IEC TS 60904-1-2:2019

IEC TS 60904-1-2 ®
Edition 1.0 2019-01
TECHNICAL
SPECIFICATION
colour
inside
Photovoltaic devices –
Part 1-2: Measurement of current-voltage characteristics of bifacial photovoltaic
(PV) devices
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IEC TS 60904-1-2 ®
Edition 1.0 2019-01
TECHNICAL
SPECIFICATION
colour
inside
Photovoltaic devices –
Part 1-2: Measurement of current-voltage characteristics of bifacial photovoltaic

(PV) devices
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-6409-6

– 2 – IEC TS 60904-1-2:2019 © IEC 2019
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
3.1 Bifacial PV device . 7
3.2 Bifaciality . 7
3.3 Rear irradiance driven power gain yield . 7
4 General considerations . 7
5 Apparatus . 8
5.1 General . 8
5.2 Solar simulator with adjustable irradiance levels for single-side illumination . 8
5.3 Solar simulator with adjustable irradiance levels for double-side illumination . 8
5.4 Natural sunlight . 8
5.5 Non-irradiated background and background compensation . 8
6 Additional I-V characterisations for bifacial devices . 9
6.1 General . 9
6.2 Determination of bifacialities . 10
6.3 Determination of the rear irradiance driven power gain yield . 11
6.3.1 General . 11
6.3.2 Outdoor rear irradiance driven power gain yield measurement . 12
6.3.3 Indoor rear irradiance driven power gain yield measurement with single-
side illumination . 13
6.3.4 Indoor rear irradiance driven power gain yield measurement with
double-side illumination . 14
7 I-V characterisation of bifacial PV devices in practice . 15
7.1 General . 15
7.2 I-V measurement of reference bifacial PV devices . 15
7.3 I-V measurement of bifacial PV devices using a reference bifacial device . 16
8 Report . 17
Figure 1 – Scheme of a bifacial PV module and the required non-irradiated
background and aperture . 9
Figure 2 – Front- and rear-side characterization for bifaciality . 10
Figure 3 – Outdoor measurement . 12
Figure 4 – Examples of P as a function of irradiance level on the rear side G (for
max r
outdoor or double-side illumination) or its 1-side equivalent irradiance G for a device
f
of bifaciality ϕ = 80 % . 14
Figure 5 – Transmittances of the device (T ) and its encapsulant (T ) . 15
DUT ENC
Figure 6 – Example of Pmax,BiFi100 and Pmax,BiFi200 derived from the measurement of Pmax
at STC conditions, P and the BiFi coefficient of the reference used in formulae
max,STC
(8) and (9) . 17

Table 1 – Maximum peak power, P , measured at different rear irradiances, G ,
max r
(double-side with Gf = 1 000) or alternatively equivalent front irradiances, GE, and the
rear irradiance driven power gain yield, BiFi, derived from the slope of the linear fit on
Pmax(G ). Also calculated values Pmax,BiFi100 and Pmax,BiFi200. . 14
r
Table 2 – Example of P and P derived from the measurement at STC
max,BiFi100 max,BiFi200
conditions (Gr = 0 and Gf = 1 000) and the rear irradiance driven power gain obtained
from the bifacial reference device, BiFi,ref. . 17

– 4 – IEC TS 60904-1-2:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC DEVICES –
Part 1-2: Measurement of current-voltage characteristics of
bifacial photovoltaic (PV) devices

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. In
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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 Specification are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC TS 60904-1-2, which is a Technical Specification, has been prepared by IEC technical
committee 82: Solar photovoltaic energy systems.

The text of this Technical Specification is based on the following documents:
Draft TS Report on voting
82/1403/DTS 82/1508/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.
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.
A bilingual version of this publication may be issued at a later date.

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
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– 6 – IEC TS 60904-1-2:2019 © IEC 2019
PHOTOVOLTAIC DEVICES –
Part 1-2: Measurement of current-voltage characteristics of
bifacial photovoltaic (PV) devices

1 Scope
This part of IEC 60904 describes procedures for the measurement of the current-voltage (I-V)
characteristics of bifacial photovoltaic devices in natural or simulated sunlight. It is applicable
to single PV cells, sub-assemblies of such cells or entire PV modules.
The requirements for measurement of I-V characteristics of standard (monofacial) PV devices
are c
...