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IEC 60904-7
Edition 4.0 2019-08
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Photovoltaic devices –
Part 7: Computation of the spectral mismatch correction for measurements of
photovoltaic devices
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IEC 60904-7
Edition 4.0 2019-08
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Photovoltaic devices –
Part 7: Computation of the spectral mismatch correction for measurements of
photovoltaic devices
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-7329-6
– 2 – IEC 60904-7:2019 RLV © IEC 2019
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
Apparatus . 7
4 Description of method . 7
5 Determination of spectral response responsivity . 7
6 Determination of test spectrum . 9
7 Determination of the spectral mismatch factor . 9
7.1 General . 10
7.2 Simplified formula for a thermopile detector (pyranometer) . 12
8 Report . 9
Bibliography .
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC DEVICES –
Part 7: Computation of the spectral mismatch correction
for measurements of photovoltaic devices
FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.
– 4 – IEC 60904-7:2019 RLV © IEC 2019
International Standard IEC 60904-7 has been prepared by IEC technical committee 82: Solar
photovoltaic energy systems.
This fourth edition cancels and replaces the third edition published in 2008. It constitutes a
technical revision.
The main technical changes with respect to the previous edition are as follows:
• For better compatibility and less redundancy, the clause “Determination of test spectrum”
refers to IEC 60904-9.
• The spectral mismatch factor is called SMM instead of MM to enable differentiation to the
angular mismatch factor AMM and spectral angular mismatch factor SAMM.
• Formulae for the derivation and application of the spectral mismatch factor SMM are
added.
• Links to new standards are given, e.g. concerning multi-junction devices.
• Corrected wording (responsivity instead of response and irradiance instead of intensity).
The text of this International Standard is based on the following documents:
FDIS Report on voting
82/1590/FDIS 82/1605/RVD
Full information on the voting for the approval of this International Standard 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 of 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
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
PHOTOVOLTAIC DEVICES –
Part 7: Computation of the spectral mismatch correction
for measurements of photovoltaic devices
1 Scope and object
This part of IEC 60904 describes the procedure for correcting the bias spectral mismatch
error introduced in the testing of a photovoltaic device, caused by the mismatch between the
test spectrum and the reference spectrum (e.g. AM1.5 spectrum) and by the mismatch
between the spectral responses responsivities (SR) of the reference cell device and of the
device under test specimen and therewith reduce the systematic uncertainty. The procedure
applies only to photovoltaic devices linear in SR as defined in IEC 60904-10. This procedure
is valid for single-junction devices but the principle may be extended to cover multi-junction
devices.
The purpose of this document is to give guidelines for the correction of measurement bias the
spectral mismatch error, should there be a spectral mismatch betweenthe test spectrum and
the reference spectrum as well as between the reference device SR and the device under test
specimen SR. The calculated spectral mismatch correction is only valid for the specific
combination of test and reference devices measured with a particular test spectrum.
Since a PV device has a wavelength-dependent response spectral responsivity, its
performance is significantly affected by the spectral distribution of the incident radiation,
which in natural sunlight varies with several factors such as location, weather, time of year,
time of day, orientation of the receiving surface, etc., and with a solar simulator varies with its
type and conditions. If the irradiance is measured with a thermopile-type radiometer (that is
not spectrally selective) or with a PV reference solar cell device (IEC 60904-2), the spectral
irradiance distribution of the incoming light must be known to make the necessary corrections
to obtain the performance of the PV device under the reference solar spectral irradiance
distribution defined in IEC 60904-3.
If a reference PV device or a thermopile type detector is used to measure the irradiance, then,
following the procedure given in this document, it is possible to calculate the spectral
mismatch correction necessary to obtain the short-circuit current of the test PV device under
test under the reference solar spectral irradiance distribution in IEC 60904-3 or any other
reference spectrum. If the reference PV device has the same relative spectral response
responsivity as the test PV device under test then the reference device automatically takes
into account deviations of the real light measured spectral irradiance distribution from the
standard reference spectral irradiance distribution, and no further correction of spectral bias
mismatch errors is necessary. In this case, location and weather conditions are not critical
when the reference device method is used for outdoor performance measurements provided
both reference cell and test PV device have the same relative spectral response under natural
sunlight. Also, for identical relative SRs, the spectral classification of the simulator is not
critical for indoor measurements with solar simulators.
If the performance of a PV device is measured using a known spectral irradiance distribution,
its short-circuit current at any other spectral irradiance distribution can be computed using the
spectral response responsivity of the PV test device under test.
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
– 6 – IEC 60904-7:2019 RLV © IEC 2019
cited applies. For undated references, the latest edition of the referenced document (including
any amendmen
...