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ASTM E2939-13

(Practice)

Standard Practice for Determining Reporting Conditions and Expected Capacity for Photovoltaic Non-Concentrator Systems

Standard Practice for Determining Reporting Conditions and Expected Capacity for Photovoltaic Non-Concentrator Systems

SIGNIFICANCE AND USE
5.1 This practice can be used to determine an expected capacity for an existing or a proposed photovoltaic system in a particular location during a specified period of time (see data collection period in Test Method E2848).  
5.2 The expected capacity calculated in accordance with this practice can be compared with the capacity measured according to Test Method E2848 when the RC are the same.  
5.3 The comparison of expected capacity and measured capacity can be used as a criterion for plant acceptance.  
5.4 The user of this practice must select the performance simulation period over which the reporting conditions and expected capacity will be derived. Seasonal variations will likely cause both of these to change with differing performance simulation periods.  
5.5 When this practice is used in conjunction with Test Method E2848, the performance simulation period and the data collection period must agree. If they do not agree, the comparison between expected and measured capacity will not be meaningful.  
5.6 Historical or measured5 plane-of-array irradiance, ambient air temperature and wind speed data can be used to select reporting conditions and calculate expected capacity. If historical data are used, the data collection period should match the time period of the measured data in terms of season and length.  
5.7 The simulated power output that is used to calculate the expected capacity should be derived from a performance model designed to represent the photovoltaic system which will be reported per Test Method E2848.
SCOPE
1.1 This practice provides procedures for determining the expected capacity of a specific photovoltaic system in a specific geographical location that is in operation under natural sunlight during a specified period of time. The expected capacity is intended for comparison with the measured capacity determined by Test Method E2848.  
1.2 This practice is intended for use with Test Method E2848 as a procedure to select appropriate reporting conditions (RC), including solar irradiance in the plane of the modules, ambient temperature, and wind speed, needed for the photovoltaic system capacity measurement.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

Status
Historical
Publication Date
31-Aug-2013
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

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ASTM E2939-13 - Standard Practice for Determining Reporting Conditions and Expected Capacity for Photovoltaic Non-Concentrator SystemsASTM E2939-13 - Standard Practice for Determining Reporting Conditions and Expected Capacity for Photovoltaic Non-Concentrator Systems
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ASTM E2939-13 - Standard Practice for Determining Reporting Conditions and Expected Capacity for Photovoltaic Non-Concentrator Systems
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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
Designation: E2939 − 13
Standard Practice for
Determining Reporting Conditions and Expected Capacity
for Photovoltaic Non-Concentrator Systems
This standard is issued under the fixed designation E2939; 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.
1. Scope 3. Terminology
3.1 Definitions of terms used in this practice may be found
1.1 This practice provides procedures for determining the
in Terminology E772, IEEE 1547-2003, and Test Method
expected capacity of a specific photovoltaic system in a
E2848.
specific geographical location that is in operation under natural
sunlight during a specified period of time. The expected
3.2 Definitions:
capacityisintendedforcomparisonwiththemeasuredcapacity
3.2.1 expected capacity, photovoltaic system, n—the pre-
determined by Test Method E2848.
dicted power rating that is derived from meteorological data
andaperformancemodelthatdescribesaspecificPVsystemin
1.2 This practice is intended for use with Test Method
a specific location and time period.
E2848 as a procedure to select appropriate reporting conditions
(RC), including solar irradiance in the plane of the modules,
3.2.2 measured capacity, photovolaic system, n—the output
ambient temperature, and wind speed, needed for the photo-
power of a photovoltaic system measured according to Test
voltaic system capacity measurement.
Method E2848.
3.2.3 performance model, photovoltaic system, n—a com-
1.3 The values stated in SI units are to be regarded as
puter model which, at a minimum, simulates the operation of a
standard. No other units of measurement are included in this
particular photovoltaic system using plane-of-array irradiance,
standard.
ambient temperature and wind speed data as inputs to calculate
1.4 This standard does not purport to address all of the
the instantaneous, simulated power output.
safety concerns, if any, associated with its use. It is the
3.2.4 performance simulation period, photovoltaic system,
responsibility of the user of this standard to establish appro-
n—the period of time over which a single expected capacity
priate safety and health practices and determine the applica-
prediction is performed. Compare with data collection period
bility of regulatory limitations prior to use.
in Test Method E2848.
2. Referenced Documents 3.2.5 plane-of-array irradiance, POA, n—see solar
irradiance, hemispherical in Terminology E772.
2.1 ASTM Standards:
3.2.6 simulated power output, photovoltaic system,
E772 Terminology of Solar Energy Conversion
n—photovoltaic system power output derived from meteoro-
E2848 Test Method for Reporting Photovoltaic Non-
logical data and a performance model.
Concentrator System Performance
3.2.7 time resolution, meteorological data, n—the time
2.2 IEEE Standards:
interval between individual meteorological data points that has
IEEE 1547-2003 Standard for Interconnecting Distributed
amaximumaveragingintervalof1h,usedtocalculateboththe
Resources with Electric Power Systems
reporting conditions and the expected capacity.
4. Summary of Practice
This practice is under the jurisdiction of ASTM Committee E44 on Solar,
Geothermal and OtherAlternative Energy Sources and is the direct responsibility of
4.1 Test Method E2848 provides a procedure to measure the
Subcommittee E44.09 on Photovoltaic Electric Power Conversion.
capacity of a photovoltaic system. The procedure involves a
Current edition approved Sept. 1, 2013. Published September 2013. DOI:
multiple linear regression of output power as a function of
10.1520/E2939-13
plane-of-array irradiance, ambient air temperature, and wind
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
speed data collected during the data collection period, which is
Standards volume information, refer to the standard’s Document Summary page on
a relatively short time period, typically between 3 and 30 days.
the ASTM website.
Using the regression results, the expected capacity (in watts) is
Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE),
445 Hoes Ln., Piscataway, NJ 08854, http://www.ieee.org. then calculated by substitution of a set of reporting conditions
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2939 − 13
consisting of plane-of-array irradiance, ambient air collection period must agree. If they do not agree, the com-
temperature, and wind speed appropriate for the system under parison between expected and measured capacity will not be
test into the regression equation. meaningful.
4.2 Although Test Method E2848 states that its procedure is 5.6 Historical or measured plane-of-array irradiance, am-
suitable for acceptance testing of newly installed photovoltaic bient air temperature and wind speed data can be used to select
systems (i.e. acceptance testing), it provides only general reporting conditions and calculate expected capacity. If histori-
guidance for the selection of the reporting conditions and no cal data are used, the data collection period should match the
guidance for predicting expected capacity prior to test. Both time period of the measured data in terms of season and length.
the reporting conditions and the expected capacity are neces-
5.7 The simulated power output that is used to calculate the
sary for acceptance testing.
expectedcapacityshouldbederivedfromaperformancemodel
4.3 This practice provides guidance for selecting the report- designed to represent the photovoltaic system which will be
ing conditions needed for Test Method E2848. This practice reported per Test Method E2848.
also provides a procedure for determining the expected capac-
6. Meteorological Data Procurement
ity of a photovoltaic system.
6.1 Select a meteorological data set that includes at a
4.4 The procedure for determining expected capacity con-
minimum, plane-of-array irradiance, ambient temperature and
sists of the following steps:
wind speed for a minimum of 5 contiguous days. This dataset
4.4.1 Procure meteorological data that will be representa-
4 will be used to calculate reporting conditions and expected
tive of the POAirradiance, ambient air temperature, and wind
capacity. Another disadvantage is that historical data is rarely
speed conditions during the data collection period.
measured in the plan-of-array. Therefore, the data will have to
4.4.1.1 This is best accomplished by using meteorological
be transposed into the plane-of-array which will have errors
data that is of the same time of year and same weather
when compared to actual measurements. Historical or mea-
conditions seen or expected to be seen during E2848.
sured meteorological data may be used to calculate reporting
4.4.2 Procure or develop a performance model representa-
conditions and expected capacity. Both have advantages and
tive of the photovoltaic system,
disadvantages.
4.4.3 Substitute the meteorological data into the perfor-
mance model to calculate the instantaneous, simulated power 6.2 The advantage of using historical data to calculate
reporting conditions is that the reporting conditions and asso-
output of the photovoltaic system, and
4.4.4 Use the data set to calculate the expected capacity ciated expected capacity can be calculated in advance of the
construction of a project. This is beneficial when this practice
according to Section 9 of Test Method E2848.
and Test Method E2848 are used for the purpose of acceptance
4.5 The expected capacity can then be compared with the
testing. The disadvantage of using historical data for calculat-
capacity measured during an acceptance test of a photovoltaic
ing reporting conditions is that actual meteorological condi-
system, if both capacities are determined from the same
tions du
...

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5.1 This practice can be used to determine an expected capacity for an existing or a proposed photovoltaic system in a particular location during a specified period of time (see data collection period in Test Method E2848).  
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SCOPE
1.1 These test methods provide procedures to determine the insulation resistance of a photovoltaic (PV) module, i.e. the electrical resistance between the module's internal electrical components and its exposed, electrically conductive, non-current carrying parts and surfaces.  
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1.5 This guide does not cover fire emanating from other sources.  
1.6 This guide does not cover mechanical, structural, electrical, or other considerations key to photovoltaic module and system design and installation.  
1.7 This guide does not cover disposal of modules damaged by a fire, or other material hazards related to such modules.  
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4.4 Fig. 1 illustrates the hot spot effect in a module of a series string of cells, one of which, cell Y, is partially shadowed. The amount of electrical power dissipated in Y is equal to the product of the module current and the reverse voltage developed across Y. For any irradiance level, when the reverse voltage across Y is equal to the voltage generated by the remaining (s-1) cells in the module, power dissipation is at a maximum when the module is short-circuited. This is shown in Fig. 1 by the shaded rectangle constructed at the intersection of the reverse I-V characteristic of Y with the image of the forward I-V characteristic of the (s-1) cells.
FIG. 1 Hot Spot Effect  
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FIG. 2 Bypass Diode Effect  
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1.1 This test method provides a procedure to determine the ability of a photovoltaic (PV) module to endure the long-term effects of periodic “hot spot” heating associated with common fault conditions such as severely cracked or mismatched cells, single-point open circuit failures (for example, interconnect failures), partial (or nonuniform) shadowing, or soiling. Such effects typically include solder melting or deterioration of the encapsulation, but in severe cases could progress to combustion of the PV module and surrounding materials.  
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Standard Practice for Evaluating Absorptive Solar Receiver Materials When Exposed to Conditions Simulating Stagnation in Solar Collectors with Cover Plates

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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  
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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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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.  
2.2.3 Resultant velocity is used to simulate the velocity that may be reached by hail accompanied by wind. The resultant velocity used in this practice is determined by vector addition of a 20 m/s (45 mph) horizontal velocity to the vertical terminal velocity.  
2.2.4 Ice balls are used in this practice to simulate hailstones because natural hailstones are not readily available to use, and ice balls closely approximate hailstones. However, no direct relationship has been established between the effect of impact of ice balls and hailstones. Hailstones are highly variable in properties such as shape, density, and frangibility.2 These properties affect factors such as the kinetic energy delivered to the cover plate, the period during ...
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 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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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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