Pv Student Manual

7/30/2019 Pv Student Manual

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Fundamentals oF

Photovoltaics

For the Fire service


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F f P

f F s

September, 00

Rodney Slaughter,raining Consultant

With Funding Provided by,

Caliornia Solar Energy Industries Association

Sacramento Municipal Utility District (SMUD)


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acKnoWledGements

Tis training program became necessary when theemergency response community started to recognizeand ask questions regarding the presence and preva-lence o Photovoltaic technology. Te Sacramento

Municipal Utility District (SMUD) in collaborationwith the Caliornia Solar Energy Industries Associa-tion (CAL SEIA) responded with the unding o thistraining program. SMUD and CAL SEIA recognizedthe need to train emergency responders to operatesaely when working around solar electric systems.

I am personally grateul or the opportunity todevelop this important program or both the re andsolar electric industries. I would like to specicallythank my good riend Sue Kateley o the Caliornia

Energy Commission or her dedication and supportor this project. Sue has worked with me or over veyears in trying to nd a unding solution or thisprogram. I would also like to recognize Jon Bertolinoo SMUD or providing the unding and the programguidance along with Les Nelson, Executive Directoro CAL SEIA, or providing the industry contacts andkeeping this program on track.

Many o the ideas and direction or this training pro-gram came ater I attended the Photovolatics Designand Installation class taught by Jay Peltz and KrisSutton, instructors or Solar Energy International. Aun and act lled week at solar camp in Occiden-tal, Caliornia jump started the development o thistraining program. Im very grateul to my classmateMarc Fontana who provided many o the photographsrom solar camp now a part o this training program.By coincidence, I visited the Occidental Fire Depart-ment to borrow a salvage cover so that I could blockout the sunlight and render the solar panels we wereinstalling inoperable. I met Ron Lunardi, Fire Chieo the Occidental Community Services District. ChieLunardi not only has a vast amount o re serviceexperience but he is also an electrical contractor witha keen interest in this program.

I am particularly grateul to Johnny Weiss, Presidento Solar Energy International. O all the reerencematerial used to research the subject o Photovolta-ics, S.E.Is the Photovoltaics Design and InstallationManual was the most comprehensive o all!

I also called on a number o riends and associates toreview and provide recommendations to this trainingprogram. Lee Parker o the Modesto Fire Departmentprovided technical review o this program. Lee is a

Master Instructor in the Caliornia Fire raining andEducation System. I trust Lees reghting experienceand his knowledge o re ground operations that areshared universally with the re service community.Bob Gill, Fire Chie o Central Calaveras Fire &Rescue is also an accomplished instructor in the eldo Hazardous Materials. Ive relied on Bobs Hazmatbackground in other training programs and knew hewas a good choice to review this program as well.

Reviewers rom Southern Caliornia include associ-

ates Russ ingley, Dirk Drossel, and Scott Corrin.Russ ingley, Fire Chie o the Hermosa Beach FireDepartment, lends the Southern Caliornia reght-ing perspective and experience to the text. Dirk Dros-sel, re inspector with the Burbank Fire Department,has had plan review experience which includes severalphotovoltaic applications, while Scott Corrin, Cam-pus Fire Marshal or U.C. Riverside, brought his codeand regulation experience, along with his own interesto photovoltaic systems into the review. Compliment-ing Scotts code background is Howard Cooke, Fire

Inspector or the Sacramento Fire Department. How-ard brings practical code application to the project inhis work inspecting SMUDs solar-related projects.

At the same time this text was under development,I had the opportunity to meet Michael Callan, a year veteran o the Wallingord, Connecticut FireDepartment. Michaels body o work includes train-ing in hazardous materials as well as gas and electricutility emergencies. Along with the number o con-versations weve had, his text Responding to Utility

Emergencies also became a reliable source book orthis program.

Te completion o this project was accomplishedusing the services o my student assistant, JustinBibler, whose goal to become an English proessorwas put to the test in proo reading this document.Another riend, ammara Askea, Owner o Scenti-mental Packets and Design, brought her unique skillsto ormatting and publishing the compact disk.


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I am also very thankul or the support o my or-mer Chie, Ronny J. Coleman, Caliornia State FireMarshal (retired), in writing the Foreword to this text.As any author knows, your name maybe on the cover,

but its the names and reputations o a wide range opeople whose knowledge and experience make a proj-ect like this viable. I am grateul and thankul to eachand every one!

All the Best,

Rodney Slaughter

t rw P By:

Sue Kateley, Fuels & ransportation Supervisor,Caliornia Energy Commission

Jon Bertolino,Sacramento Municipal Utilities District

Les Nelson,Caliornia Solar Energy Industries Association

Lee Parker, CaptainModesto Fire Department

Bob Gill, Chie CentralCalaveras County Fire & Rescue

Russ ingley, Fire ChieHermosa Beach Fire Department

Scott Corrin, Fire ChieU.C. Riverside Fire Department

Dirk Drossel, Fire InspectorBurbank Fire Department

Howard Cooke, Fire Inspector,Sacramento Fire Department

Pgp cy f:

Marc Fontana

Alan Wing, Wing Solar and Wood

U.S. Department o Energy,

Rodney Slaughter

Shirley Mae Slaughter

P a P By:

ammara Askea,Scentimental Packets and Design

Justin Bibler, Editor


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TABLE OFcontents

FOREWORD ______________________________________________6

ABOU HE AUHOR _____________________________________7

INRODUCION __________________________________________9

PHOOVOLAIC CELLS AND COMPONENS________________13

PHOOVOLAIC PERFORMANCE __________________________23

PHOOVOLAIC APPLICAIONS ___________________________27

CODES AND SANDARDS _________________________________35

EMERGENCY RESPONSE __________________________________41

GLOSSARY OF ERMS _____________________________________49

REFERENCES ____________________________________________61


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ForeWord

ry J. c

A requently quoted phenomenon o coping withchange is or people to reer to the leading edge.Tis conjures up the image o being in ront o some-thing and has a somewhat positive spin to it. Otherswho have experienced the unintended consequenceso change have oten called it the bleeding edge ochange. Tis is because change oten creates conse-quences that have negative impacts.

Among my historical collection o interesting news-paper columns, I have an issue o Argus, publishedin San Francisco in the late 880s. In that article abattalion chie o the San Francisco Fire Departmentwrote a passionate letter to the editor strongly advisingthe city athers to prohibit the installation o electric-

ity in buildings. Te article identied the many risksand hazards associated with electricity. It stated that ithe city allowed the continued installation o electric-ity it would cause res and quite possibly result in thedeath o reghters. Tat battalion chie was right.But, electricity was installed and is now a act o liethat has resulted in a quality o lie that exceeds thatreghters concern.

Te reality or many in the re service is that technol-ogy will continue to evolve. When that technology

evolves, the re service can either be on the leadingedge or suer the bleeding edge. Te dierence mayoten be determined by how well trained and edu-cated the re service is on the specics o a technologyas it emerges into the main stream o society.

Rodney Slaughters eort to produce leading edgeinormation has been an important part o makingthe re ghting a saer occupation through awareness.Tis is not his rst eort and it will certainly not behis last. What is more important is that those whocan benet the most rom this knowledge need to beincorporating this inormation into both the train-ing and education systems or the re service. Hav-ing read Rodneys work on electric powered vehicles,alternative ueled vehicles, and other technologicaladvances, I pay a lot o attention to what I see when Iam in the eld. Tis particular course is no exception.

For example, I recently conducted an inspection o awildland community in which a signicant number o

homes were solar powered. Checking into an airportto rent a car recently, I was asked i I preerred anelectrical powered vehicle. Te technology that I seeserving society will continue to evolve outside o theinuence o the re service.

o update and paraphrase Benjamin Franklin, anounce o awareness is worth a ton o state compensationbenets. Te inormation contained in this programmay just be the dierence between a reghter han-dling an event successully or them becoming a job

injury statistic. Te ormer is preerred over the latter.


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aBout the author

Rodney Slaughter is the author and instructionaldesigner or this project. Rodney has years o reservice experience; beginning his re service careerin , as a military and civilian re ghter or theUnited States Air Force, with assignments in Florida,Hawaii, and Caliornia. Since 88, Rodney has beenemployed as a Deputy with the Caliornia State FireMarshals Oce working in training, code enorce-ment, grant coordination and codes and regulations.

Rodney has a keen interest in environmental issues asthey relate to the re service. Tis interest is reectedin the number o training programs he has developedor the re service community, which includes: tirere prevention and suppression, emergency responseto electric and hybrid electric vehicles, compressedand liqueed natural gas vehicles, and urban-wildland

interace re prevention and mitigation. Rodney hastraveled the country teaching re departments the neart o successul grant writing. Rodney is a nationallyrecognized instructor and a requent speaker/trainer atre-related classes and conerences around the country.Rodney studied Fire Science at Honolulu CommunityCollege, and has a Bachelor o Arts in Anthropologyrom Caliornia State University o Sacramento.


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introduction/overvieW

FundamentalsoF

PhotovoltaicsFor

the Fire service

While terrorism, weapons o massdestruction, and natural disastersdominate the mindset o emergencyresponders; subtle changes in oursociety, and the technologies that weuse, have been let largely unnoticed.Increased cost in hydrocarbon uelsand the electrical energy associatedwith it, have orced many Americansto look or alternative energy options.Tese options range rom solar, wind

and micro-hydro electric energy pro-duction at the building site.

Unsuspecting reghters respondingto a structural re could be unpleas-antly surprised to discover that oncethe main electrical power to thebuilding has been disconnected, asecondary source o power may still bepresent and charged with lethal volt-ages o electricity.

With a variety o alternative electricalgeneration systems available, none isbecoming more prevalent than solarelectric. Fireghters can be sure thatthey, at some point in the uture, willhave at least one emergency involvinga building with a solar electric system.

W ?

In 00 worldwide production o

electricity rom the sun was at ,megawatts (MW). Tis is expected toincrease by 0% in 00. By 00, .gigawatts (GW) are projected.

O the , megawatts produced in00 worldwide; Germany produced% or 8 MW, Japan produced% or MW and the UnitedStates comes in at a distant third place

with % or 0 MW. Te State oCaliornia is Americas leader and gen-erates the majority o solar electricityin the country.

According to the Caliornia EnergyCommission (CEC), the state has morethan ,00 grid-connected commer-cial and residential Photovoltaic (PV)system installations representing megawatts o power as o April 00.

Te trend will continue with the CECrebate program, ederal tax incentivesand the increased cost o energy.

Te Caliornia Governors goal, tohave million solar roos generatingan additional ,000 MW o electric-ity by 0, will also uel this grow-ing trend. Note that ,000 MW willdouble the , MW in worldwideproduction o solar energy or 00!Caliornia is and will continue to bethe countrys largest producer o solarelectricity. Tat means Caliornia re-ghters in both rural and urban areaswill be equally aected by solar elec-tricity now and well into the uture.

A multi-amily housing development in

Livermore, Caliornia is outtted with

photovoltaic modules. (Photo Credit:

Marc Fontana).


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0

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a s e sy sf?

With so much solar power already available, one hasto ask the question: Are solar electric systems sae?Te answer is an emphatic yes! Under normal operat-ing conditions these systems provide a sae, secure andenvironmentally riendly source o energy. Te solarelectric industry itsel has maintained an incrediblesaety record with no documented cases o lie lostrom an electrical shock.

In emergency conditions involving solar electric com-

ponents however, re ghting personnel need to beaware o the potential dangers and hazards. Te obvi-ous danger is electric shock. In addition, i the panelsbecome involved in a re or explosion, an inhalationhazard rom the chemicals used to manuacture thesolar panels could also pose a potential health risk.

In an exhaustive search or recorded re ghterinjuries, a solar industry news source, Photon Interna-tional, ound a single case in Switzerland in Novem-ber 00 where a reghter received an electrical

shock while working a structural re at a retirementhome. Fortunately, the re ghter sustained no seri-ous injuries. Tis single incident spotlights the needor a preemptive awareness level class or emergencyresponders.

During the 00 San Diego, Caliornia restorm,where thousands o homes burned, including homeswith solar electric systems, there were no reportedinjuries involving solar electricity (Phototon Inter-national, May 00). Recognizing the need to keepemergency responders sae, SMUD and CAL SEIAunded this program to ensure continued reghtersaety while working around solar electric, or moreappropriately, photovoltaic (PV) systems.

Te bottom line is that while solar electric systems are

sae under normal operating conditions, no energytechnology is risk ree when all aspects o its utiliza-tion are taken into account. Every technology hassome attendant direct and indirect health and saetyconcerns (Etnier and Watson, September 8). Ourocus or this program is on reghter saety.

t Pp f Pg

is to guide you through the basics o photovoltaicdesign and application. You will learn about the asso-ciated components o the photovoltaic systems and

how they are integrated into the building. With thisshared background you will be able to respond to anyemergency involving solar electric systems saely.

t G f Pg

is to provide the re service with an awareness ophotovoltaic systems, so that they can make inormeddecisions during an emergency.

t obj

o achieve this goal, every student o this training

program will be able to:

Recall the principles o solar electricity production.

Identiy the components o a photovoltaic system.

Identiy applications o photovoltaic systems.

Apply codes and regulations to photovoltaic installa-tions.

Te 2003 San Diego Firestorm threatened the Scripps Ranch

community. (Photo Credit Bob Epplet Oce o Emergency

Services)


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Recall electrical saety principles when workingaround solar and all electrical systems.

Establish standard operating guidelines or yourdepartment when responding to a building emergencywhere employs solar electric systems are installed.

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Tis training program was published in its entirety ona compact disk to provide an inexpensive distributiono standardized training materials and get this inor-

mation into as many hands, and minds, as possible.Te compact disk contains inormation or individualsel study or or use as part o a ormal training pro-gram in an instructor-lead classroom setting.

Te compact disk contains all the training materialsneeded to teach this class as a stand alone trainingprogram or one that can easily be incorporated intolarger training programs involving building tech-nologies. Tese training materials include a studentmanual, instructor guide, and Powerpoint slide show.

Te student manual provides an overview o thePhotovoltaic technology along with standard operat-ing guidelines or emergency responders. ext boxeswith Important Notes spotlight inormation use-ul to emergency responders. A glossary o terms isincluded in the student manual or both solar indus-try personnel unamiliar with reghting terms andor reghters unamiliar with electrical and utilityterms. A complete list o reerence is provided to notonly give credit to source inormation, but also toidentiy resources or those who would like to do a

little more research o their own on the topic. A listo web-related resources is also provided or the samepurpose.

Te instructor guide is intended to assist the instruc-tor in presenting this material in a classroom setting.Behavioral objectives, length o time to deliver eachsection, reerences, and recommended materials areall on the rst page o each lesson plan. Recom-

mended student activities are also included in selectlesson plans.

Te Powerpoint slide show provides bullet points andgraphics or the each o the lesson plans. Instructorsare encouraged to customize and incorporate photo-graphs o solar systems and applications in your area.

Te class is designed primarily or reghting person-nel, but installers and people new to the industry willnd the saety considerations a valuable resource aswell. Above all, the express purpose o this program is

personnel saety!

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FundamentalsoF

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Give me thesplendid silent

sun with all its

beams full-

dazzling.

Walt Whitman,

Photovoltaic cells and comPonents

ay f s c

Te solar cell is the smallest unit andthe backbone o the Photovoltaic(PV) system. Tere are two types omanuactured PVs: silicon cell oramorphous silicon. In either case, theris a very thin layer o silicon; /00tho an inch thick. By the way, siliconis not only one o the most abundantelements on the planet, but the siliconused in PV systems is similar in purity

and quality to that used in the semi-conductor industry.

Silicon is a semiconductor. Somemanuacturers layer slices o siliconwith atoms o boron or phosphorus ina process known as doping. Boron isused or the positive layer o the cellin that it has an electron deciency.Boron has room, or a hole, in the outershell o the atom to add an electron

(Solar Energy International, 00).

Phosphorus, on the other hand, has anextra electron and is used or the nega-tive layer o the solar cell.

Te solar cell and the photovoltaiceect begin at the sourcethe Sun,o course! Every single day enoughsolar energy alls on the earth to sup-ply all the worlds energy needs orour to ve years (Got Sun Go Solar)!Te Suns ull intensity and bright-ness is ,000 watts per meter squared(reerred to as insolation). Tis inten-sity can be diminished according tothe micro climate and site specic con-

ditions (shade). But even on overcastdays caused by smog or clouds, solarelectricity can still be generated by thesolar panels, although at signicantlyreduced eciencies.

In the Northern Hemisphere, peaksun per day is about hours, between0 am and pm (peak energy produc-tion). Not surprisingly, most photovol-taic systems are orientated towards the

south to maximize the amount o lightalling on the photovoltaic panels. Butwe are getting ahead o ourselveswhat are photovoltaic panels and howdo they work?

photon

electrons

p/n junction

phosphorus -

boron +


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FundamentalsoF

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Photons generated rom the sun energize and knockloose the extra electron in the negative layer whichcrosses the positive-negative (P-N) junction to ll thehole on the positive Boron side. Te energy releasedin the process produces . volt o direct current (DC)and ows through the metal contacts built onto thecell. Tese energized electrons combine with electronsrom the other solar cells in the system, ow throughthe circuitry o the wiring system, run the appliances,and then ow back into the negative layer only to bere-energized once again.

Te composition o the silicon crystalline structurevaries rom manuacturer to manuacturer. Te purestsilicon structure employs the growth o a single crystal(monocrystalline) cut in to thin waers. Multiplecrystals cast together and sliced into thin waers ormpolycrystalline structures.

Other manuacturers dont make cells at a ll, insteadusing a chemical process which deposits silicon on asubstrate material. Tese panels dont have the circlesbecause the entire surace o the substrate is the cell.Silicon deposited on glass or stainless steel as a thinlm is reerred to as amorphous (Solar Energy Inter-national, 00).

o improve PV eciency and to reduce productioncost, the industry is using and experimenting withother materials such as cadmium telluride and galliumarsenide. Te industry is also developing syntheticalternatives to the silicon waers.

my

Monocrystalline is the oldest and most expensiveproduction technique. Complete modules have outputcapacities o to %. Boules (large cylinders) opure single-crystal silicon are grown in an oven, andthen sliced into semi-circular waers beore beingdoped and assembled (Solar Living, th Ed). Mono-crystalline achieves the highest eciency in electricenergy production and its production cost is higherthan other silicon types.

Pyy

In this production technique, pure molten silicon iscast into molds, then sliced into waers, doped andassembled. Polycrystalline is lower in conversion e-ciency compared to Monocrystalline, averaging about to % output capacity. Polycrystalline is shaped asa square, taking in as much o the available area o thePV module as possible.

New single amily housing projects like this in Livermore,

Caliornia have upgrade options that include photovoltaic

systems. Tis polycrystalline PV system is rated at 3.6 kW and

is grid connected. (Photo Credit: David Springer, Davis

Energy Group).

ap

Amorphous silicon is made by vaporizing silicon anddepositing it on a glass or exible surace. Some amor-

phous PV panels are exible and are able to be rolledand used or remote electricity generation. In thiscase, strips o amorphous PV can be wired togetherto orm an array. One advantage o thin lm (amor-phous) PV products are that they can be laid betweenthe seams o metal roos and held into place with anadhesive backing. Other amorphous panels are madeon a rigid substrate so that they can be installed inthe same manner as the other types o PV panels. Te


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exibility o this technology allows it to be used ina wider range o applications. Te production tech-nique costs less than other production techniques,but the output capacity, is reduced to to %. Asquare oot o amorphous silicon averages about watts, compared to monocrystalline or polycrystal-line which average about 0 watts per square oot(Solar Living th Ed).

P m

Solar cells are covered with an antireective mate-rial, placed on a backing material and encapsulatedtogether within a glass and aluminum rame. Whenseveral cells are connected together in series andparallel the voltage and amperage is accumulated toachieve the desired electrical output. Photovoltaic cellsconnected together in this manner orm a PV moduleWeather-proo electrical connections are mountedon the back o the module or quick connections toother modules that comprise the PV array. Modules

can come in a variety o sizes and rated output. Testandard size module is -volts, consisting o solar cells. An average size crystalline module weighsbetween 0 and pounds.

ip n: A wide range of toxic and hazardous chemicals are used in the PV manufacturing

process. When a module is exposed to fire or an explosion, trace chemicals can be released into the

atmosphere. The inhalation of PV modules fumes and smoke could affect human health. (Etnier and

Watson) With the concentration of PV modules in commercial applications (larger PV arrays), the risk

would be higher for surrounding populations than for PV systems on residential fires. In the case of a

large commercial photovoltaic array involved in a fire or explosion, surrounding populations should

be warned to shelter in place until the emergency is over.

A semitransparent amorphous silicon product used as a gas sta-

tion canopy in Faireld, Caliornia. (Photo Credit: BP Solar)


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An installer adds a PV module into the array. (Photo Credit:

Rodney Slaughter)

Photovoltaic panels have no moving parts and requirevery little maintenance. A building owner may need tooccasionally hose and/or squeegee dust, dirt and birddroppings o the panels to keep them operating atpeak eciency. Te panels themselves are completely

weather proo, so there is little danger to the buildingoccupants who perorm this maintenance unction.

P ay

wo or more modules connected together orm a pho-tovoltaic array. Te modules are wired together in aseries to accumulate voltage, and the strings are wiredtogether in parallel to increase amperage. Residentialsystem outputs o 00 volts are not uncommon. Teaverage household in Caliornia uses about ,00 kilo-watt-hours per year, and a PV system in the three-to

our-kilowatt range would be adequate to meet mosthomeowners electricity needs. A 0 module arraywould operate at over ,000 watts and weigh approxi-mately 00 to ,00 pounds. Tis weight would bespread equally over a 0 square oot area o the roo,resulting in a roo weight load o approximately .pounds per square oot.

P t sg

You will see some residential PV systems that have beenconstructed as roo tiles or roo shingles. Tese PV tiles

or shingles are integrated into the homes roo coveringand become part o the structure. Tis type o PV sys-tems is a orm o building-integrated design. PV rootiles duplicate the depth o cement or clay tile roos,and PV shingles do the same or composition shingles.It takes more installation time, wiring and bundlingindividual tiles or shingles together to install thesetypes o systems. Tis PV roong system is aestheti-cally pleasing but can cost considerably more than themounting process or modules and arrays.

Centex Homes has built model homes in San Ramon,

Caliornia. Te homes were unveiled in the summer o 2004.

Te photograph shows PV tiles being installed on a tiled roo.

(Photo Credit: Davis Energy)

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ip n:The PV array can be home to awide range of insects, including ants, spiders andwasps. Each of these has been known to inhabit thearray framing, electrical junction boxes and otherenclosures. Be prepared for the unexpected shouldyou reach under the array or open a junction box(Solar Energy International).


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For building owners living in high re hazard severityzones, roong systems must meet itle o the Cali-ornia Building Code or Class A roong materials.Building integrated PV systems (PV tiles or shingles)would also have to meet this regulation.

Some manuacturers o PV roong tiles have hadtheir products tested and have met the standard orClass A roong. Manuacturers o PV shingles haveachieved their Class A rating by using a re resistantunderlayment beneath the section o the roo covered

by PV shingles. PV modules that are mounted onracks above the roo covering would not have to meetthe roong requirementbut the roong materialunderneath would.

By sy

Lead acid batteries are used to store solar-generatedelectricity. Batteries are used most requently in o-grid PV systems, although batteries are also used ingrid-connected applications where the user wishes tohave electricity availability when local blackouts occur.

Without batteries, a PV system cannot provide elec-tricity when the electrical grid is not energized.

A battery is an electrochemical cell in which anelectrical potential (voltage) is generated at the batteryterminals by a dierence in potential between the posi-tive and negative electrodes. When an electrical load(appliance) is connected to the battery terminals anelectrical circuit is completed.

A battery cells consists o ve major components; elec-trodes, separators, terminals, electrolyte and a case or

enclosure. Several batteries are wired together achievethe desired voltage and amperage to run select house-hold appliances when the sun is not shinning.

Tere are two terminals per battery, one negativeand one positive. Te positive electrode o a lead acidbattery consists o a lead grid covered with lead oxide(PbO). Te negative electrode is essentially lead (Pb)with an inert expander that causes the surace to beporous. Tese electrodes are interspersed and electri-

cally insulated rom one another with an inert separa-tor. Te electrolyte is suluric acid (HSO) whichmost oten is in a liquid orm but can be immobilizedin a glass mat or suspended in a gel.

Pinnacles National Monument in Caliornia installed a

9.6-kilowatt photovoltaic system. Te system provides power

or three employee residences, a ranger station, visitor center,

campground, comort station, well pump, and two wastewate

euent pumps. It eliminates the uel bill or a diesel generatothat produced 143 tons o carbon dioxide each year. (Photo

Credit: National Park Service)

FundamentalsoF

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ip n: As a rule, batteries do not burn;or rather, they burn with great difficulty. If batteriesare exposed to fire, however, the fumes andgases generated are extremely corrosive. Spilledelectrolyte can react and produce toxic fumesand release flammable and explosive gases whenit comes into contact with other metals. Due tothe potential of explosive gases, prevent all openflames and avoid creating sparks. In emergenciesinvolving batteries, always wear full protectiveclothing and self-contained breathing apparatus(SCBA) on positive pressure. Extinguish lead-acidbattery fires with CO, foam or dry chemical fireextinguishers.


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A bank o batteries similar to the one shown here would be

used to back-up the PV system in o grid applications. (Photo

Credit: Alan Wing)

Te electrical potential between the positive andnegative electrodes is about volts direct current(DC). Te voltage varies with temperature, the stateo charge, and whether the cell is being charged or

discharged. During discharge, the voltage decreasesas the state o charge decreases. As the batteryapproaches a state o ull discharge, the exchange oelectrons rom the positive and negative electrodescontinues until both are covered with lead sulate andare at equal electrical potential; reerred to as a dis-charged cell.

During the charging process, the reactions occur inthe opposite direction to reorm both electrodes backto lead and lead oxide respectively. As the reormationproceeds, the electrical potential o the cell is returnedto its original value o approximately volts.

Outside the battery current ows rom the positiveterminal, through the appliance and returns to thenegative terminal. I the electrical load is replacedby an external power source that reverses the ow othe current through the battery, the battery can be

charged. Tis process is used to reorm the electrodesto their original chemical state, or ull charge.

During charging, the battery can enter a state o overcharge in which the electrodes will o-gas oxygenrom the positive electrode and hydrogen rom thenegative electrode. In conventional, ree owingelectrolyte batteries, the gasses bubble through theelectrolyte to the surace and out o the battery, result-ing in a drop in the batteries electrolyte level (Slaugh-ter/Rawson). Te escaping gases are highly ammable.For this reason, sparks and open ames are notallowed in the area o the batteries.

c

o keep battery charge levels in check, a chargecontroller is used in the PV system. Te addition o abattery charge controller prevents over-charging andreduces the danger o o-gassing. Many o the com-mercial controllers on the market also protect the bat-tery rom over-discharges as well. A PV charge controlsenses battery voltage. When the batteries are ully

charged, the control will stop or decrease the amounto current owing rom the PV array into the bat-tery. When the batteries are being discharged to a lowlevel, many o the controllers will shut o the currentowing rom the battery to the DC loads. Chargecontrollers come in a variety o sizes, rom a ew ampsto as much as 0 amps.

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ip n: Never cut into the batteriesunder any circumstances! Even though the voltagegenerating system may be disconnected fromthe battery bank, the batteries themselves stillhave potential for electrical shock. If the battery ispunctured by a conductive object, assume that theobject has electrical potential.


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Te battery controller shown here was used in an o-grid PV

system. (Photo Credit: Alan Wing)

i

Te PV array, batteries and charge controllers allunction on direct current. Tis is great or the o-grid building owner who is also using direct currentappliances. However, these DC appliances are more

expensive, limited in variety, and harder to nd thantheir alternating current counterparts. So, or thebuilding owner to take advantage o a wider range oappliances, or to connect to the grid, the PV directcurrent has to be converted to alternating current.Tis is accomplished with a PV inverter.

Te inverter changes the direct current to alternatingcurrent at 0 hz. Inverters are classied according tothe waveorm they produce. Tere are three types oinverters; square wave, modied square wave and sine

wave. Sine wave inverters are used in many applica-tions because they produce a high quality waveormused to operate sensitive electrical equipment. Util-ity connected inverters are required or grid-tied PVsystems. Utility grid inverters are typically o the sinewave type in order to correspond to the requency othe utility supplied power and are designed to shut

down the solar generated electricity when there is nogrid power. When converting DC to AC a signicantamount o heat is generated. Inverters are designedwith a heat sink assembly to dissipate the heat awayrom the system.

FundamentalsoF

PhotovoltaicsFor

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Inverters come in a wide range o styles, classications, and

optional eatures. Te one shown here is manuactured by PV

Power and includes a digital read out. (Photo Credit: RodneySlaughter)

mg sy

Tere are a variety o ways that PV modules andarrays can be mounted. ypically a roo with a south-ern exposure allows a quick and eective installation.Although there are systems that can be mounteddirectly on the roo, in many cases, specialized rooracks lit the array rom the roo deck allowing or air


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0

to circulate under the modules. Many PV systems aredesigned to withstand 80 mile per hour winds.

Fixed pole mounted PV system oreground with roo mounted

PV modules and solar thermal modules on the roo in the

background. (Photo Credit: Alan Wing)

A solar water heating panel is installed below the PV array.

(Photo Credit: Les Nelson, CAL SEIA)

PV systems can also be mounted on the ground usingcustomized racks, or they can be mounted on poles.Sophisticated tracking systems that allow the entirearray to move with the direction o the sun are a ea-ture o pole mounted systems.

o s tg

Can you distinguish PV panels or modules rom othersolar technologies like solar thermal systems or sky-lights? Solar thermal panels (solar water heating col-lectors), are used to heat water or the swimming pool

or or domestic hot water. Unlike PV panels, whichconvert up to % o the suns energy into electricity,solar thermal panels convert % o the suns energyinto heat. Another type o solar thermal panels is usedexclusively or heating swimming pools. Tese panelstypically consist o a polymer material, and usually layat on the roo. Solar pool heating panels usually haveno glass cover plate or other metal enclosure.

Solar thermal panels run copper tubing inside analuminum box with a at or convex glass cover.

Solar thermal panels are not inherently dangerous toemergency responders-- unless re ghters trip overthem while working on the roo! Tere is no wiringassociated with solar thermal panels- only plumbingand hot water. It is important to be aware that bothtechnologies can be in use on the same roo at thesame time.

Skylights are a unction o passive solar designallowing natural light to enter the interior o thebuilding. When they are available, re ghters can use

skylights to ventilate the building o superheated gas-ses and smoke expeditiously. Skylights rom the inte-rior o the structure, with a sheet rocked ceiling, willbe sheet rocked up to the underside o the skylight.Tis is advantageous to re ghters in that the chim-ney created by the sheet rock underneath the skylightalso provides some protection rom superheated gasand smoke getting into the attic area. Another advan-tage is that a broken skylight is cheaper to x than ahole chopped in the roo assembly.

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Skylights come in a variety o shapes and sizes andare airly distinctive with clear, translucent or tintedplastic or glass. o keep rain rom getting inside theskylight, they are integrated into the roo with metalashing around the base. A skylight with integratedphotovoltaic will have a distinctive amorphous rectan-gular pattern in the glass. Once again it is conceivablethat skylights may be on the same roo as PV panelsand solar thermal panels.

Laminated to the skylight glass are photovoltaic cells that pro-

duce electricity as well as serve as an element in the shading

and day lighting design at the Toreau Center or Sustain-

ability, Presidio National Park, San Francisco, Caliornia.

(Photo Credit: Lawrence Berkeley Lab)

P if

PV panels are distinctive, making them relatively easyto recognize when you know what to look or. In the

case o monocrystalline, the PV panel looks like thereare a group o semi-circular squares that are laid outin a rectangular panel. Polycrystalline panels havesquare cells laid out in a rectangular panel. In eithercase these modules are usually laid on a racking sys-tem elevating them a couple o inches above the roo.Amorphous panels have a pattern o rectangles inte-grated across the entire panel. Te color o all thesesolar cells ranges rom black to blue.

It is not recommended that re ghting person-nel attempt to remove or cut into the PV modules.Attempts to do so could potentially release all theenergy inherent in the system simultaneously. Simi-larly, there is no need to cut into or remove a solarthermal module (water heating collector) during astructural emergency.

Skylights with integrated PV circuits should not bebroken or ventilation purposes. All other skylightscan be used or ventilation purposes i it meets the

strategic and tactical objective o the emergency.When the PV array covers the south acing roo, andthe need to ventilate occurs, choose a spot on the east,west or north acing slope o the roo and cut a venti-lation hole at the highest point over the re.

summarY

Te greatest danger or emergency responders is thelack o PV knowledge needed to saely operate aroundthis emerging technology. Tis section provided youwith an introduction to the photovoltaic system.

Identication o the PV array and all the related com-ponents is critical in an emergency response; under-standing how the PV system is integrated into thebuildings electrical distribution system is importantto sae reground operations.

Photovoltaic technology is an incredible scientic andengineering eat. But as wonderul as this technol-ogy is, there are still some limitations. Many peoplebelieve that purchasing a photovoltaic system willallow them to say good-bye to their electric company

and their utility bills orever! As you will see that issimply not the case. In many cases the utility indus-try becomes a partner in the PV system by providingmany people with the back-up electricity they needwhen the sun is not shinning!

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Photovoltaic technology does notconvert 00% o the Suns energy intoelectricity. Te highest eciency PVtechnology available today is used onsatellites, and or applications such asthe Space Station, where cost is lesso a consideration. Tese types o PVcells are able to convert as much as0 % o sunlight into electricity. Tehighest eciency PV products usedin conventional building applications

today convert rom 0 to 0 % osunlight into electricity.

Environmental actors like overcastdays caused by clouds and smog canlower system eciency. Site actorssuch as chimneys, trees and nearbybuildings can shade the panels duringpart o the day and greatly reduce theoutput or the entire array. And, likepeople themselves, PV systems oper-

ate best within a comortable range otemperatures.

PV output will be greatly reducedwhen the temperature o the indi-vidual cells goes above 0 degreesFahrenheit. For this reason panelsare usually installed on a rackingsystem that lits the panels o theroo to allow air to circulate aroundthe modules, thereby keeping the PVarray cooler. Extreme cold tempera-tures can have the opposite eect.Increased output o 0 to 0% hasbeen recorded in cold temperatureswith clear days, and sunlight reect-ing o snow banks.

o achieve peak perormance, sun-light should strike the PV panel ata 0 degree angle. O course, thesun changes position during the day,

FundamentalsoF

PhotovoltaicsFor

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Is it fact, orhave I dreamt

itthat, by

means of

electricity, the

world ofmatter has

become a

great nerve,

vibrating

thousands

of miles in abreathless point

in time.Nathaniel Hawthorne,

The House of the Seven

Gables,

Photovoltaic PerFormance

Pv h Bf1839 French scientist Edmond Becquerel discov-

ers the photovoltaic eect while experiment-ing with an electrolytic cell made up o twometal electrodes placed in an electricity-conducting solutionelectricity-generationincreased when exposed to light.

1873Willoughby Smith discovered the photo-conductivity o selenium.

1876 In 8 William Grylls Adams and RichardEvans Day discover that selenium produceselectricity when exposed to light.

1905Albert Einstein published his paper on thephotoelectric eect (along with a paper onhis theory o relativity) and wins the NobelPrize or his theories in .

1918 Polish scientist Jan Czochralski developed away to grow single-cryst al silicon.

1954 Te photovoltaic technology is born in theUnited States when Daryl Chapin,

Calvin Fuller, and Gerald Pearson developthe silicon photovoltaic (PV) cell at BellLabs.

1958 Te Vanguard I space satellite used a small(less than one watt) array to power itsradios.

1962 Bell elephone Laboratories launches therst telecommunications satellite, the el-star (initial power watts).

1964 NASA launches the rst Nimbus space-crata satellite powered by a 0-wattphotovoltaic array.

1982 Te rst, photovoltaic megawatt-scale powerstation goes on-line in Hisperia, Caliornia.It has a -megawatt capacity system.

1982Worldwide photovoltaic production exceeds. megawatts.

1983ARCO Solar dedicates a -megawatt photo-voltaic substation in central Caliornia. Te0-acre, unmanned acility supplies thePG&Es utility grid with enough power or,000-,00 homes.

1984 Te Sacramento Municipal Utility Districtcommissions its rst -megawatt photovol-taic electricity generating acility.

1999 Cumulative worldwide installed photovol-taic capacity reaches 000 megawatts.


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and between seasons. For this reason a PV designerconducts a site inspection to determine availability osunshine throughout the year, including a number osite specic characteristics such as average daily insola-tion, site latitude, magnetic declination (true south),tilt angle and site specic inormation such as localweather and climate, all the while keeping an eye outor shading obstacles. Regardless o these consider-ations, however, all the PV systems in the Northernhemisphere will be orientated towards true south.

P cp

Te point o photovoltaic technology is to generateelectricity. More signicantly, electricity generatedrom a clean and reliable sourcethe Sun! While you

work with and around electricity every day, you mayneed a reresher on what electricity is and the termi-nology associated with it.

Electricity is the ow o electrons through a conduc-tor. PV designers are driven by the electrical conceptsassociated with this ow o electronsvoltage (volts),amperage (amps) and wattage (watts).

Voltage is the measure o electrical potential betweentwo points. Te unit o orce, or pressure, it takes to

FundamentalsoF

PhotovoltaicsFor

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When designing a PV system, engineers and installerstypically underestimate the PV module output by to % rom the manuacturers tested output. Tis

calculation allows or a buer in the specications toensure that the installed system will meet the buildingowners energy needs.

Another actor in design eciency is the output o thesystem and the act that the mono and polycrystal-line cell degrades about . to .% every year. Tislow degradation percentage, gives PV manuacturersthe condence to guarantee that their solar panelswill be operational or at least years. Te reality isthat these systems may actually outlive many o their

original owners.

A Fire Department salvage cover was used in a ailedattempt to block sunlight rom reaching the newlyinstalled PV array.

ip n: While there are many factorsthat affect PV performance over a period of time,emergency response personnel should rememberthat even in the worst daylight conditions the PVarray is still generating electricitymaybe not atits peak performance, but if you get shocked bycutting into the system, the performance issue is amoot point.

ip n: When the sun is shining there

is no way to turn off the PV system. German firefighters tried using foam to obliterate the sunlighton the array. The foam is translucent and cannotcompletely block all the Suns intensity. Moreimportantly, the foam kept sliding off the surface ofthe PV array.

A re department salvage cover was employed in Caliornia

only to discover that while it signicantly reduced the Suns

intensity and the electrical energy that it generatesit did

not completely block out the Sun and the system still generated

enough volts and amps to shock a potential victim. (Photo

Credit: Marc Fontana)


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motivate electrons to move through a circuit is mea-

sured in volts. Te rate at which the electrons owthrough the circuit is measured in amps. Wattage issimply a measure o the amount o electrical powerprovided by the circuit. A watt is the rate an applianceuses electrical energy, or rather the amount o workdone when one amp at one volt ows through oneohm o resistance. One watt is equivalent to /horsepower. A watt is the product o voltage (volts)multiplied by (amps).

When you put all these terms and concepts together

you end up with Ohms Law. Ohms Law is a math-ematical equation to help you calculate all o theseterms when you know at least two o the values. Teormula looks like this:

Volts x Amps = Watts

So, consider your circular saw that draws . amps opower when plugged into a 0 volt wall outlet, it will

consume, .a X 0v = 00 watts o power. You can

ip this equation around to nd other values.

Watts Amps = Volts and Watts Volts = Amps

For PV designers and installers this ormula is impor-tant when calculating the energy demand o thebuilding they are trying to power with a PV system.Since consumers need to know to know how muchenergy they use, the watt-hour is an important mea-surement and one that PV designers can work with.o calculate watt hours all you need to know is the

rated wattage or the appliance and how the long theappliance stays on. Add together all the appliances inthe building and you get an idea o how many poten-tial watt-hours maybe needed by the system.

Imagine i you calculated all the watt-hours in theroom you are sitting in right now? How many watt-hours do you suppose is being used? I you count thelights, the stereo or television, the electric heater orthe air conditioner, the gure could be staggeringin

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the thousands o watts, and over a period o one hour,thousands o watts per hour (one thousand wattsconsumed over the period o one hour is one kilowatthour, or kWh). Once you get into these numbers youwill see that the kWh consumed in the normal courseo living are substantial. Your own monthly utility billwill show the amount o energy you and your amily

consume in terms o kilowatt hours.

Why is this inormation so important to PV design-ers and installers? PV systems need to be sized tomeet consumer energy use. But the catch is that aPV system is still relatively expensive and the averageAmerican consumer uses a lot o electrical energy.Te bigger the system, the higher the out-o-pocketexpense to the building owner: to the tune o tens othousands o dollars. Not only that, but a PV systemcannot deliver a constant amount o energy every day

in every season.Te trick here is energy conservation. Reputabledesigners and installers will analyze the consumersenergy usage and expectations rom the system. Teywill make recommendations on how to conserveenergy beore they talk about sizing and installing thePV system.

summarY

Te physics o electricity never change, regardless o

how the electricity is generated. Tere are a number oactors that aect overall system perormance. Geo-graphical location, site specics, including roo slopeand declination (degrees east or west o true south),system size, the electrical demands o the system, andthe PV components themselves are all actors related toperormance. Recognizing these actors is another keyto personnel saety when working around PV systems.


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Understanding how solar cells gener-ate electricity is one thing. Under-standing what to do with all thatelectricity is another. In most cases, aPV system will generate more electric-ity during the sunniest part o the daythan can be used at that time. Pho-tovoltaic designers and installers haveseveral options in regards to systemdesign in order to address this issue.Te rst is to store excess electricity in

a bank o batteries so that the electric-ity can be used when the sun is notshining. Tis design is typical o ano-grid system. Te second option isto credit all excess electricity generatedback to the utility company. Tis istypical o a grid-connected system.

A third option is to store electricityin the battery bank and then creditexcess electricity back to the utility

grid. Tis battery back-up systemensures that the building owner willhave enough electricity stored in caseo a utility grid power outage. Whilebattery back-up systems do exist, theyare not common. Its ar more costeective (and probably easier or mostbuilding owners to maintain) to back-up an o-grid, or grid-tied system orthat matter, with a generator.

Te design choice, the building site,and the building owners expecta-tions will all be considered to deter-mine the type o equipment thatwill be installed at a given site. Teobvious advantage o a solar energysystem is that it produces clean andreliable energy that can be used ina wide range o applications. In actthe application o solar electric is so

prevalent in your lie that you prob-ably dont even think about it.

dy u

You are amiliar with day use solartechnology where solar cells or mod-ules are wired directly to solar gener-ated appliances like a calculator, toys,an, blower or pump. Tese are simpleand inexpensive solar electric applica-tions. Tese appliances operate when

the solar cell is exposed to the sun or abright light.

ig P w

By Bk-up

Other applications that you may beamiliar with might include integratedphotovoltaic with battery back-upwhere the solar energy is stored inrechargeable batteries so that theappliance can be used when the sun

isnt shining. Tese appliances includewatches, radios, ashlights, telecom-munication equipment, railroad lightsand low voltage landscape lightingsystems. Again these are airly simple,inexpensive and specic applicationso the photovoltaic technology (thinkabout the cost o running electricalwires to all o the thousands o solar-powered call boxes along Caliorniasreeways). Even i you dont use PV

directly you are doing so indirectly.Communication systems and satelliteswith integrated PV systems providepower that improves the eciency oour everyday lives even though youmay not be aware o it!

FundamentalsoF

PhotovoltaicsFor

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Te worldwe live in is

but thickened

light.Ralph Waldo Emerson,

The Scholar,

Photovoltaic aPPlications


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In December o 1998 Astronauts Jerry L. Ross (let) and

James H. Newman work together on the nal o three space

walks o the SS-88 mission. (Photo Credit: NASA)

d c (dc) sy

Recreational vehicles, boats or buildings in ruralareas where there is no access to the power grid (ogrid applications), can employ photovoltaic systemswith storage batteries and direct current appliances.With batteries employed in the system, the operatorcan store the solar-electric energy generated duringthe day or use in the evenings or on cloudy days.Components used in a direct current system include;a photovoltaic module or array, charge controller, bat-

teries, and direct current appliances.

d c ag c sy (dc ac)

Another technique, or people in rural areas to powertheir homes is to convert the direct current (DC)generated rom the PV system to alternating current(AC). While still independent rom the utility powergrid, the homeowner can take advantage o a widerrange o aordable electrical appliances. Tese systemswould include similar components ound in the DCsystem, such as: solar modules or array, charge con-troller, and batteries, plus the addition o an inverter,to convert DC to AC.

Like modern day sails, the solar panels on the roo o this

Lake Oroville houseboat provides power. (Photo Credit: Alan

Wing)

FundamentalsoF

PhotovoltaicsFor

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ip n: The Hot Stick fire departmentscarry on their engines only detects alternatingcurrent (AC). Using a hot stick on the PV side of thesystem will not detect direct current (DC), therebymisleading fire fighting personnel into believingthat electricity is no longer present! There arecommercially available clamp-on AC/DC metersthat would be the preferred method for detectingvoltages in the wring system.


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FundamentalsoF

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Te US Fish and Wildlie Service needed a cleaner, quieter power source or this island 30 miles west o San Francisco. Tis

reliable 9.1 kW photovoltaic system runs the acility that serves as a home or USFWS biologists who study the islands 6000 sea

lions and thousands o birds. (Photo Credit: Farallon National Wildlie Reuge)

PV works best when the sun is shining. In Caliornia, og and rainy days can last or several weeks longer thanmost battery systems can store energy. Some PV systems are additionally backed-up with generators (commonly)or other alternative devices such as micro-hydroelectric or wind powered generating systems.

Battery backed-up PV systems are designed to provide electricity or a specic period o time without sunshine.People with o-grid systems are usually very energy conscious, choosing to live without some o the conve-niences that grid-tied homeowners are accustomed to. Tey are willing to spend time monitoring the uid levelsand charge/recharge capacity o their battery systems. For the peace o mind that comes rom living o grid theyappear to be happy to monitor their own systems.


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0

FundamentalsoF

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Tis rural home in northern Caliornia uses both an o-grid

PV system along with a solar thermal system. (Photo Credit:

Alan Wing)

Te bank o back-up batteries stores PV generated electricity.

(Photo Credit Alan Wing)

Te controller monitors the electricity entering and exiting the

back-up battery system. (Photo Credit Alan Wing)

ip n: Volunteer firefighters in ruralareas need to understand the photovoltaictechnology and identify the locations of thesesystems. Not only should you be aware of theelectrical shock hazards posed by the photovoltaicarray, but you have the additional responsibilityto mitigate banks of batteries and their associatedhazards during a structural fire.

Te inverters used in this system convert PV generated direct

current to alternating current. (Photo Credit: Alan Wing)


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FundamentalsoF

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Te roo top o the USPS processing and distribution center in

Marina Del Rey, Caliornia shows the use o a 127 kw mono-

crystalline PV system. (Photo Credit Power Light Corporation)

Te inverter or this system is signicantly larger than those

you would expect to nd on a residential system. (Photo

Credit: U.S. Postal Service)

G-t sy

Another option, and one o the most prevalent orhomeowners and businesses, is the grid-tied system.Tis system allows the building owner to generateand use solar power during the day and deliver excesspower directly to the utility grid: eectively revers-ing the meter. When the system is not generatingenough electricity or the home or business, electric-ity is imported rom the electric grid. Net metering isachieved when the utility billing practices, or tarris,allow or a netting out o these electrical ows and

corresponding costs at the end o a month or year;net metering. In this type o system the utility gridprovides the back-up and eliminates the need orbatteries in the system. System components wouldinclude a PV array and a grid-tied inverter.

ip n: It may not be possible to see a PVsystem on a flat roofed building from street level.It is incumbent on the building owner/operatorsto label solar electric systems at the main electri-cal panel. The fire department must preplan forstructural emergencies on specific commercial and

industrial buildings in their jurisdiction.

PV

Module

Inverter and AC

Service Panel

AC Utility

Meter Power Line

PV Components


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FundamentalsoF

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Grid-tied systems automatically shut-down whenthere is no utility grid power present. Loss o powerrom the utility will essentially knock out all electric-ity in the building including the ability to use the

electricity generated rom the PV system. However,the electrical lines rom the PV panels to the inverterare still energized! Electric power rom the inverter tothe rest o the buildings wiring system and to the gridbecomes isolated during a power outage. Tis systemprotects utility company personnel rom electricalshock while working on the lines during power out-ages ensuring that the solar electricity is not beingback-ed into the system.

Tis PV system at the Cal Expo in Sacramento, Caliornia, was installed in September 2000. Te 540-kilowatt PV system

produces enough energy to power about 180 homes. Te solar arrays serve as a shaded oasis or 1,000 cars in a desert o scorching

blacktop. (Photo Credit: Kyocera Solar)

As an extra measure o saety, re ghting personnelcan also use the manual disconnect on the inverter toensure that the PV system is in act isolated rom therest o the building. In many cases, PV systems can be

identied with warning stickers and labels at the mainelectrical panel next to the inverter.

Bg ig dg

Te architectural design and building technologytrend is to incorporate PV systems into the buildingsexterior nish. Tese systems appear as PV roongsystems, windows, skylights or patio covers. Tese sys-tems are more expensive, and thereore not as preva-lent as roo or ground mounted systems. But they dopose new design opportunities or building designersand owners.ip n: When you lock out the mainelectrical power to the building you are disabling

the power from the grid, simulating a poweroutage, which isolates the power from the PV arrayat the inverter. Remember, electricity is still presentfrom the PV panels to the inverter.

ip n: Solar electric panels look a lotlike solar thermal panels. Solar thermal panels areused to heat water for pools and domestic hotwater.. Solar electric and solar thermal panels looklike skylights. Using skylights to ventilate a buildingshould only be an option if you know that it is trulyjust a skylight!


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FundamentalsoF

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A design trend in Europe is to nd clever ways oincorporating PV systems into the architecture orlandscape o the building site. As PV becomes moreprevalent in American planning, you can expect to seePV incorporated into ountains, sculpture, shelteringstructures and lighting systems in landscaping proj-ects. Building design may incorporate PV sun shadesor appear as shutters around multiple windowsoreven be installed in the window itsel! Blending thistechnology into traditional building and landscapedesign is one o the many challenges designers areinvolved in and presents new challenges or emergencyresponders in identiying PV technology when sizing-up an emergency.

Pre-re planning residential and commercial build-ings will help you identiy where building integrateddesigns are located. Roos on residential buildingintegrated PV systems are still airly easy to identiyby the shiny surace when compared to the rest o theroong material that surrounds it.

PV glazing or windows and skylights can beinstalled in the curtain wall o a high rise or designedinto a skylight or atrium. Tis technology uses a lm

attached to electric leads and sandwiched betweenpanes o glass. Te PV panel unctions to not onlygenerate electricity but also lters the harsh sunlightcoming through the window. Tis type o PV systemis less eective in generating electricity than thesolar panels on the roo, so a number o south acingwindows are covered to generate the required amounto energy or the building.

Tin-lm Millienna photovoltaic modules (494 total) romBP Solar were used on the Solar Cube. Te cube stands 135

eet tall on top o the Discovery Science Center in Santa

Ana, CA and can be seen or many miles rom the neighbor-

ing Interstate Highway 5. Solar Design Associates designed,

engineered, and constructed the 20-kilowatt grid-connected

array. (Photo Credit: Solar Design Associates)

ip n: Emergency responderscan no longer assume that once the mainelectrical disconnect has been shut off that itwill automatically ensure that all power to the

building has been disconnected. The wiring andconnections from the photovoltaic panel to theinverter are still energized and caution should betaken not to cut into these conduits.

ip n: It is not recommended that youbreak the glass protecting any type of solar cell,whether it is a panel, window or skylight. Breakingthrough the glazing can potentially unleash all ofthe inherent energy in the system instantaneously,posing a significant shock hazard to the fire fighter.


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summarY

Te uture o photovoltaic technology will continueto be integrated into our daily lives. Te uture trendwill be to integrate PV seamlessly and unobtrusivelyinto buildings and building sites. Tis trend will makePV system identication a little more challenging oremergency responders.

Our dependence on non-renewable energy sources hasto shit to renewable resources like PV or the sur-vival o the Caliornia way o lie! Compared to otherenergy options like nuclear, hydrocarbon and largescale hydroelectric, photovoltaic technology is a saer,cleaner, and environmentally riendly alternative.


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At the heart o the building codes arethe lie saety considerations or thebuilding occupants and emergencyresponders. Granted, photovoltaicsystems are saer to use and operatethan many other energy technologies.Nevertheless, lie saety considerations,standardization and interoperabilitywith other electrical systems drivethe building codes and regulations towhere they are today. Te intent o

this section is to highlight a ew o theimportant saety requirements inherentin the Caliornia Building, Electrical,and Fire Codes and the National Stan-dards as they relate to photovoltaics.

Wg if

Knowing that charged electrical linesare inherent in the building even aterthe main power supply has been lockedout/tagged out raises the questions:

Where do PV circuits exist within thebuilding envelope and how do youidentiy them? Is there a mechanism todisconnect the system?

You can mentally trace the path o PVcircuits rom the PV array throughthe building to the controller, batteriesand/or on to the inverter next to themain electrical panel. When a directcurrent photovoltaic conductor is run

outside a building membrane, it willbe contained in metallic raceways orenclosures rom the point o penetra-tion o the surace o the building tothe rst readily accessible disconnect-ing means.

Tis installer is running PV conductors into

metallic junction box and conduit. (PhotoCredit: Marc Fontana)

As an extra measure o protection, theNEC species that conductors o di-erent output systems (utility grid, gen-erator, hydro electric, or wind) will becontained in separate raceways, cabletrays, cable, outlet box, junction box,or similar ttings. Never cut into theseconduits or raceways.

sy d

Both the Uniorm Fire Code (...)and the NEC (0. & 0.)address the ability to disconnect anelectrical system. Te Uniorm FireCode specically adds that the dis-connecting means is accessible to there department. NEC requirementsprovide the details or disconnectingall conductors in the system. Some othese requirements include:FundamentalsoF

PhotovoltaicsFor

the Fire service

Progressimposes not only

new possibilities

for the future

but new restric-

tions.Norbert Weiner, TheHuman Use of Human

Beings,

codes and standards


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FundamentalsoF

PhotovoltaicsFor

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Means shall be provided to disconnect all current-carrying conductors o a photovoltaic power sourcerom all other conductors in a building or otherstructure.

Te photovoltaic disconnecting means shall beinstalled at a readily accessible location either on theoutside o a building or structure or inside nearestthe point o entrance o the system conductors.

Te photovoltaic system disconnecting means shall

not be installed in bathrooms.

Each photovoltaic system disconnecting means shallbe permanently marked to identiy it as a photovol-taic system disconnect.

Te photovoltaic system disconnecting means shallconsist o not more than six switches or six circuitbreakers mounted in a single enclosure, in a groupo separate enclosures, or in or on a switchboard.

Te photovoltaic system disconnecting means shallbe grouped with other disconnecting means.

A photovoltaic disconnecting means shall not berequired at the photovoltaic module or array loca-tion.

Means shall be provided to disconnect equipment,such as inverters, batteries, charge controllers, andthe like, rom all ungrounded conductors o allsources. I the equipment is energized rom more

than one source, the disconnecting means shall begrouped and identied.

Battery installations, where there are more thantwenty-our -volt cells connected in series (8 volts,nominal), shall have a disconnecting means, acces-sible only to qualied persons, that disconnects thegrounded circuit conductor(s) in the battery electri-cal system or maintenance.

A single disconnecting means shall be permitted orthe combined ac output o one or more inverters orac modules in an interactive system.

Te disconnecting means or ungrounded conduc-tors shall consist o a manually operable switch(es)or circuit breaker(s) complying with all o the ol-lowing requirements: Located where readily accessible

Externally operable without exposing the

operator to contact with live parts

Plainly indicating whether in the open or closedposition

Having an interrupting rating sucient or thenominal circuit voltage and the current that isavailable at the line terminals o the equipment

Where all terminals o the disconnecting meansmay be energized in the open position, a warning

sign shall be mounted on or adjacent to the discon-necting means. Te sign shall be clearly legible andhave the ollowing words or equivalent:

WarninG

electric shocK haZard.

do not touch terminals. terminals

on Both the line and

load sides maY Be enerGiZed

in the oPen Position.


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Tere are a number o redundant system disconnectsbuilt into a PV system. Disconnects can be locatednext to the main electrical panel, the inverter, thecontroller, and the battery bank. As mentioned earlier,an inverter in a grid-tied or interactive solar photovol-taic system will automatically de-energize its outputrom the PV system and the AC distribution networko the building upon the loss o voltage in the system.Te system will remain in this state until the electricalproduction and distribution network voltage has beenrestored.

Te inverter (red box) center is fanked by (gray) junction

boxes each with a knie switch that can isolate power rom the

PV array and the main circuit panel. (Photo Credit: Marc

Fontana)

Importantly, a normally interactive solar photovoltaicsystem can be permitted to operate as a stand-alone sys-tem to supply loads that have been disconnected romelectrical production and distribution network sources.You would nd this arrangement in grid-tied systemswith a battery back-up or generator back-up system.

Wg (c)

Te type and size o wiring used in photovoltaicsystems is determined by several actors, includingwhether the current is direct or alternating. Low

voltage DC systems oten have larger wiring sizes ascompared to AC systems. Te circuit conductors andovercurrent devices are sized to carry not less than percent o the maximum calculated currents.Also, wiring exposed to the weather must be rated andlabeled or outdoor use. Importantly, to reduce rehazards, roo mounted PV systems, conductors, andcomponents are all required to be grounded.

G F P

Te ground-ault protection device or system detects

a ground ault, interrupting the ow o ault current,and providing an indication o the ault. Specicrequirements are listed in the NEC or providingground ault protection or PV systems and compo-nents. Tese include:

Labels and markings applied near the ground-ault indicator at a visible location, stating that, ia ground ault is indicated, the normally groundedconductors may be energized and ungrounded.

In one- and two-amily dwellings, live parts inphotovoltaic source circuits and photovoltaic outputcircuits over 0 volts to ground shall not be acces-sible to other than qualied persons while energized

Te DC circuit grounding connection shall bemade at any single point on the photovoltaic outputcircuit.

Locating the grounding connection point as close aspracticable to the photovoltaic source better protectsthe system rom voltage surges due to lightning.

Exposed noncurrent-carrying metal parts o mod-ule rames, equipment, and conductor enclosuresshall be grounded regardless o voltage.


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Installer is connecting a ground wire to each module in the

PV array. (Photo Credit: Rodney Slaughter)

Pv m

In a photovoltaic module, the maximum system volt-age is calculated and corrected or the lowest expectedambient temperature. Tis voltage is used to deter-mine the voltage rating o cables, disconnects, over-

current devices, and other equipment.In one- and two-amily dwellings, photovoltaic sourcecircuits and photovoltaic output circuits that do notinclude lampholders, xtures, or receptacles and arepermitted to have a maximum photovoltaic systemvoltage o up to 00 volts. Other installations with amaximum photovoltaic system voltage over 00 voltsshall comply with Article 0.

A label or the direct-current photovoltaic powersource will be provided by the installer at an accessible

location at the disconnecting means or the powersource providing inormation on:

() Operating current

() Operating voltage

() Maximum system voltage

() Short-circuit current

On the back oa PV module

you will nd the

modules junction

box along with

a label show-

ing the modules

rated capacity

and Underwriters

Laboratory label.

(Photo Credit:

Marc Fontana).

B

Storage batteries in a photovoltaic system should beinstalled in accordance with the provisions o Article80. Te interconnected battery cells are consideredgrounded when the photovoltaic power source isinstalled in accordance with the NEC.

Storage batteries or dwellings will have the cellsconnected to operate at less than 0 volts nominal.Lead-acid storage batteries or dwellings shall have nomore than twenty-our -volt cells connected in series

(8-volts nominal).

In that, the batteries in photovoltaic systems are sub-ject to extensive chargedischarge cycles, they typi-cally require requent maintenance such as checkingelectrolyte and cleaning the connections. For this rea-son live parts o battery systems or dwellings shouldbe guarded to prevent accidental contact by persons orobjects, regardless o voltage or battery type.


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Batteries shown here in a well ventilated garage on wooden

storage racks connected together in series and parallel. (Photo

Credit: Alan Wing)

klered buildings used or acility standby power,emergency power, or uninterrupted power supplieswill also contain these saety eatures:

Valve-regulated leadacid (VRLA) battery systemsshould have a listed device or other approved methodto preclude, detect, and control thermal runaway.

Battery systems are permitted in the same roomas the equipment that they support. Tese systemsshould be housed in a noncombustible, locked cabi-net or other enclosure to prevent access by unauthor-

ized personnel unless located in a separate equipmentroom accessible only to authorized personnel.

In other than assembly, educational, detention andcorrection acilities, health care, ambulatory healthcare, day care centers, residential board and care,and residential occupancies, battery systems shouldbe located in a room separated rom other portionso the building by a minimum o a -hour re bar-rier.

In assembly, educational, detention and correctionacilities, health care, ambulatory health care, daycare centers, residential board and care, and residen-tial occupancies, battery systems should be locatedin a room separated rom other portions o thebuilding by a minimum o a -hour re barrier.

An approved method and materials or the con-trol o a spill o electrolyte shall be provided. Anapproved method to neutralize spilled electrolyteshould be provided capable o neutralizing a spillrom the largest leadacid battery to a pH between.0 and .0.

Ventilation shall be provided or rooms and cabinetsin accordance with the mechanical code and one othe ollowing:

. Te ventilation system shall be designed to limitthe maximum concentration o hydrogen to .0percent o the total volume o the room duringthe worst-case event o simultaneous boost

Flooded, vented, lead-acid batteries with more thantwenty-our -volt cells connected in series (8 volts,nominal) shall not use conductive cases or shall notbe installed in conductive cases. Conductive racks

used to support the nonconductive cases shall bepermitted where no rack material is located within0 mm ( in.) o the tops o the nonconductivecases. Tis requirement shall not apply to any typeo valve-regulated lead-acid (VRLA) battery or anyother types o sealed batteries that may require steelcases or proper operation.

As mentioned earlier, equipment is provided to con-trol the charging process o the battery. All adjustingmeans or control o the charging process should only

be accessible only to qualied persons. Te reasonor this is that certain battery types such as valve-regulated lead acid or nickel cadmium can experiencethermal ailure when overcharged.

Additional requirements or batteries can also beound in Chapter , NFPA , Uniorm Fire Code(00). Stationary lead-acid battery systems having anelectrolyte capacity o more than 00 gal (8. L) insprinklered buildings or 0 gal (8. L) in unsprin-


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0

charging o all the batteries, in accordance withnationally recognized standards.

. Continuous ventilation shall be provided at arate o not less than t/min/t (. L/sec/m) o oor area o the room or cabinet.

Te battery environment shall be controlled or ana-lyzed to maintain temperature in a sae operatingrange or the specic battery technology used.

Doors or accesses into rooms, buildings, or areascontaining stationary leadacid battery systemsshould be provided with approved signs. Te signswill state that the room contains leadacid batterysystems, that the battery room contains energizedelectrical circuits, and that the battery electrolytesolutions are corrosive liquids.

Battery cabinets shall be provided with exterior labelsthat identiy the manuacturer and model number othe system and electrical rating (voltage and current)o the contained battery system. Within the cabinet,signs shall be provided to indicate the relevant electri-cal, chemical, and re hazard.

In seismically active areas, battery systems shallbe seismically braced in accordance with the build-ing code.

An approved automatic smoke detection systemshall be installed in such areas and supervised by anapproved central, proprietary, or remote station ser-vice or a local alarm that will give an audible signalat a constantly attended location.

Fire and lie saety plan review will ensure thatreghters have adequate access to the roo. It isimportant that re inspectors and plan reviewers

get involved in the building permit and inspectionprocess and to pass available inormation o PV instal-lations on to the operational section o their depart-ments. Fire ghters need to take this inormation anddevelop preplans or the commercial and residentialstructures in their jurisdictions.

Preplans should note electrical lock out and identiythe location o PV components such as inverters,batteries, controllers, panels, and system disconnects.Once a structure with a PV system becomes involvedin a structural emergency or re, your department willhave all the available inormation at their ngertips.

summarY

Fireghters have successully dealt with lead acidbatteries and battery systems or decades. Personalprotective equipment, knowledge o battery systems,

and the ability to isolate the battery system, as pro-vided by the codes, also provide the extra measure opersonal saety.

Te Building, Electrical, and Fire Codes ensure thesaety or occupants and emergency responders. Auto-matic disconnect, along with manual service discon-nects throughout the PV system allow emergencyresponders to contain the electricity at the source.Putting all this inormation together in a standardoperating procedure is the nal step in your ability to

operate around these systems saely.


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We are hereto make a choice

between the

quick and the

dead

Bernard Baruch,United Nations AtomicEnergy Commission,

Te days o rushing in to a structurewithout rst making an assessmentand size-up o the emergency havelong past. In the Introduction to thismanual we suggested that re ght-ers need to be aware o photovoltaictechnologies and the potential dangersand hazards. Te potential dangers, inthe orm o an electrical shock and thepotential hazards in the orm o haz-ardous chemicals released during a re

or an explosion are the two primarysaety concerns. Other saety concernsinvolve trip hazards and load weighton the roo. Tis section will reviewthese dangers and hazards as well asmake recommendations on how youcan personally protect yoursel.

Ffg i hz

Te manuacturing o silicon cells isvery similar to the process used in the

semi-conductor industry. A wide rangeo hazardous chemicals are used in thismanuacturing process. By the timethe solar module is ready or instal-lation, only a ew o these chemicalsexist in the nished product, in minutequantities, and they are sealed in themodule rame and coverings. During are or explosion the rame can quicklydegrade exposing these chemicals todirect ame and then become dissi-

pated in the smoke plume.

When you compare the list o knownchemicals to the Department oransportations 00 EmergencyGuide Book and the Fire FightersHandbook o Hazardous Materialsyou realize how serious some o thesechemicals are to human health:

B

O all the chemicals used in photovol-taic manuacture, Boron is the leastproblematic or emergency respondersand the public alike. Boron is one othe simplest o atoms with an atomicnumber o on the periodic table.Tere are only our elements simplerthan boron. Boron hydrolyzes inwater to orm a slightly alkaline solu-tion, which is why Boron is good or

cleaning (Borax Soap). Boron burnsgreen and is used in pyrotechnics orcolor. Boron poses no health eects tohumans or the environment.

c t

Te same, however, cannot be said orCadmium elluride. A known car-cinogen, the primary route o exposureis inhalation. Dust and umes rom

cadmium or its compounds may causeirritation o the nose and throat. Ihigh concentrations are inhaled (espe-cially rom a reshly ormed plume)a delayed reaction o coughing, chestpain, sweating, chills, shortness obreath and weakness may develop. Insevere cases o exposure the result canbe pulmonary edema and death.

Acute exposure to tellurium may causean odor o garlic on breath and per-spiration, dry mouth, metallic taste,sleepiness, loss o appetite and nau-sea. Chronic overexposure may causelung injury (emphysema) and kidneydysunction (proteinuria). Inhalationo cadmium telluride will aggravatediseases o the lungs and kidneys.

With that said, the Photovoltaicsystem contains trace amounts o

emerGencY resPonse


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these elements per cell. Te potential exposure hazardto a small residential array will be minimal. Largerarrays, like those ound in large commercial applica-tions, ully enguled in a roo re could be a potentialexposure hazard to emergency responders and thepopulation down wind o the smoke plume. Citizenswith respiratory ailments, children, and the elderlyshould be sheltered in place until the emergency hasbeen abated.

G a

Te health eects o Gallium Arsenide have notbeen thoroughly studied. It is however, consideredhighly toxic and carcinogenic. Gallium rivals siliconas a semiconductor in that it too has some remark-able electronic properties. However, silicon is muchmore abundant, and thereore less expensive, andit has greater physical strength than gallium. Gal-lium Arsenide, when combined with germanium andindium gallium phosphide, are the basis o a triplejunction solar cell which holds the record eciencyo over %. Tis is the same solar technology that

is powering the robots Sprit and Opportunity whichare exploring the surace o Mars and is being used inexperimental solar cars here on Earth.

Pp

Te umes rom phosphorus compounds are consid-ered highly toxic. NIOSH recommended exposurelimit to phosphorus is mg/m. A lethal dose ophosphorus is 0 milligrams. Phosphorus is extremelyimportant to the agricultural industry as a primary

ingredient in the production o ertilizer. Pure whitephosphorus is extremely volatile and spontaneouslyignites when exposed to the air. Te type o phos-phorus used as a dopant in the manuacture o pho-tovoltaic cells is not in its pure orm, but any orm ophosphorus will react to extreme heat. Respiratoryprotection is required or people working aroundphosphorus.

r P

Te inhalation hazards rom the chemicals inherentin PV modules enguled in a re or explosion can bemitigated as long as reghters wear their SCBAsand personal protective equipment during a structuralreghting operation. It is the decision o the IncidentCommander whether or not the emergency consti-tutes sheltering in place the population downwind othe emergency. Fire or explosion emergencies involv-ing large number o PV arrays, as in a commercialapplication, may necessitate having people downwind

o the emergency shelter in place.

Personal pro

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