IEC TR 60904-14:2020

IEC TR 60904-14 ®
Edition 1.0 2020-11
TECHNICAL
REPORT
colour
inside
Photovoltaic devices –
Part 14: Guidelines for production line measurements of single-junction PV
module maximum power output and reporting at standard test conditions
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IEC TR 60904-14 ®
Edition 1.0 2020-11
TECHNICAL
REPORT
colour
inside
Photovoltaic devices –
Part 14: Guidelines for production line measurements of single-junction PV

module maximum power output and reporting at standard test conditions

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-9082-8

– 2 – IEC TR 60904-14:2020 © IEC 2020
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Measurement principles . 7
4.1 Measurement of I-V curves . 7
4.2 Standard test conditions . 8
4.2.1 General . 8
4.2.2 Additional practical considerations . 9
4.2.3 Deviations from STC, errors, and uncertainties . 9
4.3 Solar simulators . 12
4.3.1 General . 12
4.3.2 Solar simulator requirements in relevant IEC documents . 13
4.3.3 Spectral distribution of irradiance . 13
4.3.4 Spatial non-uniformity of irradiance. 14
4.3.5 Temporal instability of irradiance . 15
4.3.6 Angular distribution of irradiance . 16
4.4 Reference modules . 16
4.4.1 General . 16
4.4.2 Irradiance monitoring . 17
4.4.3 Reference device requirements in relevant IEC documents . 17
4.4.4 Reference module characteristics . 18
4.5 Calibration and operation procedures of measurement equipment . 19
4.5.1 General . 19
4.5.2 Calibration and operation procedure requirements in relevant IEC
documents . 19
4.5.3 Calibration frequency . 20
4.5.4 Factors affecting calibration of measurement equipment . 20
5 Measurement systems analysis . 25
5.1 General . 25
5.2 Evaluation of measurement repeatability and reproducibility . 25
Bibliography . 28

Figure 1 – Application of IEC documents to report STC P values, adapted from
max
published work [1]. . 8
Figure 2 – Graphical summary of STC (cross-sectional view of module) . 9
Figure 3 – Example traceability chain for production PV modules, adapted from
published work [10] . 18
Dashed lines represent optional validation checks. . 22
Figure 4 – Flowchart describing solar simulator irradiance adjustment based on
reference module P ; adapted from published work [7] . 22
max
Figure 5 – Illustration of four-terminal electrical connection to a PV module . 24

Table 1 – Factors contributing to P uncertainty . 11
max
Table 2 – Summary of effects due to deviations from STC and factors of 4.2.2 . 12
Table 3 – Types of production module P errors that can be partially cancelled by
max
setting solar simulator irradiance using a matched reference module . 21
Table 4 – Small sampling analysis (n = 4, p = 4) over a single day, including variation
in module placement and module electrical connection [10] (solar simulator irradiance
was set for each trial using the reference module’s P ) . 26
max
– 4 – IEC TR 60904-14:2020 © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC DEVICES –
Part 14: Guidelines for production line measurements
of single-junction PV module maximum power output
and reporting at standard test conditions

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
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data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 60904-14, which is a Technical Report, has been prepared by IEC technical committee
82: Solar photovoltaic energy systems.
The text of this Technical Report is based on the following documents:
Draft TR Report on voting
82/1748/DTR 82/1785A/RVDTR
Full information on the voting for the approval of this Technical Report 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.
A list of all parts in the IEC 60904 series, published under the general title Photovoltaic devices,
can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
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of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC TR 60904-14:2020 © IEC 2020
PHOTOVOLTAIC DEVICES –
Part 14: Guidelines for production line measurements
of single-junction PV module maximum power output
and reporting at standard test conditions

1 Scope
This document provides guidelines for measurements of the maximum power (P ) output of
max
single-junction photovoltaic (PV) modules and for reporting at standard test conditions (STC) in
industrial production line settings. Such measurements typically:
• Record current-voltage (I-V) data while illuminating the module with a solar simulator;
• Are performed on 100 % of manufactured modules, in order to determine whether they meet
nameplate requirements for various b
...