lesson inquiry question what factors influence the energy ...€¦ · 2 learning a ctivities what...

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Lesson ChaLLengeRedesign the school solar PV system to maximize its energy output.

Lesson InQUIRY QUesTIon

activity sheets

• JudgingtheSchoolSolarPVSystems(ActivitysheetA)

• RedesigningtheSchoolSolarPVSystem(ActivitysheetB)

• RatingtheSolarPVSystem(ActivitysheetC)

Briefing sheets• FactorsThatInfluencetheEfficiencyofSolarPV

Systems(BriefingsheetA)

Image sets• SchoolSolarPVSystem(ImagesetA)

assessment materials • AssessingMyAbilitytoRedesigntheSchoolPV

System(AssessmentmaterialsA)

Background knowledge Ì solar panels Ì photovoltaic (PV) cells

Critical thinking vocabulary Ì observation Ì inference Ì judge

Criteria for judgment Ì criteria for the optimal

placement of a rooftop solar PV system

» orientation » tilt » shading

Thinking strategies

Ì bar graph rating

habits of mind

Ì attentive to detail Ì critically-minded

Inthislesson,studentsdiscoverhowtheenergyoutputofsolarpanelscanbeinfluencedbyvariousfactors.Tobeginthelesson,studentsviewimagesofschoolrooftopsolarPVsystemsandjudgewhichsystemwouldbethemostefficient.StudentsusetheirdecisionstodevelopthecriteriafortheoptimalplacementofarooftopsolarPVsystem.StudentsthenusethecriteriatojudgetheplacementoftwoschoolrooftopsolarPVsystems.Toconcludethelesson,studentsusetheirlearningtoredesignplansandillustrationsofaschoolrooftopsolarPVsystemtooptimizeitsefficiency.

sUmmaRY

maTeRIaLs

Broad understandingStudents will understand the three factors that influence the efficiency of school rooftop solar PV systems.

ThInkIng TooLs

What factors influence the energy output of a solar panel?

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sWhat factors influence the energy output of a solar panel?

Introduce the criteria

1. OrganizestudentsintopairsandprovideeachgroupwithacopyofJudging the School Solar PV Systems(ActivitysheetA).Considerdisplayingtheactivitysheetusinganinteractivedisplayordigitalprojector.

2. Explaintostudentsthattheefficiencyofsolarphotovoltaic(PV)panelsandtheamountofelectricitysystemsproduceisaffectedbymanyconditions.Askgroupstocarefullyobservetheimagesofrooftopsolarsystemsontheactivitysheet:Whichsystemwouldbemoreefficient,SchoolAorSchoolB?Whichmightproducethemostelectricity?Encouragegroupstonoteorcircletheirobservationsontheiractivitysheets.

3. Invitegroupstosharetheirdecisionswiththeclass.Asgroupsshare,invitethemtopointoutordescribethedetailsfromtheimagesthatinfluencedtheirdecisions.Forexample,studentsmightsuggestthatthesolarsystemonSchoolAmightproducemoreelectricitybecausethepanelsfacesouth.Alternatively,studentscouldsuggestthatthesystemonSchoolBwouldproducemoreelectricitybecausethefirstrowofpanelsdoesnotshadethesecondrow.

4. Usestudents’suggestionstoco-developorpresentthecriteriafortheoptimalorbestplacementofarooftopsolarPVsystem:• Orientation:Thedirectionthatthesolarpanelsfaceaffectstheamountofenergyfrom

thesunthatthepanelswillreceive.InAlberta,arrangingsolarpanelstofaceduesouthprovidesthegreatestexposuretothesun.

• Tilt: Theangleofthesolarpanelaffectstheamountofenergyfromthesunthatpanelsreceive.TheoptimalangleoftiltforarooftopsolarPVsystemisanangleequaltothelocallatitude.

• Shading:Shadingaffectstheamountofenergyfromthesunthatthepanelsreceive.Shadefromtrees,mountains,nearbyhomesandbuildings,andothersolarpanelscandecreasetheamountofenergythatapanelreceives.

Considerdisplayingthecriteriaforuselaterinthislesson.5. Promptgroupstorevisittheiroriginaldecisionsinlightofthecriteria:Wouldtheychange

theiroriginaldecision?Whatdetailsfromtheimagesappeartomatchthecriteria?6. Sharethelessoninquiryquestion“Whatfactorsinfluencetheenergyoutputofasolar

panel?”andthechallenge“RedesigntheschoolsolarPVsystemtomaximizeitsenergyoutput”withtheclass.InformstudentsthattheirtaskwillbetoredesignaschoolsolarPVsystemusinginformationaboutthefactorsthatinfluenceefficiency.

7. ProvideeachstudentwithacopyofRedesigning the School Solar PV System(ActivitysheetB).Exploretheimageoftheschoolwithstudents:Whatdetailscouldhelpdeterminethebestpositionfortherooftopsolararrays?Forexample,studentsmightinferthattheshadowfromthetreeswouldonlybeontheroofinthemorning.

8. Drawstudents’attentiontothetableontheactivitysheet.Encouragestudentstonotetheirinitialideasforthebestpositionoftherooftopsolararraysintheappropriatesectionofthetable.Assurestudentsthattheywillbeabletoaddtoandrefinetheirinitialideasthroughoutthelesson.

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explore the factors that influence solar PV system efficiency

1. ProvideeachgroupwithacopyofFactors That Influence the Efficiency of Solar PV Systems (BriefingsheetA),andeachstudentwithacopyofRating the Solar PV System(ActivitysheetC).EnsurethateachgroupalsohasacopyofActivitysheetA,introducedearlierinthislesson.

2. InformgroupsthattheirnexttaskistouseinformationfromthebriefingsheetandthecriteriatorateeachoftheschoolrooftopsolarPVsystems.ConsiderassigningSchoolAtosomegroups,SchoolBtotheothers.Drawstudents’attentiontothetopofActivitysheetC,andpromptthemtousethecheckboxtoindicatetheirassignedschool.

3. Guidestudents’attentiontothe“Rating”columnofthetable.ExplainthattheywillusethebargraphstoratehowwellthesolarPVsystemmeetseachofthecriteria.Forexample,ifgroupsdeterminethattheirassignedPVsystemisfacinganoptimaldirection,theymightshadeinorcoloureachofthebars.Remindgroupsthattheywilluseevidencefromthebriefingsheettosupporttheirratings.

4. ProvidegroupswithtimetocompletetheratingsfortheirassignedschoolrooftopsolarPVsystem.

5. Invitegroupstosharetheirratingsandevidencewiththeclass.Groupsmightsuggestthefollowing:• SchoolA:

» Orientation:ThissolarPVsystemmightreceiveahighratingforthearraysfacesouth.» Tilt:ThissolarPVsystemmightreceivealowerratingforthefirstrowofpanelsshadesthesecond.Thearraysmightalsogetcaughtinthewind.

» Shading:ThissolarPVsystemmightreceiveamediumrating,foralthoughthearraysfacesouth,thefirstrowwouldshadethesecondrowduringthesunniesttimeoftheday.

• SchoolB:» Orientation:ThissolarPVsystemmightreceivealowerratingforthearraysappeartobefacingtotheeast.

» Tilt:ThissolarPVsystemmightreceiveamediumratingforthearraysappeartobealmostflatontheroofsotheywouldnotgetcaughtinthewind.However,thearraysseemtobetiltedtofacetheeast,notthesouth,sotheywouldreceivelessdirectsunlight.

» Shading:ThissolarPVsystemmightreceivealowerratingfortherewouldbeshadeonthearraysduringthemorning.

6. Guidestudents’attentiontotheright-handcolumnoftheactivitysheet.DirectgroupstonotewhatimprovementsmightbemadetothedesignoftheirassignedsolarPVsystem.

7. Encouragegroupstosharetheirsuggestionsforimprovementwiththeclass.8. Directstudents’attentionbacktoActivitysheetBandtheirinitialthoughtsfortheir

redesignedschoolsolarPVsystem.PromptthemtoreflectonwhattheyhavelearnedaboutthefactorsthatinfluencetheefficiencyofsolarPVsystems.Whatnewideaswouldtheyaddtotheirplan?Whichfirstideasmighttheyreviseorchange?Encouragestudentstorevisetheirinitialideas.

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Respond to the challenge

1. Drawstudents’attentionbacktothefirstpageofActivitysheetB.ExplainthattheirfinaltaskistorespondtothelessonchallengebyredesigningtheschoolsolarPVsystemtomaximizeitsenergyoutput.Explainthattheywillusetheinformationandideasfromearlierinthelessontodrawtwotwelve-panelrooftopsolararraysontheschool(thisisthesamesizeasthearraysonActivitysheetA).

2. Encouragestudentstocreateadraftsketchoftheirinitialideasforthebestpositionofthesolararraysontheschool.Invitestudentstosharetheirinitialplanswithatrustedpartner.Guidestudentsinusingthecriteriatoaffirmoneaspectoftheirclassmate’sdesign,andoneaspectthatmightberefinedorimproved.

3. PromptstudentstousethefeedbacktocompletetheirredesignoftheschoolrooftopsolarPVsystem.

Reflect on the learning

1. DisplaytheimageoftheschoolsolarPVarrayfromImagesetAusinganinteractivedisplayordigitalprojector.

2. Invitestudentstocarefullyobservethepositioningofthesolararray:WillthisrooftopsolarPVsystembeoptimallyefficient?Whichofthecriteriadoesitmeet?Whichofthecriteriadoesitnotmeet?

3. Ifthestudents’schoolhasarooftopsolarPVsystem,considerhavingstudentsobserveitspositioningandorientation.Invitestudentstousetheirobservationstomakeinferencesabouttheefficiencyoftheschool’ssolarPVsystem.

assess the learning

1. ProvideeachstudentwithacopyofAssessing My Ability to Redesign the School PV System(AssessmentmaterialsA)andencouragestudentstoself-assesstheirabilitytousethecriteriatooptimizetheschoolrooftopsolarPVsystem.

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Judg

ing

the

Scho

ol S

olar

PV

Syst

ems

Activity sheet A

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What factors influence the energy output of a solar panel?Activity sheet A (Cont’d)Ju

dgin

g th

e Sc

hool

Sol

ar P

V Sy

stem

s (Co

nt’d

)

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Rede

sign

ing

the

Scho

ol S

olar

PV

Syst

em

Activity sheet B

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What factors influence the energy output of a solar panel?Activity sheet B (Cont’d)Re

desi

gnin

g th

e Sc

hool

Sol

ar P

V Sy

stem

(Con

t’d)

Crite

ria

Idea

s for

my

rede

sign

ed so

lar P

V sy

stem

Orientation

The

dire

ctio

n th

at

the

sola

r pan

els f

ace

affec

ts th

e am

ount

of

ener

gy fr

om th

e su

n th

at th

e pa

nels

will

re

ceiv

e.

Tilt

The

angl

e of

the

sola

r pa

nel a

ffect

s the

am

ount

of e

nerg

y fro

m th

e su

n th

at

pane

ls re

ceiv

e.

Shading

Shad

ing

affec

ts th

e am

ount

of e

nerg

y fro

m th

e su

n th

at th

e pa

nels

rece

ive.

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What factors influence the energy output of a solar panel?Activity sheet C

Crite

ria

Ratin

gsu

ppor

ting

evid

ence

Poss

ible

impr

ovem

ents

Orientation

The

dire

ctio

n th

at th

e so

lar p

anel

s fac

e aff

ects

th

e am

ount

of e

nerg

y fro

m th

e su

n th

at th

e pa

nels

will

rece

ive.

Tilt

The

angl

e of

the

sola

r pa

nel a

ffect

s the

am

ount

of

ene

rgy

from

the

sun

that

pan

els r

ecei

ve.

Shading

Shad

ing

affec

ts th

e am

ount

of

ene

rgy

from

the

sun

that

the

pane

ls re

ceiv

e.

Rati

ng th

e So

lar P

V Sy

stem

Colo

ur o

r sha

de in

the

bars

to sh

ow h

ow w

ell t

he sc

hool

ro

oftop

sola

r PV

syst

em m

eets

the

crite

ria. T

he m

ore

colo

ured

or s

hade

d ba

rs, t

he b

ette

r the

sola

r pan

el

mee

ts th

e cr

iteria

.Le

sseffi

cien

tM

oreeffi

cien

t

scho

ol:

a

B

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Factors That Influence the Efficiency of Solar PV Systems

Briefing sheet A

There are three main factors that influence the efficiency of rooftop solar PV systems.• orientation: The direction that a solar panel faces affects the amount of energy from

the sun that a panel will receive. In Alberta, solar panels that face due south receive the most energy.

• Tilt: The angle of the solar panel will affect the amount of energy from the sun that a solar panel receives.

» The optimal, or best, angle of tilt for a rooftop solar PV system is an angle equal to the local latitude. For example, the optimal angle for a rooftop solar panel on a home in Edmonton, AB, would be 53.5 degrees to ground (the latitude of Edmonton is 53.5 degrees north).

» For a sloping roof, it is usually best to mount the solar panel flat on the roof. » On a flat roof, the panel should be angled at no more than 15 degrees.

• shading: The amount energy received from the sun by a panel is affected by shading. A solar panel that is shaded will produce less than half as much electricity as a solar panel that is not shaded. Trees, mountains, nearby homes and buildings, and other objects cause shading and decrease the amount of energy that the solar panel receives from the sun.

These criteria describe the conditions needed by a solar panel for optimal efficiency. When a solar panel is efficient, it can generate more electricity. However, it is not always possible or safe to install solar panels at these angles and orientations.

For example, installing a solar panel at a steep angle makes it more likely to be damaged by wind. When it is very windy, the solar panel could act like a sail. The panel could be damaged or even blown off the roof. Solar panels that are installed flat on a roof are less likely to act like a sail in the wind. Although mounting solar panels flat on sloped roofs may produce less electricity, it is usually safer to do so.

Installing solar panels flat on a roof also helps prevent “interrow shading.” This happens when one row of solar panels shades another row. Interrow shading decreases the amount of electricity solar panels can produce.

Rather than installing solar panels at unsafe angles, a new home or school could be designed with a roof at the angle of latitude. This would optimize energy output while also being safe.

The geographic location and other related factors such as sunshine hours, cloud cover, fog, rain, snow, dust, smog, and smoke also affect the amount of energy from the sun that a solar panel will receive.

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Scho

ol S

olar

PV

Syst

em

Image set A

Cour

tesy

of S

ky F

ire E

nerg

y

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What factors influence the energy output of a solar panel?Assessment materials A

success criteria how am I doing?

IcanusecriteriatoevaluatetheefficiencyofasolarPVsystem.Examples:

Nextsteps(e.g.,usethecriteria,usemorespecificdetails,askforhelp):

Icanusecriteriatosuggesthowthepositioningofaschoolrooftopsolararraymightbeimproved.Examples:


IcanreworktheplansforaschoolrooftopsolarPVarraytomakeitmoreefficient.Examples:


Assessing My Ability to Redesign the School PV System

Name:

1.Provideexamplesthatshowhowyouhavemetthesuccesscriteria.2.Usetheratingscaletoindicatehowwellyouhavemetthesuccesscriteria.3.Describethenextstepsinyourlearning.

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