Photovoltaic systems - Power conversion equipment performance - Energy evaluation method

IEC TS 63156:2021 describes the procedure for evaluating the energy conversion performance of stand-alone or grid-connected power conversion equipment (PCE) used in PV systems. This procedure includes the calculation of inverter performance to anticipate the energy yield of PV systems. This evaluation method is based on standard power efficiency calculation procedures for PCE found in IEC 61683 and IEC 62891, but provides additional methods for evaluating the expected overall energy efficiency for a particular location given solar load profiles. This document can be used as the energy evaluation method for PCE in IEC TS 61724-3, which defines a procedure for evaluating a PV system’s actual energy production relative to its modeled or expected performance.

General Information

Status
Published
Publication Date
03-Feb-2021
Current Stage
PPUB - Publication issued
Completion Date
04-Feb-2021
Ref Project

Buy Standard

Technical specification
IEC TS 63156:2021 - Photovoltaic systems - Power conversion equipment performance - Energy evaluation method
English language
23 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (sample)

IEC TS 63156
Edition 1.0 2021-02
TECHNICAL
SPECIFICATION
Photovoltaic systems – Power conversion equipment performance – Energy
evaluation method
IEC TS 63156:2021-02(en)
---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2021 IEC, Geneva, Switzerland

All rights reserved. Unless otherwise specified, 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

either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC

copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or

your local IEC member National Committee for further information.
IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC

The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes

International Standards for all electrical, electronic and related technologies.
About IEC publications

The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the

latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC online collection - oc.iec.ch

The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the

variety of criteria (reference number, text, technical publications previews. With a subscription you will always

committee, …). It also gives information on projects, replaced have access to up to date content tailored to your needs.

and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 000 terminological entries in English
details all new publications released. Available online and
and French, with equivalent terms in 18 additional languages.
once a month by email.
Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
---------------------- Page: 2 ----------------------
IEC TS 63156
Edition 1.0 2021-02
TECHNICAL
SPECIFICATION
Photovoltaic systems – Power conversion equipment performance – Energy
evaluation method
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-9303-4

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

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TS 63156:2021 © IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 3

INTRODUCTION ..................................................................................................................... 5

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

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

3 Terms and definitions ...................................................................................................... 6

4 Workflow of energy conversion efficiency evaluation method ......................................... 10

4.1 General ................................................................................................................. 10

4.2 Flow of energy conversion efficiency evaluation test ............................................. 11

4.3 Flow of energy conversion efficiency calculation ................................................... 12

5 Energy efficiency measurement conditions .................................................................... 13

5.1 Energy efficiency test circuit ................................................................................. 13

5.2 Test conditions ..................................................................................................... 14

6 Static energy conversion efficiency evaluation ............................................................... 14

7 Dynamic energy conversion efficiency evaluation .......................................................... 14

8 Weighted energy conversion efficiency calculation ........................................................ 14

Annex A (informative) Rate of change of irradiance ............................................................. 15

A.1 Analysis of irradiance profile .......................................................................................... 15

A.2 Rate of change of irradiance .......................................................................................... 18

Annex B (informative) Static energy conversion efficiency test sequence ............................. 19

Annex C (informative) Dynamic energy conversion efficiency test sequence ........................ 20

Annex D (informative) Weighted energy conversion efficiency ............................................. 22

Bibliography .......................................................................................................................... 23

Figure 1 – Flowchart of energy conversion efficiency evaluation test .................................... 11

Figure 2 – Flowchart of energy conversion efficiency calculation .......................................... 12

Figure 3 – Power conversion equipment test circuits ............................................................. 13

Figure A.1 – Example of irradiance profile ............................................................................ 17

−2 −1

Figure A.2 – Histogram of the irradiance in Figure A.1 (< 2 W•m •s ) ............................... 17

−2 −1

Figure A.3 – Histogram of rate of change of irradiance (>2 W•m •s ) ............................... 18

Figure C.1 – Test sequence for fluctuations between medium and high irradiation

intensities ............................................................................................................................. 20

Table 1 – Weighted energy conversion efficiency .................................................................. 14

Table A.1 – Weighted factor ratios for F ................................................................... 18

n=1 to 7

Table A.2 – Weighted factor ratios for J , J , etc. ................................................................. 18

1 2

Table B.1 – Static energy efficiency ...................................................................................... 19

Table C.1 – Dynamic energy efficiency test with input power from 30 % to 100 % ................. 21

Table C.2 – Dynamic energy efficiency data ......................................................................... 21

Table D.1 – Static energy conversion efficiency .................................................................... 22

Table D.2 – Dynamic energy conversion efficiency ............................................................... 22

Table D.3 – Weighted total conversion efficiency .................................................................. 22

---------------------- Page: 4 ----------------------
IEC TS 63156:2021 © IEC 2021 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC SYSTEMS –
POWER CONVERSION EQUIPMENT PERFORMANCE –
ENERGY EVALUATION METHOD
FOREWORD

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

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

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

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

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

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

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

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

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

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

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

interested IEC National Committees.

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

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

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

misinterpretation by any end user.

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

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

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

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

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

services carried out by independent certification bodies.

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

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

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

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

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

Publications.

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

indispensable for the correct application of this publication.

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

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

The main task of IEC technical committees is to prepare International Standards. In exceptional

circumstances, a technical committee may propose the publication of a Technical Specification

when

• the required support cannot be obtained for the publication of an International Standard,

despite repeated efforts, or

• the subject is still under technical development or where, for any other reason, there is the

future but no immediate possibility of an agreement on an International Standard.

Technical Specifications are subject to review within three years of publication to decide

whether they can be transformed into International Standards.

IEC TS 63156, which is a Technical Specification, has been prepared by IEC technical

committee 82: Solar photovoltaic energy systems.
---------------------- Page: 5 ----------------------
– 4 – IEC TS 63156:2021 © IEC 2021
The text of this Technical Specification is based on the following documents:
Draft TS Report on voting
82/1755/DTS 82/1801A/RVDTS

Full information on the voting for the approval of this Technical Specification can be found in

the report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

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

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

specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
---------------------- Page: 6 ----------------------
IEC TS 63156:2021 © IEC 2021 – 5 –
INTRODUCTION

The performance of a photovoltaic power generation system is influenced by various factors,

such as meteorological conditions, installation environment (e.g. shade sources, soiling),

design, and so on. The performance of a power conversion equipment is one of the significant

indices for evaluating the performance of a PV system. IEC 61683 and IEC 62891 describe

procedures for measuring the static (constant) conversion efficiency of power conversion

equipment and MPPT efficiency, respectively. However, the standards do not define conversion

efficiency under dynamic changes in factors such as meteorological changes, installation

environment changes or temporal changes.

The CEC efficiency test protocol and EN 50530 define dynamic performance tests and

procedures partially, but do not define a calculation procedure for evaluating the quantity of

energy produced by a PV system. IEC TS 61724-3 describes a procedure for measuring and

analysing the energy production of a specific photovoltaic system relative to the production

expected for the same system from actual weather conditions for a certain period, but does not

define the procedure for measuring the performance of power conversion equipment under

actual environments.

Since there are areas where meteorological conditions, especially irradiance, change greatly

and could affect the performance of power conversion equipment, a performance evaluation

method under dynamic conditions needs to be defined. This document describes the procedure

for evaluating the dynamic performance and energy production efficiency of power conversion

equipment in a particular location using site-specific solar profiles.
---------------------- Page: 7 ----------------------
– 6 – IEC TS 63156:2021 © IEC 2021
PHOTOVOLTAIC SYSTEMS –
POWER CONVERSION EQUIPMENT PERFORMANCE –
ENERGY EVALUATION METHOD
1 Scope

This document describes the procedure for evaluating the energy conversion performance of

stand-alone or grid-connected power conversion equipment (PCE) used in PV systems. This

procedure includes the calculation of inverter performance to anticipate the energy yield of PV

systems. This evaluation method is based on standard power efficiency calculation procedures

for PCE found in IEC 61683 and IEC 62891, but provides additional methods for evaluating the

expected overall energy efficiency for a particular location given solar load profiles. This

document can be used as the energy evaluation method for PCE in IEC TS 61724-3, which

defines a procedure for evaluating a PV system’s actual energy production relative to its

modeled or expected performance.
2 Normative references

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

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

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

amendments) applies.

IEC 61683, Photovoltaic systems – Power conditioners – Procedure for measuring efficiency

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

IEC 62891, Maximum power point tracking efficiency of grid connected photovoltaic inverters

3 Terms and definitions

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

the following apply.

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

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
irradiance
electromagnetic radiated power per unit area
−2.
Note 1 to entry: Unit: W•m
3.2
in-plane irradiance
total irradiance on the plane of a PV cell or module
−2..
Note 1 to entry: Unit: W•m
---------------------- Page: 8 ----------------------
IEC TS 63156:2021 © IEC 2021 – 7 –
3.3
rate of change of irradiance
change in irradiance amount during 1 s
−2 −1.
Note 1 to entry: Unit: W•m •s
3.4
rated input voltage
DC,r

rated input voltage specified by the manufacturer, to which other data sheet information refers

Note 1 to entry: Unit: V.
3.5
rated input power
DC,r

rated input power of the power conversion equipment, which can be converted under continuous

operating conditions
Note 1 to entry: Unit: W.
3.6
rated output voltage
AC,r
utility grid voltage to which other data sheet information refers
Note 1 to entry: Unit: V.
3.7
rated output power
AC,r

active power that the power conversion equipment can output during continuous operation

Note 1 to entry: Unit: W.
3.8
PV simulator MPP-Power
MPP,PVS
MPP power provided by the PV simulator
Note 1 to entry: Unit: W.
3.9
input power
measured input power of the device under test
Note 1 to entry: Unit: W.
3.10
PV simulator MPP voltage
MPP,PVS
MPP voltage provided by the PV simulator
Note 1 to entry: Unit: V.
---------------------- Page: 9 ----------------------
– 8 – IEC TS 63156:2021 © IEC 2021
3.11
input voltage
measured input voltage of the device under test
Note 1 to entry: Unit: V.
3.12
PV simulator MPP current
MPP,PVS
MPP current provided by the PV simulator
Note 1 to entry: Unit: A.
3.13
input current
measured input current of the device under test
Note 1 to entry: Unit: A.
3.14
output power
measured AC output power of the device under test
Note 1 to entry: Unit: W.
3.15
output voltage
measured AC voltage of the device under test
Note 1 to entry: Unit: V.
3.16
output current
measured AC output current of the device under test
Note 1 to entry: Unit: A.
3.17
MPPT efficiency
MPPT

ratio of the energy drawn by the device under test within a defined measuring period T to the

energy provided theoretically by the PV simulator at the maximum power point (MPP):

P ( t )dt
η = (1)
MPPT
P ( t )dt
MPP
where
η is MPPT efficiency;
MPPT
---------------------- Page: 10 ----------------------
IEC TS 63156:2021 © IEC 2021 – 9 –

P (t) is the instantaneous value of the power drawn by the device under test, in kW;

P (t) is the instantaneous value of the MPP power provided theoretically by the PV

MPP
simulator, in kW.
Note 1 to entry: Unit: dimension
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.