IEC 61683:1999

Photovoltaic systems - Power conditioners - Procedure for measuring efficiency

IEC 61683:1999 Describes guidelines for measuring the efficiency of power conditioners used in stand-alone and utility-interactive photovoltaic systems, where the output of the power conditioner is a stable a.c. voltage of constant frequency or a stable d.c. voltage.

Systèmes photovoltaïques - Conditionneurs d’énergie électrique - Procédure de mesure du rendement

IEC 61683:1999 décrit les lignes directrices pour mesurer le rendement des conditionneurs d'énergie électrique utilisés dans les systèmes photovoltaïques autonomes et interactifs avec le réseau, avec lesquels la sortie du conditionneur d'énergie électrique est une tension alternative stable de fréquence constante ou une tension continue stable.

General Information

• Status: Published
• Publication Date: 24-Nov-1999
• ICS: 27.160 - Solar energy engineering
• Technical Committee: TC 82 - Solar photovoltaic energy systems
• Drafting Committee: WG 3 - TC 82/WG 3
• Current Stage: PPUB - Publication issued
• Start Date: 25-Nov-1999
• Completion Date: 15-Dec-1999

Overview

IEC 61683:1999 - "Photovoltaic systems - Power conditioners - Procedure for measuring efficiency" is an IEC standard that defines a standardized, factory-level procedure to measure the electrical efficiency of power conditioners (inverters/DC–DC converters) used in both stand‑alone and utility‑interactive photovoltaic (PV) systems. The standard focuses on direct measurement of input and output power for devices that produce a stable a.c. voltage at constant frequency or a stable d.c. voltage. An isolation transformer is included where applicable. The standard explicitly excludes indirect items such as maximum power‑point tracking (MPPT) accuracy.

Key topics and requirements

• Scope and definitions: Defines terms such as rated output efficiency, partial output efficiency, energy efficiency, no‑load loss and standby loss.
• Test conditions:
  • Ambient temperature: 25 °C ± 2 °C (must be recorded).
  • Output voltage and frequency at manufacturer’s nominal values.
  • Input voltages: tests at manufacturer’s minimum rated input, nominal/average input, and 90% of maximum input (battery‑input units may be tested at nominal only).
  • Record input/output ripple and distortion (THD) for every measurement.
• Load matrix: Efficiency measured across a matrix of power levels (5%, 10%, 25%, 50%, 75%, 100%, 120% of rated VA as applicable) and load types:
  • Resistive (unity PF)
  • Reactive loads at PF = 0.25 (or minimum), 0.5, 0.75
  • Non‑linear loads (specified THD ≈ 80% ± 5%) at 25% and 50% of rated VA
  • Complex combinations (non‑linear + reactive)
• Measurements and calculations:
  • Direct input/output power measurements and standard formulas for rated and partial output efficiency; auxiliary input power must be included.
  • Energy efficiency and efficiency tolerances; guidance for no‑load and standby loss measurement.
• Test circuits and documentation: Specifies required test circuits, measurement procedures, and reporting formats (tabular/graphical). Informative annexes cover power conditioner descriptions, conversion factors and weighted‑average energy efficiency.

Applications and users

IEC 61683 is intended for:

• PV inverter and power conditioner manufacturers - to verify and publish efficiency claims.
• Test laboratories and certification bodies - for consistent, repeatable efficiency testing and accreditation.
• PV system designers and specifiers / procurement teams - to compare device efficiencies for system sizing, yield estimates and economic modeling.
• Research and development teams - for benchmarking conversion performance under defined loads and input conditions.

Keywords: IEC 61683, photovoltaic, power conditioners, inverter efficiency, efficiency measurement, PV systems, energy efficiency testing, MPPT, no‑load loss, standby loss.

Related standards

• IEC 60146‑1‑1:1991 (semiconductor converters - basic requirements) - normative reference.
• IEC 60050, IEC 60027, IEC 60417, IEC 60617 - referenced for terminology and symbols.

Standards Content (Sample)

INTERNATIONAL
IEC
STANDARD
First edition
1999-11
Photovoltaic systems –
Power conditioners –
Procedure for measuring efficiency
Systèmes photovoltaïques –
Conditionneurs de puissance –
Procédure de mesure du rendement
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
1999-11
Photovoltaic systems –
Power conditioners –
Procedure for measuring efficiency
Systèmes photovoltaïques –
Conditionneurs de puissance –
Procédure de mesure du rendement
 IEC 1999  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
R
International Electrotechnical Commission
For price, see current catalogue

– 2 – 61683 © IEC:1999(E)
CONTENTS
Page
FOREWORD . 3
INTRODUCTION .4
Clause
1 Scope . 5
2 Normative reference . 5
3 Definitions. 5
4 Efficiency measurement conditions . 6
4.1 DC power source for testing. 6
4.2 Temperature . 6
4.3 Output voltage and frequency . 6
4.4 Input voltage. 7
4.5 Ripple and distortion. 7
4.6 Resistive loads/utility grid . 7
4.7 Reactive loads . 7
4.8 Resistive plus non-linear loads . 8
4.9 Complex loads . 8
5 Efficiency calculations. 8
5.1 Rated output efficiency . 8
5.2 Partial output efficiency. 8
5.3 Energy efficiency . 9
5.4 Efficiency tolerances. 9
6 Efficiency test circuits . 9
6.1 Test circuits . 9
6.2 Measurement procedure . 10
7 Loss measurement. 10
7.1 No-load loss . 10
7.2 Standby loss . 11
Annex A (informative) Power conditioner description . 12
Annex B (informative) Power efficiency and conversion factor . 14
Annex C (informative) Weighted-average energy efficiency . 16
Annex D (informative) Derivation of efficiency tolerance in table 2. 19
Bibliography . 20

61683 © IEC:1999(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC SYSTEMS – POWER CONDITIONERS –
PROCEDURE FOR MEASURING EFFICIENCY
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 specifications, 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 61683 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
82/229/FDIS 82/233/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
Annexes A, B, C and D are for information only.
A bilingual version of this standard may be issued at a later date.
The committee has decided that this publication remains valid until 2003. At this date, in
accordance with the committee’s decision, the publication will be
reconfirmed;
withdrawn;
replaced by a revised edition, or
amended.
– 4 – 61683 © IEC:1999(E)
INTRODUCTION
Among the principal characteristics of power conditioners, efficiency is considered as an
important factor. A standardized procedure for measuring the efficiency of power conditioners
is necessary for their widespread use in photovoltaic systems by increasing the reliability of
their claimed efficiency.
Generally speaking, power conditioner efficiency is affected by the following parameters:
– power level;
– input voltage;
– output voltage;
– power factor;
– harmonic content;
– load non-linearity;
– temperature.
These parameters are considered to be included in the test condition of this standard
explicitly or implicitly.
The purpose of this standard is to provide the means to evaluate the intrinsic efficiency of
power conditioners by a direct measurement of input and output power in the factory.
Therefore, indirect items such as maximum power-point tracking accuracy are outside the
scope of this document. It is expected that those will be dealt with in future relevant IEC
standard(s).
61683 © IEC:1999(E) – 5 –
PHOTOVOLTAIC SYSTEMS – POWER CONDITIONERS –
PROCEDURE FOR MEASURING EFFICIENCY
1 Scope
This standard describes guidelines for measuring the efficiency of power conditioners used in
stand-alone and utility-interactive photovoltaic systems, where the output of the power conditioner
is a stable a.c. voltage of constant frequency or a stable d.c. voltage. The efficiency is
calculated from a direct measurement of input and output power in the factory. An isolation
transformer is included where it is applicable.
2 Normative reference
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this International Standard. For dated references, subsequent
amendments to, or revisions of, any of these publications do not apply. However, 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. For undated
references, the latest edition of the normative document referred to applies. Members of IEC
and ISO maintain registers of currently valid International Standards.
IEC 60146-1-1:1991, Semiconductor convertors – General requirements and line commutated
convertors – Part 1-1: Specifications of basic requirements
3 Definitions
For the purposes of this standard, the following definitions apply. All efficiency definitions are
applied to electric power conversion alone and do not consider any heat production. The
above normative references contain other definitions.
In annex A, the definition of power conditioner is given. Power efficiency and conversion
factor are explained in annex B.
3.1
rated output efficiency
ratio of output power to input power when the power conditioner is operating at its rated
output
3.2
partial output efficiency
ratio of output power to input power when the power conditioner is operating below its rated
output
3.3
energy efficiency
ratio of output energy to input energy during an identified period

– 6 – 61683 © IEC:1999(E)
3.4
efficiency tolerance
permissible tolerance between the manufacturer's specified efficiency and the measured
efficiency
3.5
PV array simulator
simulator which has I-V characteristics equivalent to a PV array
3.6
no-load loss
input power of the power conditioner when its load is disconnected or its output power is zero
3.7
standby loss
for a utility interactive power conditioner, power drawn from the utility grid when the power
conditioner is in standby mode. For a stand-alone power conditioner, d.c. input power when
the power conditioner is in standby mode
3.8
maximum power point tracking (MPPT)
control strategy whereby the power conditioner input voltage is always at or near the
maximum power point of the PV array
4 Efficiency measurement conditions
Efficiency shall be measured under the matrix of conditions as described in the following
clauses and table 1. Specific conditions may be excluded by mutual agreement when those
conditions are outside the manufacturer's allowable operating range. The resulting data shall
be presented in tabular form and may also be presented graphically.
NOTE For example, stand-alone power conditioners are typically designed to handle short-term overload signifi-
cantly above the rated power. The test at 120 % of rated capacity is included to give an indication of the
performance of the power conditioner under these conditions. Some power conditioners are not designed to
provide more than their rated output and might be damaged if operated at 120 % of rated capacity. In such cases,
test documentation shall note that the test was excluded due to limitation in the power conditioner.
4.1 DC power source for testing
For power conditioners operating with fixed input voltage, the d.c. power source shall be a
storage battery or constant voltage power source to maintain the input voltage.
For power conditioners that employ maximum power point tracking (MPPT) and shunt-type
power conditioners, either a photovoltaic array or a photovoltaic array simulator shall be
utilized.
4.2 Temperature
All measurements are to be made at an ambient temperature of 25 °C ± 2 °C. Other ambient
temperatures may be allowed by mutual agreement. However, the temperature used must be
clearly stated in all documentation.
4.3 Output voltage and frequency
The output voltage and frequency shall be maintained at the manufacturer's stated nominal
values.
61683 © IEC:1999(E) – 7 –
Table 1 – Efficiency recording sheet
Input voltage: _________(±_____ V)
Total load, % of rated VA 5 10 25 50 75 100 120
Grid-connected Resistive load – ()* () () () () ()
Stand-alone Resistive load () () () () () () ()
Reactive load
PF = 0,25 or minimum – – () () – () –
PF = 0,50 (> minimum) – – () () – () –
PF = 0,75 (> minimum) – – () () – () –
Non-linear load
NL = 25 % of rated VA – – () () – () –
NL = 50 % of rated VA – – – () – () –
Complex load ––– () – () –
* The symbol () denotes a condition to be tested.
4.4 Input voltage
Measurements performed in each of the following tests shall be repeated at three power
conditioner input voltages:
a) manufacturer's minimum rated input voltage;
b) the inverter's nominal voltage or the average of its rated input range;
c) 90 % of the inverter's maximum input voltage.
In the case where a power conditioner is to be connected with a battery at its input terminals,
only the nominal or rated input voltage may be applied.
4.5 Ripple and distortion
Record input voltage and current ripple for each measurement. Also record output voltage and
current distortion (if a.c.) or ripple (if d.c.). Ensure that these measurements remain within the
manufacturer's specified values. Note that ripple and distortion may not be specified at low
power levels, but readings shall be recorded.
4.6 Resistive loads/utility grid
At unity power factor, or at the intrinsic power factor of grid-connected inverters without power
factor adjustment, measure the efficiency for power levels of 10 %, 25 %, 50 %, 75 %, 100 %
and 120 % of the inverter's rating. Stand-alone inverters shall also be measured at a power
level of 5 % of rated. The power conditioner test should be conducted with a specified
resistive and reactive grid impedance.
4.7 Reactive loads
For stand-alone inverters, measure the efficiency with a load which provides a power factor
equal to the manufacturer's specified minimum level (or 0,25, whichever is greater) and at
power levels of 25 %, 50 % and 100 % of rated VA. Repeat for power factors of 0,5 and 0,75
(do not go below the manufacturer's specified minimum PF) and power levels of 25 %, 50 %,
and 100 % of rated VA.
– 8 – 61683 © IEC:1999(E)
4.8 Resistive plus non-linear loads
For stand-alone inverters, measure the efficiency with a fixed non-linear load (total harmonic
distortion (THD) = (80 ± 5) %) equal to (25 ± 5) % of the inverter's rated VA plus sufficient
resistive load in parallel to achieve a total load of 25 %, 50 % and 100 % of rated VA. Repeat
the measurements with a fixed non-linear load equivalent to (50 ± 5) % of the inverter’s
rated VA plus sufficient resistive load in parallel to achieve a total load of 50 % and 100 %
of rated VA. The type of non-linear load must be clearly stated in all documentation.
4.9 Complex loads
When a non-linear plus a sufficient reactive load condition is specified for stand-alone inverters,
measure the efficiency with a fixed non-linear load (THD = (80 ± 5) %) equal to (50 ± 5) % of
the inverter's rated VA plus a sufficient reactive load (PF = 0,5) in parallel to achieve a total
load of
...

IEC 61683 ®
Edition 1.0 1999-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Photovoltaic systems – Power conditioners – Procedure for measuring
efficiency
Systèmes photovoltaïques – Conditionneurs d’énergie électrique –
Procédure de mesure du rendement

Copyright © 1999 IEC, Geneva, Switzerland

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IEC 61683 ®
Edition 1.0 1999-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Photovoltaic systems – Power conditioners – Procedure for measuring

efficiency
Systèmes photovoltaïques – Conditionneurs d’énergie électrique –

Procédure de mesure du rendement

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.160 ISBN 978-2-8322-1092-2

– 2 – IEC 61683:1999 © IEC 1999
CONTENTS
FOREWORD . 3
INTRODUCTION . 4
1 Scope . 5
2 Normative reference . 5
3 Definitions . 5
4 Efficiency measurement conditions . 6
4.1 DC power source for testing . 6
4.2 Temperature . 6
4.3 Output voltage and frequency . 6
4.4 Input voltage . 7
4.5 Ripple and distortion . 7
4.6 Resistive loads/utility grid . 7
4.7 Reactive loads. 7
4.8 Resistive plus non-linear loads . 8
4.9 Complex loads . 8
5 Efficiency calculations . 8
5.1 Rated output efficiency . 8
5.2 Partial output efficiency . 8
5.3 Energy efficiency . 9
5.4 Efficiency tolerances . 9
6 Efficiency test circuits . 9
6.1 Test circuits . 9
6.2 Measurement procedure . 10
7 Loss measurement . 10
7.1 No-load loss . 10
7.2 Standby loss . 11

Annex A (informative) Power conditioner description. 12
Annex B (informative) Power efficiency and conversion factor. 14
Annex C (informative) Weighted-average energy efficiency . 16
Annex D (informative) Derivation of efficiency tolerance in table 2 . 19
Bibliography . 20

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC SYSTEMS – POWER CONDITIONERS –
PROCEDURE FOR MEASURING EFFICIENCY

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 specifications, 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 61683 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
82/229/FDIS 82/233/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
Annexes A, B, C and D are for information only.
A bilingual version of this standard may be issued at a later date.
The committee has decided that this publication remains valid until 2003. At this date, in
accordance with the committee’s decision, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
– 4 – IEC 61683:1999 © IEC 1999
INTRODUCTION
Among the principal characteristics of power conditioners, efficiency is considered as an
important factor. A standardized procedure for measuring the efficiency of power conditioners
is necessary for their widespread use in photovoltaic systems by increasing the reliability of
their claimed efficiency.
Generally speaking, power conditioner efficiency is affected by the following parameters:
– power level;
– input voltage;
– output voltage;
– power factor;
– harmonic content;
– load non-linearity;
– temperature.
These parameters are considered to be included in the test condition of this standard
explicitly or implicitly.
The purpose of this standard is to provide the means to evaluate the intrinsic efficiency of
power conditioners by a direct measurement of input and output power in the factory.
Therefore, indirect items such as maximum power-point tracking accuracy are outside the
scope of this document. It is expected that those will be dealt with in future relevant IEC
standard(s).
PHOTOVOLTAIC SYSTEMS – POWER CONDITIONERS –
PROCEDURE FOR MEASURING EFFICIENCY

1 Scope
This standard describes guidelines for measuring the efficiency of power conditioners used in
stand-alone and utility-interactive photovoltaic systems, where the output of the power conditioner
is a stable a.c. voltage of constant frequency or a stable d.c. voltage. The efficiency is
calculated from a direct measurement of input and output power in the factory. An isolation
transformer is included where it is applicable.
2 Normative reference
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this International Standard. For dated references, subsequent
amendments to, or revisions of, any of these publications do not apply. However, 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. For undated
references, the latest edition of the normative document referred to applies. Members of IEC
and ISO maintain registers of currently valid International Standards.
IEC 60146-1-1:1991, Semiconductor convertors – General requirements and line commutated
convertors – Part 1-1: Specifications of basic requirements
3 Definitions
For the purposes of this standard, the following definitions apply. All efficiency definitions are
applied to electric power conversion alone and do not consider any heat production. The
above normative references contain other definitions.
In annex A, the definition of power conditioner is given. Power efficiency and conversion
factor are explained in annex B.
3.1
rated output efficiency
ratio of output power to input power when the power conditioner is operating at its rated
output
3.2
partial output efficiency
ratio of output power to input power when the power conditioner is operating below its rated
output
3.3
energy efficiency
ratio of output energy to input energy during an identified period

– 6 – IEC 61683:1999 © IEC 1999
3.4
efficiency tolerance
permissible tolerance between the manufacturer's specified efficiency and the measured
efficiency
3.5
PV array simulator
simulator which has I-V characteristics equivalent to a PV array
3.6
no-load loss
input power of the power conditioner when its load is disconnected or its output power is zero
3.7
standby loss
for a utility interactive power conditioner, power drawn from the utility grid when the power
conditioner is in standby mode. For a stand-alone power conditioner, d.c. input power when
the power conditioner is in standby mode
3.8
maximum power point tracking (MPPT)
control strategy whereby the power conditioner input voltage is always at or near the
maximum power point of the PV array
4 Efficiency measurement conditions
Efficiency shall be measured under the matrix of conditions as described in the following
clauses and table 1. Specific conditions may be excluded by mutual agreement when those
conditions are outside the manufacturer's allowable operating range. The resulting data shall
be presented in tabular form and may also be presented graphically.
NOTE For example, stand-alone power conditioners are typically designed to handle short-term overload signifi-
cantly above the rated power. The test at 120 % of rated capacity is included to give an indication of the
performance of the power conditioner under these conditions. Some power conditioners are not designed to
provide more than their rated output and might be damaged if operated at 120 % of rated capacity. In such cases,
test documentation shall note that the test was excluded due to limitation in the power conditioner.
4.1 DC power source for testing
For power conditioners operating with fixed input voltage, the d.c. power source shall be a
storage battery or constant voltage power source to maintain the input voltage.
For power conditioners that employ maximum power point tracking (MPPT) and shunt-type
power conditioners, either a photovoltaic array or a photovoltaic array simulator shall be
utilized.
4.2 Temperature
All measurements are to be made at an ambient temperature of 25 °C ± 2 °C. Other ambient
temperatures may be allowed by mutual agreement. However, the temperature used must be
clearly stated in all documentation.
4.3 Output voltage and frequency
The output voltage and frequency shall be maintained at the manufacturer's stated nominal
values.
Table 1 – Efficiency recording sheet
Input voltage: _________(±_____ V)
Total load, % of rated VA 5 10 25 50 75 100 120
Grid-connected Resistive load – () * () () () () ()
Stand-alone Resistive load () () () () () () ()
Reactive load
PF = 0,25 or minimum – – () () – () –
PF = 0,50 (> minimum) – – () () – () –
PF = 0,75 (> minimum) – – () () – () –
Non-linear load
NL = 25 % of rated VA – – () () – () –
NL = 50 % of rated VA – – – () – () –
Complex load – – – () – () –
* The symbol () denotes a condition to be tested.
4.4 Input voltage
Measurements performed in each of the following tests shall be repeated at three power
conditioner input voltages:
a) manufacturer's minimum rated input voltage;
b) the inverter's nominal voltage or the average of its rated input range;
c) 90 % of the inverter's maximum input voltage.
In the case where a power conditioner is to be connected with a battery at its input terminals,
only the nominal or rated input voltage may be applied.
4.5 Ripple and distortion
Record input voltage and current ripple for each measurement. Also record output voltage and
current distortion (if a.c.) or ripple (if d.c.). Ensure that these measurements remain within the
manufacturer's specified values. Note that ripple and distortion may not be specified at low
power levels, but readings shall be recorded.
4.6 Resistive loads/utility grid
At unity power factor, or at the intrinsic power factor of grid-connected inverters without power
factor adjustment, measure the efficiency for power levels of 10 %, 25 %, 50 %, 75 %, 100 %
and 120 % of the inverter's rating. Stand-alone inverters shall also be measured at a power
level of 5 % of rated. The power conditioner test should be conducted with a specified
resistive and reactive grid impedance.
4.7 Reactive loads
For stand-alone inverters, measure the efficiency with a load which provides a power factor
equal to the manufacturer's specified minimum level (or 0,25, whichever is greater) and at
power levels of 25 %, 50 % and 100 % of rated VA. Repeat for power factors of 0,5 and 0,75
(do not go below the manufacturer's specified minimum PF) and power levels of 25 %, 50 %,
and 100 % of rated VA.
– 8 – IEC 61683:1999 © IEC 1999
4.8 Resistive plus non-linear loads
For stand-alone inverters, measure the efficiency with a fixed non-linear load (total harmonic
distortion (THD) = (80 ± 5) %) equal to (25 ± 5) % of the inverter's rated VA plus sufficient
resistive load in parallel to achieve a total load of 25 %, 50 % and 100 % of rated VA. Repeat
the measurements with a fixed non-linear load equivalent to (50 ± 5) % of the inverter’s
rated VA plus sufficient resistive load in parallel to achieve a total load of 50 % and 100 %
of rated VA. The type of non-linear load must be clearly stated in all documentation.
4.9 Complex loads
When a non-linear plus a sufficient reactive load condition is specified for stand-alone inverters,
measure the efficiency with a fixed non-linear load (THD = (80 ± 5) %) equal to (50 ± 5) % of
the inverter's rated VA plus a sufficient reactive load (PF = 0,5) in parallel to achieve a total
load of 50 % and 100 % of rated VA. The type of complex load shall be clearly stated in all
documentation.
5 Efficiency calculations
5.1 Rated output efficiency
Rated output efficiency shall be calculated from measured data as follows:
(1)
η = (P / P )×100
R o i
where
η is the rated output efficiency (%);
R
P is the rated output power from power conditioner (kW);
o
P is the input power to power conditioner at rated output (kW).

i
NOTE Any auxiliary input power (kW), such as for the inverter's control system (or gate driver) shall be included
in P in equation (1).
i
5.2 Partial output efficiency
Partial output efficiency shall be calculated from measured data as follows:
η = (P / P )×100 (2)
par op ip
where
η is the partial output efficiency (%);
par
is the partial output power from power conditioner (kW);
P
op
P is the input power to power conditioner at partial output (kW).
ip
NOTE Any auxiliary input power (kW) such as for the inverter's control system (or gate driver) shall be included
into P in equation (2).
i
5.3 Energy efficiency
Energy efficiency shall be calculated from measured data as follows:
η = (W /W )×100 (3)
E o i
where
η is the energy efficiency (%);
E
W is the output energy during a specified operating period (kWh);
o
W is the input energy during a specified operating period (kWh).
i
NOTE 1 The operating period and the load profile shall be determined by mutual agreement between user and
manufacturer.
NOTE 2 Some auxiliary input energy (kWh) such as for the inverter's control system (or gate driver) shall be
included in W in equation (3).
i
NOTE 3 See annex C for an explanation of weighted-average energy efficiency η which can supplant the energy
wt
efficiency.
5.4 Efficiency tolerances
When an efficiency value has been guaranteed, the tolerance of this value shall be within the
value at rated conditions indicated in table 2.
Table 2 – Efficiency tolerances
Item Tolerance Remarks
Efficiency of power conditioner −0,2(1−η)η(%) η : guaranteed efficiency
NOTE The efficiency tolerance is derived in annex D. See 4.3 of IEC 60146-1-1. The tolerance corresponds
to +0,2 per unit of the losses with a minimum efficiency tolerance of –0,002 per unit.
6 Efficiency test circuits
6.1 Test circuits
Figure 1 shows recommended test circuits for power conditioners which have a single-phase
a.c. output or d.c. output. It can as well be regarded as a single-phase representation of a test
set-up for multiphase power conditioners.
Figures 1a and 1b shall be applied to stand-alone and utility-interactive power conditioners
respectively.
The proposed test circuits in figure 1 are not mandatory, but together with the test descrip-
tions, are intended to establish a base for mutual agreement between user and manufacturer.
The type of power source shall be indicated on all tests and shall adhere to the requirements
of 4.1.
– 10 – IEC 61683:1999 © IEC 1999
6.2 Measurement procedure
a) Efficiency is calculated with equation (1) or (2) using measured P , P or P , P . DC input
i o ip op
power P , P can be measured by wattmeter W , or determined by multiplying the d.c.
i ip 1
voltmeter V and d.c. ammeter A readings. Output power P , P is measured with
1 1 o op
wattmeter W .
b) DC input voltage, which is measured by d.c. voltmeter V , shall be varied in the defined
range where the output current, which is measured with a.c. ammeter A , is varied from
low output to the rated output.
c) An average indicating instrument shall be used for the d.c. voltmeter and d.c. ammeter. A
true r.m.s. type of indicating instrument shall be used for the a.c. voltmeter and a.c.
ammeter. The d.c. wattmeter W shall be a d.c. measuring type. The wattmeter W shall
1 2
be an a.c. or d.c. measuring type according to the output.
d) Power factor (PF in per cent) can be measured by a power factor meter PF, or calculated
from the readings of V , A , W and as follows:
2 2 2
PF= (W /(V × A ))× 100 (4)
2 2 2
e) Each meter may be an analogue type or a digital type. The measurement accuracy shall
be better than ±0,5 % of the full-scale value for each power measured. Digital power
instruments for W and W are also recommended.
1 2
f) An MPPT dynamically adjusts the input voltage so as to maximize the output power. In
principle, the monitoring equipment shall sample all of the electrical parameters, such as
input voltage and current, output power and current, within the update period of the MPPT.
If the MPPT and input source (PV array or PV array simulator) interact in such a way that
the input voltage varies by less than 5 %, then averaging of readings is acceptable. The
averaging period shall be 30 s or longer.
7 Loss measurement
7.1 No-load loss
No-load loss shall be measured as follows.
If the power conditioner is a stand-alone type, the reading of d.c. input voltage, output voltage
and frequency is given with meters V , V and F respectively in figure 1a, and shall be
1 2
adjusted to the rated values.
The no-load loss is thus the indicated value of d.c. input wattmeter, W , when the load is
disconnected from the power conditioner.
If the power conditioner is a utility-interactive type, the reading of d.c. input voltmeter V , a.c.
output voltmeter V and frequency meter F in figure 1b shall be adjusted to meet the specified
voltages and frequency.
No-load loss is thus the indicated value of d.c. input wattmeter, W , when a.c. wattmeter, W ,
1 2
indicates a zero value. For the measurement, allow the power conditioner time to transfer to
its no-load operating state, if applicable.

7.2 Standby loss
Standby loss shall be measured as follows.
If the power conditioner is a utility-interactive type, standby loss is defined as the consumption of
utility power when the power conditioner is not operating but is under standby condition.
Standby loss is indicated with a.c. wattmeter, W in figure 1b at the rated a.c. output voltage.
If the power conditioner is a stand-alone type, standby loss is defined as the consumption from
the d.c. source when the power conditioner is not operating but is under standby condition.
Standby loss is indicated with d.c. wattmeter, W in figure 1a (without a.c. or d.c. output voltage).
A W W A
+ PF*
1 1 2 2
PC
L
PS V V F*
under
1 2
test
−
IEC  1566/99
Figure 1a – Stand-alone type
Utility
grid
A W W A
+ PF
1 1 2 2
PC
PS V V
under F
1 2
test
−
IEC  1567/99
Figure 1b – Utility-interactive type
PC power conditioner L load
PS variable voltage-current d.c. power supply F frequency meter
A DC ammeter V DC voltmeter
1 1
A AC or d.c. ammeter V AC or d.c. voltmeter
2 2
W DC wattmeter PF power factor meter
W AC or d.c. wattmeter
NOTE 1 The d.c. input voltage or current ripple will vary according to the d.c. power supply's internal impedance,
and should be defined by mutual agreement between user and manufacturer. For example, the impedance might be
selected as the current-voltage ratio ∆V/∆I at the operating point on the PV array I-V curve. When the power
conditioner includes the MPPT, a PV array simulator is recommended as the d.c. power source.
NOTE 2 Frequency meter F* and power factor meter PF* are ignored in the case of d.c. output.
Figure 1 – Power conditioner test circuits

– 12 – IEC 61683:1999 © IEC 1999
Annex A
(informative)
Power conditioner description
A power conditioner is defined in IEC 61277.
Some types of photovoltaic system configurations relate to their purpose and size. Figure A.1
shows the generic system configuration proposed in IEC 61277. In figure A.1, the power
conditioner (PC) is inside the dotted line. The power conditioner may consist of one or more
of the following: d.c. conditioner, d.c./d.c. interface, inverter, a.c./a.c. interface, a.c. utility
interface, and a part of master control and monitoring (MCM) subsystem. The power flows are
indicated by the arrows. When a PV system has a d.c. storage subsystem, it is assumed that
the storage is connected to the input of the power conditioner in parallel with the array (see
figures A.2 and A.3).
Under normal conditions, the power conditioner a.c. output voltage and frequency are
constant value when the system is connected to the utility grid (in a utility-interactive type) or
to the a.c. loads (in a stand-alone type). However, when a.c. loads consist of pumps or
blowers with variable speed induction motors, the a.c. voltage and frequency may be variable.
In this standard, systems with a constant a.c. output voltage and frequency as well as
systems with a d.c. output are discussed. Figures A.2 and A.3 show the configuration of the
PV system and the power conditioner described in this standard.
(PC)
Power conditioner
Master control and monitoring (MCM)
DC
Inverter
PV array
conditioner
DC/DC AC/AC AC utility
interface
interface interface
DC storage
device
Auxiliary DC Auxiliary AC AC
d.c. supply load a.c. supply load
utility
IEC  1568/99
Figure A.1 – Major subsystems and power flow diagram for a PV system

(PC)
Power conditioner
Master control and monitoring (MCM)
Inverter
PV array
AC/AC AC Utility
interface interface
DC storage
device
AC AC
load utility
IEC  1569/99
Figure A.2 – Power conditioner configuration with a.c. output assumed for
the efficiency measurement
(PC)
Power conditioner
Master control and monitoring (MCM)
DC
PV array
conditioner
DC/DC
interface
DC storage
device
DC
load IEC  1570/99
Figure A.3 – Power conditioner configuration with d.c. output assumed for
the efficiency measurement
– 14 – IEC 61683:1999 © IEC 1999
Annex B
(informative)
Power efficiency and conversion factor

There are two types of efficiencies shown in IEC 60146-2; one is a power efficiency, the other
is a conversion factor. Power efficiency is defined as the ratio of active output power and
active input power. Conversion factor is the ratio between output and input fundamental
power levels. The formulae for these two parameters:

η = (P /P )×100 (%)
P aAC aDC
η = (P / P )×100 (%)
C fAC fDC
where
η is the power efficiency;
P
P is the a.c. active power;
aAC
P is the d.c. active power;
aDC
η is the conversion factor;
C
P is the a.c. fundamental power;
fAC
P is the d.c. mean power (mean voltage mean current).
×
fDC
Active power P is calculated as
a
T T
1 1
P = v(t)i(t)dt or = p(t)dt
a
∫ ∫
T 0 T 0
where
v(t) is the time-varying voltage;
p(t) is the time-varying power;
i(t) is the time-varying current;
T is the duration of one cycle.
The difference between the above two efficiencies is due to the evaluation of the harmonic
components. IEC 60146 unifies them into power efficiency. Their differences depend on their
voltage and current waveforms as shown in table B.1 and are only meaningful in case 5.
Considering the purpose of IEC standards and the illustration in table B.1, the power
efficiency is used as the efficiency of power conditioners.
As shown in table B.1, case 1 or case 4, the difference between η and η is only 0,1% when
C P
the d.c. voltage and current ripple are 10 % or when a.c. 5th r.m.s. voltage content is 2 %
pp,
and the 5th current content is 5 %. This means that the conversion factor is practically the
same as the power efficiency. It shall, however, be noted that in the case of a square wave,
as in case 5, the power efficiency shall be used because the difference is large, i.e.,
η /η = 0,81.
C P
The integration time (duration of one cycle) T shall be 30 s or more and the resultant mean
power efficiency value shall be used as the efficiency of the power conditioner.

Table B.1 – Variation of power efficiency η and conversion factor η by difference of voltage or current waveforms
P C
Example DC input (case 1) DC input (case 2) AC output (case 3) AC output (case 4) AC output (case 5)

Voltage
waveform
V V
Current
waveform
I
I
Condition Voltage has no ripple Voltage and current Voltage: sinusoidal Harmonic component: Voltage and current
components have same ripple Current: square wave Voltage: 5th, 2 % r.m.s. are both a 50 % duty
(10 % ) with reversed (50 % duty cycle) Current: 5th, 5 % r.m.s. cycle square wave
pp
in-phase
phase
1,0 1,0 1,0 1/(1+ 0,02×0,05)= 0,999
P / P
(4 /π ) / 0,5= 0,81
fAC aAC
P / P
fDC aDC 1,0 1/[1− (0,1/ 2 2) ]= 1,001 1,0 1,0 1,0
η /η 1,0 0,999 1,0 0,999 0,81
C P
η = η η ≤ η η = η η ≤ η η < η
Comparison C P C P C P C P C P
NOTE η = P /P , η = P /P , η /η = (P /P )/(P /P ).
C fAC fDC P aAC aDC C P fAC aAc fDC aDC

– 16 – IEC 61683:1999 © IEC 1999
Annex C
(informative)
Weighted-average energy efficiency

The energy of a power conditioner depends on both the irradiance profile and the load profile.
The energy efficiency of a power conditioner shall be calculated by the ratio of the output to
the input energy actually measured over a certain period (such as a month or a year).
For reference, a method of estimating the energy efficiency using a weighted-average energy
efficiency is described.
The weighted-average energy efficiency, η is calculated as the sum of the products of
,
WT
each power level efficiency and related weighting coefficient.
When the system is a utility-interactive type without a storage subsystem, the weighting
coefficients depend on a regional irradiance duration curve.
When the system is a stand-alone type with a storage subsystem, the weighting coefficients
depend on the load duration curve.
Clauses C.1 and C.2 show the calculation procedures for η for utility-interactive systems
WT
and stand-alone systems.
C.1 η of power conditioner for utility-interactive PV systems
WT
Utility-interactive PV systems, which have no storage and for which reverse-power flow is
accepted, are described. In this case, d.c. power generated by the PV array is supplied direct
into the power conditioner (PC). Almost all of the input power to the PC is converted to a.c.
power. A part of it is dissipated as the PC loss.
The weighted-average energy efficiency, η , is an index to evaluate annual energy
WT
efficiency in which a weighting coefficient, K , is used for each input power level. Here, the
i
irradiance is divided into several discrete levels. By using a duration time T , d.c. input power
i
level, P output power level, P and PC efficiency, η , for each level i, η is defined as
Ii, Oi,
i WT
follows:
P ⋅ T
Oi i P ⋅η ⋅ T++P ⋅η ⋅ T
∑
I1 1 1 In n n
η = =
WT
(C.1)
P ⋅ T++P ⋅ T
P ⋅ T
I1 1 In n
Ii i
∑
= K ⋅η + K ⋅η ++K ⋅η
1 1 2 2 n n
where
K = P ⋅T P ⋅T
i Ii i Ii i
∑
and
K = 1 and i= 1, 2, 3.
i
∑
If the irradiance duration curve is given as shown in figure C.1, equation (C.1) can be
rewritten as follows:
1T 2T 3T 4T
1 2 3 4
η = η + η + η + η ≥η (C.2)
WT 1 4 2 4 3 4 4 4 ER
T T T T
WT WT WT WT
T = 1T + 2T + 3T + 4T
WT 1 2 3 4
where η is the specified energy efficiency;
ER
η , is the power conditioner efficiency when its d.c. input power is 1/4,. of the
1 4
rated value respectively.
4/4
3/4
2/4
1/4
T T T T
4 3 2 1
Duration IEC  1571/99
Figure C.1 – An example of an irradiance duration curve
C.2 η of power conditioner for stand-alone PV systems
WT
In stand-alone PV systems with a storage subsystem, power generated from the PV array is
stored and stabilized by the batteries. DC power is converted into regulated d.c. power or
constant-voltage and constant-frequency a.c. power by a power conditioner (PC) and supplied
to the load. In this case, some fraction of the generated power is dissipated as a loss in the
batteries and power conditioner.
The calculation of the weighted-average energy efficiency, η , for stand-alone PV systems
WT
requires weighting coefficients for respective load levels.
By using a load duration time T , d.c. input power P , a.c. output power P and PC efficiency
i Ii Oi
for respective load level η , η is defined as follows:
i WT
P ⋅ T P ⋅ T ++ P ⋅ T
Oi i O1 1 On n
∑ ∑
ηη = =
WWTT
P ⋅ T + P ⋅ T /η + P ⋅ T /η
P ⋅ T
I 0 0 O1 1 1 On n n
Ii i
∑
(C.3)
=
K + K /η ++ K /η
0 1 1 n n
Irradiance level
– 18 – IEC 61683:1999 © IEC 1999
K = P ⋅ T / (P ⋅ T ) (C.4)
0 l0 0 Oi i
∑
K = P ⋅ T / (P ⋅ T ), K = 1
i Oi i∑ Oi i ∑ i
where
P is the no-load loss.
l0
If the load profile and its duration curve are given as shown in figures C.2 and C.3,
equation (C.3) can be rewritten as follows:
η = ≥η (C.5)
WT ER
K +1T /T /η + 2T /T /η + 3T /T /η + 4T /T /η
0 1 WT 1 4 2 WT 2 4 3 WT 3 4 4 WT 4 4
where
η is the specified energy efficiency;
ER
η , is the power conditioner efficiency when the load is 1/4,. of the rated value
1 4
respectively.
4/4
3/4
2/4
1/4
0 6 12 18 24
Time
IEC  1572/99
Figure C.2 – An example of a load profile
4/4
3/4
2/4
1/4
T T T T T
4 3 2 1 0
Duration
IEC  1573/99
Figure C.3 – An example of a load duration curve

Load level
Load level
Annex D
(informative)
Derivation of efficiency tolerance in table 2

The guaranteed efficiency, η, is
P
R
η=
P + P
R L
where
P is the rated output power;
R
P is the guaranteed loss.
L
From IEC 60146-1-1, 4.3.3, loss, P the allowance shall be +0,2 per unit. In this case, the
L,
efficiency, η′, is given by:
P
R
′
η =
P +1,2P
R L
Therefore, the tolerance η′−η is derived as:
P P
R R
′
η−η= −η= −η= −η
P + 1,2P P + 1,2(1η−1)P 1+ 1,2 (1η−1)
R L R R
η 1 1
= −η=η [ −1]=η [ −1]
η+ 1,2(1−η) η+ 1,2(1−η) − 0,2η+ 1,2
− 0,2+ 0,2η −1+η
=η =η
− 0,2η+1,2 −η+ 6
≥−η (1−η)/ 5 (η≤ 1).
Finally, the tolerance is given by the following equation:
′
η −η=−0,2 (1−η)η (%)
This means that tolerance decreases as guaranteed efficiency increases. For instance, for
the guaranteed efficiencies of 90 % and 95 %, the tolerances are –1,8 % and –0,95 %
respectively.
– 20 – IEC 61683:1999 © IEC 1999
Bibliography
IEC 60146 (all parts), Semiconductor convertors
IEC 60146-2:1974, Semiconductor convertors – Part 2: Semiconductor self-commutated convertors
IEC 61277:1995, Terrestrial photovoltaic (PV) power generating systems – General and guide

____________
– 22 – IEC 61683:1999 © IEC 1999
SOMMAIRE
AVANT-PROPOS . 23
INTRODUCTION . 25
1 Domaine d'application . 26
2 Références normatives . 26
3 Définitions . 26
4 Conditions de mesure du rendement . 27
4.1 Source d’énergie en courant continu pour essai . 27
4.2 Température . 28
4.3 Tension et fréquence de sortie . 28
4.4 Tension d’entrée . 28
4.5 Ondulation et distorsion . 28
4.6 Charges résistives/réseau électrique . 29
4.7 Charges réactives . 29
4.8 Charges résistives et charges non linéaires. 29
4.9 Charges complexes . 29
5 Calculs du rendement . 29
5.1 Rendement de sortie assigné . 29
5.2 Rendement de sortie partiel. 30
5.3 Rendement énergétique . 30
5.4 Tolérances de rendement . 30
6 Circuits d’essai de rendement . 31
6.1 Circuits d’essai . 31
6.2 Procédure de mesure . 31
7 Mesurage des pertes . 32
7.1 Pertes à vide . 32
7.2 Pertes en mode veille . 32

Annexe A (informative) Description du conditionneur d’énergie électrique . 34
Annexe B (informative) Rendement et facteur de conversion . 37
Annexe C (informative) Rendement énergétique moyen pondéré .
...