Photovoltaic devices - Procedures for temperature and irradiance corrections to measured I-V characteristics

This document defines procedures to be followed for temperature and irradiance corrections to the measured I-V (current-voltage) characteristics (also known as I-V curves) of photovoltaic (PV) devices. It also defines the procedures used to determine factors relevant to these corrections. Requirements for I-V measurement of PV devices are laid down in IEC 60904-1 and its relevant subparts. The PV devices include a single solar cell with or without a protective cover, a sub-assembly of solar cells, or a module. A different set of relevant parameters for I-V curve correction applies for each type of device. The determination of temperature coefficients for a module (or subassembly of cells) may be calculated from single cell measurements, but this is not the case for the internal series resistance and curve correction factor, which should be separately measured for a module or subassembly of cells. Refer to Annex A for alternative procedures for series resistance determination. The use of I-V correction parameters are valid for the PV device for which they have been measured. Variations may occur within a production lot or the type class.

Verfahren zur Umrechung von gemessenen Strom-Spannungs-Kennlinien von photovoltaischen Bauelementen auf andere Temperaturen und Bestrahlungsstärken

Dispositifs photovoltaïques - Procédures pour les corrections en fonction de la température et de l'éclairement à appliquer aux caractéristiques I-V mesurées

IEC 60891:2021 définit des procédures à suivre pour les corrections en fonction de la température et de l'éclairement appliquées aux caractéristiques I-V (courant-tension) mesurées (également appelées courbes I-V) des dispositifs photovoltaïques (PV). Il définit également les procédures utilisées pour déterminer les facteurs appropriés pour ces corrections. Les exigences pour le mesurage I-V des dispositifs PV sont données dans l'IEC 60904-1 et ses sous-parties applicables. Cette troisième édition annule et remplace la deuxième édition parue en 2009. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: - ajout de recommandations concernant la procédure de correction à utiliser selon l'application; - introduction de la procédure de transposition 4 applicable aux technologies c-Si avec des coefficients de température inconnus; - introduction de différentes classifications dans les procédures existantes afin d'améliorer la précision de mesure et de réduire l'incertitude de mesure; - ajout d'une annexe informative qui présente des méthodes supplémentaires qui peuvent être utilisées pour déterminer la résistance-série.

Fotonapetostne naprave - Postopki za temperaturno in sevalno korekcijo izmerjenih karakteristik I-U

V tem dokumentu so opredeljeni postopki, ki jih je treba upoštevati za temperaturno in sevalno korekcijo izmerjenih karakteristik I-U (tok – napetost; imenovane tudi krivulje I-U) fotonapetostnih naprav. Opredeljuje tudi postopke, ki se uporabljajo za določanje pomembnih dejavnikov za to korekcijo. Zahteve za merjenje karakteristik I-U fotonapetostnih naprav so podane v standardu IEC 60904-1 in ustreznih poddelih tega standarda. Fotonapetostne naprave vključujejo enojno sončno celico z zaščitnim pokrovom ali brez njega, podsestav sončnih celic ali modul. Za vsako vrsto naprave se uporablja drugačen nabor ustreznih parametrov za korekcijo krivulje I-U. Določitev temperaturnih koeficientov za modul (ali podsestav celic) se lahko izračuna iz meritev enojne celice; vendar to ne velja za dejavnik notranje upornosti serije in korekcije krivulje, ki naj se izmeri posebej za modul oziroma podsestav celic. Za alternativne postopke za določanje upornosti serije glej dodatek A.
Parametri za korekcijo I-U se uporabljajo za fotonapetostno napravo, za katero so bili izmerjeni. Pojavijo se lahko razlike znotraj proizvodne serije ali vrste razreda.

General Information

Status
Published
Publication Date
18-Jan-2022
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
13-Dec-2021
Due Date
17-Feb-2022
Completion Date
19-Jan-2022

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SLOVENSKI STANDARD
SIST EN IEC 60891:2022
01-februar-2022
Nadomešča:
SIST EN 60891:2011
Fotonapetostne naprave - Postopki za temperaturno in sevalno korekcijo
izmerjenih karakteristik I-U
Photovoltaic devices - Procedures for temperature and irradiance corrections to
measured I-V characteristics
Verfahren zur Umrechung von gemessenen Strom-Spannungs-Kennlinien von
photovoltaischen Bauelementen auf andere Temperaturen und Bestrahlungsstärken
Dispositifs photovoltaïques - Procédures pour les corrections en fonction de la
température et de l'éclairement à appliquer aux caractéristiques I-V mesurées
Ta slovenski standard je istoveten z: EN IEC 60891:2021
ICS:
27.160 Sončna energija Solar energy engineering
SIST EN IEC 60891:2022 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN IEC 60891:2022
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SIST EN IEC 60891:2022
EUROPEAN STANDARD EN IEC 60891
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2021
ICS 27.160 Supersedes EN 60891:2010 and all of its amendments
and corrigenda (if any)
English Version
Photovoltaic devices - Procedures for temperature and
irradiance corrections to measured I-V characteristics
(IEC 60891:2021)

Dispositifs photovoltaïques - Procédures pour les Verfahren zur Umrechnung von gemessenen Strom-

corrections en fonction de la température et de l'éclairement Spannungs-Kennlinien von photovoltaischen Bauelementen

à appliquer aux caractéristiques I-V mesurées auf andere Temperaturen und Bestrahlungsstärken

(IEC 60891:2021) (IEC 60891:2021)

This European Standard was approved by CENELEC on 2021-12-01. CENELEC members are bound to comply with the CEN/CENELEC

Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC

Management Centre or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation

under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the

same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the

Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2021 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN IEC 60891:2021 E
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SIST EN IEC 60891:2022
EN IEC 60891:2021 (E)
European foreword

The text of document 82/1936/FDIS, future edition 3 of IEC 60891, prepared by IEC/TC 82 “Solar

photovoltaic energy systems” was submitted to the IEC-CENELEC parallel vote and approved by

CENELEC as EN IEC 60891:2021.
The following dates are fixed:

• latest date by which the document has to be implemented at national (dop) 2022–09–01

level by publication of an identical national standard or by endorsement

• latest date by which the national standards conflicting with the (dow) 2024–12–01

document have to be withdrawn

This document supersedes EN 60891:2010 and all of its amendments and corrigenda (if any).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Any feedback and questions on this document should be directed to the users’ national committee. A

complete listing of these bodies can be found on the CENELEC website.
Endorsement notice

The text of the International Standard IEC 60891:2021 was approved by CENELEC as a European

Standard without any modification.
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SIST EN IEC 60891:2022
EN IEC 60891:2021 (E)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments)

applies.

NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the

relevant EN/HD applies.

NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available

here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60904-1 - Photovoltaic devices - Part 1: EN IEC 60904-1 -
Measurement of photovoltaic current-
voltage characteristics
IEC/TS 60904-1-2 Photovoltaic devices - Part 1–2:
Measurement of current-voltage
characteristics of bifacial photovoltaic (PV)
devices
IEC 60904-2 - Photovoltaic devices - Part 2: EN 60904-2 -
Requirements for photovoltaic reference
devices
IEC 60904-7 - Photovoltaic devices - Part 7: Computation EN IEC 60904-7 -
of the spectral mismatch correction for
measurements of photovoltaic devices
IEC 60904-8 - Photovoltaic devices - Part 8: EN 60904-8 -
Measurement of spectral responsivity of a
photovoltaic (PV) device
IEC 60904-9 - Photovoltaic devices - Part 9: Classification EN IEC 60904-9 -
of solar simulator characteristics

IEC 60904-10 2020 Photovoltaic devices - Part 10: Methods of EN IEC 60904-10 2020

linear dependence and linearity
measurements
IEC 61215-2 - Terrestrial photovoltaic (PV) modules - EN IEC 61215-2 -
Design qualification and type approval -
Part 2: Test procedures
IEC/TS 61836 - Solar photovoltaic energy systems - - -
Terms, definitions and symbols
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SIST EN IEC 60891:2022
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SIST EN IEC 60891:2022
IEC 60891
Edition 3.0 2021-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Photovoltaic devices – Procedures for temperature and irradiance corrections
to measured I-V characteristics
Dispositifs photovoltaïques – Procédures pour les corrections en fonction de la
température et de l'éclairement à appliquer aux caractéristiques I-V mesurées
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.160 ISBN 978-2-8322-1036-0

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
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SIST EN IEC 60891:2022
– 2 – IEC 60891:2021 © IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 4

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms and definitions, symbols and abbreviated terms .................................................... 7

4 Correction procedures ..................................................................................................... 8

4.1 General ................................................................................................................... 8

4.2 Correction procedure 1 ......................................................................................... 11

4.3 Correction procedure 2 ......................................................................................... 12

4.4 Correction procedure 3 ......................................................................................... 14

4.4.1 General ......................................................................................................... 14

4.4.2 Correction for the irradiance and temperature from two measured I-V

curves ........................................................................................................... 14

4.4.3 Correction to various irradiances and temperatures from three I-V

curves ........................................................................................................... 17

4.4.4 Correction to various irradiances and temperatures from four measured

I-V curves ...................................................................................................... 17

4.5 Correction procedure 4 ......................................................................................... 18

5 Determination of temperature coefficients ...................................................................... 20

5.1 General ................................................................................................................. 20

5.2 Apparatus ............................................................................................................. 20

5.3 Procedure in natural or steady-state simulated sunlight ........................................ 22

5.4 Procedure with a pulsed solar simulator ................................................................ 23

5.5 Calculation of temperature coefficients ................................................................. 23

6 Determination of internal series resistance R and R′ .................................................. 24

S S

6.1 General ................................................................................................................. 24

6.2 Determination of R in correction procedures 1 and 4 ........................................... 25

6.3 Determination of B and B in correction procedure 2 ........................................... 27

1 2

6.4 Determination of R′ in correction procedure 2 ..................................................... 28

6.5 Determination of R in correction procedure 4 ...................................................... 30

7 Determination of the curve correction factor κ and κ′ ..................................................... 31

7.1 General ................................................................................................................. 31

7.2 Procedure ............................................................................................................. 31

8 Reporting ...................................................................................................................... 32

Annex A (informative) Alternative procedures for series resistance determination ................ 34

A.1 General ................................................................................................................. 34

A.2 Differential resistance at V against inverse irradiance method .......................... 34

Bibliography .......................................................................................................................... 35

Figure 1 – Example of the correction of the I-V characteristics by formulae (10) and

(11) ...................................................................................................................................... 16

Figure 2 – Schematic diagram of the relation of G and T which can be chosen in the

3 3

simultaneous correction for irradiance and temperature, for a fixed set of T , G , T ,

1 1 2

and G by formulae (12) and (13) ......................................................................................... 16

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SIST EN IEC 60891:2022
IEC 60891:2021 © IEC 2021 – 3 –

Figure 3 – Schematic diagram of the processes for correcting the I-V characteristics to

various ranges of irradiance and temperature based on three measured

characteristics ...................................................................................................................... 17

Figure 4 – Schematic diagram of the processes for correcting the I-V characteristics to

various ranges of irradiance and temperature based on four measured characteristics ......... 18

Figure 5 – Example positions for measuring the temperature of the test module behind

the cells ................................................................................................................................ 21

Figure 6 – Determination of internal series resistance ........................................................... 26

Figure 7 – Determination of internal series resistance when the corrected I-V

characteristics intersect ........................................................................................................ 27

Figure 8 – Determination of irradiance correction factors B and B and internal series

1 2

resistance, R′ ...................................................................................................................... 29

Figure 9 – Determination of internal series resistance of a PV module from a single I-V

curve .................................................................................................................................... 31

Figure 10 – Determination of curve correction factor ............................................................. 32

Figure A.1 – Determination of internal series resistance ....................................................... 34

Table 1 – Overview of correction procedures for irradiance corrections (i.e. T = T ) .............. 9

1 2

Table 2 – Overview of correction procedures for temperature corrections (i.e. G = G ) ....... 10

1 2
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SIST EN IEC 60891:2022
– 4 – IEC 60891:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC DEVICES – PROCEDURES FOR TEMPERATURE AND
IRRADIANCE CORRECTIONS TO MEASURED I-V CHARACTERISTICS
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international

co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and

in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,

Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their

preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with

may participate in this preparatory work. International, governmental and non-governmental organizations liaising

with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for

Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence between

any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.

5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent

rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 60891 has been prepared by IEC technical committee 82: Solar

photovoltaic energy systems.

This third edition cancels and replaces the second edition published in 2009. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:

– adds guidance on which correction procedure shall be used depending on application;

– introduces translation procedure 4 applicable to c-Si technologies with unknown

temperature coefficients;

– introduces various clarifications in existing procedures to improve measurement accuracy

and reduce measurement uncertainty;

– adds an informative annex for supplementary methods that can be used for series resistance

determination.
---------------------- Page: 10 ----------------------
SIST EN IEC 60891:2022
IEC 60891:2021 © IEC 2021 – 5 –
The text of this International Standard is based on the following documents:
FDIS Report on voting
82/1936/FDIS 82/1957/RVD

Full information on the voting for its approval can be found in the report on voting indicated in

the above table.
The language used for the development of this International Standard is English.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in

accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available

at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are

described in greater detail at www.iec.ch/standardsdev/publications.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under webstore.iec.ch in the data related to the

specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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SIST EN IEC 60891:2022
– 6 – IEC 60891:2021 © IEC 2021
PHOTOVOLTAIC DEVICES – PROCEDURES FOR TEMPERATURE AND
IRRADIANCE CORRECTIONS TO MEASURED I-V CHARACTERISTICS
1 Scope

This document defines procedures to be followed for temperature and irradiance corrections to

the measured I-V (current-voltage) characteristics (also known as I-V curves) of photovoltaic

(PV) devices. It also defines the procedures used to determine factors relevant to these

corrections. Requirements for I-V measurement of PV devices are laid down in IEC 60904-1

and its relevant subparts.

The PV devices include a single solar cell with or without a protective cover, a sub-assembly of

solar cells, or a module. A different set of relevant parameters for I-V curve correction applies

for each type of device. The determination of temperature coefficients for a module (or sub-

assembly of cells) may be calculated from single cell measurements, but this is not the case for

the internal series resistance and curve correction factor, which should be separately measured

for a module or subassembly of cells. Refer to Annex A for alternative procedures for series

resistance determination.

The use of I-V correction parameters is valid for the PV device for which they have been

measured. Variations may occur within a production lot or the type of class.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies.

For undated references, the latest edition of the referenced document (including any

amendments) applies.

IEC 60904-1, Photovoltaic devices – Part 1: Measurements of photovoltaic current-voltage

characteristics

IEC TS 60904-1-2, Photovoltaic devices – Part 1-2: Measurement of current-voltage

characteristics of bifacial photovoltaic (PV) devices

IEC 60904-2, Photovoltaic devices – Part 2: Requirements for reference solar devices

IEC 60904-7, Photovoltaic devices – Part 7: Computation of the spectral mismatch correction

for measurements of photovoltaic devices

IEC 60904-8, Photovoltaic devices – Part 8: Measurement of spectral responsivity of a

photovoltaic (PV) device

IEC 60904-9, Photovoltaic devices – Part 9: Classification of solar simulator characteristics

IEC 60904-10:2020, Photovoltaic devices – Part 10: Methods of linear dependence and linearity

measurements

IEC 61215-2, Terrestrial photovoltaic (PV) modules – Design qualification and type approval –

Part 2: Test procedures

IEC TS 61836, Solar photovoltaic energy systems – Terms, definitions, and symbols

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SIST EN IEC 60891:2022
IEC 60891:2021 © IEC 2021 – 7 –
3 Terms and definitions, symbols and abbreviated terms

For the purposes of this document, the terms and definitions given in IEC TS 61836, together

with the following, apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1

irradiance correction factor for open-circuit voltage which is linked with the diode thermal

voltage, V of the p-n junction and n
t S
Note 1 to entry: It is used in correction procedure 2.
3.2

irradiance correction factor for open-circuit voltage which accounts for non-linearity of V with

irradiance scaling
Note 1 to entry: It is used in correction procedure 2.
3.3
DUT
device under test
3.4
internal series resistance of the DUT employed by correction procedures 1 and 4
3.5
internal series resistance of the DUT employed by correction procedure 2

Note 1 to entry: Although determined by a different method than R , both quantities share the same physical

meaning and therefore their values for the same DUT are similar.
3.6
number of cells serially connected in the DUT
3.7

interpolation constant employed in correction procedure 3, that has a relation with the irradiance

and temperature
3.8

product of ideality factor of the DUT with the bandgap of the photovoltaic material divided by

electron’s elementary charge
Note 1 to entry: It is used in correction procedure 4.
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SIST EN IEC 60891:2022
– 8 – IEC 60891:2021 © IEC 2021
4 Correction procedures
4.1 General
This document provides four procedures for correcting measured current-voltage

characteristics to other conditions of temperature and irradiance, such as Standard Test

Conditions (STC), that can be applied. The first procedure describes a system of linear

equations for current and voltage, which is best applicable for irradiance corrections within

±40% of the target irradiance. The second procedure is an alternative algebraic correction

method which yields better results for large irradiance corrections (exceeding ±40 %). Both

procedures require that correction parameters of the PV device are known. If not known they

need to be determined prior to performing the correction. The third procedure is an interpolation

method which does not require correction parameters as input. It can be applied when a

minimum of two current-voltage curves have been measured for the DUT. This correction

method is applicable in the temperature and irradiance range spanned by the two current

voltage curves. The fourth procedure is based on the single-diode model and provides a

methodology for determining a correction parameter R from a single I-V curve, when the

parameter is unknown. The method is best applicable to irradiance corrections when the

2 2

measured and target irradiance are both in the range 300 W/m to 1 200 W/m and the series

resistance R is unknown. It is suitable for translations when the characteristics under STC

have to be estimated from a single experimental I-V curve.

Table 1 and Table 2 provide an overview of the four different correction procedures, and

describe qualitatively the advantages, disadvantages and required correction parameters for

each procedure. The purpose of these tables is to provide guidance to the user of this document

on which correction procedure to use for different applications.

For simultaneous corrections of irradiance and temperature, the benefits and limitations listed

in Table 1 and Table 2 apply concurrently.

Common to all procedures is that I-V characteristics of the PV device are to be measured in

accordance with IEC 60904-1 and its relevant subparts.

All PV devices should be linear at least within the range of irradiances and device temperature

over which corrections are made. Details on how to assess the deviation from the ideal linear

dependence are described in IEC 60904-10.
An estimate of the translation accuracy is required (see Clause 8).

Usually, the total irradiance G shall be calculated from the measured short-circuit current of the

PV reference device (I ) as defined in IEC 60904-2, and its calibration value at STC (I ).

RC RC,STC

A correction should be applied to account for the actual temperature of the reference device

T using the specified relative temperature coefficient of short-circuit current of the reference

device (𝛼𝛼 ) which is given at 25 °C and 1 000 W/m .
RC,rel
1000 𝑊𝑊𝑚𝑚 ×𝐼𝐼
𝐺𝐺 =
(1)
𝐼𝐼 ×�1 +𝛼𝛼 × (𝑇𝑇 − 25°𝐶𝐶)�
RC,STC RC,rel RC
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SIST EN IEC 60891:2022
IEC 60891:2021 © IEC 2021 – 9 –

Ideally, the reference device shall be linear in short-circuit current over the entire irradiance

range of interest, as defined in IEC 60904-10. In practice, even for linear devices it is

recommended to apply a correction for linearity of the reference device according to

IEC 60904-10. If the device is not linear according to IEC 60904-10 over the entire irradiance

range of interest, then corrections shall be applied to avoid errors in the corrections of its I-V

characteristics. The PV reference device shall either be spectrally matched to the DUT, or a

spectral mismatch (SMM) correction shall be performed in conformance with IEC 60904-7.

Since the spectral responsivity of the device can vary with temperature, the apparent change

in temperature coefficient with spectra should be taken into account in the correction. An

interpolation method of temperature against SMM correction can minimize the error sources.

Table 1 – Overview of correction procedures for irradiance corrections (i.e. T = T )

1 2
Procedure 1
Correction parameter requirement: R
Advantages Disadvantages

• Suitable where R is determined (typically • Assumes superposition of current at all voltages

within ± 40 % of the irradiance at which R was
determined)

• Works reasonably well over a broader range of • Cannot produce complete I-V curves for higher

irradiance (typically within ± 80 % of the irradiance corrections (part of I-V curve between

irradiance at which R was determined) for
P and V is missing), when the I-V curve is not
max OC

devices that are linear with respect to measured sufficiently far into the negative current

irradiance according to IEC 60904-10. This is regime. In this case extrapolation for V is

typically the case for c-Si.
necessary
Procedure 2
Correction parameter requirement: B , B , R′ . κ′ and β
1 2 S rel
Advantages Disadvantages
• Requires more parameters to be known than
• Suitable in the irradiance range where R′ is
procedures 1 and 4
determined (typically within ± 40 % of the
irradiance at which R′ was determined)

• Works reasonably well over a broader range of • Not recommended for I-V translation over

irradiance (typically within ± 80 % of the irradiance exceeding ±
...

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