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18 Fig re 5 – Gra hic re resentation of the cor ection factor f or temp rature dif feren es to nominal ir adian e/lo d con ition as a fu ction of the relative ir adian e/lo d.. It in lu

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CONTENTS

FOREWORD 4

1 Sco e 6

2 Normative ref eren es 6

3 Terms an definition 7

4 Req irements of in p ction eq ipment 9

4.1 General 9

4.2 Minimum req irements for IR-cameras u ed f or in p ctin PV plants 9

4.3 Req irements for photo cameras for doc mentation of the fin in s 10 4.4 Req irements for eq ipment to record the ambient con ition 10 5 In p ction proced re 1

5.1 General 1

5.2 Vis al in p ction 12 5.3 En ironmental con ition 12 5.4 Imagin proced re 13 5.4.1 General 1

3 5.4.2 Usin f ast car iers for IR-camera, e.g a rial drones 13 5.4.3 Emis ivity 14 6 Sof tware for evaluation 15 7 Evaluation 1

5 7.1 General 15 7.2 Evaluation of IR images 16 7.3 Thermal a normal ties 17 7.3.1 General 1

7 7.3.2 Clas es of a normal ties (CoA) 17 7.3.3 Abnormal ties of PV mod les 17 7.3.4 Abnormal ties of other BOS comp nents 17 7.4 Projection of temp rature dif feren es to nominal ir adian e 18 7.4.1 General 18 7.4.2 Mod les 2

7.4.3 Other BOS comp nents 21

8 In p ction re ort 21

(normative) In p ction proced re explanation 2

An ex A A.1 Ge metric resolution of the camera 2

A.2 An le of view 2

A.3 Matrix for cel identification 2

(normative) Qual fication of p rson el 2

An ex B (normative) Matrix for thermal a normal ties of PV mod les 2

An ex C (informative) Poly on me s rement as a method of evaluation 3

An ex D (informative) Be uf ort s ale 3

An ex E Bibl ogra h 3

Fig re 1 – Imp ct of camera movin sp ed 14

Fig re 2 – De en en e of the emis ivity of glas on the an le of view [10] 15

Fig re 3 – Examples of in uen e of win (lef t) and clou movement (rig t on

Fig re 4 – Example inf rared thermograms of a PV strin combiner b x with ca les,

contacts, fu es an switc es b f ore (left an after (rig t maintenan e on a f aulty

contact 18

Fig re 5 – Gra hic re resentation of the cor ection factor f or temp rature dif feren es

to nominal ir adian e/lo d con ition as a fu ction of the relative ir adian e/lo d 19

Fig re 6 – Example of image re ortin 2

Fig re A.1 – Ge metric resolution of the IR camera 2

Fig re A.2 – An le of view 2

Fig re A.3 – View f or the desig ation of cel p sition, viewed f om the f ront of a 6 -cel mod le, with the ju ction b x at the to (re r side) 2

Fig re D.1 – Arithmetic me n value by p ly on me s rement 3

Fig re D.2 – Arithmetic me n an sp t value by p ly on me s rement 3

Ta le 1 – Minimum req irements f or IR-cameras 9

Ta le 2 – Req irements for eq ipment to record the ambient con ition 1

Ta le 3 – Req ired in p ction con ition 12 Ta le 4 – Alocation in clas es of a normal ties 17 Ta le 5 – Example cor ection f actors for temp rature diff eren es to nominal lo d con ition b sed on f ormula ab ve an Fig re 5 2

Ta le E.1 – Be ufort s ale taken f orm World Mete rolgical Organization (www.wmo.int an Royal Meteorological Society (www.rmets.org) 3

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En uiry draft Re ort o v tin

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This doc ment has b en drafted in ac ordan e with the ISO/IEC Directives, Part 2

A l st of al p rts in the IEC 6 4 6 series, publ s ed u der the general title P hotovoltaic (PV)

systems – Re uireme ts for testing, do ume tation a d mainte a c , can b fou d on the

IEC we site

The commite has decided that the contents of this publ cation wi remain u c an ed u ti

the sta i ty date in icated on the IEC we site u der "ht p:/we store.iec.c " in the data

related to the sp cif i publ cation At this date, the publcation wi b

• tran formed into an International stan ard,

• reconfirmed,

• with rawn,

• re laced by a revised edition, or

A bi n ual version of this publ cation may b is ued at a later date

IMPORTANT – The 'colour inside' logo on th cov r pa e of this publ c tion in ic te

that it contains colours whic are consid re to be us ful f or the cor e t

understa din of its conte ts Us rs s ould theref ore print this doc me t using a

colour printer

This p rt of IEC 6 4 6 defines outdo r thermogra hic (inf ared) in p ction of PV mod les

an plants in o eration The in p ction can in lu e ca les, contacts, fu es, switc es,

in erters, an b t eries This in p ction s p orts the preventive maintenan e f or fire

protection, the avai a i ty of the s stem f or p wer prod ction, an the in p ction of the

q al ty of the PV mod les In lu ed in this doc ment are the req irements f or the

me s rement eq ipment, ambient con ition , in p ction proced re, in p ction re ort,

p rson el q al f i ation an a matrix for thermal a normal ties as a g idel ne for the

in p ction

This doc ment defines outdo r thermogra h on photovoltaic (PV) mod les an Balan e-of

s stem (BOS) comp nents of PV p wer plants in o eration, u in p s ive tec niq es

(stan ard s stem o eratin con ition u der natural s nl g t, without an external p wer or

ir adiation sources) IEC 6 9 4-12-1 covers general method f or la oratory or prod ction-l ne

PV mod le thermogra hic imagin but not the sp cific detai s that are most relevant to

outdo r imagin of o erational p wer plants in lu in BOS comp nents

Two dif ferent levels of in p ction are c r ently u ed:

a) A simplfied thermogra hic in p ction This is a lmited in p ction to verify that the PV

mod les an BOS comp nents are f un tionin , with red ced req irements f or the

q alf i ation of p rson el F r example, d rin a b sic commis ionin of a PV plant

Authoritative con lu ion regardin mod le q al ty are not p s ible with this in p ction,

an examples of a normal ties are provided to aid the in p ctor

b) A detaied thermogra hic in p ction an analy is This may in lu e thermal sig atures

whic dif fer f rom the examples provided, an therefore req ires a de p r u derstan in of

the thermal a normal ties For example, it may b u ed f or p riodic in p ction ac ordin

to the IEC 6 4 6 series an for trouble-s o tin the cau e of u derp rormin s stems

Absolute temp rature me s rements may b made An authorized expert in PV plants,

together with thermogra h exp rts can p rf orm the in p ction

The folowin doc ments are ref er ed to in the text in s c a way that some or al of their

content con titutes req irements of this doc ment For dated referen es, only the edition

cited a pl es For u dated referen es, the latest edition of the referen ed doc ment (in lu in

an amen ments) a pl es

IEC 6 0 0-131, Internat ion l El ectrote h ic l Vo a ul ary – Part 131: Circ it t he ry

IEC 6 216-2, Electric l insulatin mat erials – Th rmal e d ura c pro erties – P art 2:

Determinatio of t hermal e dura c pro erties of elect ric l insulat in materials – Ch ic of

test criteria

IEC 6 216-5, Electric l insulatin mat erials – Th rmal e d ura c pro erties – P art 5:

IEC 6 2 9-1, L w-v l ta e fuses – Part 1: Ge eral re uireme ts

IEC 610 5, Ele trome h nic l c ntact ors for h use ol d a d simil ar p rp ses

IEC 61215-1, Ter estrial p otovoltaic (P V) mod ules – Design q al ific tion a d typ a pro al –

P art 1: Test re uireme ts

IEC 614 9-1, L w-v ltag switc g ar a d c ntrol ge r as embl ies – Part 1: Ge eral rul es

IEC 617 4-1, Ph t ovoltaic system p rorma c – Part 1: Monitoring

IEC 617 0-1, Ph t ov lt aic (PV) mod ul e safety q al ific tion –Part 1: Re uireme ts for

c nstru t ion

IEC 617 0-2, Ph t ovolt aic (PV) mod ule safety q a fic t ion –P art 1: Re uireme ts for t est ing

IEC TS 618 6, Solar p oto olt aic e erg systems – Terms, definitions a d symb ls

IEC 6 10 -1, Safety of p wer c nverters for use in p otovoltaic p wer systems – P art 1:

Ge eral re uireme ts

IEC 6 4 6-1, Ph t ov l taic (PV) syst ems – Re uireme ts for testin , d oc me tat ion a d

maint en n e – P art 1: Grid c n e t ed systems – Do ume tat io , c mmis ionin tests a d

insp ct ion

IEC 6 4 6-2:–, P hotovol taic (PV) systems – Re uireme ts for testing, do ume tat io a d

mainten n e – P art 2: Grid c n e t ed p ot ov lt aic (PV) systems – M ainten n e of PV

systems

1

IEC 6 9 0:–, Ele tric c bles for p otov l taic syst ems with a v lt ag ratin of 1,5 k V d.c

1

ISO 9 8 , Sol ar e erg – Vo a ulary

ISO 9 12, No -d estru t iv test in — Qu l ific tion a d c rt ific t ion of NDT Perso n l

VATh- Directive, El ectrical Infared Insp ctions – L w Vol ta e P lan ing, e e ut io a d

(htp:/ www.vath.de/doc /ric tl nien/VATh-Ric tl nie Elektro NS+PV_ n l_we pdf)

EN 16 14-3, Non-destru tive testing – Th rmo ra hic testing of elect ric install at ions

EN 5 1 0-1, Op ratio of ele tric l install at ions – P art 1: Ge eral re uireme ts

DGUV BGV/GUV-V A3 E, Ac id ent preventio re ul at ions, El ectric l inst al l ations a d

ISO an IEC maintain terminological data ases f or u e in stan ardization at the fol owin

ad res es:

• IEC Electro edia: avai a le at ht p:/ www.electro edia.org/

• ISO Onl ne browsin platform: avai a le at htp:/ www.iso.org/o p

3.1

abnormal thermal be a ior

thermal sig ature of an element that can ot b explained by its o eratin con ition or its

tec nical desig , e.g p sition of lo d resistors

[SOURCE: EC 6 0 0-9 3:2 13, Amen ment 1:2 14, 9 3-01-2 ; modified: ada ted to thermal

Note 1 to e try: Me s re in Celsiu ( C)

Note 2 to e try: Some ma ufa ture of IR c mera u e th term: ambie t temp rature

3.3

atmospheric air temperature

defined in Celsiu (°C) for the ge gra hic in tal ation location as me s red an doc mented

by mete rological services for this ge gra hic location

ratio of the thermal radiation that is emited by the s rf ace of an o ject comp red to a blac

b d radiator b th at the same temp rature

3.7

Insta ta eous Field of View

IFOV

f ield of view of one pixel of an IR-camera-len combination

Note 1 to e try: Me s re in mi ira ia (mra )

_ _ _ _ _ _

3.8

Nois Equiv le t Temperature Diff ere c

NETD

smalest temp rature dif feren e detecta le by an IR-camera

Note 1 to e try: Me s re in mi ik lvin (mK)

3.9

thermal ste dy state con itions

u a le me s rement con ition , whic s ow sta le temp ratures an temp rature diff eren es

4 Requirements of inspe tion equipment

This clau e states the minimum req irements f or eq ipment u ed f or thermogra hic (inf rared)

in p ction within the s o e of this doc ment It in lu es req irements for the infared (IR)

camera, the photo camera an eq ipment to record ambient con ition

Al eq ipment s al b date an time s n hronized prior to u e, to e si y matc images to

s stem con ition , f or example the in plane ir adiation, an DC-lo d of the plant

4.2 Minimum re uireme ts f or IR-c mera us d f or inspe ting PV pla ts

The sp cif i ation of the infared camera s al fulfi the minimum req irements ac ordin to

Ta le 1

Table 1 – Minimum re uireme ts f or IR-c mera

h Adju ta le fu ctio s Fo u , temp rature le el a d s a

i Me s reme t fu ctio s Me s rin s ot, me s rin are with a era e a d ma imum

temp rature

Fe ture Minimum req irements

th rmo ra hic c mera s al b tra e bly c lbrate at le st e ery

two y ars Th c lbratio h s tob d c me te If th c mera is

n t c mpla t (a s lute temp rature a d/or temp rature

diff ere c s), it ma b re dju te b th ma ufa turer

k Do ume tatio Storin of th inf rare picture with al ra iometric informatio to b

a le to d termin a s lute temp rature No -a iometric picture

c n o ly pro id p tern a d e e tu ly temp rature diff ere c s

1 Camera o eratin in wa ele gth ra g of 2 µm to 5 µm s al o ly b u e for th rmo ra h of ele tric l

BOS c mp n nts, e.g fu e Du to th tra s are c of gla s in th ra g of 3 µm th u e of th t ra g o

P mo ule c n le d to me s reme t erors

2 3 cmle gth of e g p r pix l e u ls 5 x 5 pix l o a 6“ P c l

3 Th re l me s rin s ot mo tly is d fin d a 3 x 3 pix l f or hig -q alty o tic

Use of an IR camera with resolution ≥ 3 0 x 2 0 pixels an a se arate photo camera are

recommen ed, with monitor an remote control or a swivel n display

4.3 Re uireme ts for photo c mera for doc me tation of the f indings

Vis al photos doc mentin the state of the mod le/plant are recommen ed, however vis al

photos of an thermal a normalty are required One photo of every safety relevant

a normalty (se Ta le 4) s al b taken

The resolution of the vis al photo s al b sig ificantly hig er than the IR image an s al

have a simiar f ield of view to s f ficiently ca ture al detais of the o ject (e.g bu b rs,

rib on of a solar cel , broken f ont glas , f use an fu e holder) It s al b en ured that IR

an vis al photo ca ture the same are of interest whi e f ulfi in the resolution req irement

A se arate photo camera an IR camera are recommen ed, in order to en ure s f ficient

resolution of vis al photo ( ypical y at le st 3 times hig er)

NOT In ma y c s s, th b sic p oto c mera whic is inte rate into th inf rare c mera is n t a le to pro id

th re u ste re olutio For a IR c mera of 6 0 x 4 0 pix l a s p rate p oto c mera with at le st 9 Mpix is

s ita le

4.4 Re uireme ts for e uipme t to re ord the ambie t conditions

To detect thermogra hic a normal ties cor ectly, certain ambient con ition have to b met

Eq ipment to me s re these con ition s ould b compl ant to the minimum req irements in

Ta le 2

Table 2 – Re uireme ts for e uipme t to re ord

b Ambie t (air temp rature Temp rature s n or (s ield d

f rom dire t lg t a d win )

Note th t th in erter re din ma n t giv a c rate re ults or b c lbrate Th u h it ma b u eful for

s meBOS c mp n nts, it ma als n t h v re olutio for P strin -le el c re t me s reme t

5 Inspection proce ure

An in p ction of the PV plant s ould b done d rin the commis ionin an o eration of the

p wer plant, in ac ordan e with a pl ca le he lth an safety reg lation The recommen ed

interval f or p riodic thermogra h in p ction is f our ye rs but the a pl ed intervals for a

sp cific in talation s al b agreed up n with the owner / o erator, or they mig t b defined

by national electric codes an saf ety reg lation f or electrical in tal ation

The owner, o erator or an authorized p rson s al give the in p ctor(s) an introd ction into

the saf ety sp cific reg lation of the PV plant to b in p cted, in lu in detai s of the plant

an electrical layout A secon p rson s ould b present d rin in p ction, an may b

req ired by local saf ety reg lation At le st one of the p rson p r ormin the in p ction

s al have tec nical k owled e of the sp cific s stem, an of PV plants in general

In p ction s al b done fol owin a plca le safety reg lation , for example in ac ordan e

to EN 5 1 0-1 or DGUV BGV/GUV-V A3 E

The detai ed in p ction s o e s al b def i ed prior to the in p ction an agre d in writin

b twe n the in olved p rties

The plant s al b u der o eratin con ition The p rt of the s stem u der evaluation s al

b in thermal ste d state con ition an f re of p rtial s adin (if p s ible) Soi n s ould b

low (les than 10 % o eratin c r ent Imp los ) an homogene u , without cau in p rtial

s adin (e.g by bird dro pin s, le ves, vegetation) to avoid thermal ef fects If stron soi n

or p rtial s adin d e to, for example bird dro pin s, is o served on the PV mod les, it is

recommen ed to cle n the entire s stem prior to in p ction Note that the p r orman e of the

s stem may c an e as a res lt of the cle nin En ure mod les are at thermal ste d state

af ter cle nin prior to p rf ormin infared imagin in p ction

For q antification of soi n , it is recommen ed to con u t me s rements ac ordin to

IEC 617 4-1 This mig t b helpf ul to comp re me s rements f rom p riodic in p ction

Colectin IR images can b done in diff erent way , e.g u in trip d , by han or drones

Care s al b taken that the method selected sti me ts the resolution req irements, an to

en ure u derstan in of the method u ed (e.g reflection ) An k own deviation or

National reg lation an laws may a ply to u in IR cameras an other eq ipment l ke

drones

The in p ction res lts verify the statu at the time of in p ction Is ues of intermitent or

c an in nature may or may not b ca tured at the time of in p ction

5.2 Vis al inspe tion

Prior to the thermogra hic in p ction of the PV plant, it is recommen to do a vis al

in p ction to determine whether the req irements of 5.1 are met Observation s c as bird

dro pin s, stron soi n , burn spots on mod les or other Balan e of Sy tem (BOS)

comp nents s al b doc mented by photos an location prior to the thermogra hic

in p ction If p s ible, those findin s s ould b resolved (e.g by cle nin ) prior to the

thermogra hic in p ction esp cial y d rin comis ionin Photos p st-cle nin (pre-imagin )

s ould b doc mented However, it may b desire ble to con u t the thermogra hy

in p ction without cle nin , e.g f or a ro t-cau e analy is for a p or p rf ormin PV p wer

plant

Up n o servation of thermal anomal es, it is desire ble to vis al y in p ct the comp nent an

vis al y o serve an a normal con ition in the are The PV mod le vis al in p ction

proced res in IEC 61215-1 an IEC 617 0-2 may b u eful referen es A vis al photo s al

b ca tured f or every thermal a normalty typ

5.3 En ironme tal conditions

The in p ction s ould b p rf ormed u der the con ition sp cified in Ta le 3

Table 3 – Re uire in pe tion conditions

a Ira ia c

• Minimum 6 0W/m

2

in th pla e of th P mo ule f or P mo ule in p ctio

• Me s re o eratin c re t s al b a minimum of 3 % of ate s stem c re t

within th in p cte c r e t p th (ty ic ly > 3 % of P mo ule n me plate Is at

d Soi n No or low Cle nin re omme d, e.g if bird dro pin s e ist

NOT For clo d c v ra e, fin f urth r informatio in ISO 15 6 :2 0

Af ter c an e in o eratin con ition , for example lo d or ir adian e (d e to e.g cir u clou s)

of >10 % p r min te, a waitin time of 15 min is recommen ed to regain the ste d state

me s rement con ition

The clou coverage s ould not con ist of more than 2 okta of c mulu clou s, b cau e of

misle din reflection on the mod les

5.4 Ima ing proc dure

The distan e b twe n the in p cted o ject an the IR-camera s al f ulfi the ge metrical

resolution, sp cified in 4.2, whi e req ired safety distan es ac ordin to safety reg lation are

met (Se Clau es A.1 an A.2)

The IR-camera image s al b taken as p rp n ic lar to the PV mod le s race as p s ible

At the same time, self reflection of me s rin p rson el an IR-camera a p ratu , an

ref lection of he ted o jects l ke s n, ne r by bui din s an tre s s al b avoided In cases

where the image can ot b taken p rp n ic lar to the PV mod le s rf ace, e.g a smal

in tal ation with l mited a i ty to raise the camera, the an le b twe n the camera an the PV

mod le plane s ould sti b gre ter than 3 ° (se Clau e A.2)

Adju t the camera emis ivity b sed on s rf ace con ition of the o ject u der in estigation

(e.g soi n of mod le f ront glas or d st on s in p rts of e.g fu e holders)

The DC-lo d of the plant s al b monitored an recorded to avoid me s rements u der

u def i ed lo d con ition d e to grid events (e.g strin s are o en circ it or s ort circ it

Together with the thermogra hic image, a photo of the same are s al b taken for e c typ

of thermal findin The exact p sition of al the f i din s in the in p cted s stem s al b

doc mented, as wel as the o eratin con ition in lu in local DC lo d an en ironmental

con ition

Two diff erent levels of q al ty of examination are c r ently u ed:

a) Simplfied in p ction:

The simpl f ied thermogra hic in p ction with red ced req irements for the q alf i ation of

p rson el (se An ex B) This is for a lmited in p ction to test the b sic f un tionin of the

PV mod les For example, d rin the commis ionin of s stems Authoritative con lu ion

regardin mod le q al ty are not p s ible No a solute temp ratures are determined,

theref ore thermal pat ern are u ed to evaluate the a normal ties Ref er to the examples

in An ex C

b) Detai ed in p ction:

The detai ed thermogra hic in p ction an analy is, whic may in lu e thermal p t ern

whic diff er fom the examples in the An exes This may be u ef ul f or trouble-s o tin

an for p riodic in p ction ac ordin to IEC 6 4 6-1 an future IEC 6 4 6-2 Absolute

temp rature me s rements are determined d rin this detaied in p ction An authorized

exp rt f or PV plants, together with thermogra hic exp rts, s al have ad an ed

q alf i ation as p r An ex B

5.4.2 Using f ast c r iers f or IR-c mera, e.g a rial dron s

Aerial drones are in re sin ly b in u ed as p rt of the to l kit for fault detection an

local zation in PV plants It s ould b noted that whi e drones help s ale, automate an

ac elerate detection of faulty are s within a large p wer plant, s c tec niq es can lac the

resolution to detect fine comp nent artif acts or identify sp cif i fai ure modes Su h an

in p ction by drones is clas ified as simplfied in p ction proced re of the whole PV ar ay in

order to fin PV s b ar ay /strin s/mod les with o viou notice ble pro lems

In the case where imagin is p r ormed u in a fast car ier, the movin sp ed of the camera

s ould alway b c osen with resp ct to the time con tant of the camera’s IR-detector to

avoid sme rin ef fects (comp re the f ol owin pictures in Fig re 1) Sme rin influen es

vis al p t ern an a solute an relative temp ratures Relevant sme rin eff ects on common

IR camera b lometer detectors, when u ed f or PV-mod les an s stems, may alre d a p ar

For large-area imagin s c as throu h u e of drones, con ider ir adian e an s stem

sta i ty, esp cial y if images wi b stitc ed together an not in ivid al y ma p d to s stem

p r orman e (in tantane u DC strin c r ent

En ure the ge metric resolution req irements are met, esp cial y if the distan e b twe n the

IR camera an PV mod le is large If the req irements are not met, it is a deviation to the

proced re

NOT A ty ic l a pro c is to d this simplf i d in p ctio at th wh le P ara to fin P mo ule or strin s

with n tic a le pro lems Af terward a d taie in p ctio is d n at th s P mo ule This p rtial or d taie

in p ctio c n b a re d in a c ntra t, alo g with th thre h ld f or d cidin wh t s rt of is u in th simplf i d

pro e ure wo ld war a t th d taie a pro c d s rib d in this d c me t

a) Picture c ptured with slow c mera mo in

spe d with ut n tic able sme rin

b) Picture c ptured at hig c mera mo in spe d

with u a c ptable sme rin

Figure 1 – Impa t of c mera moving spe d

5.4.3 Emis ivity

Estimatin the emis ivity of the examined s rf ace is the resp n ibi ty of the q al fied

thermogra her, p rtic larly in the case of detai ed in p ction The emis ivity of a s r ace

de en s on man f actors Man of them are les relevant f or the given tas (s c as the

exact sp ctral ran e of the (LW)-IR-camera, s rf ace an ambient temp rature, s race

ge metry, etc.)

For the simpl f ied in p ction, the most imp rtant de en en ies an some common values are

given f or common s rf ace an ambient temp ratures, s r aces without holes an (LW

)-IR-cameras (note that les common MW-IR-cameras dif fer sig ificantly):

For the practice of thermogra hy on PV mod les an BOS comp nents, it is imp rtant to

u derstan the f ol owin thre de en en ies: first material, secon s r ace (in lu es soi n )

an third an le of view De en en ies an values are given by examples

a) Materials s c as u oxidised metal (p rts made out of stainles ste l), p ls ed

aluminium p rts an some BOS comp nents have very low emis ivities arou d ε = 0,1 to

ε = 0,3, therefore an ac urate temp rature determination is not p s ible

b) Most in ulation s nthetic an ceramic have emis ivity arou d ε = 0,9

c) Rou h oxidated aluminium of mod le f rames an mou tin clamps an some BOS

comp nents typical y s ow values a ove u oxidised metal, but b low glas , typical y

a out ε = 0,4 to ε = 0,7

d) Materials l ke glas have hig er emis ivities arou d ε = 0,8 Glas with a rou h s r ace,

s c as textured glas or glas with hig degre of soi n may have an emis ivity up to

e) On non-f er ou glas the emis ivity decre ses with the an le of view, so at arou d 4 ° the

emis ivity wi b arou d ε = 0,8 an at 3 ° it can b arou d ε = 0,7 or lower

(Se Fig re 2 an also Clau e A.2.)

Figure 2 – Depe de c of the emis ivity of

gla s on th a gle of view [10]

6 Sof tware f or e aluation

Usin software, it is p s ible to tran f er the radiation den ity values me s red by the I

R-camera into a solute temp rature values The calc lation may b done directly u in the

IR-camera sof tware, whic updates the temp rature la els on the display s re n an in the

saved f ile Care s al b taken when interpretin any temp rature values, as they may not b

a solute temp ratures if the cor ect p rameters were not set To o tain temp rature values, it

is neces ary to set sp cific p rameters, in p rtic lar:

a) emis ivity, ε,

b) reflected temp rature, T

refl

c) temp rature level an sp n,

d) diff erent me s rin to ls (e.g sp t me s rement, p ly on ) u der sp cification of

minimum, maximum an arithmetic me n value f or the temp rature data

7 Ev luation

The f ol owin me s rements an o servation are imp rtant for evaluation or val dation:

a) maximum temp ratures,

b) temp rature diff eren es,

c) temp rature profi es,

e) win sp ed an direction (se example in Fig re 3 lef t),

f ) previou mec anical stres f rom in tal ation history logfi e,

Durin a simpl fied thermogra hic in p ction of a PV plant no exact temp ratures are

determined Here the main foc s is only on evaluatin certain thermogra hic p tern as

s own in An ex C To evaluate a solute temp rature an temp rature dif feren es, a detai ed

in p ction s al b done with a pro riate q al f ied p rsonel (se An ex B) General g idan e

can b fou d in EN 16 14-3 an VATh-Directive

a) Patern (Simpl f ied in p ction, se An ex C)

The a normaity is clas ified an evaluated by a k own thermal p t ern Me s rement of

a solute an relative temp rature values are not nec esary but can s p lement thermal

p tern as plau ibi ty c ec

b) Temp ratures of p int a normal ties (Detai ed in p ction, se An ex D)

Use an algorithm to determine hig est temp rature in the image This can b done u in

diff erent typ s of to ls s c as “f e han sp t or “maximum sp t within an are ” in the

camera an image proces in sof tware

c) Exten ed are s (Detai ed in p ction, se An ex D)

Use diff erent typ s of to ls s c as “rectan le”, “circle” or “p ly on are s” to calc late the

me n temp ratures of the are s, u in the camera an image proces in software

d) Relative temp ratures (Detaied in p ction, se An ex D)

Can b calc lated b twe n p int a normal ties an /or the me n values of exten ed are s,

with con ideration of the u certainty of me s rement

e) Absolute temp ratures (Detaied in p ction, se An ex D)

Can b me s red at p int a normal ties an the me n values of exten ed are s, with

At e tion: Absolute temp ratures on PV generators vary d e to win an con ection

diff eren es with time an p sition in the PV ar ay an plant

7.3 Thermal abnormal tie

This s bclau e a pl es in p rtic lar for detai ed in p ction

7.3.2 Cla s s of abnormal tie (CoA)

For the al ocation into clas es of a normal ties (CoA), the sp cific p tern an me s red

temp ratures have to b comp red with the examples of thermogra hic images an

dif feren es in temp rature s own in An ex C Ta le 4 introd ces thre clas es of

a normales an their f ol ow up action This is imp rtant sin e there mig t b imminent

dan er (electric s oc or f ire) to p ronal an pro erty

Table 4 – Al oc tion in cla s s of abnormal tie

Cla s of Ab ormalty (CoA) 1 (n a n rmaltie – OK) 2 (th rmal a n rmalty – tA) 3 (s fety rele a t th rmal

Thermal images an res ltin temp rature dif feren es s al alway b evaluated in the

context of the ambient con ition , typ of mou tin , an mod le as embly (glas -glas

mod le, glas -oi mod le, integrated polymers, etc.)

If a doubtles clas ification f rom the f ont side of a PV mod le is not p s ible, a b c side

view (o tical an thermogra hic) or further me s rement tec niq es s al b uti zed or a

more q al fied p rson el ( hermogra h of level 2 or eq ivalent s al b come in olved

Su gested action for f urther me s rements an rectification are des rib d in An ex C

7.3.4 Abnormal tie of other BOS compone ts

The BOS comp nent in p ction in lu es, but is not lmited to, ca les, contacts, f uses,

switc es, in erters an b t eries An example is given f or a f aulty (a normal) contact

Clas if i ation of a normal ties wi de en on the BOS comp nent No sp cific PV

req irements are develo ed, yet For the time b in , ref er to the a pl ca le prod ct stan ard

an general electro thermogra h tec niq es for electrical comp nents an their defined

req irements Se Fig re 4

Fig re 4 – Ex mple infrare thermograms of a PV strin combiner box

with c ble , conta ts, fu e a d switc e bef ore (lef t) a d af ter (rig t)

mainte a c on a fa lty conta t

7.4 Proje tion of temperature dif fere c s to nominal ir a ia c

The f ol owin gives g idan e f or the extra olation of the me s red temp rature dif feren e

b twe n f un tionin an non/p rtial-f un tionin comp nents u der actual con ition , to the

exp cted temp rature diff eren e u der nominal in plane ir adian e of the PV mod le, defined

as 1 0 0 W/m

2

This a pl es f or PV mod les an f or other BOS comp nents for an thermal

a normalty, an do s not con ider other con ition s c as win sp ed whic are se arately

re orted

Here, thermal a normal ties are diff erentiated b twe n:

a) p int a normal es (e.g local zed hot-sp ts in solar cels or a f use), an

b) exten ed are a normal ty (e.g an entire warm/hot solar cel or a he t sin plate)

For temp rature dif feren e extra olation the f ol owin formula s al b u ed:

∆푇

2

=�퐺

2

퐺

1

�푥

∆푇

1

NOT 1 Refere c f or th formula: Guid ln s to th rmo ra hic in p ctio of ele tric l in talatio s; Th ma

Perc -Niels n; Je s Christia Sore s n; 19 4 [1]

where

∆T

i

is the temp rature dif feren e b twe n f un tional an non-f un tionin comp nents

u der identical ir adian e con ition i;

G

i

is the ir adian e or lo d (DC c r ent at con ition i;

In ex i = 1 is the value at actual/p rtial ir adian e/lo d (se Ta le 3 for minimum req ired

p rtial ir adian e/lo d con ition );

In ex i = 2 is the value at nominal lo d/emp rature (10 % ir adian e/lo d con ition);

x is the exp nential f actor, con iderin diff erent s a es of a normal ties For imp ct

• For a p int a normal ty (p int he t source with radial he t tran p rt – typical y up to a

couple of s uare mi imetres in size an mu h smaler than a cel – for example, f or

a 6” c-Si cel a p int a normal ty is typical y les than 3 mm

2

) the folowin a pl es:

exp nential f actor x is typical y b twe n 1,5 an 1,8, where x = 2,0 re resents only c r ent

in u ed he t f rom a p int sp t, without any he t dis ip tion by radiation

NOT 2 "6 in h c l" is a e pre sio c re tly u e in th P in u try; 6' c re p n s to 15,2 cm Howe er,

oth r simiar siz s are u e in th P in u try a wel

• For exten ed are a normal ty (lateral exten ed he t source – typical y of the size of one

or more cel s) the f ol owin a ples:

exp nential factor x is typical y x = 1 an theref ore re resents a l ne r de en en e of

temp rature on ir adian e / c r ent lo d

Figure 5 – Graphic repre e tation of th cor e tion fa tor for temperature

dif fere c s to nominal ir a ia c /loa conditions a a f unction of

th relativ ir a ia c /loa

For con enien e, the exp nential factor x an the ir adian e/lo d terms can b combined into

a “cor ection factor”, to directly extra olate ∆T f rom the me s red to the nominal con ition

Values f or these cor ection f actors for p int a normal ties an exten ed are a normal ties of

PV mod les an BOS comp nents can b f ou d in the cor esp n in column of Ta le 5 an