ASTM E2481-08
(Test Method)Standard Test Method for Hot Spot Protection Testing of Photovoltaic Modules
Standard Test Method for Hot Spot Protection Testing of Photovoltaic Modules
SIGNIFICANCE AND USE
The design of a photovoltaic module or system intended to provide safe conversion of the sun's radiant energy into useful electricity must take into consideration the possibility of partial shadowing of the module(s) during operation. This test method describes a procedure for verifying that the design and construction of the module provides adequate protection against the potential harmful effects of hot spots during normal installation and use.
This test method describes a procedure for determining the ability of the module to provide protection from internal defects which could cause loss of electrical insulation or combustion hazards.
Hot-spot heating occurs in a module when its operating current exceeds the reduced short-circuit current (Isc) of a shadowed or faulty cell or group of cells. When such a condition occurs, the affected cell or group of cells is forced into reverse bias and must dissipate power, which can cause overheating.
Note 1—The correct use of bypass diodes can prevent hot spot damage from occurring.
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.
By-pass 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.
Note 2—If the module does not contain bypass diodes, check the manufacturer’s instructions to ...
SCOPE
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 non-uniform) 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.
1.2 There are two ways that cells can cause a hot spot problem; either by having a high resistance so that there is a large resistance in the circuit, or by having a low resistance area (shunt) such that there is a high-current flow in a localized region. This test method selects cells of both types to be stressed.
1.3 This test method does not establish pass or fail levels. The determination of acceptable or unacceptable results is beyond the scope of this test method.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E2481 − 08
StandardTest Method for
1
Hot Spot Protection Testing of Photovoltaic Modules
This standard is issued under the fixed designation E2481; 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 E1036 Test Methods for Electrical Performance of Noncon-
centrator Terrestrial Photovoltaic Modules and Arrays
1.1 This test method provides a procedure to determine the
Using Reference Cells
ability of a photovoltaic (PV) module to endure the long-term
E1328 Terminology Relating to Photovoltaic Solar Energy
effects of periodic “hot spot” heating associated with common
3
Conversion (Withdrawn 2012)
fault conditions such as severely cracked or mismatched cells,
E1799 Practice for Visual Inspections of Photovoltaic Mod-
single-point open circuit failures (for example, interconnect
ules
failures), partial (or non-uniform) shadowing or soiling. Such
E1802 Test Methods for Wet Insulation Integrity Testing of
effects typically include solder melting or deterioration of the
Photovoltaic Modules
encapsulation, but in severe cases could progress to combus-
tion of the PV module and surrounding materials.
3. Terminology
1.2 There are two ways that cells can cause a hot spot
3.1 Definitions—definitions of terms used in this test
problem; either by having a high resistance so that there is a
method may be found in Terminology E772 and Terminology
large resistance in the circuit, or by having a low resistance
E1328.
area (shunt) such that there is a high-current flow in a localized
3.2 Definitions of Terms Specific to This Standard:
region. This test method selects cells of both types to be
3.2.1 hot spot—aconditionthatoccurs,usuallyasaresultof
stressed.
shadowing, when a solar cell or group of cells is forced into
1.3 This test method does not establish pass or fail levels.
reverse bias and must dissipate power, which can result in
The determination of acceptable or unacceptable results is
abnormally high cell temperatures.
beyond the scope of this test method.
4. Significance and Use
1.4 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
4.1 The design of a photovoltaic module or system intended
standard.
to provide safe conversion of the sun’s radiant energy into
1.5 This standard does not purport to address all of the useful electricity must take into consideration the possibility of
safety concerns, if any, associated with its use. It is the partial shadowing of the module(s) during operation. This test
responsibility of the user of this standard to establish appro- method describes a procedure for verifying that the design and
priate safety and health practices and determine the applica- construction of the module provides adequate protection
bility of regulatory limitations prior to use. against the potential harmful effects of hot spots during normal
installation and use.
2. Referenced Documents
4.2 This test method describes a procedure for determining
2
2.1 ASTM Standards:
the ability of the module to provide protection from internal
E772 Terminology of Solar Energy Conversion
defects which could cause loss of electrical insulation or
E927 Specification for Solar Simulation for Photovoltaic
combustion hazards.
Testing
4.3 Hot-spot heating occurs in a module when its operating
current exceeds the reduced short-circuit current (Isc) of a
1
This test method is under the jurisdiction of ASTM Committee E44 on Solar,
shadowed or faulty cell or group of cells. When such a
Geothermal and OtherAlternative Energy Sources and is the direct responsibility of
condition occurs, the affected cell or group of cells is forced
Subcommittee E44.09 on Photovoltaic Electric Power Conversion.
into reverse bias and must dissipate power, which can cause
Current edition approved Nov. 1, 2008. Published December 2008. Originally
overheating.
approved in 2006. Last previous edition approved in 2006 as E2481-06. DOI:
10.1520/E2481-08.
2
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
3
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E2481 − 08
NOTE 1—The correct use of bypass diodes can prevent hot spot damage
4.6.1.3 Because the heating is localized, hot spot
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:E2481–06 Designation:E2481–08
Standard Test Method for
1
Hot Spot Protection Testing of Photovoltaic Modules
This standard is issued under the fixed designation E 2481; 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
1.1 Thistestmethodprovidesaproceduretodeterminetheabilityofaphotovoltaic(PV)moduletoendurethelong-termeffects
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 non-uniform) 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.
1.2 There are two ways that cells can cause a hot spot problem; either by having a high resistance so that there is a large
resistance in the circuit, or by having a low resistance area (shunt) such that there is a high-current flow in a localized region. This
test method selects cells of both types to be stressed.
1.3 This test method does not establish pass or fail levels. The determination of acceptable or unacceptable results is beyond
the scope of this test method.
1.4
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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
E 772 Terminology Relating to Solar Energy Conversion
E 927 Specification for Solar Simulation for Photovoltaic Testing
E 1036 Test Methods for Electrical Performance of Nonconcentrator Terrestrial Photovoltaic Modules and Arrays Using
Reference Cells
E 1328 Terminology Relating to Photovoltaic Solar Energy Conversion
E 1799 Practice for Visual Inspections of Photovoltaic Modules
E 1802 Test Methods for Wet Insulation Integrity Testing of Photovoltaic Modules
3. Terminology
3.1 Definitions—definitions of terms used in this test method may be found in Terminology E 772 and Terminology E 1328.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 hot spot—aconditionthatoccurs,usuallyasaresultofshadowing,whenasolarcellorgroupofcellsisforcedintoreverse
bias and must dissipate power, which can result in abnormally high cell temperatures.
4. Significance and Use
4.1 The design of a photovoltaic module or system intended to provide safe conversion of the sun’s radiant energy into useful
electricity must take into consideration the possibility of partial shadowing of the module(s) during operation. This test method
describes a procedure for verifying that the design and construction of the module provides adequate protection against the
potential harmful effects of hot spots during normal installation and use.
4.2 This test method describes a procedure for determining the ability of the module to provide protection from internal defects
which could cause loss of electrical insulation or combustion hazards.
1
This test method is under the jurisdiction of ASTM Committee E44 on Solar, Geothermal and Other Alternative Energy Sources and is the direct responsibility of
Subcommittee E44.09 on Photovoltaic Electric Power Conversion.
Current edition approved MarchNov. 1, 2006.2008. Published March December 2008. Originally approved in 2006. Last previous edition approved in 2006 as E 2481-06.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume 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.
1
---------------------- Page: 1 ----------------------
E2481–08
4.3 Hot-spotheatingoccursinamodulewhenitsoperatingcurrentexceedsthereducedshort-circuitcurrent(Isc)ofashadowed
or faulty cell or group of cells. When such a condition occurs, the affected cell or group of cells is forced into reverse bias and
must dissipate power, wh
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:E2481–06 Designation:E2481–08
Standard Test Method for
1
Hot Spot Protection Testing of Photovoltaic Modules
This standard is issued under the fixed designation E 2481; 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
1.1 Thistestmethodprovidesaproceduretodeterminetheabilityofaphotovoltaic(PV)moduletoendurethelong-termeffects
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 non-uniform) 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.
1.2 There are two ways that cells can cause a hot spot problem; either by having a high resistance so that there is a large
resistance in the circuit, or by having a low resistance area (shunt) such that there is a high-current flow in a localized region. This
test method selects cells of both types to be stressed.
1.3 This test method does not establish pass or fail levels. The determination of acceptable or unacceptable results is beyond
the scope of this test method.
1.4
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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
E 772 Terminology Relating to Solar Energy Conversion
E 927 Specification for Solar Simulation for Photovoltaic Testing
E 1036 Test Methods for Electrical Performance of Nonconcentrator Terrestrial Photovoltaic Modules and Arrays Using
Reference Cells
E 1328 Terminology Relating to Photovoltaic Solar Energy Conversion
E 1799 Practice for Visual Inspections of Photovoltaic Modules
E 1802 Test Methods for Wet Insulation Integrity Testing of Photovoltaic Modules
3. Terminology
3.1 Definitions—definitions of terms used in this test method may be found in Terminology E 772 and Terminology E 1328.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 hot spot—aconditionthatoccurs,usuallyasaresultofshadowing,whenasolarcellorgroupofcellsisforcedintoreverse
bias and must dissipate power, which can result in abnormally high cell temperatures.
4. Significance and Use
4.1 The design of a photovoltaic module or system intended to provide safe conversion of the sun’s radiant energy into useful
electricity must take into consideration the possibility of partial shadowing of the module(s) during operation. This test method
describes a procedure for verifying that the design and construction of the module provides adequate protection against the
potential harmful effects of hot spots during normal installation and use.
4.2 This test method describes a procedure for determining the ability of the module to provide protection from internal defects
which could cause loss of electrical insulation or combustion hazards.
1
This test method is under the jurisdiction of ASTM Committee E44 on Solar, Geothermal and Other Alternative Energy Sources and is the direct responsibility of
Subcommittee E44.09 on Photovoltaic Electric Power Conversion.
Current edition approved MarchNov. 1, 2006.2008. Published March December 2008. Originally approved in 2006. Last previous edition approved in 2006 as E 2481-06.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume 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.
1
---------------------- Page: 1 ----------------------
E2481–08
4.3 Hot-spotheatingoccursinamodulewhenitsoperatingcurrentexceedsthereducedshort-circuitcurrent(Isc)ofashadowed
or faulty cell or group of cells. When such a condition occurs, the affected cell or group of cells is forced into reverse bias and
must dissipate power, wh
...
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