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ASTM C1549-04

(Test Method)

Standard Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer

Standard Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer

SIGNIFICANCE AND USE
The temperatures of opaque surfaces exposed to solar radiation are generally higher than the adjacent air temperatures. In the case of roofs or walls enclosing conditioned spaces, increased inward heat flows result. In the case of equipment or storage containers exposed to the sun, increased operating temperatures usually result. The extent to which solar radiation affects surface temperatures depends on the solar reflectance of the exposed surface. A solar reflectance of 1.0 (100 % reflected) would mean no effect on surface temperature while a solar reflectance of 0 (none reflected, all absorbed) would result in the maximum effect. Coatings of specific solar reflectance are used to change the temperature of surfaces exposed to sunlight. Coatings and surface finishes are commonly specified in terms of solar reflectance. The initial (clean) solar reflectance must be maintained during the life of the coating or finish to have the expected thermal performance.
The test method provides a means for periodic testing of surfaces in the field or in the laboratory. Monitor changes in solar reflectance due to aging and exposure, or both, with this test method.
This test method is used to measure the solar reflectance of a flat opaque surface. The precision of the average of several measurements is usually governed by the variability of reflectances on the surface being tested.
Use the solar reflectance that is determined by this method to calculate the solar energy absorbed by an opaque surface as shown in Eq 1.
5.4.1 Combine the absorbed solar energy with conductive, convective and other radiative terms to construct a heat balance around an element or calculate a Solar Reflectance Index such as that discussed in Practice E 1980.
SCOPE
1.1 This test method covers a technique for determining the solar reflectance of flat opaque materials in a laboratory or in the field using a commercial portable solar reflectometer. The purpose of the test method is to provide solar reflectance data required to evaluate temperatures and heat flows across surfaces exposed to solar radiation.
1.2 This test method does not supplant Test Method E 903 which measures solar reflectance over the wavelength range 250 to 2500 nm using integrating spheres. The portable solar reflectometer is calibrated using specimens of known solar reflectance to determine solar reflectance from measurements at four wavelengths in the solar spectrum: 380 nm, 500 nm, 650 nm, and 1220 nm. This technique is supported by comparison of reflectometer measurements with measurements obtained using Test Method E 903. This test method is applicable to specimens of materials having both specular and diffuse optical properties. It is particularly suited to the measurement of the solar reflectance of opaque materials.
1.3 The values stated in SI units are to be regarded as the standard. The values in parenthesis are for information only.
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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

Status
Historical
Publication Date
31-Aug-2004
ICS
27.160 - Solar energy engineering
Technical Committee
C16 - Thermal Insulation
Drafting Committee
C16.30 - Thermal Measurement
Current Stage
Ref Project

Relations

Replaces
ASTM C1549-02 - Standard Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer
Effective Date
01-Sep-2004
Replaced By
ASTM C1549-09 - Standard Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer
Effective Date
01-Nov-2009
Referred By
ASTM C1864-17(2022) - Standard Test Method for Determination of Solar Reflectance of Directionally Reflective Material Using Portable Solar Reflectometer
Effective Date
01-Sep-2004
Referred By
ASTM D7897-18(2023) - Standard Practice for Laboratory Soiling and Weathering of Roofing Materials to Simulate Effects of Natural Exposure on Solar Reflectance and Thermal Emittance
Effective Date
01-Sep-2004
Referred By
ASTM D2824/D2824M-18 - Standard Specification for Aluminum-Pigmented Asphalt Roof Coatings, Nonfibered, and Fibered without Asbestos
Effective Date
01-Sep-2004
Referred By
ASTM D3794-22 - Standard Guide for Testing Coil Coatings
Effective Date
01-Sep-2004
Referred By
ASTM E2813-18 - Standard Practice for Building Enclosure Commissioning
Effective Date
01-Sep-2004

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ASTM C1549-04 - Standard Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar ReflectometerASTM C1549-04 - Standard Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer
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ASTM C1549-04 - Standard Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer
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Standards Content (Sample)

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.
Designation: C1549 – 04
Standard Test Method for
Determination of Solar Reflectance Near Ambient
1
Temperature Using a Portable Solar Reflectometer
This standard is issued under the fixed designation C1549; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
3
1. Scope Transmittance of Materials Using Integrating Spheres
E1980 Practice for Calculating Solar Reflectance Index of
1.1 This test method covers a technique for determining the
Horizontal and Low-Sloped Opaque Surfaces
solar reflectance of flat opaque materials in a laboratory or in
2.2 Additional Reference:
the field using a commercial portable solar reflectometer. The
“Instructions for the Solar Spectrum Reflectometer Model
purpose of the test method is to provide solar reflectance data
4
SSR-ER,” Devices and Services Company
required to evaluate temperatures and heat flows across sur-
faces exposed to solar radiation.
3. Terminology
1.2 This test method does not supplant Test Method E903
3.1 Definitions—For definitions of some terms used in the
which measures solar reflectance over the wavelength range
test method, refer to Terminology C168.
250 to 2500 nm using integrating spheres. The portable solar
3.2 Definitions of Terms Specific to This Standard:
reflectometer is calibrated using specimens of known solar
3.2.1 air mass—air mass is related to the path length of
reflectance to determine solar reflectance from measurements
solar radiation through the Earth’s atmosphere to the site of
at four wavelengths in the solar spectrum: 380 nm, 500 nm,
interest.Airmass1isforapathofnormalsolarradiationatthe
650 nm, and 1220 nm. This technique is supported by
Earth’s equator while air mass 2 indicates two times this path
comparison of reflectometer measurements with measurements
length.
obtained using Test Method E903. This test method is appli-
3.2.2 solar reflectance—the fraction of incident solar radia-
cable to specimens of materials having both specular and
tion upon a surface that is reflected from the surface.
diffuse optical properties. It is particularly suited to the
3.3 Symbols:
measurement of the solar reflectance of opaque materials.
2
A = area normal to incident radiation, m
1.3 The values stated in SI units are to be regarded as the
2
Q = rate at which radiant heat is absorbed per m of
abs
standard. The values in parenthesis are for information only.
area, W
1.4 This standard does not purport to address all of the
2
q = solar flux, W/m
solar
safety concerns, if any, associated with its use. It is the
r = solar reflectance, dimensionless
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Summary of Test Method
bility of regulatory limitations prior to use.
4.1 This test method employs a diffuse tungsten halogen
2
2. Referenced Documents lamp to illuminate a flat specimen for two seconds out of a
ten-second measurement cycle. Reflected light is measured at
2.1 ASTM Standards:
an angle of 20° from the incident angle with four detectors.
C168 Terminology Relating to Thermal Insulation
Each detector is equipped with color filters to tailor its
E691 Practice for Conducting an Interlaboratory Study to
electrical response to a range of wavelengths in the solar
Determine the Precision of a Test Method
spectrum. Software in the instrument combines the outputs of
E903 Test Method for Solar Absorptance, Reflectance, and
thefourdetectorsinappropriateproportionstoapproximatethe
response for incident solar radiation through air mass 0, 1, 1.5,
or 2. The solar reflectance for the desired air mass is selectable
1
ThistestmethodisunderthejurisdictionofASTMCommitteeC16onThermal
Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
Measurements.
3
Current edition approved Sept. 1, 2004. Published October 2004. Originally Withdrawn. The last approved version of this historical standard is referenced
approved in 2002. Last previous edition approved in 2002 as C1549 – 02. DOI: on www.astm.org.
4
10.1520/C1549-04. The sole source of supply of the apparatus known to the committee at this time
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or isDevices&ServicesCompany,10024MonroeDrive,Dallas,TX75229.Ifyouare
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM aware of alternative suppliers, please provide this information to ASTM Interna-
Standards volume information, refer to the standard’s Document Summary page on tional Headquarters.Your comments will receive careful consideration at a meeting
1
the ASTM website. of the responsible technic
...

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FIG. 1 Hot Spot Effect  
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ASTM E2848-13(2023)(Test Method)
Standard Test Method for Reporting Photovoltaic Non-Concentrator System Performance

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5.1 Because there are a number of choices in this test method that depend on different applications and system configurations, it is the responsibility of the user of this test method to specify the details and protocol of an individual system power measurement prior to the beginning of a measurement.  
5.2 Unlike device-level measurements that report performance at a fixed device temperature of 25 °C, such as Test Methods E1036, this test method uses regression to a reference ambient air temperature.  
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5.2.3 The user of this test method must select the time period over which system data are collected, and the averaging interval for the data collection within the constraints of 8.3.  
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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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1.2.3 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 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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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.  
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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:  
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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  
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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 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.  
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 E816-15(2023)(Test Method)
Standard Test Method for Calibration of Pyrheliometers by Comparison to Reference Pyrheliometers

SIGNIFICANCE AND USE
4.1 Though the sun trackers employed, the number of instantaneous readings, and the data acquisition equipment used will vary from instrument to instrument and from laboratory to laboratory, this test method provides for the minimum acceptable conditions, procedures, and techniques required.  
4.2 While the greatest accuracy will be obtained when calibrating pyrheliometers with a self-calibrating absolute cavity pyrheliometer that has been demonstrated by intercomparison to be within ±0.5 % of the mean irradiance of a family of similar absolute instruments, acceptable accuracy can be achieved by careful attention to the requirements of this test method when transferring calibration from a secondary reference to a field pyrheliometer.  
4.3 By meeting the requirements of this test method, traceability of calibration to the World Radiometric Reference (WRR) can be achieved through one or more of the following recognized intercomparisons:  
4.3.1 International Pyrheliometric Comparison (IPC) VII, Davos, Switzerland, held in 1990, and every five years thereafter, and the PMO-2 absolute cavity pyrheliometer that is the primary reference instrument of WMO.6  
4.3.2 Any WMO-sanctioned intercomparison of self-calibrating absolute cavity pyrheliometers held in WMO Region IV (North and Central America).  
4.3.3 Any sanctioned or non-sanctioned intercomparison held in the United States the purpose of which is to transfer the WRR from the primary reference absolute cavity pyrheliometer maintained as the primary reference standard of the United States by the National Oceanic and Atmospheric Administration's Solar Radiation Facility in Boulder, CO.7  
4.3.4 Any future intercomparisons of comparable reference quality in which at least one self-calibrating absolute cavity pyrheliometer is present that participated in IPC VII or a subsequent IPC, and in which that pyrheliometer is treated as the intercomparison's reference instrument.  
4.3.5 Any of the absolute radiometers p...
SCOPE
1.1 This test method has been harmonized with, and is technically equivalent to, ISO 9059.  
1.2 Two types of calibrations are covered by this test method. One is the calibration of a secondary reference pyrheliometer using an absolute cavity pyrheliometer as the primary standard pyrheliometer, and the other is the transfer of calibration from a secondary reference to one or more field pyrheliometers. This test method prescribes the calibration procedures and the calibration hierarchy, or traceability, for transfer of the calibrations.
Note 1: It is not uncommon, and is indeed desirable, for both the reference and field pyrheliometers to be of the same manufacturer and model designation.  
1.3 This test method is relevant primarily for the calibration of reference pyrheliometers with field angles of 5° to 6°, using as the primary reference instrument a self-calibrating absolute cavity pyrheliometer having field angles of about 5°. Pyrheliometers with field angles greater than 6.5° shall not be designated as reference pyrheliometers.  
1.4 When this test method is used to transfer calibration to field pyrheliometers having field angles both less than 5° or greater than 6.5°, it will be necessary to employ the procedure defined by Angstrom and Rodhe.2  
1.5 This test method requires that the spectral response of the absolute cavity chosen as the primary standard pyrheliometer be nonselective over the range from 0.3 μm to 10 μm wavelength. Both reference and field pyrheliometers covered by this test method shall be nonselective over a range from 0.3 μm to 4 μm wavelength.  
1.6 The primary and secondary reference pyrheliometers shall not be field instruments and their exposure to sunlight shall be limited to calibration or intercomparisons. These reference instruments shall be stored in an isolated cabinet or room equipped with standard laboratory temperature and humidity control.
Note 2: At a laboratory where cali...

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