IEC 62804 Ed. 1.0DRAFT Rev D
System voltage durability test for crystalline silicon modules –design qualification and type approval
1.  Scope and objective
This International Standard lays down IEC requirements for the design qualification and type approval for the operation of terrestrial photovoltaic modules under the stress of system bias voltage. High voltage potential that exists between the active circuit and the grounded module frame or exterior can lead to module degradation by multiple mechanisms including ionic transport in the encapsulant, superstrate or substrate, hot carriers in the cell, redistribution of charges that degrade the active layer of the cell, failure of adhesion at interfaces, and corrosion of module components. These degradation mechanisms associated with the high voltage have been labeled potential-induced degradation, polarization, electrolytic corrosion, and electrochemical corrosion.  They are most active in wet or damp environments, and in environments prone to soiling of modules with conductive, acidic, caustic, or ionic species.  In the field, modules using crystalline silicon cells have been observed to degrade in positive as well as negative polarity strings depending on the cell construction and module materials and design.  The testing in this standard therefore is designed to
evaluate the effects of stress of both polarities for modules that may be operated in either polarity according to the ma nufacturer’s specifications.
The object of this test sequence is two-fold
(1) define a common test for evaluating crystalline silicon PV module
durability to system voltage stress
(2) define test levels applied to modules, as far as is possible within
reasonable constraints of cost and time, to show the module is durable to stresses that the combination of system voltage, humidity, and
temperature exert up to the levels found in humid (Köppen Cfa) environments.
The actual durability of modules to system voltage stress will depend on the actual usage environment and the conditions under which they are operated.
2.  Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. In the case of any discrepancy between this document and those referenced, the text of this document will applied.
IEC 60068-2-78 Environmental testing –Part 2-78: Tests –Test Cab: Damp heat, steady state.
IEC 61215 Crystalline silicon terrestrial photovoltaic (PV) modules. Design qualification and type approval.
IEC 61730-2 Photovoltaic (PV) module safety qualification –Part 2: Requirements for testing.
3.  Samples
Two representative and identical samples for each polarity of the system voltage that is specified or allowed in the module documentation and one control sample shall be provided. Modules not explicitly requiring string connections with one terminal grounded must be tested in both polarities. The sample modules shall be constructed with the same process and design as the model type to be evaluated – it shall contain components including cells, encapsulant, backsheet, glass, and frame of
the same manufacturing process (process tool design and process conditions) as the model type to be evaluated.
Modules for qualification testing shall be taken at random from a production batch or batches, in accordance with the procedure given in IEC 60410. The modules shall have been manufactured from specified materials and components in accordance with the relevant drawings and process sheets and have been subjected to the manufacturer's normal inspection, quality control and production acceptance procedures. The modules shall be complete in every detail and shall be accompanied by the manufacturer's handling, mounting and connection instructions, including the maximum permissible system voltage. If modules to be tested are prototypes of a new design and not from production, this fact shall be noted in the test report.
When the modules to be tested are prototypes of a new design and not from production, this fact shall be noted in the test report (see Clause 7).
The test results relate only to the sample structure as tested. If a module manufacturer uses several sources for PV module components, tool designs, or differing process set points and tolerances, an additional pair of test samples are required for test for each construction permutation and for each po
larity. Samples shall be chosen in such a way that each material and component used is represented.
If the module documentation and the nameplate specify usage of the module in strings of only one voltage polarity with respect to earth ground, the number of modules selected for test shall be halved and stressed only in that specified polarity.
If the PV module is provided with or is specified for use with a specific means for grounding, then the grounding means shall be provided and considered a part of the test sample.
If the PV module is provided with or is specified for use with means for mounting, then the means for mounting shall be provided and considered a part of the test sample.
4.0  Marking
Each module shall carry the following clear and indelible markings:
–name, monogram or symbol of manufacturer;
–type or model number;
degrade–serial number;
–polarity of terminals or leads (colour coding is permissible);
–maximum system voltage for which the module is suitable.
–nominal and minimum values of maximum output power at STC after preconditioning, as specified by the manufacturer for the product type
The date and place of manufacture shall be marked on the module or be traceable from the serial number.
5.0  Pass Criteria
a) The degradation of maximum output power between initial and final power measurement does not exceed 5%;
b) There is no visual evidence of a major defect, as defined in Clause 7 of IEC 61215 and Clause 10.1.3 of IEC 61730-2;
c) The wet leakage current test requirements is met at the end of the test sequence;
d) The insulation test requirements are met at the beginning and the end of each sequence.
e) Specific requirements of the individual test components are met.
6.0  Test procedures
Tests included in Figure 1 must be performed in the specified order. Any changes and deviations shall be recorded and reported in details, as required in Clause 7, item l).
6.1 All modules, including the control, shall be exposed to sunlight (either real
or simulated) to a target irradiation level of 5 kWhm–2 up to a maximum of
20 kWhm–2while open-circuited in accordance with Clause 5 of IEC
61215.
6.2 Perform IEC 61215 Clause 10.1 and IEC 61730-2 MST 01 Visual
Inspections
6.3 Perform IEC 61215  Clause 10.2 maximum power determination
6.4 Perform IEC 61215  Clause 10.3 insulation  test
6.5 Perform IEC 61730-2 ground continuity test MST 13 if the module has
exposed conductive parts.
6.6 Apply voltage stress to modules in damp heat environment
6.6.1 Apparatus. DC high-voltage power source, with current limitation,
capable of applying the maximum system voltage in the designated
polarity of the module
6.6.2 Stress levels/severities.
The following conditions shall be applied:
Chamber air temperature 60 °C ± 2°C,
Chamber relative humidity 85 % ± 5 % RH,
Test duration 96 h dwell at above stated temperature and relative
humidity,
Voltage: module rated system voltage and polarities.
The test shall be carried out within a damp heat chamber in accordance with IEC 60068-2-78; however, this document shall supersede where conditions and specifications differ.
6.6.3 Procedure
a. The module shall be placed into an environmental chamber with a non-
porous electrically insulating mounting material. Modules shall be
placed by default with the face in any upright position; however, this
placement may be changed if it is helpful to achieve the module
documentation or nameplate mounting or grounding instructions
Note: Insulator mounts are used to prevent alternative paths for leakage current between the biased active circuit and the
manufacturers intended ground points, if any are provided, and for the
safety of personnel and equipment. The insulation of the individual
modules from each other may also be required to control the path to ground.
b. Positive and negative electrical terminal wires (leads, tags, studs,
screws, connectors) shall be connected to one another and to the high voltage terminal of the power supply with insulated wire.
c. For continuous metallic frames encasing the perimeter of the module,
the ground terminal of the high voltage power supply shall be connected with an insulated wire terminated with a crimped-on ring terminal attached with a stainless steel nut, bolt and star washer to a module grounding point of the module. Thin layer coatings on the metallic frame shall be removed by abrasion to achieve metal-to-metal contact between the connector and the module frame.  In the
case of modules with frames that are not continuous or compliant with IEC 61730 MST 13, non-metallic frames, and metallic frames with insulating surfaces that cannot be reasonably penetrated anywhere by abrasion, all module mounting points available on the module shall be connected and fixed at that those points of attachment to the ground terminal of the high voltage power supply with insulated wire terminated with crimped-on screw connector and stainless steel washers in contact with the module.  In the case that the PV module is provided or is specified for use with a specific means for grounding, then that method of grounding shall be implemented to the extent possible.
d. If (1) the PV module is provided or is specified for use with means for
mounting and (2) the module is designed and specified not to be connected to ground, then such method of mounting the module shall be implemented to the extent possible. The base of that structure designed to be mounted to a building structure or on the ground shall be thoroughly grounded and connected to the ground terminal of the high voltage power supply during the course of the test.
e. Stresses are applied in chamber according to Clause 6.6.2. The
specified voltage will be applied at a rate of 50 to 500 V/s at the start of the ramp between ambient c
ondition and the stress level. During ramp up from ambient to the temperature specified in Clause 6.6.2, the chamber air temperature change rate shall be within 30 and 60°C/h.
Relative humidity shall be maintained between 45% and 85% during the ramp.
f. For the cooling phase to ambient, the temperature change rate shall be
within 30 and 60°C/h.  Relative humidity shall be maintained between 45% and 85% during the ramp. The specified applied voltage will be ramped to 0 V at a rate of 50 to 500 V/s when the chamber air temperature reaches 25°C.
Note:  at no time should the humidity be condensing while voltage is being applied.

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