Photovoltaic system performance - Part 1: Monitoring

This International Standard outlines terminology, equipment, and methods for performance monitoring and analysis of photovoltaic (PV) systems. It also serves as a basis for other standards which rely upon the data collected.

Betriebsverhalten von Photovoltaik-Systemen - Teil 1: Überwachung

Performance d'un système photovoltaïque - Partie 1: Surveillance

IEC 61724-1:2021 est disponible sous forme de IEC 61724-1:2021 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.L'IEC 61724-1:2021 présente une terminologie, des équipements et des méthodes relatifs à la surveillance des performances et à l’analyse des systèmes photovoltaïques (PV). Elle sert également de base à d’autres normes qui s’appuient sur les données collectées. Cette deuxième édition annule et remplace la première édition parue en 2017. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: - Présentation de la surveillance des modules PV bifaciaux. - Mise à jour des exigences relatives aux capteurs d’éclairement énergétique. - Mise à jour du mesurage de l’encrassement pour tenir compte des nouvelles technologies. - Suppression des systèmes de surveillance de classe C. - Mise à jour de différentes exigences, recommandations et notes explicatives.

Zmogljivost fotonapetostnega sistema - 1. del: Spremljanje in nadzorovanje

General Information

Status
Published
Publication Date
11-Oct-2021
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
05-Oct-2021
Due Date
10-Dec-2021
Completion Date
12-Oct-2021

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SLOVENSKI STANDARD
SIST EN IEC 61724-1:2021
01-november-2021
Nadomešča:
SIST EN 61724-1:2017
Zmogljivost fotonapetostnega sistema - 1. del: Spremljanje in nadzorovanje
Photovoltaic system performance - Part 1: Monitoring
Betriebsverhalten von Photovoltaik-Systemen - Teil 1: Überwachung
Performance d'un système photovoltaïque - Partie 1: Surveillance
Ta slovenski standard je istoveten z: EN IEC 61724-1:2021
ICS:
27.160 Sončna energija Solar energy engineering
SIST EN IEC 61724-1:2021 en

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

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SIST EN IEC 61724-1:2021
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SIST EN IEC 61724-1:2021
EUROPEAN STANDARD EN IEC 61724-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2021
ICS 27.160 Supersedes EN 61724-1:2017 and all of its amendments
and corrigenda (if any)
English Version
Photovoltaic system performance - Part 1: Monitoring
(IEC 61724-1:2021)

Performances des systèmes photovoltaïques - Partie 1: Betriebsverhalten von Photovoltaik-Systemen - Teil 1:

Surveillance Überwachung
(IEC 61724-1:2021) (IEC 61724-1:2021)

This European Standard was approved by CENELEC on 2021-08-25. 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 61724-1:2021 E
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SIST EN IEC 61724-1:2021
EN IEC 61724-1:2021 (E)
European foreword

The text of document 82/1904/FDIS, future edition 2 of IEC 61724-1, prepared by IEC/TC 82 “Solar

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

CENELEC as EN IEC 61724-1:2021.
The following dates are fixed:

• latest date by which the document has to be implemented at national (dop) 2022–05–25

level by publication of an identical national standard or by endorsement

• latest date by which the national standards conflicting with the (dow) 2024–08–25

document have to be withdrawn

This document supersedes EN 61724-1:2017 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 61724-1:2021 was approved by CENELEC as a European

Standard without any modification.

In the official version, for Bibliography, the following note has to be added for the standard indicated:

IEC 60904-3 NOTE Harmonized as EN IEC 60904-3
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SIST EN IEC 61724-1:2021
EN IEC 61724-1:2021 (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 60050-131 - International Electrotechnical Vocabulary - -
(IEV) - Part 131: Circuit theory
IEC 60904-2 - Photovoltaic devices - Part 2: EN 60904-2 -
Requirements for photovoltaic reference
devices
IEC 60904-5 - Photovoltaic devices - Part 5: EN 60904-5 -
Determination of the equivalent cell
temperature (ECT) of photovoltaic (PV)
devices by the open-circuit voltage method
IEC 60904-7 - Photovoltaic devices - Part 7: Computation EN IEC 60904-7 -
of the spectral mismatch correction for
measurements of photovoltaic devices
IEC 61215 series Terrestrial photovoltaic (PV) modules - EN IEC 61215 series
Design qualification and type approval
IEC 61557-12 - Electrical safety in low voltage distribution - -
systems up to 1 000 V AC and 1 500 V DC
- Equipment for testing, measuring or
monitoring of protective measures - Part
12: Power metering and monitoring
devices (PMD)
IEC/TS 61724-2 Photovoltaic system performance - Part 2:
Capacity evaluation method
IEC/TS 61724-3 Photovoltaic system performance - Part 3:
Energy evaluation method
IEC/TS 61836 Solar photovoltaic energy systems - -
Terms, definitions and symbols
IEC 62053-22 - Electricity metering equipment - Particular EN IEC 62053-22 -
requirements - Part 22: Static meters for
AC active energy (classes 0,1S, 0,2S and
0,5S)
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SIST EN IEC 61724-1:2021
EN IEC 61724-1:2021 (E)
IEC 62670-3 - Photovoltaic concentrators (CPV) – EN 62670-3 -
Performance testing - Part 3: Performance
measurements and power rating
IEC 62817 2014 Photovoltaic systems - Design qualification EN 62817 2015
of solar trackers
ISO/IEC Guide 98-1 - Uncertainty of measurement – Part 1: - -
Introduction to the expression of
uncertainty in measurement
ISO/IEC Guide 98-3 - Uncertainty of measurement - Part 3: - -
Guide to the expression of uncertainty in
measurement (GUM:1995)
ISO 9060 2018 Solar energy - Specification and
classification of instruments for measuring
hemispherical solar and direct solar
radiation
ISO 9488 Solar energy - Vocabulary EN ISO 9488
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SIST EN IEC 61724-1:2021
IEC 61724-1
Edition 2.0 2021-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Photovoltaic system performance –
Part 1: Monitoring
Performances des systèmes photovoltaïques –
Partie 1: Surveillance
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.160 ISBN 978-2-8322-1002-5

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 61724-1:2021
– 2 – IEC 61724-1:2021 © IEC 2021
CONTENTS

FOREWORD ......................................................................................................................... 6

INTRODUCTION ................................................................................................................... 8

1 Scope .......................................................................................................................... 10

2 Normative references................................................................................................... 10

3 Terms and definitions .................................................................................................. 11

4 Monitoring system classification ................................................................................... 15

5 General ....................................................................................................................... 16

5.1 Measurement precision and uncertainty ............................................................... 16

5.2 Calibration .......................................................................................................... 16

5.3 Repeated elements ............................................................................................. 16

5.4 Power consumption ............................................................................................. 16

5.5 Documentation .................................................................................................... 16

5.6 Inspection ........................................................................................................... 16

6 Data acquisition timing and reporting ........................................................................... 16

6.1 Samples, records, and reports ............................................................................. 16

6.2 Timestamps ........................................................................................................ 18

6.3 Parameter names ................................................................................................ 18

7 Required measurements .............................................................................................. 18

8 Irradiance .................................................................................................................... 23

8.1 Sensor types ....................................................................................................... 23

8.2 General requirements .......................................................................................... 23

8.2.1 Overview ..................................................................................................... 23

8.2.2 Sensor requirements .................................................................................... 23

8.2.3 Sensor locations .......................................................................................... 24

8.2.4 Recalibration................................................................................................ 25

8.2.5 Soiling mitigation ......................................................................................... 25

8.2.6 Dew and frost mitigation ............................................................................... 25

8.2.7 Inspection and maintenance ......................................................................... 26

8.2.8 Sensor alignment ......................................................................................... 26

8.3 Measurements .................................................................................................... 26

8.3.1 Global horizontal irradiance .......................................................................... 26

8.3.2 In-plane irradiance ....................................................................................... 26

8.3.3 In-plane rear-side irradiance ......................................................................... 27

8.3.4 In-plane rear-side irradiance ratio ................................................................. 27

8.3.5 Horizontal albedo ......................................................................................... 27

8.3.6 Direct normal irradiance ............................................................................... 27

8.3.7 Diffuse horizontal irradiance ......................................................................... 27

8.3.8 Spectrally matched irradiance ...................................................................... 27

8.3.9 In-plane irradiance for concentrator systems ................................................. 28

8.3.10 Spectral irradiance for concentrator systems ................................................ 29

8.3.11 Circumsolar measurements for concentrator systems .................................... 29

8.3.12 Satellite remote sensing of irradiance ........................................................... 30

9 Environmental factors .................................................................................................. 31

9.1 PV module temperature ....................................................................................... 31

9.2 Ambient air temperature ...................................................................................... 31

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9.3 Wind speed and direction .................................................................................... 32

9.4 Soiling ratio ......................................................................................................... 32

9.5 Rainfall ............................................................................................................... 33

9.6 Snow .................................................................................................................. 33

9.7 Humidity ............................................................................................................. 33

10 Tracker system ............................................................................................................ 33

10.1 Single-axis trackers ............................................................................................. 33

10.2 Dual-axis trackers ............................................................................................... 33

10.2.1 Monitoring .................................................................................................... 33

10.2.2 Pointing error sensor alignment .................................................................... 33

11 Electrical measurements .............................................................................................. 34

11.1 Inverter-level measurements ............................................................................... 34

11.2 Plant-level measurements ................................................................................... 34

12 Data processing and quality check ............................................................................... 35

12.1 Night ................................................................................................................... 35

12.2 Quality check ...................................................................................................... 35

12.2.1 Removing invalid readings ........................................................................... 35

12.2.2 Treatment of missing data ............................................................................ 35

13 Calculated parameters ................................................................................................. 36

13.1 Overview............................................................................................................. 36

13.2 Summations ........................................................................................................ 36

13.3 Irradiation ........................................................................................................... 36

13.4 Electrical energy ................................................................................................. 37

13.4.1 General ....................................................................................................... 37

13.4.2 DC output energy ......................................................................................... 37

13.4.3 AC output energy ......................................................................................... 37

13.5 Array power rating ............................................................................................... 37

13.5.1 DC power rating ........................................................................................... 37

13.5.2 AC power rating ........................................................................................... 38

13.6 Yields ................................................................................................................. 38

13.6.1 General ....................................................................................................... 38

13.6.2 PV array energy yield ................................................................................... 38

13.6.3 Final system yield ........................................................................................ 38

13.6.4 Reference yield ............................................................................................ 39

13.6.5 Bifacial reference yield ................................................................................. 39

13.7 Yield losses ........................................................................................................ 39

13.7.1 General ....................................................................................................... 39

13.7.2 Array capture loss ........................................................................................ 39

13.7.3 Balance of systems (BOS) loss..................................................................... 40

13.8 Efficiencies ......................................................................................................... 40

13.8.1 Array (DC) efficiency .................................................................................... 40

13.8.2 System (AC) efficiency ................................................................................. 40

13.8.3 BOS efficiency ............................................................................................. 40

14 Performance metrics .................................................................................................... 41

14.1 Overview............................................................................................................. 41

14.2 Summations ........................................................................................................ 41

14.3 Performance ratios .............................................................................................. 41

14.3.1 Performance ratio ........................................................................................ 41

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SIST EN IEC 61724-1:2021
– 4 – IEC 61724-1:2021 © IEC 2021

14.3.2 Temperature-corrected performance ratios ................................................... 42

14.3.3 Bifacial performance ratios ........................................................................... 44

14.4 Performance indices ............................................................................................ 44

15 Data filtering ................................................................................................................ 45

15.1 Use of available data ........................................................................................... 45

15.2 Filtering data to specific conditions ...................................................................... 45

15.3 Reduced inverter, grid, or load availability ........................................................... 45

Annex A (informative) Sampling interval ............................................................................. 46

A.1 General considerations ........................................................................................ 46

A.2 Time constants .................................................................................................... 46

A.3 Aliasing error ...................................................................................................... 46

A.4 Example.............................................................................................................. 47

Annex B (informative) Module temperature sensor selection and attachment ....................... 48

B.1 Objective ............................................................................................................ 48

B.2 Sensor and material selection .............................................................................. 48

B.2.1 Optimal sensor types ................................................................................... 48

B.2.2 Optimal tapes .............................................................................................. 48

B.2.3 Cyanoacrylate adhesives and backsheet integrity ......................................... 49

B.3 Sensor attachment .............................................................................................. 49

B.3.1 Permanent versus temporary ........................................................................ 49

B.3.2 Attachment location ..................................................................................... 49

B.3.3 Bifacial modules ........................................................................................... 49

B.3.4 Method ........................................................................................................ 49

Annex C (normative) Soiling measurement using clean and soiled PV reference device

pair ................................................................................................................................... 52

C.1 Overview............................................................................................................. 52

C.2 Equipment .......................................................................................................... 52

C.3 Normalization ...................................................................................................... 52

C.4 Measurement method 1 – max power reduction due to soiling .............................. 53

C.5 Measurement method 2 – short-circuit current reduction due to soiling ................. 53

C.6 Non-uniform soiling ............................................................................................. 53

C.7 Daily average value ............................................................................................. 54

C.8 Renormalization .................................................................................................. 54

Annex D (informative) Derate factors .................................................................................. 55

Annex E (normative) Systems with local loads, storage, or auxiliary sources ....................... 57

E.1 System types ...................................................................................................... 57

E.2 Parameters and formulas .................................................................................... 59

Bibliography ....................................................................................................................... 66

Figure 1 – Possible elements of PV systems ......................................................................... 8

Figure 2 – Samples, records and reports ............................................................................. 17

Figure B.1 – Sensor attachment, permanent ........................................................................ 50

Figure B.2 – Sensor attachment, temporary ......................................................................... 50

Figure B.3 – Sensor element wire strain relief ...................................................................... 51

Figure E.1 – Energy flow between possible elements of different PV system types ............... 57

Table 1 – Sampling and recording interval requirements ...................................................... 18

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IEC 61724-1:2021 © IEC 2021 – 5 –

Table 2 – Measured parameters and requirements .............................................................. 20

Table 3 – Multiplier referenced in Table 2 ............................................................................ 23

Table 4 – Irradiance sensor requirements ............................................................................ 24

Table 5 – Inverter-level electrical measurement requirements .............................................. 34

Table 6 – Plant-level AC electrical output measurement requirements .................................. 34

Table 7 – Calculated parameters ......................................................................................... 36

Table 8 – Performance metrics ............................................................................................ 41

Table E.1 – Elements of different PV system types .............................................................. 58

Table E.2 – Parameters and formulas for different system types .......................................... 59

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SIST EN IEC 61724-1:2021
– 6 – IEC 61724-1:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC SYSTEM PERFORMANCE –
Part 1: Monitoring
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

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

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

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

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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 61724-1 has been prepared by IEC technical committee 82: Solar

photovoltaic energy systems.

This second edition cancels and replaces the first edition, published in 2017. This edition

constitutes a technical revision.

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

edition:
...

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