ASTM E1021-15(2019)
(Test Method)Standard Test Method for Spectral Responsivity Measurements of Photovoltaic Devices
Standard Test Method for Spectral Responsivity Measurements of Photovoltaic Devices
SIGNIFICANCE AND USE
5.1 The spectral responsivity of a photovoltaic device is necessary for computing spectral mismatch parameter (see Test Method E973). Spectral mismatch is used in Test Method E948 to measure the performance of photovoltaic cells in simulated sunlight, in Test Methods E1036 to measure the performance of photovoltaic modules and arrays, in Test Method E1125 to calibrate photovoltaic primary reference cells using a tabular spectrum, and in Test Method E1362 to calibrate photovoltaic secondary reference cells. The spectral mismatch parameter can be computed using absolute or relative spectral responsivity data.
5.2 This test method measures the differential spectral responsivity of a photovoltaic device. The procedure requires the use of white-light bias to enable the user to evaluate the dependence of the differential spectral responsivity on the intensity of light reaching the device. When such dependence exists, the overall spectral responsivity should be equivalent to the differential spectral responsivity at a light bias level somewhere between zero and the intended operating conditions of the device. Depending on the linearity response of the DUT over the intensity range up to the intended operating conditions, it may not be necessary to set up a very high light bias level.
5.3 The spectral responsivity of a photovoltaic device is useful for understanding device performance and material characteristics.
5.4 The procedure described herein is appropriate for use in either research and development applications or in product quality control by manufacturers.
5.5 The reference photodetector’s calibration must be traceable to SI units through a National Institute of Standards and Technology (NIST) spectral responsivity scale or other relevant radiometric scale.3 ,4 The calibration mode of the photodetector (irradiance or power) will affect the procedures used and the kinds of measurements that can be performed.
5.6 This test method does not address issues...
SCOPE
1.1 This test method is to be used to determine either the absolute or relative spectral responsivity response of a single-junction photovoltaic device.
1.2 Because quantum efficiency is directly related to spectral responsivity, this test method may be used to determine the quantum efficiency of a single-junction photovoltaic device (see 10.10).
1.3 This test method requires the use of a bias light.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1021 − 15 (Reapproved 2019) An American National Standard
Standard Test Method for
Spectral Responsivity Measurements of Photovoltaic
Devices
This standard is issued under the fixed designation E1021; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E948Test Method for Electrical Performance of Photovol-
taic Cells Using Reference Cells Under Simulated Sun-
1.1 This test method is to be used to determine either the
light
absolute or relative spectral responsivity response of a single-
E973Test Method for Determination of the Spectral Mis-
junction photovoltaic device.
match Parameter Between a Photovoltaic Device and a
1.2 Because quantum efficiency is directly related to spec-
Photovoltaic Reference Cell
tralresponsivity,thistestmethodmaybeusedtodeterminethe
E1036Test Methods for Electrical Performance of Noncon-
quantum efficiency of a single-junction photovoltaic device
centrator Terrestrial Photovoltaic Modules and Arrays
(see 10.10).
Using Reference Cells
E1125 Test Method for Calibration of Primary Non-
1.3 This test method requires the use of a bias light.
ConcentratorTerrestrial Photovoltaic Reference Cells Us-
1.4 The values stated in SI units are to be regarded as
ing a Tabular Spectrum
standard. No other units of measurement are included in this
E1362Test Methods for Calibration of Non-Concentrator
standard.
Photovoltaic Non-Primary Reference Cells
1.5 This standard does not purport to address all of the
E2236Test Methods for Measurement of Electrical Perfor-
safety concerns, if any, associated with its use. It is the
mance and Spectral Response of Nonconcentrator Multi-
responsibility of the user of this standard to establish appro-
junction Photovoltaic Cells and Modules
priate safety, health, and environmental practices and deter-
G173TablesforReferenceSolarSpectralIrradiances:Direct
mine the applicability of regulatory limitations prior to use.
Normal and Hemispherical on 37° Tilted Surface
1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3. Terminology
ization established in the Decision on Principles for the
3.1 Definitions—Definitions of terms used in this test
Development of International Standards, Guides and Recom-
method may be found in Terminology E772.
mendations issued by the World Trade Organization Technical
3.2 Definitions of Terms Specific to This Standard:
Barriers to Trade (TBT) Committee.
3.2.1 chopper, n—a rotating blade or other device used to
modulate a light source.
2. Referenced Documents
3.2.2 device under test (DUT), n—aphotovoltaicdevicethat
2.1 ASTM Standards:
is subjected to a spectral responsivity measurement.
E691Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
3.2.3 irradiance mode calibration, n—a calibration method
E772Terminology of Solar Energy Conversion
in which the reference photodetector measures the irradiance
E927Classification for Solar Simulators for Electrical Per-
produced by the monochromatic beam.
formance Testing of Photovoltaic Devices
3.2.4 monitor photodetector, n—a photodetector incorpo-
rated into the optical system to monitor the amount of light
reaching the device under test, enabling adjustments to be
This test method is under the jurisdiction of ASTM Committee E44 on Solar,
made to accommodate varying light intensity.
GeothermalandOtherAlternativeEnergySourcesandisthedirectresponsibilityof
Subcommittee E44.09 on Photovoltaic Electric Power Conversion.
3.2.5 monochromatic beam, n—choppedlightfromamono-
Current edition approved April 1, 2019. Published April 2019. Originally
chromatic source reaching the reference photodetector or
approved in 1993. Last previous edition approved in 2015 as E1021–15. DOI:
device under test.
10.1520/E1021-15R19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.6 monochromator, n—an optical device that allows a
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
selected wavelength of light to pass while blocking other
Standardsvolume information, refer to the standard’s Document Summary page on
the ASTM website. wavelengths.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1021 − 15 (2019)
3.2.7 power mode calibration, n—a calibration method in φ—power of the monochromatic beam or irradiance of the
–2
which the reference photodetector measures the power in the monochromatic beam, W or W·m ,
–19
monochromatic beam. q—elementary charge, 1.602176565×10 C,
Q—external quantum efficiency dimensionless or percent,
3.2.8 reference photodetector, n—a calibrated photodetector
R —absolute spectral responsivity for irradiance mode,
ia
with a known spectral responsivity over a wavelength range
2 –1
A·m ·W ,
and used to quantify the amount of light in a monochromatic
–1
R —absolutespectralresponsivityforpowermode,A·W ,
pa
beam.
R —relative spectral responsivity for irradiance mode,
ir
3.2.9 spectral bandwidth, n—the range of wavelengths in a
dimensionless,
monochromatic light source, determined as the difference
R —relative spectral responsivity for power mode,
pr
between its half-maximum-intensity wavelengths.
dimensionless,
–1 2 –1
3.3 Symbols:
SR—spectral responsivity, A·W or A·m ·W .
3.3.1 The following symbols and units are used in this test
3.3.2 Symbolic quantities that are functions of wavelength
method:
appear as X(λ).
A—illuminated device area, m ,
−1
4. Summary of Test Method
c—speed of light in vacuum, 299792458 m·s ,
CV —monitor photodetector calibration value for irradi-
Mi
4.1 The spectral responsivity of a photovoltaic device,
2 −1
ance mode, A·m ·W ,
defined as the output current per input irradiance or radiant
CV —monitor photodetector calibration value for power
Mp
power at a given wavelength, and normally reported over the
−1
mode, A·W
wavelength range to which the device responds, is determined
ε—small wavelength interval, nm or µm,
by the following procedure:
−2
E — reference total irradiance, W·m ,
o
4.1.1 Amonochromatic, chopped or pulsed beam of light is
–2 –1
E (λ)—reference spectral irradiance, W·m ·nm or
o
directed at normal incidence onto the cell. Simultaneously, a
–2 –1
W·m ·µm ,
continuous white light beam (bias light) is used to illuminate
–2
E —monochromatic source irradiance, W·m ,
M
the DUT at irradiance levels intended for end use operating
Err—fractional error in measurement, dimensionless,
conditions of the device. See Fig. 1.
–34
h—Planck’s constant, 6.62606957×10 J·s,
4.1.2 The magnitude of the ac (chopped) component of the
I—current, A,
current at the intended voltage is monitored as the wavelength
I —monitor photodetector current during calibration, A,
mc
of the incident light is varied over the spectral response range
l —monitor photodetector current during test, A,
mt
of the device.
I —solar cell short-circuit current, A,
sc
4.2 Measurement of the absolute spectral responsivity of a
I —I under E (λ), A,
o sc o
–2 device requires knowledge of the absolute beam power or
J —solar cell short-circuit current density, A·m ,
sc
irradiance produced by the monochromatic beam. The total
K—relative-to-absolute spectral responsivity conversion
i
2 –1 power or irradiance of the monochromatic beam incident on
constant for irradiance mode, A·m ·W ,
the device is determined by the reference photodetector (see
K —relative-to-absolute spectral responsivity conversion
p
–1 6.1). The absolute spectral responsivity of the device can then
constant for power mode, A·W ,
be computed using the measured device photocurrent and the
λ—wavelength, nm or µm,
power or irradiance of the monochromatic beam.
λ —a specific wavelength, nm or µm,
o
M—spectral mismatch parameter, 4.3 The choice of power versus irradiance mode may
P—monochromatic beam power reaching the photodetector, depend on the spatial non-uniformity of the test device or the
W, incident monochromatic beam. Overall spectral response of a
FIG. 1 Example of Spatial Placement of Optical Components for Spectral Responsivity Measurement
E1021 − 15 (2019)
test device with substantial spatial non-uniformity of response 5.8 This test method is intended for use with a single-
shouldbeperformedinirradiancemodewithamonochromatic junction photovoltaic cell. It can also be used to measure the
beam of high spatial uniformity. spectral responsivity of a single junction within a series-
connected, multiple-junction photovoltaic device if electrical
4.4 Thetestprocedurecanbeadaptedtoprovideabsoluteor
contact can be made to the individual junction(s) of interest.
relative spectral responsivity measurements, depending on the
calibration device used, its calibration mode and the relative 5.9 With additional procedures (see Test Methods E2236),
sizes of the calibration device, the monochromatic beam size, one can determine the spectral responsivity of individual
and the device being measured. junctionswithinseries-connected,multiple-junction,photovol-
taic devices when electrical contact can only be made to the
5. Significance and Use
entire device’s two terminals.
5.1 The spectral responsivity of a photovoltaic device is 5
5.10 Using forward biasing techniques , it is possible to
necessaryforcomputingspectralmismatchparameter(seeTest
extendtheprocedureinthistestmethodtomeasurethespectral
MethodE973).SpectralmismatchisusedinTestMethodE948
responsivity of individual series-connected cells within photo-
to measure the performance of photovoltaic cells in simulated
voltaicmodules.Thesetechniquesarebeyondthescopeofthis
sunlight,inTestMethodsE1036tomeasuretheperformanceof
test method.
photovoltaic modules and arrays, in Test Method E1125 to
calibrate photovoltaic primary reference cells using a tabular
6. Apparatus
spectrum, and in Test Method E1362 to calibrate photovoltaic
6.1 Reference Photodetector:
secondary reference cells. The spectral mismatch parameter
6.1.1 The following detectors are acceptable for use in the
can be computed using absolute or relative spectral responsiv-
calibration of the monochromatic light source:
ity data.
6.1.1.1 Pyroelectric radiometer, and
5.2 This test method measures the differential spectral
6.1.1.2 Cryogenic radiometer, and
responsivity of a photovoltaic device. The procedure requires
6.1.1.3 Spectrally calibrated photodiode, photodiode irradi-
the use of white-light bias to enable the user to evaluate the
ance detector, or solar cell, calibrated in power or irradiance
dependence of the differential spectral responsivity on the
mode.
intensity of light reaching the device. When such dependence
NOTE 1—A spectrally calibrated photodiode should have calibration
exists, the overall spectral responsivity should be equivalent to
data that includes the entire spectral response range of the device to be
the differential spectral responsivity at a light bias level
tested. If a part of the range is omitted, it will limit the spectral range of
somewherebetweenzeroandtheintendedoperatingconditions theresultsofthistest,causinganerrorincomputingthespectralmismatch
parameter.
of the device. Depending on the linearity response of the DUT
NOTE2—Aphotodetectorcalibratedinpowermodemusthavespatially
over the intensity range up to the intended operating
uniform spectral responsivity over its photosensitive region. A photode-
conditions, it may not be necessary to set up a very high light
tector calibrated in irradiance mode may have spatially non-uniform
bias level.
spectralresponsivitycharacteristics,andmustonlybeusedwithauniform
monochromatic beam larger than its surface area. See also Table 1.
5.3 The spectral responsivity of a photovoltaic device is
6.1.2 Thereferencephotodetectormusthaveaknownlinear
useful for understanding device performance and material
current versus incident light intensity ratio over the range of
characteristics.
intensitiesandwavelengthsofthemonochromaticlightsource.
5.4 The procedure described herein is appropriate for use in
6.1.3 The reference photodetector’s calibration must be
either research and development applications or in product
traceable to SI units through a National Institute of Standards
quality control by manufacturers.
and Technology (NIST) spectral responsivity scale or other
3,4
5.5 The reference photodetector’s calibration must be trace-
relevant radiometric scale.
able to SI units through a National Institute of Standards and
6.1.4 The uniformity of responsivity over the surface of the
Technology (NIST) spectral responsivity scale or other rel-
reference photodetector must be characterized if it will not be
3,4
evant radiometric scale. The calibration mode of the photo-
entirely illuminated (overfill illumination) by the monochro-
detector (irradiance or power) will affect the procedures used
matic light beam. A photodetector with spatially uniform
and the kinds of measurements that can be performed.
sensitivity is suitable for use in both power mode and irradi-
ance mode measurements. Non-uniform detectors are suitable
5.6 This test method does not address issues of sample
for use in irradiance mode with uniform light beams only. The
stability.
non-uniformity of the incident radiation should be ideally
5.7 Usingresultsobtainedbythistestmethodandadditional
betterthan 62%.Forbestresults,useaphotodetectorwiththe
measurements including reflectance versus wavelength, one
best spatial response uniformity available. The spatial unifor-
cancomputetheinternalquantumefficiencyofadevice.These
mity map of the reference detector are typically provided as
measurements are beyond the scope of this test method.
part of the calibration documents for one or two wavelengths.
Larason, T. C., Bruce, S. S., and Parr,A. C., NIST Special Publication 250-41
Spectroradiometric Detector Measurements, Washington, DC, U.S. Government Emery, K. A., “Measurement and Characterization of Solar Cells and
Printing Office, 1998. Also available at http://ois.nist.gov/sdm/ Modules,” Handbook of Photovoltaic Science and Engineering, Chapter 16, pp.
Eppeldauer, G., Racz, M., and Larason, T., “Optical characterization of 701-747, Luque, A., and Hegedus, S., Eds., John Wiley & Sons, W. Sussex, U.K.,
diffuser-input standard irradiance meters,” SPIE Vol 3573, 1998, pp. 220-224. ISBN0-471-49196-9.
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