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ASTM E948-05

(Test Method)

Standard Test Method for Electrical Performance of Photovoltaic Cells Using Reference Cells Under Simulated Sunlight

Standard Test Method for Electrical Performance of Photovoltaic Cells Using Reference Cells Under Simulated Sunlight

SCOPE
1.1 This test method covers the determination of the electrical performance of a photovoltaic cell under simulated sunlight by means of a calibrated reference cell procedure.
1.2 Electrical performance measurements are reported with respect to a select set of standard reporting conditions (SRC) (see ) or to user-specified conditions.
1.2.1 The SRC or user-specified conditions include the cell temperature, the total irradiance, and the reference spectral irradiance distribution.
1.3 This test method is applicable only to photovoltaic cells with a linear response over the range of interest.
1.4 The cell parameters determined by this test method apply only at the time of test, and imply no past or future performance level.
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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

Status
Historical
Publication Date
31-Mar-2005
ICS
27.160 - Solar energy engineering
Technical Committee
E44 - Solar, Geothermal and Other Alternative Energy Sources
Drafting Committee
E44.09 - Photovoltaic Electric Power Conversion
Current Stage
Ref Project

Relations

Replaces
ASTM E948-95(2001) - Standard Test Method for Electrical Performance of Photovoltaic Cells Using Reference Cells Under Simulated Sunlight
Effective Date
01-Apr-2005
Replaced By
ASTM E948-05a - Standard Test Method for Electrical Performance of Photovoltaic Cells Using Reference Cells Under Simulated Sunlight
Effective Date
01-Sep-2005
Referred By
ASTM E973-16(2020) - Standard Test Method for Determination of the Spectral Mismatch Parameter Between a Photovoltaic Device and a Photovoltaic Reference Cell
Effective Date
01-Apr-2005
Referred By
ASTM E772-15(2021) - Standard Terminology of Solar Energy Conversion
Effective Date
01-Apr-2005
Referred By
ASTM E1036-15(2019) - Standard Test Methods for Electrical Performance of Nonconcentrator Terrestrial Photovoltaic Modules and Arrays Using Reference Cells
Effective Date
01-Apr-2005
Referred By
ASTM E2848-13(2023) - Standard Test Method for Reporting Photovoltaic Non-Concentrator System Performance
Effective Date
01-Apr-2005
Referred By
ASTM E1125-16(2020) - Standard Test Method for Calibration of Primary Non-Concentrator Terrestrial Photovoltaic Reference Cells Using a Tabular Spectrum
Effective Date
01-Apr-2005
Referred By
ASTM E1362-15(2019) - Standard Test Methods for Calibration of Non-Concentrator Photovoltaic Non-Primary Reference Cells
Effective Date
01-Apr-2005
Referred By
ASTM E1040-10(2020) - Standard Specification for Physical Characteristics of Nonconcentrator Terrestrial Photovoltaic Reference Cells
Effective Date
01-Apr-2005
Referred By
ASTM E2236-10(2019) - Standard Test Methods for Measurement of Electrical Performance and Spectral Response of Nonconcentrator Multijunction Photovoltaic Cells and Modules
Effective Date
01-Apr-2005
Referred By
ASTM E1143-05(2019) - Standard Test Method for Determining the Linearity of a Photovoltaic Device Parameter with Respect To a Test Parameter
Effective Date
01-Apr-2005
Referred By
ASTM E927-19 - Standard Classification for Solar Simulators for Electrical Performance Testing of Photovoltaic Devices
Effective Date
01-Apr-2005
Referred By
ASTM E1021-15(2019) - Standard Test Method for Spectral Responsivity Measurements of Photovoltaic Devices
Effective Date
01-Apr-2005

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ASTM E948-05 - Standard Test Method for Electrical Performance of Photovoltaic Cells Using Reference Cells Under Simulated SunlightASTM E948-05 - Standard Test Method for Electrical Performance of Photovoltaic Cells Using Reference Cells Under Simulated Sunlight
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ASTM E948-05 - Standard Test Method for Electrical Performance of Photovoltaic Cells Using Reference Cells Under Simulated Sunlight
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
An American National Standard
Designation:E948–05
Standard Test Method for
Electrical Performance of Photovoltaic Cells Using
1
Reference Cells Under Simulated Sunlight
This standard is issued under the fixed designation E948; 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 (e) indicates an editorial change since the last revision or reapproval.
TABLE 1 Standard Reporting Conditions
1. Scope
1.1 This test method covers the determination of the elec- NOTE 1—The extraterrestrial solar constant and spectral irradiance
contained in Tables E490 do not represent the latest measurements of
trical performance of a photovoltaic cell under simulated
3
these quantities. The World Radiation Center recommends a value of
sunlight by means of a calibrated reference cell procedure.
−2
1367Wm for the solar constant along with more reliable measurements
1.2 Electrical performance measurements are reported with
of the extraterrestrial spectral irradiance.
respect to a select set of standard reporting conditions (SRC)
Reference Spectral Irradiance Total Irradiance Temperature
(see Table 1) or to user-specified conditions.
−2
Distribution (Wm ) (°C)
1.2.1 The SRC or user-specified conditions include the cell
Tables E 891 1000 25
temperature, the total irradiance, and the reference spectral
Tables E 892 1000 25
irradiance distribution. Tables E 490 1353 25
1.3 This test method is applicable only to photovoltaic cells
with a linear response over the range of interest.
E892 Tables for Terrestrial Solar Spectral Irradiance atAir
1.4 The cell parameters determined by this test method
Mass 1.5 for a 37° Tilted Surface
apply only at the time of test, and imply no past or future
E927 Specification for Solar Simulation for Terrestrial
performance level.
Photovoltaic Testing
1.5 This standard does not purport to address all of the
E973 Test Method for Determination of the Spectral Mis-
safety concerns, if any, associated with its use. It is the
match Parameter Between a Photovoltaic Device and a
responsibility of the user of this standard to establish appro-
Photovoltaic Reference Cell
priate safety and health practices and determine the applica-
E1021 Test Methods for Measuring Spectral Response of
bility of regulatory limitations prior to use.
Photovoltaic Cells
2. Referenced Documents
E 1039 Test Method for Calibration of Silicon Non-
2
Concentrator Photovoltaic Primary Reference Cells Under
2.1 ASTM Standards:
E490 Solar Constant and Zero Air Mass Solar Spectral Global Irradiation
E1040 Specification for Physical Characteristics of Non-
Irradiance Tables
E491 Practice for Solar Simulation for Thermal Balance concentrator Terrestrial Photovoltaic Reference Cells
E1125 Test Method for Calibration of Primary Non-
Testing of Spacecraft
E691 Practice for Conducting an Interlaboratory Study to Concentrator Terrestrial Photovoltaic Reference Cells Us-
ing a Tabular Spectrum
Determine the Precision of a Test Method
E772 Terminology Relating to Solar Energy Conversion E1328 Terminology Relating to Photovoltaic Solar Energy
Conversion
E891 Terrestrial Direct Normal Solar Spectral Irradiance
E1362 Test Method for Calibration of Non-Concentrator
Tables for Air Mass 1.5
Photovoltaic Secondary Reference Cells
G173 Tables for Reference Solar Spectral Irradiances:
Direct Normal and Hemispherical on 37° Tilted Surface
1
This test method is under the jurisdiction of ASTM Committee E44 on Solar,
Geothermal,andOtherAlternativeEnergySourcesandisthedirectresponsibilityof
3. Terminology
Subcommittee E44.09 on Photovoltaic Electric Power Conversion.
3.1 Definitions—Definitions of terms in this test method
Current edition approved April 1, 2005. Published May 2005. Originally
approved in 1993. Last previous edition approved in 2001 as E948–95(01).
may be found inTerminology E772 andTerminology E1328.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2 Definitions of Terms Specific to This Standard:
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3.2.1 cell temperature, °C, n—the temperature of the semi-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. conductor junction of a photovoltaic cell.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
E948–05
3.2.2 junction temperature, n—synonym for cell tempera- 5. Significance and Use
ture.
5.1 It is the intent of this test method to provide a recog-
3.2.3 light source, n—a source of radiant energy used for
nized method for testing and reporting the electrical perf
...

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FIG. 1 Hot Spot Effect  
4.5 Bypass diodes, if present, as shown in Fig. 2, begin conducting when a series-connected string in a module is in reverse bias, thereby limiting the power dissipation in the reduced-output cell.  
FIG. 2 Bypass Diode Effect  
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5.3 The irradiance shall be measured in the plane of the modules under test. If multiple planes exist (particularly in the case of rolling terrain), then the plane or planes in which irradiance measurement will occur must be reported with the test results. In the case where this test method is to be used for acceptance testing of a photovoltaic system or reporting of photovoltaic system performance for contractual purposes, the plane or planes in which irradiance measurement will occur must be agreed upon by the parties to the test prior to the start of the test.
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1.1 This test method provides measurement and analysis procedures for determining the capacity of a specific photovoltaic system built in a particular place and in operation under natural sunlight.  
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1.2.3 Monitoring of photovoltaic system performance.  
1.3 This test method should not be used for:  
1.3.1 Testing of individual photovoltaic modules for comparison to nameplate power ratings,  
1.3.2 Testing of individual photovoltaic modules or systems for comparison to other photovoltaic modules or systems, and  
1.3.3 Testing of photovoltaic systems for the purpose of comparing the performance of photovoltaic systems located in different places.  
1.4 In this test method, photovoltaic system power is reported with respect to a set of reporting conditions (RC) including solar irradiance in the plane of the modules, ambient temperature, and wind speed (see Section 6). Measurements under a variety of reporting conditions are allowed to facilitate testing and comparison of results.  
1.5 This test method assumes that the solar cell temperature is directly influenced by ambient temperature and wind speed; if not the regression results may be less meaningful.  
1.6 The capacity measured according to this test method should not be used to make representations about the energy generation capabilities of the system.  
1.7 This test method is not applicable to concentrator photovoltaic systems; as an alternative, Test Method E2527 should be considered for such systems.  
1.8 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.9 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...

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ASTM E781-86(2023)(Practice)
Standard Practice for Evaluating Absorptive Solar Receiver Materials When Exposed to Conditions Simulating Stagnation in Solar Collectors with Cover Plates

SIGNIFICANCE AND USE
4.1 Although this practice is intended for evaluating solar absorber materials and coatings used in flat-plate collectors, no single procedure can duplicate the wide range of temperatures and environmental conditions to which these materials may be exposed during in-service conditions.  
4.2 This practice is intended as a screening test for absorber materials and coatings. All conditions are chosen to be representative of those encountered in solar collectors with single cover plates and with no added means of limiting the temperature during stagnation conditions.  
4.3 This practice uses exposure in a simulated collector with a single cover plate. Although collectors with additional cover plates will produce higher temperatures at stagnation, this procedure is considered to provide adequate thermal testing for most applications.
Note 1: Mathematical modeling has shown that a selective absorber, single glazed flat-plate solar collector can attain absorber plate stagnation temperatures as high as 226 °C (437 °F) with an ambient temperature of 37.8 °C (100 °F) and zero wind velocity, and a double glazed one as high as 245 °C (482 °F) under these conditions. The same configuration solar collector with a nonselective absorber can attain absorber stagnation temperatures as high as 146 °C (284 °F) if single glazed, and 185 °C (360 °F) if double glazed, with the same environmental conditions (see “Performance Criteria for Solar Heating and Cooling Systems in Commercial Buildings,” NBS Technical Note 1187).4  
4.4 This practice evaluates the thermal stability of absorber materials. It does not evaluate the moisture stability of absorber materials used in actual solar collectors exposed outdoors. Moisture intrusion into solar collectors is a frequent occurrence in addition to condensation caused by diurnal breathing.  
4.5 This practice differentiates between the testing of spectrally selective absorbers and nonselective absorbers.  
4.5.1 Testing Spectrally Selective...
SCOPE
1.1 This practice covers a test procedure for evaluating absorptive solar receiver materials and coatings when exposed to sunlight under cover plate(s) for long durations. This practice is intended to evaluate the exposure resistance of absorber materials and coatings used in flat-plate collectors where maximum non-operational stagnation temperatures will be approximately 200 °C (392 °F).  
1.2 This practice shall not apply to receiver materials used in solar collectors without covers (unglazed) or in evacuated collectors, that is, those that use a vacuum to suppress convective and conductive thermal losses.  
1.3 The values stated in SI units are to be regarded as the standard.  
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1.5 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.

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ASTM E822-92(2023)(Practice)
Standard Practice for Determining Resistance of Solar Collector Covers to Hail by Impact with Propelled Ice Balls

SIGNIFICANCE AND USE
2.1 In many geographic areas there is concern about the effect of falling hail upon solar collector covers. This practice may be used to determine the ability of flat-plate solar collector covers to withstand the impact forces of hailstones. In this practice, the ability of a solar collector cover plate to withstand hail impact is related to its tested ability to withstand impact from ice balls. The effects of the impact on the material are highly variable and dependent upon the material.  
2.2 This practice describes a standard procedure for mounting the test specimen, conducting the impact test, and reporting the effects.  
2.2.1 The procedures for mounting cover plate materials and collectors are provided to ensure that they are tested in a configuration that relates to their use in a solar collector.  
2.2.2 The corner locations of the four impacts are chosen to represent vulnerable sites on the cover plate. Impacts near corner supports are more critical than impacts elsewhere. Only a single impact is specified at each of the impact locations. For test control purposes, multiple impacts in a single location are not permitted because a subcritical impact may still cause damage that would alter the response to subsequent impacts.  
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SCOPE
1.1 This practice covers a procedure for determining the ability of cover plates for flat-plate solar collectors to withstand impact forces of falling hail. Propelled ice balls are used to simulate falling hailstones. This practice is not intended to apply to photovoltaic cells or arrays.  
1.2 This practice defines two types of test specimens, describes methods for mounting specimens, specifies impact locations on each test specimen, provides an equation for determining the velocity of any size ice ball, provides a method for impacting the test specimens with ice balls, and specifies parameters that must be recorded and reported.  
1.3 This practice does not establish pass or fail levels. The determination of acceptable or unacceptable levels of ice-ball impact resistance is beyond the scope of this practice.  
1.4 The size of ice ball to be used in conducting this test is not specified in this practice. This practice can be used with various sizes of ice balls.  
1.5 The categories of solar collector cover plate materials to which this practice may be applied cover the range of:  
1.5.1 Brittle sheet, such as glass,  
1.5.2 Semirigid sheet, such as plastic, and  
1.5.3 Flexible membrane, such as plastic film.  
1.6 Solar collector cover materials should be tested as:  
1.6.1 Part of an assembled collector (Type 1 specimen), or  
1.6.2 Mounted on a separate test frame cover plate holder (Type 2 specimen).  
1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.8 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.  
1.9 This international standard was developed in accordance with internatio...

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ASTM
ASTM E881-92(2022)(Practice)
Standard Practice for Exposure of Solar Collector Cover Materials to Natural Weathering Under Conditions Simulating Stagnation Mode

SIGNIFICANCE AND USE
4.1 This practice describes a weathering box test fixture and establishes limits for the heat loss coefficients. Uniform exposure guidelines are provided to minimize the variables encountered during outdoor exposure testing.  
4.2 Since the combination of elevated temperature and solar radiation may cause some solar collector cover materials to degrade more rapidly than either exposure alone, a weathering box that elevates the temperature of the cover materials is used.  
4.3 This practice may be used to assist in the evaluation of solar collector cover materials in the stagnation mode. No single temperature or procedure can duplicate the range of temperatures and environmental conditions to which cover materials may be exposed during stagnation conditions. To assist in evaluation of solar collector cover materials in the operational mode, Practice E782 should be used. Insufficient data exist to obtain exact correlation between the behavior of materials exposed in accordance with this practice and actual in-service performance.  
4.4 This practice may also be useful in comparing the performance of different materials at one site or the performance of the same material at different sites, or both.  
4.5 Means of evaluating the effects of weathering are provided in Practice E765, and in other ASTM test methods that evaluate material properties.  
4.6 Exposures of the type described in this practice may be used to evaluate the stability of solar collector cover materials when exposed outdoors to the varied influences that comprise weather. Exposure conditions are complex and changeable. Important factors are material temperature, climate, time of year, presence of industrial pollution, etc. Generally, because it is difficult to define or measure precisely the factors influencing degradation due to weathering, results of outdoor exposure tests must be taken as indicative only. Repeated exposure testing at different seasons over a period of more than one year is req...
SCOPE
1.1 This practice covers a procedure for the exposure of solar collector cover materials to the natural weather environment at elevated temperatures that approximate stagnation conditions in solar collectors having a combined back and edge loss coefficient of less than 1.5 W/(m2·°C).  
1.2 This practice is suitable for exposure of both glass and plastic solar collector cover materials. Provisions are made for exposure of single and double cover assemblies to accommodate the need for exposure of both inner and outer solar collector cover materials.  
1.3 This practice does not apply to cover materials for evacuated collectors, photovoltaic cells, flat-plate collectors having a combined back and edge loss coefficient greater than 1.5 W/(m2·°C), or flat-plate collectors whose design incorporates means for limiting temperatures during stagnation.  
1.4 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.  
1.5 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.

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ASTM
ASTM E782-95(2022)(Practice)
Standard Practice for Exposure of Cover Materials for Solar Collectors to Natural Weathering Under Conditions Simulating Operational Mode

SIGNIFICANCE AND USE
3.1 This practice describes a weathering box test fixture and provides uniform exposure guidelines to minimize the variables encountered during outdoor exposure testing.  
3.2 This practice may be useful in comparing the performance of different materials at one site or the performance of the same material at different sites, or both.  
3.3 Since the combination of elevated temperature and solar radiation may cause some solar collector cover materials to degrade more rapidly than either alone, a weathering box that elevates the temperature of the cover materials is used.  
3.4 This practice is intended to assist in the evaluation of solar collector cover materials in the operational, not stagnation mode. Insufficient data exist to obtain exact correlation between the behavior of materials exposed according to this practice and actual in-service performance.  
3.5 Means of evaluation of effects of weathering are provided in Practice E781, and in other ASTM test methods that evaluate material properties.  
3.6 Tests of the type described in this practice may be used to evaluate the stability of solar collector cover materials when exposed outdoors to the varied influences which comprise weather. Exposure conditions are complex and changeable. Important factors are solar radiation, temperature, moisture, time of year, presence of pollutants, etc. These factors vary from site to site and should be considered in selecting locations for exposure. Control samples must always be used in weathering tests for comparative analysis. Outdoor exposure for at least two years is required to make evident changes, such as surface degradation without the use of sophisticated analytical equipment.  
3.7 Temperature conditions attained with this box may not exactly duplicate those that occur under operational conditions with fluid flow. Dependent on environmental exposure conditions, the cover plate temperatures obtained with this box may be higher or lower than those obtained und...
SCOPE
1.1 This practice provides a procedure for the exposure of cover materials for flat-plate solar collectors to the natural weather environment at temperatures that are elevated to approximate operating conditions.  
1.2 This practice is suitable for exposure of both glass and plastic solar collector cover materials. Provisions are made for exposure of single and double cover assemblies to accommodate the need for exposure of both inner and outer solar collector cover materials.  
1.3 This practice does not apply to cover materials for evacuated collectors or photovoltaics.  
1.4 The values stated in SI units are to be regarded as the 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.

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