IEC TS 62607-7-2:2023
(Main)Nanomanufacturing - Key control characteristics - Part 7-2: Nano-enabled photovoltaics - Device evaluation method for indoor light
Nanomanufacturing - Key control characteristics - Part 7-2: Nano-enabled photovoltaics - Device evaluation method for indoor light
IEC TS 62607-7-2:2023 specifies the efficiency testing of photovoltaic cells (excluding multi-junction cells) under indoor light. Although it is primarily intended for nano-enabled photovoltaic cells (organic thin-film, dye-sensitized solar cells (DSC), and Perovskite solar cells), it can also be applied to other types of photovoltaic cells, such as Si, CIGS, GaAs cells, and so on.
General Information
Standards Content (Sample)
IEC TS 62607-7-2 ®
Edition 1.0 2023-07
TECHNICAL
SPECIFICATION
Nanomanufacturing – Key control characteristics –
Part 7-2: Nano-enabled photovoltaics – Device evaluation method for indoor
light
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IEC TS 62607-7-2 ®
Edition 1.0 2023-07
TECHNICAL
SPECIFICATION
Nanomanufacturing – Key control characteristics –
Part 7-2: Nano-enabled photovoltaics – Device evaluation method for indoor
light
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 07.120; 07.030; 27.160 ISBN 978-2-8322-7255-8
– 2 – IEC TS 62607-7-2:2023 © IEC 2023
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Abbreviated terms . 9
5 Methods for measuring current-voltage characterization . 10
5.1 General . 10
5.2 Requirements . 10
5.2.1 Device under test (DUT) . 10
5.2.2 Illumination adjustment . 10
5.2.3 Measurement procedure . 11
5.3 Important additional information . 13
6 Indoor reference photovoltaic cells . 14
6.1 Requirements . 14
6.1.1 Selecting indoor reference photovoltaic cells . 14
6.1.2 Calibrating indoor reference photovoltaic cells . 14
6.2 Important notes . 15
7 Standard indoor light – Requirements . 16
7.1 Standard indoor illuminance . 16
7.2 Standard indoor light . 16
7.3 Spectral irradiance of standard indoor light . 16
8 Traceability . 19
8.1 Description – General . 19
8.2 Calibration chain example . 19
9 Temperature correction . 20
9.1 Requirements . 20
9.2 Temperature of the DUT . 20
10 Spectral-mismatch correction . 20
10.1 Requirements . 20
10.1.1 Indoor reference photovoltaic-cell method . 20
10.1.2 Recording results. 21
10.2 Important additional information . 21
11 Spectral responsivity . 21
11.1 Requirements . 21
11.1.1 Spectral responsivity, S(λ) . 21
11.1.2 Measurement methods . 21
11.2 Important notes . 21
12 Illumination sources . 22
12.1 Requirements . 22
12.1.1 Indoor spectral coincidence . 22
12.1.2 Illuminance non-uniformity . 22
12.1.3 Temporal stability . 23
12.1.4 Light source classification . 23
12.1.5 Indoor standard relative spectral responsivity . 23
12.2 Illuminance non-uniformity . 35
13 Nonlinearity . 35
13.1 Requirements . 35
13.2 Important notes . 35
Annex A (informative) Explanations of the provisions, descriptions, and other content
in the standard main body of this document. . 36
A.1 Purpose of this document . 36
A.2 Target of this document . 36
A.3 Issues discussed during deliberation . 36
A.3.1 Adjusting light intensity with an illuminometer . 36
A.3.2 Indoor spectral coincidence . 36
A.3.3 Stability of a DUT (5.2.2) . 37
A.3.4 Maximum power (P ). 37
max
A.4 Supplemental remarks on requirements . 38
A.4.1 Requirements for the DUTs (5.2.1) . 38
A.4.2 Standard indoor light (Clause 7) . 38
A.4.3 Methods for adjusting illuminance (5.2.2) . 39
A.4.4 Quasi-reference photovoltaic cell . 42
A.4.5 Standard indoor light (7.1, 7.2) . 42
A.4.6 Spectral responsivity (11.1.2) . 42
A.4.7 Illumination source and indoor spectral coincidence (12.1.1) . 43
A.4.8 Illumination sources and non-uniformity of brightness (12.1.2) . 44
A.4.9 Temporal stability (12.1.3) . 44
A.4.10 Classification of illumination sources (12.1.5) . 44
A.4.11 Nonlinearity (13.1) . 45
A.5 Correspondence between this document and the IEC 60904 series . 45
Bibliography . 47
Figure 1 – Spectral irradiance of standard indoor light at 1 000 lx . 19
Figure 2 – Calibration chain example . 20
Figure 3 – Standard relative spectral responsivity . 34
Figure A.1 – Configurations of illuminance adjusting methods described in a) A.4.3.2,
b) A.4.3.3 and c) A.4.3.4 . 39
Figure A.2 – PRISM or spectroradiometer method . 40
Figure A.3 – Measurement laboratories. 41
Figure A.4 – Temporal fluctuation of illuminance of a fluorescent lamp . 44
Table 1 – Standard indoor illuminance . 12
Table 2 – Result record . 13
Table 3 – Calibration record . 15
Table 4 – Spectral irradiance (mW/m /nm) of standard indoor light at 1 000 lx . 16
Table 5 – Light source classification . 23
Table 6 – Indoor standard relative spectral responsivity (%) . 24
Table A.1 – Spectral coincidence of F to reference spectrum CIE FL10 . 42
Table A.2 – Spectral coincidence of L to reference spectrum CIE LED-B4 . 42
Table A.3 – Correspondence between clauses of this document and IEC 60904 . 46
Table A.4 – New concepts in this document derived from IEC 60904 . 46
– 4 – IEC TS 62607-7-2:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
NANOMANUFACTURING –
KEY CONTROL CHARACTERISTICS –
Part 7-2: Nano-enabled photovoltaics –
Device evaluation method for indoor light
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
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indispensable for the correct application of this publication.
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC TS 62607-7-2 has been prepared by IEC technical committee 113: Nanotechnology for
electrotechnical products and systems. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
113/710/DTS 113/737/RVDTS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts of the IEC TS 62607 series, published under the general title
Nanomanufacturing – Key control characteristics, 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 webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• transformed into an International Standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – IEC TS 62607-7-2:2023 © IEC 2023
INTRODUCTION
Commercialization of nano-enabled solar cells, such as organic solar cells, is being promoted
by utilizing their advantages over conventional solar cells, such as light weight, flexibility, colour,
transparency, and coating processability. Energy harvesting applications that generate power
using indoor light have been recognized as important applications for nano solar cells in
conjunction with recent advances in the Internet of Things. In general, nano solar cells have a
large band gap and are suitable for power generation under indoor lighting whose spectra are
localized in the visible light region. In addition, since the low illuminance characteristics can be
improved by devising the configuration, it is expected to be suitable for energy harvesting using
indoor light.
The IEC 60904 series specifies evaluation methods for sunlight. In IEC 60904, the most
important factors in evaluating a solar cell are the selection of a light source and the method of
adjusting its irradiance for measurement. By changing the light source from sunlight to indoor
light, an evaluation method under indoor light can be obtained. The clause structure of this
document corresponds to that of IEC 60904. While light sources are limited to sunlight in the
outdoor environment, various light sources are used indoors, such as fluorescent lamps and
LED lamps in addition to sunlight. The indoor brightness is expressed by illuminance in lux (lx),
which takes into account the sensitivity of the human eye. Strictly speaking, since the spectral
characteristics of the eyes are different from those of solar cells, there is not always a
correlation between the illuminance and the power generation of solar cells. For example, a
crystalline Si solar cell could generate power using only near-infrared light which is invisible to
human eyes, i.e. zero lux. However, high-efficiency lighting other than incandescent lamps has
a spectrum concentrated in the visible light region, thus expressing the efficiency of an indoor
solar cell based on the spectrum of sunlight is not appropriate.
In this document, such uncertainties due to the use of illuminance instead or irradiance are
eliminated by setting a reference spectrum for indoor light sources. The reference indoor light
spectra are representatives of the spectrum of light sources used for indoor lighting, are defined
only between 380 nm and 780 nm, and have no component outside of this wavelength range.
Therefore, this document provides a method to evaluate solar cells with illuminance. Since the
illuminance is obtained by the overlap integral of the spectral irradiance of the light source and
the luminosity, there could be an infinite number of spectral irradiances that give the same
illuminance. A large error could arise due to light in the wavelength region with low luminosity.
In an extreme case, invisible light has a finite output even at zero illuminance. In this document,
however, the output by zero lux illuminance is supposed to be zero, that is, the output is not
guaranteed.
The target of this document is to define the output of a solar cell in a bright (finite illuminance)
indoor environment. The output with light other than the reference spectrum is out of this target.
If it is necessary to include such cases, they will be treated as individual cases. In that case,
one would extend the reference spectrum and build an evaluation technique that uses irradiance
instead of illuminance. Special illumination conditions can be used by using a user-defined
reference spectrum. In this case, however, illuminance can be meaningless if the illumination
contains a significant amount of invisible light.
Illumination includes not only the light that the eyes of humans are sensitive to, but also the
infrared energy contained in incandescent lighting and sunlight that enters from outdoors. But
because incandescent lighting is used less and less due to its poor energy efficiency, this
document defines measurement methods with two standard indoor light sources specified by
CIE: FL10 and LED-B4, corresponding to the fluorescent lamp and the white LED lamp,
respectively, the correlated colour temperatures (CCT) of which are approximately 5 000 K.
Other light sources such as sunlight or incandescent lamps are not appropriate because they
contain much invisible infrared light and illuminance is not a good measure for performance
evaluation of photovoltaic devices, because they contain a significant amount of invisible light.
This document, along with FL10 and LED-B4, establishes methods for evaluating photovoltaic
cells under indoor conditions. This document assumes that an arbitrary photovoltaic cell will be
measured under indoor lighting. For requirements not listed in this document, refer to the
relevant normative references.
NANOMANUFACTURING –
KEY CONTROL CHARACTERISTICS –
Part 7-2: Nano-enabled photovoltaics –
Device evaluation method for indoor light
1 Scope
This Technical Specification specifies the efficiency testing of photovoltaic cells (excluding
multi-junction cells) under indoor light. Although it is primarily intended for nano-enabled
photovoltaic cells (organic thin-film, dye-sensitized solar cells (DSC), and Perovskite solar
cells), it can also be applied to other types of photovoltaic cells, such as Si, CIGS, GaAs cells,
and so on.
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.
JIS C 1609-1, Illuminance meters – Part 1: General measuring instruments
DIN 5032-7, Photometry – Part 7: Classification of illuminance meters and luminance meters
ISO/CIE 19476, Characterization of the performance of illuminance meters and luminance
meters
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
response time
time required for current to respond after a change is made to the applied voltage
t
Note 1 to entry: Response time is represented by τ in the formula for expressing
It() I(0)+∆I 1− exp−
τ
change in current over time.
3.2
indoor primary reference photovoltaic cell
photovoltaic cell calibrated from a radiometer, standard detector, or standard indoor light that
is traceable to SI units
=
– 8 – IEC TS 62607-7-2:2023 © IEC 2023
3.3
indoor standard relative spectral responsivity
measure to define indoor spectral coincidence without relying on the device under test itself
3.4
indoor reference photovoltaic cell
photovoltaic cell used to adjust the intensity of the indoor light source
3.5
indoor spectral coincidence
measure of spectral matching between standard indoor light and the illumination source used
for a measurement
Note 1 to entry: It is expressed as a ratio of short-circuit currents calculated from the spectral responsivity of the
photovoltaic cell.
3.6
indoor secondary reference photovoltaic cell
photovoltaic cell calibrated from the indoor primary reference photovoltaic cell
3.7
indoor working reference photovoltaic cell
photovoltaic cell calibrated from the indoor secondary reference photovoltaic cell
3.8
standard indoor light
light source with a defined spectral distribution that is used when evaluating photovoltaic cells
under indoor light
Note 1 to entry: It covers a variety of indoor light sources, and two types of standard indoor light are adopted in this
document.
3.9
standard indoor illuminance
illuminance values used when evaluating photovoltaic cells under indoor light
Note 1 to entry: The standard indoor illuminance values are 50 lx, 200 lx and 1 000 lx.
3.10
fluorescent lamp
light source that operates by electrically exciting mercury vapour and then converting the
luminescence generated into visible light using a phosphor
3.11
dye-sensitized solar cell
photovoltaic cell created by coating metal-oxide particles (such as titanium oxide or zinc oxide)
with a molecular dye then immersing them in an ionically conductive electrolyte
3.12
illuminance
intensity of a light that illuminates a surface, as perceived by the human eye
Note 1 to entry: Illuminance is expressed in units of lux (lx).
3.13
correlated colour temperature
temperature of the black-body radiator whose CIE (u, v), or (u′, 2/3 v′), colour coordinate is
closest to that of a light source
Note 1 to entry: See Ohno, Y., "Practical Use and Calculation of CCT and Duv", Leukos, 10:1, 47-55. (2013).
3.14
measurement delay time
interval of time between the changing of the applied voltage and the start of the current
measurement when measuring an I-V curve by varying an externally applied voltage
3.15
white LED lamp
light source that produces white light by using a fluorescent substance to convert the
wavelength of light generated by violet or ultraviolet LEDs
3.16
luminosity function
numerical representation of the relative sensitivity of the human eye to the different wavelengths
of visible light
3.17
perovskite solar cell
photovoltaic cell containing a semiconductor with a perovskite structure composed of
monovalent cations, divalent metal ions, and halogen ions
3.18
organic photovoltaic cell
photovoltaic cell containing an organic semiconductor or dye in the layers where light absorption
and charge separation take place
3.19
maximum power point tracking
technique for finding the operating point (I-V or load characteristic) at which a device generates
the maximum amount of electric energy under given photo-irradiation conditions
Note 1 to entry: It is typically used for adjusting a photovoltaic cell's optimal operating point under changing
conditions such as weather and solar altitude angle, but it can also be utilized to determine the conversion efficiency
of a cell when assessing its I-V curve is not feasible.
3.20
programmable reference cell system for irradiance adjustment by spectral
measurement
method for adjusting the intensity of an illumination source through the formula
∫ S λE λ ddλ=∫S λE λ λ
( ) ( ) ( ) ( ) ,
abs ref abs mes
where S (λ) is the absolute spectral responsivity of the DUT, E (λ) is the absolute spectral
abs mes
irradiance of the illumination source, and E (λ) is the spectral irradiance of the standard light
ref
4 Abbreviated terms
PV: photovoltaic
DSC: dye-sensitized solar cell
CIGS: copper indium gallium selenide
GaAs: gallium arsenide
c-Si: crystalline silicon
a-Si: amorphous silicon
LED: light emitting diode
DUT: device under test
CCT: correlated colour temperature
– 10 – IEC TS 62607-7-2:2023 © IEC 2023
OPV: organic photovoltaic cell
V : open circuit voltage
oc
I : short circuit current
sc
FF: fill factor
EQE: external quantum efficiency
PRISM: programmable reference cell system for irradiance adjustment by spectral
measurement
MPPT: maximum power point tracking
I-V: current-voltage
SI: système international d'unités (international unit system)
5 Methods for measuring current-voltage characterization
5.1 General
IEC 60904-1 describes procedures for the measurement of current-voltage characteristics (I-V
curves) of photovoltaic (PV) devices in natural or simulated sunlight. Efficiency is not directly
an I-V parameter, but rather an additional quantity obtained from the maximum-power, the
irradiance and the device area. For guidance on area measurement see Annex A.
5.2 Requirements
5.2.1 Device under test (DUT)
Define the area A (m ) of the DUT used to calculate conversion efficiency. If the DUT is a
photovoltaic cell, attach a shadow mask then measure the area of the mask's opening and use
that as the area of the DUT. If the DUT is a module, use the area of the entire element (including
nonconductive components) as the area of the DUT.
5.2.2 Illumination adjustment
For adjusting illuminance at the DUT described in 5.2.3, one of the three methods a) to c) shall
be used.
a) Indoor reference photovoltaic-cell method: A method for adjusting the intensity of an
illumination source by matching it to the calibrated value for an indoor reference photovoltaic
cell. When performing spectral-mismatch correction, however, adjust the intensity to match
the value obtained by dividing the calibrated value by the spectral-mismatch correction
factor.
b) PRISM or spectroradiometer method: A method for adjusting the intensity of an illumination
source through the formula ∫ S λE λ ddλ=∫S λE λ λ , where S (λ) is the
( ) ( ) ( ) ( )
abs ref abs mes
abs
absolute spectral responsivity of the test photovoltaic cell, E (λ) is the absolute spectral
mes
irradiance of the light source, and E (λ) is the spectral irradiance of the standard light,
ref
using a calibrated spectroradiometer, in accordance with ASTM G138-12 (2020) [1] , for
example.
c) Illuminometer method: A method for adjusting the intensity of an illumination source to match
standard indoor illuminance by using an illuminometer calibrated according to JIS C 1609-1,
DIN 5032-7, or ISO/CIE 19476. For this method of adjusting illuminance, the class of the
light source should be restricted to Class-A or higher defined in 12.1.4.
Measure illuminance in the sample plane as measured by a reference device. If the reference
device is an illuminometer, then the measured illuminance is the output of the illuminometer. If
___________
Numbers in square brackets refer to the Bibliography.
the reference device is a reference cell or PRISM then make the measured illuminance
[L = L ∙ I / (M ∙ I )] close to L within 5 % by adjusting I , where L is the
mes ref mes cal ref mes ref
reference illuminance at which the reference cell is calibrated, I is the calibrated short-circuit
cal
current of the reference cell at L , I is the measured short-circuit current, and M is the
ref mes
spectral-mismatch correction factor (if it is not applied, M = 1). If L ≠ L then measured
mes ref
current value shall be corrected by multiplying by L / L .
eff mes
5.2.3 Measurement procedure
1) If necessary, allow the DUT to stabilize prior to measurement. IEC TR 63228 [2] describes
stabilization for emerging PVs.
2) Regulate the temperature of the DUT to 25 °C ± 1 °C.
3) Illuminance at the DUT (L ) shall be adjusted to the illuminance to the standard indoor
mes
illuminance (L ) – 50 lx, 200 lx, or 1 000 lx – according to 5.2.2.
ref
4) Determine the maximum output power (P ) by sweeping the bias voltage while illuminating
m
the DUT to perform I-V measurements.
• Make a correction to the measured current (I) by multiplying by L /L .
eff mes
• When sweeping the bias voltage, set the measurement delay time to a value at least
four times greater than the response time of the DUT.
• If the response time is unknown, set the measurement delay time so that the difference
in P values for the forward and reverse directions is 2 % or less. For slowly responding
m
elements, adjust the measurement delay time in accordance with the response speed
so that P variance is 2 % or less. In cases where P variance exceeds 2 %, record the
m m
P values and I-V characteristics for both the forward and reverse directions.
m
• Measurement stability: Perform at least five measurements for both the forward and
reverse directions, then verify that variation among those P values is 2 % or less.
m
Variation among multiple measurement values is given by
PP−
m_max m _min
,
×1 00
P
m _ average
where
P is the maximum P value;
m_max m
P is the minimum P value; and
m_min m
P is the average P value.
m_average m
• Use P as the maximum output (P ).
m_average m
5) Determine conversion efficiency η as given by
P
m
η=
GA⋅
2 2
where A is the area of the DUT (m ) and E is the irradiance per unit area (W/m ) given by
GE=∫ λλd
( )
where E(λ) is the spectral irradiance (W/m /nm) of the illumination source.
6) Irradiance values for standard indoor illuminance are listed in Table 1.
– 12 – IEC TS 62607-7-2:2023 © IEC 2023
Table 1 – Standard indoor illuminance
Standard indoor
Standard indoor
Illuminance (lx) light B4 User light source, u
)
light FL10 (mW/m
(mW/m )
∫E (λλ) d
u
1 000 3 076 3 132
KE∫=λV λ dλ 1 000
(where ( ) ( ) )
mu
∫E (λλ) d
u
200 615 626
(where KE∫=(λV) (λ) dλ 200 )
mu
∫E λλd
( )
u
50 154 157
(where KE∫=(λV) (λ) dλ 50 )
mu
7) Recording results.
The information in Table 2 should be recorded.
Table 2 – Result record
Item Subitem Details
Test date
Tested by
Device under test Type
Dimensions
P
m
Electrical characteristics I , V , FF, V , I
sc oc max max
Conversion efficiency
P Forward-direction P
m m
a
Reverse-direction P
m
Electrical characteristics Forward-direction I , V , FF, V , I
sc oc max max
a
Reverse-direction I , V , FF, V , I
sc oc max max
Conversion efficiency Forward-direction η
a
Reverse-direction η
a
I-V characteristic Record on separate sheet
Standard indoor light Type
Illuminance
b
Spectral irradiance Record on separate sheet
Irradiance
b
Wavelength range
Indoor reference PV cell Type
method (if using reference
Calibration value
PV cell method)
Calibration date
PRISM method (if using Spectral-response
PRISM method) measurement system
Type
Calibration date
Spectroradiometer
Type
Calibration date
Illuminometer method (if Type
using illuminometer method)
Calibration date
I-V measurement device Type
Calibration date
a
Record this data if P varies more than 2,0 % between the forward and reverse directions.
m
b
Record this data only if a user-defined light source was used.
5.3 Important additional information
a) If there is considerable distance between the DUT and the I-V measuring device, perform
the I-V measurement with the four-point probe method to eliminate the potential distortion
of the result by the voltage drop in the cables.
b) Connect the electrodes of the DUT to the electrical characteristics measuring device using
a lead wire or specialized jig for measuring electrical characteristics.
– 14 – IEC TS 62607-7-2:2023 © IEC 2023
c) If there are large fluctuations during measurement and stable values cannot be obtained,
include that information in the report.
d) To achieve the specified cell temperature, either directly regulate the DUT to 25 °C ± 1 °C
or leave it in an environment that is 25 °C ± 1 °C until it reaches thermal equilibrium with
that environment. It is recommended to use a DUT with an exposure area greater than 1 cm .
e) Use a shadow mask with slightly smaller dimensions than the DUT.
f) If highly accurate results are needed, it is recommended to use a Class-A illumination source
and to adjust its intensity with either the reference-cell or PRISM methods.
g) When calculating spectral-mismatch correction with the reference-cell method or
wavelength range with the PRISM method, use a wavelength range that is wider than that
of the DUT's spectral responsivity.
NOTE Limiting calculations to the wavelength range of standard indoor light can lead to errors if the light source
contains spectral components that fall outside the range specified for the standard indoor light and if the DUT is
sensitive to light within that range.
6 Indoor reference photovoltaic cells
6.1 Requirements
6.1.1 Selecting indoor reference photovoltaic cells
Prepare a number of stable photovoltaic cells with the same spectral responsivity as the cell
which will be measured, then use the following method to select a cell from among them.
a) Exclude any cells that have V , I , FF, and its appearance deviated drastically from the
oc sc
average of the group.
b) Measure the spectral responsivity of each cell under the illuminance selected for
measurement, then choose the cell that is closest to the average spectral responsivity.
Indoor secondary reference photovoltaic cells shall be cells that have less than ±2 %
spectral-mismatch error (as calculated in Clause 10).
6.1.2 Calibrating indoor reference photovoltaic cells
a) Use one of the following methods to calibrate reference cells.
1) Reference photovoltaic-cell method
• Using an indoor primary reference photovoltaic cell that is traceable to SI units,
calibrate the indoor secondary reference photovoltaic cell under the classified
illumination source.
• When calibrating, there is no need to perform a spectral-mismatch correction if the
spectral-mismatch error between the indoor primary reference photovoltaic cell and
the indoor secondary reference photovoltaic cell is within ±1 %.
• If the spectral-mismatch error between the indoor primary reference photovoltaic cell
and indoor secondary reference photovoltaic cell is greater than ±1 % when
calibrating, perform the spectral-mismatch correction.
2) Spectral-responsivity method
• Using a spectral-responsivity measurement system that has a guaranteed accuracy
of absolute values and is traceable to SI units, measure the spectral responsivity S(λ)
of the indoor secondary reference photovoltaic cell.
• Using the standard indoor light's E(λ) as defined in Clause 7, determine the
calibration value (V ) given by
cal
VS=∫ (λ)E(λ)dλ
cal abs
b) Recording results
Record the calibration results.
The information in Table 3 should be reported.
Table 3 – Calibration record
Item Details
Calibration date
Calibrated by
Reference cell Type
Size
Calibration value
Calibration method
Spectral-mismatch
correction factor
Primary reference cell Type
Size
Calibration value
Calibration method
Calibration laboratory
Calibration value
Standard indoor light Type
Illuminance
Optical spectrum
Irradiance
Measuring device used Spectral-response
measurement system
Calibration date
Spectroradiometer
Calibration date
c) Inspections
Once per year, inspect and calibrate the device used for calibration and document a log of the
inspection.
6.2 Important notes
If a stable secondary-reference cell with the same relative spectral responsivity as the DUT
cannot be obtained, use a quasi-reference photovoltaic cell, the spectral responsivity of which
is similar to the DUT with a stable photovoltaic cell, e.g., a Si photovoltaic cell combined with
an appropriate optical filter.
NOTE The quasi-reference photovoltaic cell is explained in A.4.4.
– 16 – IEC TS 62607-7-2:2023 © IEC 2023
7 Standard indoor light – Requirements
7.1 Standard indoor illuminance
Use the illuminance of standard indoor light (L , 1 000 lx, 200 lx, or 50 lx) as the standard
ref
indoor illuminance.
When using an illuminance other than the above, record the light source and illuminance used
for measurement.
7.2 Standard indoor light
Select one of the following.
a) CIE FL10 light source: the spectrum labelled "FL10" in Table 4 (fluorescent lamp with a
correlated colour temperature of 5 000 K approximately, defined by CIE).
b) CIE LED-B4 light source: the spectrum labelled "B4" in Table 4 (LED lamp with a correlated
colour temperature of 5 000 K approximately, defined by CIE).
c) U light source: a user-defined light source.
7.3 Spectral irradiance of standard indoor light
The spectral irradiance of each standard indoor light at 1 000 lx is indicated in Table 1 and
Figure 1. For 50 lx and 200 lx illuminance, just divide each value by 20 and 5, respectively.
Table 4 – Spectral irradiance (mW/m /nm) of standard indoor light at 1 000 lx
λ FL10 B4 λ FL10 B4 λ FL10 B4 λ FL10 B4
(nm) (nm) (nm) (nm)
380 1,11 0,00 480 7,91 4,89 580 11,45 15,98 680 1,47 4,05
381 1,06 0,00 481 9,36 4,70 581 12,58 15,93 681 1,53 3,96
382 1,00 0,00 482 11,21 4,55 582 13,51 15,88 682 1,60 3,87
383 0,94 0,00 483 13,21 4,43 583 14,21 15,82 683 1,67 3,79
384 0,87 0,00 484 15,11 4,33 584 14,64 15,76 684 1,73 3,70
385 0,80 0,00 485 16,64 4,25 585 14,79 15,70 685 1,79 3,62
386 0,72 0,00 486 17,61 4,20 586 14,64 15,64 686 1,83 3,54
387 0,65 0,00 487 18,04 4,16 587 14,24 15,58 687 1,86 3,46
388 0,60 0,00 488 17,99 4,15 588 13,65 15,51 688 1,85 3,38
389 0,58 0,00 489 17,53 4,16 589 12,94 15,44 689 1,81 3,31
390 0,62 0,00 490 16,73 4,19 590 12,16 15,36 690 1,74 3,23
391 0,71 0,00 491 15,67 4,25 591 11,38 15,28 691 1,62 3,16
392 0,82 0,00 492 14,42 4,33 592 10,63 15,20 692 1,48 3,08
393 0,87 0,00 493 13,08 4,43 593 9,96 15,11 693 1,32 3,01
394 0,81 0,01 494 11,72 4,5
...
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