ASTM E1038-98(2004)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:E1038–98 (Reapproved 2004)
Standard Test Method for
Determining Resistance of Photovoltaic Modules to Hail by
Impact with Propelled Ice Balls
This standard is issued under the fixed designation E1038; 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.
1. Scope E822 Practice for Determining Resistance of Solar Collec-
tor Covers to Hail by Impact with Propelled Ice Balls
1.1 This test method provides a procedure for determining
E1036 Test Methods for Electrical Performance of Non-
the ability of photovoltaic modules to withstand impact forces
concentrator Terrestrial Photovoltaic Modules and Arrays
of falling hail. Propelled ice balls are used to simulate falling
Using Reference Cells
hailstones.
E1328 Terminology Relating to Photovoltaic Solar Energy
1.2 Thistestmethoddefinestestspecimensandmethodsfor
Conversion
mounting specimens, specifies impact locations on each test
E1462 Test Methods for Insulation Integrity and Ground
specimen, provides an equation for determining the velocity of
Path Continuity of Photovoltaic Modules
any size ice ball, provides a method for impacting the test
specimens with ice balls, provides a method for determining
3. Terminology
changes in electrical performance, and specifies parameters
3.1 Definitions—For definitions of terms used in this test
that must be recorded and reported.
method, see Terminology E772 and Terminology E1328.
1.3 This test method does not establish pass or fail levels.
3.2 Symbols—The following symbols are used in this test
The determination of acceptable or unacceptable levels of ice
method.
ball impact resistance is beyond the scope of this test method.
m =ice ball mass, g,
1.4 Thesizeoftheiceballtobeusedinconductingthistest
d =ice ball diameter, mm, and
isnotspecified.Thistestmethodcanbeusedwithvarioussizes
r =ice ball radius, mm.
of ice balls.
3.2.1 Velocity:
1.5 This test method may be applied to concentrator and
−1
V =ice ball terminal, m s ,
t
nonconcentrator modules.
−1
V =wind, m s , and
w
1.6 The values stated in SI units are to be regarded as the
−1
V =ice ball resultant, m s .
r
standard. The values given in parentheses are for information
only.
4. Significance and Use
1.7 This standard does not purport to address all of the
4.1 In many geographic areas, there is concern about the
safety problems, if any, associated with its use. It is the
effect of falling hail upon photovoltaic modules. This test
responsibility of the user of this standard to establish appro-
method may be used to determine the ability of photovoltaic
priate safety and health practices and determine the applica-
modules to withstand the impact forces of hailstones. In this
bility of regulatory limitations prior to use. For specific
test method, the ability of a photovoltaic module to withstand
precautionary statements, refer to 5.1, Section 6, Note 8, and
hail impact is related to its tested ability to withstand impact
Note 9.
from ice balls. The effects of impact may be either physical or
2. Referenced Documents electrical degradation of the module.
4.2 This test method describes a standard procedure for
2.1 ASTM Standards:
2 mounting the test specimen, conducting the impact test, and
E772 Terminology Relating to Solar Energy Conversion
reporting the effects.
4.2.1 The procedures for mounting the test specimen are
This test method is under the jurisdiction of ASTM Committee E44 on Solar, provided to assure that modules are tested in a configuration
Geothermal,andOtherAlternativeEnergySourcesandisthedirectresponsibilityof
that relates to their use in a photovoltaic array.
Subcommittee E44.09 on Photovoltaic Electric Power Systems.
4.2.2 Six or more impact locations are chosen to represent
Current edition approved June 10, 1998. Published December 1998. Originally
vulnerable sites on modules and general locations are listed in
published as E1038–85. Last previous edition E1038–93.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Table 1. Only a single impact is specified at each of the impact
contactASTM Customer Service at service @astm.org. For Annual Book of ASTM
locations.
Standardsvolume information, refer to the standard’s Document Summary page on
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E1038–98 (2004)
TABLE 1 Candidate Locations and Suggested Order for Impact
the test. These determinations will be based on frequency and
Points
severity of expected hail occurrences and the intent of the
Location number Description
testing.
1 Centers of cells
4.4.1 If the testing is being performed to evaluate impact
2 Edges of cells, especially near electrical
resistance of a single module, or several modules, it may be
contacts
desirable to repeat the test using several sizes and velocities of
3 Points of minimum spacing between cells
4 Points of maximum distance from points of ice balls. In this manner, the different effects of various sizes
support in 6
and velocities of ice balls may be determined. However, no
Corners and edges of the module
point shall be impacted more than once (see 7.10).
5 Points of support for any superstrate material
6 Back of module, if exposed in stowed
4.4.2 The size and frequency of hail varies significantly
orientation
among various geographic areas. If testing is being performed
7 Electrical terminals and leads
to evaluate modules intended for use in a specific geographic
8 Centers of lenses approximately 50 mm from
lens support points
area, the ice ball size should correspond to the level of hail
impact resistance required for that area. Information on hail
size and frequency can be found in Appendix X1 of Practice
E822 and footnotes 3 and 4 of this test method, or may be
available from local historical weather records.
4.2.3 Resultant velocity is used to simulate the velocity that
4.4.3 When testing modules that are designed to be in a
may be reached by hail accompanied by wind. The resultant
stowedpositionduringhailstorms,additionalimpactlocations
velocity used in this test method is determined by vector
should be chosen accordingly.
addition of horizontal velocity to the vertical terminal velocity.
4.5 The hail impact resistance of modules may change as
4.2.4 Ice balls are used in this test method to simulate
the materials are exposed to various environmental factors.
hailstones. Hailstones are variable in properties such as shape,
This test method may be used to evaluate degradation by
density, and frangibility (for fracture characteristics, see Ref
comparisonofhailimpactresistancedatameasuredbeforeand
(10) in Practice E822). These properties affect factors such as
after exposure to other such environmental factors.
thedurationandmagnitudeoftheimpulsiveforceactingonthe
module and the area over which the impulse is distributed. Ice
5. Apparatus
balls(withadensity,frangibility,andterminalvelocitynearthe
5.1 Launcher,capableofpropellingaselectediceballatthe
range of hailstones) are the nearest hailstone approximation
specified velocity within 65%. The aiming accuracy of the
known at this time. Ice balls generally are harder and denser
launcher must be sufficient for the ice ball to strike the
than hailstones; therefore, an ice ball simulates the worst case
specified impact area, or the surrounding area must be masked
hailstone. Perhaps the major difference between ice balls and
for protection from inadvertent impacts.
hailstonesisthathailstonesaremorevariablethaniceballs.Ice
NOTE 1—Launchers that have proven suitable utilize a compressed air
balls can be uniformly and repeatedly manufactured to assure
supply, an accumulator tank, a large diameter quick-opening valve, and
a projectile with known properties.
,
3 4
interchangeablebarrelstoaccommodatedifferentsizesoficeballs (see
4.3 Data generated using this test method may be used for
Ref (14) of Practice E822). Another launcher that has been used is a
the following: (1) to evaluate impact resistance of a module,
table-mounted slingshot with an adjustable hand rest.
(2) to compare the impact resistance of several modules, (3)to
5.2 Velocity Meter, for measuring ice ball velocity to within
provide a common basis for selection of modules for use in
62%.
various geographic areas, or ( 4) to evaluate changes in impact
5.3 Test Base—Arigidmountforsupportingthetestmodule
resistance of modules due to other environmental factors, such
in a fashion that simulates actual mounti
...