IEC 61724:1998

Photovoltaic system performance monitoring - Guidelines for measurement, data exchange and analysis

Recommends procedures for the monitoring of energy-related photovoltaic (PV) system characteristics, and for the exchange and analysis of monitored data. The purpose is the assessment of the overall performance of PV systems.

Surveillance des qualités de fonctionnement des systèmes photovoltaïques - Recommandations pour la mesure, le transfert et l'analyse des données

Donne des recommandations relatives aux procédures pour le suivi des caractéristiques énergétiques des systèmes photovoltaïques (PV), ainsi qu'à l'échange et l'analyse des données enregistrées. L'objectif de ces procédures est l'évaluation des performances globales des systèmes PV.

General Information

• Status: Replaced
• Publication Date: 14-Apr-1998
• ICS: 27.180 - Wind turbine energy systems
• Technical Committee: TC 82 - Solar photovoltaic energy systems
• Drafting Committee: WG 3 - TC 82/WG 3
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 03-Mar-2017

Relations

• Replaced By: IEC 61724-1:2017 - Photovoltaic system performance - Part 1: Monitoring
• Effective Date: 05-Sep-2023
• Replaced By: IEC TS 61724-3:2016 - Photovoltaic system performance - Part 3: Energy evaluation method
• Effective Date: 05-Sep-2023
• Replaced By: IEC TS 61724-2:2016 - Photovoltaic system performance - Part 2: Capacity evaluation method
• Effective Date: 05-Sep-2023

Standards Content (Sample)

INTERNATIONAL
IEC
STANDARD
First edition
1998-04
Photovoltaic system performance monitoring –
Guidelines for measurement,
data exchange and analysis
Suivi des performances des systèmes photovoltaïques –
Recommandations pour les mesures, et le transfert
et l’analyse des données
Reference number
Numbering
As from 1 January 1997 all IEC publications are issued with a designation in the
60000 series.
Consolidated publications
Consolidated versions of some IEC publications including amendments are
available. For example, edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the
base publication, the base publication incorporating amendment 1 and the base
publication incorporating amendments 1 and 2.
Validity of this publication
The technical content of IEC publications is kept under constant review by the IEC,
thus ensuring that the content reflects current technology.
Information relating to the date of the reconfirmation of the publication is available
in the IEC catalogue.
Information on the subjects under consideration and work in progress undertaken by
the technical committee which has prepared this publication, as well as the list of
publications issued, is to be found at the following IEC sources:
• IEC web site*
• Catalogue of IEC publications
Published yearly with regular updates
(On-line catalogue)*
• IEC Bulletin
Available both at the IEC web site* and as a printed periodical
Terminology, graphical and letter symbols
For general terminology, readers are referred to IEC 60050: International
Electrotechnical Vocabulary (IEV).
For graphical symbols, and letter symbols and signs approved by the IEC for
general use, readers are referred to publications IEC 60027: Letter symbols to be
used in electrical technology, IEC 60417: Graphical symbols for use on equipment.
Index, survey and compilation of the single sheets and IEC 60617: Graphical symbols
for diagrams.
* See web site address on title page.

INTERNATIONAL
IEC
STANDARD
First edition
1998-04
Photovoltaic system performance monitoring –
Guidelines for measurement,
data exchange and analysis
Suivi des performances des systèmes photovoltaïques –
Recommandations pour les mesures, et le transfert
et l’analyse des données
 IEC 1998  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: [phone] e-mail: [e-mail] IEC web site http: //www.iec.ch
Commission Electrotechnique Internationale
PRICE CODE
Q
International Electrotechnical Commission
For price, see current catalogue

– 2 – 61724 © IEC:1998(E)
CONTENTS
Page
FOREWORD . 3
INTRODUCTION . 4
Clause
1 Scope. 5
2 Normative references. 5
3 Measured parameters. 5
4 Monitoring method. 7
4.1 Measurement of irradiance . 7
4.2 Measurement of ambient air temperature . 7
4.3 Measurement of wind speed . 7
4.4 Measurement of module temperature. 7
4.5 Measurement of voltage and current . 8
4.6 Measurement of electrical power. 8
4.7 Data acquisition system . 8
4.8 Sampling interval . 8
4.9 Data processing operation . 8
4.10 Recording interval, τ (expressed in hours). 8
r
4.11 Monitoring period. 9
5 Documentation. 9
6 Data format. 9
6.1 Separate header with multiple data records. 9
6.2 Single record format . 10
7 Check of data quality . 10
8 Derived parameters. 11
8.1 Global irradiation. 11
8.2 Electrical energy quantities . 12
8.3 BOS component performance . 13
8.4 System performance indices . 14
Annex A (informative) A suggested method of checking the data acquisition system . 16
Figure 1 – Parameters to be measured in real time . 7
Table 1 – Parameters to be measured in real time . 6
Table 2 – Derived parameters. 12

61724 © IEC:1998(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
PHOTOVOLTAIC SYSTEM PERFORMANCE MONITORING –
GUIDELINES FOR MEASUREMENT, DATA EXCHANGE AND ANALYSIS
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61724 has been prepared by IEC technical committee 82: Solar
photovoltaic energy systems.
The text of this standard is based on the following documents:
FDIS Report on voting
82/189/FDIS 82/201/RVD
Full information on the voting for approval can be found in the report on voting indicated in the
above table.
Annex A is for information only.
A bilingual version of this standard may be issued at a later date.

– 4 – 61724 © IEC:1998(E)
INTRODUCTION
This standard describes general guidelines for the monitoring and analysis of the electrical
performance of photovoltaic (PV) systems. It does not describe the performance of discrete
components, but concentrates on evaluating the performance of an array as part of a PV
system.
The intent of the data analysis is to provide a performance summary suitable for comparing PV
installations of different sizes, operating in different climates, and providing energy for different
uses, in such a way that the relative merits of different designs or operating procedures
become evident. Simpler methods might be more cost effective for small, solar home or
domestic stand-alone systems.
Guidelines are also included which describe a file format to be used for the exchange of
monitoring data between organizations.
The use of a microprocessor-based data acquisition system for monitoring is required.

61724 © IEC:1998(E) – 5 –
PHOTOVOLTAIC SYSTEM PERFORMANCE MONITORING –
GUIDELINES FOR MEASUREMENT, DATA EXCHANGE AND ANALYSIS
1 Scope
This International Standard recommends procedures for the monitoring of energy-related PV
system characteristics such as in-plane irradiance, array output, storage input and output and
power conditioner input and output; and for the exchange and analysis of monitored data. The
purpose of these procedures is to assess the overall performance of PV systems configured as
stand-alone or utility grid-connected, or as hybridised with non-PV power sources such as
engine generators and wind turbines.
This standard may not be applicable to small stand-alone systems due to the relatively high
cost of the measurement equipment.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this International Standard. At the time of publication, the editions
indicated were valid. All normative documents are subject to revision, and parties to
agreements based on this International Standard are encouraged to investigate the possibility
of applying the most recent editions of the normative documents indicated below. Members of
IEC and ISO maintain registers of currently valid International Standards.
IEC 60904-2:1989, Photovoltaic devices – Part 2: Requirements for reference solar cells
Amendment 1 (1998)
IEC 60904-6:1994, Photovoltaic devices – Part 6: Requirements for reference solar modules
Amendment 1 (1998)
IEC 61194:1992, Characteristic parameters of stand-alone photovoltaic (PV) systems
IEC 61829:1995, Crystalline silicon photovoltaic (PV) array – On-site measurement of
I-V characteristics
3 Measured parameters
Parameters to be measured are shown in table 1 and figure 1. Other parameters can be
calculated from the measured data in real time by the data acquisition system's software. Note
that all blocks in figure 1 can represent multiple components. The measured parameters and
array characteristics are defined in IEC 61194.
The parasitic power drawn by all ancillary systems shall be considered a power loss of the PV
plant and shall not be considered a load. All monitoring systems not essential for the operation
of the PV plant shall be considered part of the load. The monitoring equipment may present a
major part of the overall power consumption, and the end user should be made aware that
supplemental power may be required to satisfy the total load requirement.

– 6 – 61724 © IEC:1998(E)
Table 1 – Parameters to be measured in real time
Parameter Symbol Unit
Meteorology
1) –2
Total irradiance, in the plane of the array G W⋅m
I
Ambient air temperature in a radiation shield T °C
am
2) –1
Wind speed S m s
⋅
W
Photovoltaic array
Output voltage V V
A
Output current I A
A
Output power kW
P
A
Module temperature T °C
m
5)
Tracker tilt angle degrees
φ
T
5)
Tracker azimuth angle degrees
φ
A
3)
Energy storage
Operating voltage V V
S
4)
Current to storage I A
TS
4)
Current from storage A
I
FS
4)
Power to storage P kW
TS
4)
Power from storage P kW
FS
3)
Load
Load voltage V V
L
Load current I A
L
6)
Load power P kW
L
3)
Utility grid
Utility voltage V V
U
4)
Current to utility grid I A
TU
4)
Current from utility grid I A
FU
4), 6)
Power to utility grid P kW
TU
4), 6)
Power from utility grid P kW
FU
3)
Back-up sources
Output voltage V V
BU
Output current I A
BU
Output power P kW
BU
1)
Total irradiance, also known as the plane-of-array irradiance, defined as the radiant power, direct plus diffuse,
incident upon unit area of an inclined surface.
2)
Parameters such as wind speed are optional, but may be required by special contract or if the PV array is
subject to extreme operating conditions.
3)
AC and d.c. quantities may be distinguished by the addition of subscripts. In the case of multi-phase systems,
parameters V , I and P shall be specified for each phase.

L L L
4)
A single current or power sensor can normally be used for the measurement of current or power for directions
of both input and output. A positive sign in the sensor’s output signal represents input to the energy storage
device or utility grid and a negative sign represents output from the storage device or utility grid. Input and
output from a single sensor must be accumulated separately in software.
5)
Tracker angles are optional for systems with tracking arrays. For single axis trackers φ is used to describe the
T
position of the array about its tracking axis. For example, for a horizontal single axis tr
...

IEC 61724
Edition 1.0 1998-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Photovoltaic system performance monitoring – Guidelines for measurement,
data exchange and analysis
Surveillance des qualités de fonctionnement des systèmes photovoltaïques –
Recommandations pour la mesure, le transfert et l’analyse des données
Copyright © 1998 IEC, Geneva, Switzerland

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IEC 61724
Edition 1.0 1998-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Photovoltaic system performance monitoring – Guidelines for measurement,
data exchange and analysis
Surveillance des qualités de fonctionnement des systèmes photovoltaïques –
Recommandations pour la mesure, le transfert et l’analyse des données

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
R
CODE PRIX
ICS 27.180 ISBN 2-8318-4610-2
– 2 – 61724 © CEI:1998
SOMMAIRE
Pages
AVANT-PROPOS . 4
INTRODUCTION .6
Articles
1 Domaine d'application.8
2 Références normatives.8
3 Paramètres mesurés.8
4 Méthode de surveillance. 12
4.1 Mesurage de l'éclairement. 12
4.2 Mesure de la température de l'air ambiant . 12
4.3 Mesure de la vitesse du vent . 12
4.4 Mesure de la température du module . 14
4.5 Mesure de la tension et du courant. 14
4.6 Mesure de la puissance électrique. 14
4.7 Système d'acquisition de données. 14
4.8 Intervalle d'échantillonnage.14
4.9 Traitement des données. 16
4.10 Intervalle d'enregistrement, τ (exprimé en heures) . 16
r
4.11 Période de surveillance . 16
5 Documentation.16
6 Format des données . 16
6.1 En-tête séparé avec plusieurs enregistrements de données. 18
6.2 Format d'enregistrement unique . 20
7 Vérification des données . 20
8 Paramètres dérivés.20
8.1 Exposition énergétique globale. 22
8.2 Quantités d'énergie électrique . 26
8.3 Performance des composants hors champ photovoltaïque (BOS) . 26
8.4 Indices de performances du système. 28
Annexe A (informative) Méthode suggérée de contrôle du système d'acquisition
de données . 34
Figure 1 – Paramètres à mesurer en temps réel. 12
Tableau 1 – Paramètres à mesurer en temps réel . 10
Tableau 2 – Paramètres dérivés . 24

61724 © IEC:1998 – 3 –
CONTENTS
Page
FOREWORD . 5
INTRODUCTION . 7
Clause
1 Scope. 9
2 Normative references. 9
3 Measured parameters. 9
4 Monitoring method. 13
4.1 Measurement of irradiance . 13
4.2 Measurement of ambient air temperature . 13
4.3 Measurement of wind speed . 13
4.4 Measurement of module temperature. 15
4.5 Measurement of voltage and current . 15
4.6 Measurement of electrical power. 15
4.7 Data acquisition system . 15
4.8 Sampling interval . 15
4.9 Data processing operation . 17
4.10 Recording interval, τ (expressed in hours). 17
r
4.11 Monitoring period. 17
5 Documentation. 17
6 Data format. 17
6.1 Separate header with multiple data records. 19
6.2 Single record format . 21
7 Check of data quality . 21
8 Derived parameters. 21
8.1 Global irradiation. 23
8.2 Electrical energy quantities . 27
8.3 BOS component performance . 27
8.4 System performance indices . 29
Annex A (informative) A suggested method of checking the data acquisition system . 35
Figure 1 – Parameters to be measured in real time . 13
Table 1 – Parameters to be measured in real time . 11
Table 2 – Derived parameters. 25

– 4 – 61724 © CEI:1998
COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
___________
SURVEILLANCE DES QUALITÉS DE FONCTIONNEMENT
DES SYSTÈMES PHOTOVOLTAÏQUES –
RECOMMANDATIONS POUR LA MESURE, LE TRANSFERT
ET L'ANALYSE DES DONNÉES
AVANT-PROPOS
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...