PV systems and components.pdf

7/29/2019 PV systems and components.pdf

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1FSEC

2002

Solar Pho tovol taic Systems

and Components


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2002

Solar Pho tovo ltaic Sys tem (SPS)

! Solar Photovoltaic System (690.2)

" The total components and subsystems that, in combination,convert solar energy into electrical energy suitable for

connection to a utilization load.

load

utilization

energy

sourcepower

conditioning

energyconversion

Inverter

Charger

Controller

PV Arrayenergy

distributionload

center

batteryenergy

storage

electric

utility

network


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3FSEC

2002

Solar Pho tovo ltaic Sys tem (SPS)

Components

! PV Array: An electrical assembly of photovoltaic modules that convert

sunlight to DC electricity.

! Inverter:A device that converts DC power from batteries or PV arrays into

utility-grade AC power.

! Energy Storage:Electrical or other storage devices sometimes used to

store energy produced by PV arrays for later consumption.

! System Charge Con trol :A device used to protect batteries fromovercharge and overdischarge, sometimes provide load control functions.

! Load:Energy consuming electrical appliances served by the system.

! Balance of System (BOS) Components:Other equipment required to

control, conduct, protect and distribute power in the system.


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Solar Cell

! Solar Cell (690.2)

" The basic photovoltaic device that generates dc electricity whenexposed to light. A typical silicon solar cell produces about 0.5

volt and up to 6 amps and 3 watts for larger area cells.

electrical load

typical crystalline silicon

photovoltaic cell

(-)

(+)

pho sphorous -doped (N-type)

si l ic on layer ~ 0.3 x 10-6mbo ron -doped (P-type)

si l ico n layer ~ 250 x 10-6m

dc cu rrent flow

sun


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2002

Pho tovo l taic Modu les

! Module (690.2)

" A complete, environmentally protected unit consisting of solarcells, optics, and other components, exclusive of tracker,

designed to generate dc power when expose to sunlight.

60 watt polycrystalline

module

75 watt crystalline

module


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2002

Pho tovo ltaic Panels

! Panel (690.2)

" A collection of modules mechanically fastened together, wired,and designed to provide a field installable unit.


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2002

Photovol taic A rrays

! Array (690.2)

" A mechanical integrated assembly of modules or panels with asupport structure and foundation, tracker, and other

components, as required, to form a direct-current power-

producing unit.


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Defin i t ion s: Photovo l taic Cel ls,

Modu les, Panels and A rrays

cellmodule

panelarray


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2002

Solar cells

Blocking diodes

Module

Panel

Array

Fuses

Photovoltaic source circuits

Photovoltaic

output circuit

Ident i f icat ion of Solar Pho tovol ta ic

System Components

Adapted from NEC 2002

Figure 690.1(A)


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10FSEC

2002

Inverter

! Inverter (690.2)

" Equipment that is used to change voltage level or waveform, orboth, of electrical energy. Also known as a power processing

unit (PCU) or power conversion system (PCS), and inverter is a

device that changes dc input to ac output. Inverters may also

function as battery chargers that use alternating current fromanother course and convert it into direct current for charging

batteries.


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B i-Polar A rray

! Bipolar Photovoltaic Array (690.2)

" A photovoltaic array that has two outputs, each having oppositepolarity to a common reference point or center tap.


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2002

Defin it ions (A rt. 690.2)

! Blocking Diode

" A diode used to block reverse flow of current into a photovoltaicsource circuit. Blocking diodes are not required by this Code,

although the instructions or labels supplied with the photovoltaic

module may require them.

! Charge Controller" Equipment that controls dc voltage or dc current, or both, used

to charge a battery.

! Diversion Charge Controller

" Equipment that regulates the charging process of a battery by

diverting power from energy storage to direct-current or

alternating current loads or to an interconnected utility service.


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2002


! Electrical Production and Distribution Network

" A power production, distribution and utilization system, such asa utility system and connected loads, that is external to and not

controlled by the photovoltaic power system.

! Hybrid System

" A system comprised of multiple power sources. These powersources may include photovoltaic, wind, micro-hydro

generators, engine-driven generators, and others, but do not

include electrical production and distribution network systems.

Energy storage systems, such as batteries, do not constitute apower source for the purpose of this definition.


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! Inverter Input Circuit

" Conductors between the inverter and batteries in stand-alonesystems or the conductors between the inverter and

photovoltaic output circuits for electrical production and

distribution network.

! Inverter Output Circuit" Conductors between the inverter and an ac load center for

stand-alone systems or the conductors between the inverter

and the service equipment or another electric power production

source, such as a utility, for electrical production and distributionnetwork.


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15FSEC 2002


! Photovoltaic Power Source

" An array or aggregate of arrays that generates dc power atsystem voltage and current.

! Photovoltaic Source Circuit" Circuits between modules and from modules to the common

connection point(s) of the dc system.

! Photovoltaic Systems Voltage" The direct current (dc) voltage of any photovoltaic source or

photovoltaic output circuit. For bipolar or multiwire installations,the photovoltaic systems voltage is the highest voltage between

any two dc conductors.

! Photovoltaic Output Circuit" Circuit conductors between the photovoltaic source circuit(s)

and the inverter or dc utilization equipment.


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Types of Pho tovol taic Sys tems

! Stand-Alone Systems

" Operate independent of the utility grid, includes hybrid systems

! Utility-Interactive Systems

" Sometimes called grid-connected systems

" Operate interconnected (in parallel) with the utility grid, a bi-

directional interface is required

! Bi-Modal Systems

" May operate in either utility-interactive or stand-alone mode, but

not concurrently


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Stand -A lone Sys tems

! Stand-Alone System (690.2)

" A solar photovoltaic system that supplies power independentlyof an electrical production and distribution network.

! Operate autonomously, or independent of the electric utility grid.

! Commonly used for back-up power and where the costs of

extending utility service and other power generating means arecost-prohibitive.

! May or may not use energy storage.

! Used to power DC loads and/or AC loads from an inverter.

! Hybrid stand-alone systems may include other energy producingequipment such as engine generators, wind turbines, fuel cells or

small hydro.


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18FSEC 2002

Stand-A lone Sys tem

Main supply equipment

for ac loadsInverter

Photovoltaic output circuit

Inverter output circuit

Inverter input circuit

Charge controller

Energy storage (battery)

Main supply equipment for DC loads


Figure 690.1(B)


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19FSEC 2002

Direct-Coupled

Stand -A lone Sys tems

! Simplest type of stand-alone PV system, common

applications include water pumps and fans.! DC load is directly connected to a PV array, no energy

storage.

! No overcurrent device typically required.

PV Array DC Load


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20FSEC 2002

Stand -A lone PV Sys tem w ith Battery

Storage

! PV array charges battery which supplies power to DC

electrical loads as needed.! Without charge control, battery is susceptible to

overcharge and overdischarge.

! Charge control may only be eliminated under special

circumstances the load is well defined and the battery is

oversized.

DC LoadPV Array Battery


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21FSEC 2002

Stand -A lone PV Sys tem w ith

Batter ies and Charge Con tro l

! Charge control is required whenever the load is variable

and the battery is not oversized.! Protects the battery from overcharge and overdischarge,

and may provide load control functions.

DC LoadPV Array

Battery

Charge

Controller


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22FSEC 2002


AC and DC Loads

! The addition of inverter is required to power AC loads

from the battery bank.! Inverter may incorporate a charger function, which

allows inverter to be connected to a generator or utility

grid to charge batteries or supplement the AC load.

" Note that there is no back-feed of power to the utility grid and

this is not a utility-interactive system the grid is used strictly for

back-up.

" The inverter charger AC input is separate from the AC output of

the inverter the AC output of stand-alone inverters operatingfrom batteries is never connected to the grid only the

dedicated AC loads served by the system.


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AC and DC Loads

DC LoadPV Array

Battery

Charge

Controller

Inverter/

Charger

AC Load AC Source

(Charger Only)


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Stand -A lone PV Hybr id Sys tems

! One or more energy sources are used in addition to the

PV generator.! Common hybrid sources used in stand-alone PV

systems include engine generators, wind turbines, small

hydro and fuel cells.

! Reliance on any single generating source is reduced,

battery storage capacity and size of PV array can be

minimized.

! Hybrid PV systems are often the least costly for remotepower applications.


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25FSEC 2002

Stand-A lone PV Hybrid Sys tem

DC LoadPV Array

Battery

ChargeController

Inverter

AC LoadEngine-generator,wind turbine or grid backup

Rectifier

DC Bus

AC Bus


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26FSEC 2002

Figure 690.1(B )

Hybrid System

Wind, engine-generator,

micro-hydro and otherpower sources


Inverter AC output circuit

Inverter

Energy storage, charge controller

and system control

DC loads

Inverter DC input circuit


Figure 690.1(B)


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27FSEC 2002

In terac t ive Sys tem

! Interactive System (690.2)

" A solar photovoltaic system that operates in parallel with andmay deliver power to an electrical production and distribution

network. For the purposes of this definition, and energy storage

subsystem of a solar photovoltaic system, such as a battery, is

not another electrical production source.


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28FSEC 2002

Bas ic Uti l i ty -In teract ive or

Grid-Connected PV Sys tem

Distribution

PanelPV Array Inverter/Power

Conditioner

AC Loads

Electric

Utility


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29FSEC 2002

In terac t ive Sys tem

Electric production

and distribution

network connection

Inverter

Photovoltaic source

circuits


Inverter output circuit

Inverter input circuit


Figure 690.1(B)


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30FSEC 2002

Uti l i ty-In teract ive Systems

! Operate in parallel with the utility grid, a bi-directional

interface is required! The inverter, or power conditioning equipment is the

primary component.

! Electrical loads are supplied by either the PV system or

utility.

! Generally do not use energy storage, but bi-modal

systems may use batteries for critical load backup.

! Electrical utilities may require accessible, visibledisconnects and special metering.


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31FSEC 2002

Uti l i ty-In teract ive System -

B i-Modal Con f igurat ion

PV Array

Inverter/Charger

Battery

Storage

Critical Load

Sub Panel

Backup

AC Loads

Main Panel

PrimaryAC Loads

Electric

Utility


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32FSEC 2002

PV systems and components.pdf

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