, PE Š 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.

Š 2011 Jim Dunlop Solar

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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.

Š 2011 Jim Dunlop Solar

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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

Š 2011 Jim Dunlop Solar

Marketing & Distribution

Project Developers

Electric Utilities

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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.

Š 2011 Jim Dunlop Solar

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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

Š 2011 Jim Dunlop Solar

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Chapter 1

Introduction to Photovoltaic Systems Solar Technologies ● History and Development ● Markets and Applications ● Industry Sectors

© 2011 Jim Dunlop Solar

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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) Š 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 Off-grid 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 Grid-connected 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

Š 2011 Jim Dunlop Solar

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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

Š 2011 Jim Dunlop Solar

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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 ultra-violet

© 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

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 infra-red

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

© 2011 Jim Dunlop Solar

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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 3-7

Ecliptic Plane

90 million miles (0.983 AU)

96 million miles (1.017 AU)

Perihelion: January 2-5

Sun

Winter Solstice: December 21 / 22 Declination = ( -23.5°) Autumnal Equinox: September 22 / 23 Declination = 0°

© 2011 Jim Dunlop Solar

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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)

© 2011 Jim Dunlop Solar

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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

Š 2011 Jim Dunlop Solar

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Array Orientation

Zenith

Surface Normal

South-facing array Southwest-facing array

East

North

Tilt Angle

West

Š 2011 Jim Dunlop Solar

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

Latitude-15° tilt maximizes spring and summer performance

North South

West

© 2011 Jim Dunlop Solar

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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

Š 2011 Jim Dunlop Solar

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Chapter 4

System Components and Configurations Major Components ● Balance-of-System ● System Classifications and Designs

© 2011 Jim Dunlop Solar

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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

Š 2011 Jim Dunlop Solar

7. Battery (optional)

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Stand-Alone PV Systems with AC Loads PV Array

Charge Controller

DC Load

Battery

Inverter/ Charger

AC Load

Š 2011 Jim Dunlop Solar

AC Source (to Charger Only)

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Utility-Interactive PV System

AC Loads

PV Array

Inverter

Load Center

Electric Utility Š 2011 Jim Dunlop Solar

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Utility-Interactive 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

Š 2011 Jim Dunlop Solar

Charge Control

Battery

Electric Utility

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Chapter 5

Cells, Modules and Arrays

Principles of Operation ● I-V Characteristics ● Response to Irradiance and Temperature ● Series/Parallel Connections ● Specifications and Ratings

© 2011 Jim Dunlop Solar

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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

Boron-doped silicon (P-type) wafer < 250 µm

© 2011 Jim Dunlop Solar

Phosphorous-doped silicon (N-type) layer ~ 0.3 µm

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Key I-V Parameters f PV device performance is specified by the following I-V parameters at a given temperature and solar irradiance condition:

Isc Pmp

    

Open-circuit voltage (Voc) Short-circuit 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

Š 2011 Jim Dunlop Solar

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

© 2011 Jim Dunlop Solar

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

© 2011 Jim Dunlop Solar

Source: SolarWorld USA PV Systems TRG Preview - 33


Chapter 6

Batteries Types and Characteristics ● Functions and Features ● Specifications and Ratings

© 2011 Jim Dunlop Solar

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Battery Cell Design f A cell is the basic electrochemical unit in a battery. +

Positive plate

Electrolyte Š 2011 Jim Dunlop Solar

-

Separator

Electrical load

Negative plate

Case

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Types of Lead-Acid Batteries Flooded Lead-Acid Batteries

Valve-Regulated Lead-Acid Batteries

Gelled Absorbed Glass Mat

Š 2011 Jim Dunlop Solar

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Chapter 7

Charge Controllers Types and Characteristics ● Functions and Features ● Specifications and Ratings ● Sizing

© 2011 Jim Dunlop Solar

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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 state-of-charge, 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

Š 2011 Jim Dunlop Solar

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Typical Charge Controllers Morningstar ProStar controller

Outback MPPT controller

Morningstar TriStar controller

Morningstar lighting controller Xantrex C-series controller

Š 2011 Jim Dunlop Solar

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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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Stand-Alone & Interactive Inverters Stand-Alone Operation with Battery as DC Power Source

Battery

Stand-Alone 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

PV array size is limited by inverter power rating Š 2011 Jim Dunlop Solar

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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. Stand-Alone Systems ● Calculations and Software Tools

© 2011 Jim Dunlop Solar

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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

Š 2011 Jim Dunlop Solar

Interactive Inverter

Utility Grid Size of utility service limits maximum system output

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Sizing Stand-Alone PV Systems f Sizing stand-alone 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

Š 2011 Jim Dunlop Solar

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Chapter 10

Mechanical Integration

Design Considerations ● Array Mounting Configurations ● Structural Loads ● Installation

© 2011 Jim Dunlop Solar

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Types of Mounting Systems f Orientation type 

Fixed-tilt, adjustable and sun-tracking arrays

f Ground-mounted arrays 

Racks, poles and sun-tracking mounts

f Roof-mounted arrays   

Racks for flat roofs Standoff mounts for sloped roofs Direct mounts

f Building-integrated PV arrays 

Replace conventional building material or an architectural feature

© 2011 Jim Dunlop Solar

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Structural Evaluation

Roof surface Trusses or beams

Module support rails

PV Modules

Point attachments to structure

Š 2011 Jim Dunlop Solar

Module attachments

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Chapter 11

Electrical Integration

Terminology and Definitions ● Circuit Design Requirements ● Specifying Electrical Components ● Code-Compliant 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

Š 2011 Jim Dunlop Solar

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

Š 2011 Jim Dunlop Solar

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

© 2011 Jim Dunlop Solar

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Chapter 13

Permitting and Inspection

Permit Submittal Guidelines ● Plan Review ● System Labels ● Inspection Checklists

© 2011 Jim Dunlop Solar

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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)

Š 2011 Jim Dunlop Solar

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.

© 2011 Jim Dunlop Solar

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Chapter 14

Commissioning, Maintenance and Troubleshooting System Commissioning ● Maintenance Plans ● Diagnostics

© 2011 Jim Dunlop Solar

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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

© 2011 Jim Dunlop Solar

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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.

Š 2011 Jim Dunlop Solar

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Measuring Power f A standard watt-hour meter can be used to measure average power over brief intervals. f The watt-hour constant (Kh) indicates the watt-hours 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

© 2011 Jim Dunlop Solar

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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

Š 2011 Jim Dunlop Solar

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Life-Cycle Cost Analysis f Life-cycle 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 â&#x2C6;&#x2019; S PV where LCC = life-cycle 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 ($) SPV = present value of salvage value ($) Š 2011 Jim Dunlop Solar

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Chapter 16

PV System Safety Hazards and Avoidance ● Personal Protective Equipment ● Fall Protection ● Electrical Safety

© 2011 Jim Dunlop Solar

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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 open-sided 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.

© 2011 Jim Dunlop Solar

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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.

© 2011 Jim Dunlop Solar

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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.

Š 2011 Jim Dunlop Solar

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