IEC TS 62804-2:2022

Photovoltaic (PV) modules - Test methods for the detection of potential-induced degradation - Part 2: Thin-film

IEC TS 62804-2:2022 defines apparatus and procedures to test and evaluate the durability of photovoltaic (PV) modules to power loss by the effects of high voltage stress in a damp heat environment, referred to as potential-induced degradation (PID). This document defines a test method that compares the coulomb transfer between the active cell circuit and ground through the module packaging under voltage stress during accelerated stress testing with the coulomb transfer during outdoor testing to determine an acceleration factor for the PID.
This document tests for the degradation mechanisms involving mobile ions influencing the electric field over the semiconductor absorber layer or electronically interacting with the films such that module power is affected.

General Information

• Status: Published
• Publication Date: 28-Mar-2022
• ICS: 27.160 - Solar energy engineering
• Technical Committee: TC 82 - Solar photovoltaic energy systems
• Drafting Committee: WG 2 - TC 82/WG 2
• Current Stage: PPUB - Publication issued
• Start Date: 29-Mar-2022
• Completion Date: 28-Apr-2022

Overview

IEC TS 62804-2:2022 - "Photovoltaic (PV) modules - Test methods for the detection of potential‑induced degradation - Part 2: Thin‑film" defines standardized apparatus and procedures to detect and evaluate potential‑induced degradation (PID) in thin‑film PV modules. The technical specification focuses on PID driven by high voltage stress in damp heat environments and establishes methods to compare coulomb transfer (charge moved between the cell circuit and ground through module packaging) measured during accelerated laboratory tests and outdoor exposure to determine an acceleration factor for PID.

Key topics and technical requirements

• Scope and applicability: Test methods tailored for thin‑film modules, especially those with moisture‑sensitive components or moisture‑barrier encapsulation.
• Test types:
  • Outdoor measurements: Procedures and apparatus for field monitoring of coulomb transfer and leakage currents under system voltage stress.
  • Accelerated chamber testing: Environmental chamber procedures (damp heat, voltage bias, optional light or current bias) to reproduce PID mechanisms in a controlled, accelerated manner.
• Coulomb‑based acceleration factor: Comparison method that uses cumulative charge transfer during accelerated tests versus outdoor exposure to estimate acceleration.
• Polarity considerations: Tests for both voltage polarities where applicable, recognizing that some failure mechanisms are polarity‑dependent.
• Moisture barrier assessment: Annex A normative procedure to evaluate moisture ingress sensitivity; essential because compromised barriers can invalidate chamber acceleration results.
• Measurement and reporting: Requirements for apparatus configuration, leakage current measurement, optional monitoring, test conditions, and detailed test reporting.

Practical applications and users

• PV module manufacturers: Use for product development, PID mitigation design validation, and quality assurance of thin‑film modules.
• Independent test laboratories and certification bodies: Adopt standardized methods for PID detection, comparative testing, and issuing test reports for compliance or qualification.
• System designers and asset owners: Evaluate module durability under high system voltages in humid or soiled environments to inform component selection and O&M strategies.
• Researchers: Study PID mechanisms in thin‑film technologies, develop improved encapsulation, and quantify acceleration factors for long‑term performance projection.

Related standards and keywords

• Related IEC documents: IEC TS 62804‑1:2015 (crystalline silicon PID methods), IEC TS 62804‑1‑1:2020 (delamination), and IEC 61215‑2:2021 (includes a PID test variant).
• SEO keywords to find this content: IEC TS 62804-2:2022, potential‑induced degradation, PID thin‑film, PV module testing, coulomb transfer, damp heat, environmental chamber, PID acceleration factor, moisture barrier testing.

Standards Content (Sample)

IEC TS 62804-2 ®
Edition 1.0 2022-03
TECHNICAL
SPECIFICATION
colour
inside
Photovoltaic (PV) modules – Test methods for the detection of potential-induced
degradation –
Part 2: Thin-film
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IEC TS 62804-2 ®
Edition 1.0 2022-03
TECHNICAL
SPECIFICATION
colour
inside
Photovoltaic (PV) modules – Test methods for the detection of potential-

induced degradation –
Part 2: Thin-film
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-1093-6

– 2 – IEC TS 62804-2:2022  IEC 2022
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 10
4 Samples . 10
5 Tests . 11
5.1 General . 11
5.2 Test procedures – Outdoor measurements . 12
5.2.1 General . 12
5.2.2 Apparatus . 12
5.2.3 Optional monitoring . 15
5.2.4 Test conditions . 16
5.2.5 Procedure . 16
5.2.6 Acceleration by elevated system voltage testing outdoors . 19
5.3 Test procedures – Accelerated testing in environmental chamber . 21
5.3.1 General . 21
5.3.2 Test of modules in the dark and unpowered state . 22
5.3.3 Testing in chamber with light bias or current . 29
5.3.4 Acceleration factor determination—coulomb basis . 36
6 Test report . 37
Annex A (normative) Evaluation for moisture ingress sensitivity . 40
A.1 General . 40
A.2 Procedure . 40
A.3 Evaluation . 41
Annex B (informative) Dew point and required chamber relative humidity (RH)
setpoints depending on temperature difference between module and the chamber air . 43
Bibliography . 44

Figure 1 – Circuit suitable for electrical loading, application of system voltage bias and
evaluation of leakage current from the module on the ground return-side . 14
Figure 2 – Module mounting configuration for isolation and measurement of current
transfer to ground . 15
Figure 3 – Circuit suitable for electrical loading, application of system voltage bias and
evaluation of leakage current from the module . 15
Figure 4 – Test flow for performing PID tests in the field associated with procedures
described in 5.2.2 to 5.2.5 for evaluation of coulombic transfer from the cell circuit of
the module to earth . 17
Figure 5 – PID test flow for performing voltage stress test with module dark and
unpowered . 23
Figure 6 – Apparatus for applying system voltage bias (Vsys) to a PV module in an
environmental chamber . 25
Figure 7 – Example test time-temperature-humidity-voltage profile for application of
stress in an environmental chamber . 27
Figure 8 – Schematic for isolated power supply for application of forward bias voltage
(V ) . 30
fwd
Figure 9 – Schematic for application of system voltage (Vsys) bias on test module on
normally grounded parts . 31
Figure 10 – Apparatus for applying system voltage bias (Vsys) to a PV module in an
environmental chamber under light bias . 32
Figure 11 – PID test flow for modules placed under voltage stress and with light bias
or dark forward bias voltage . 33
Figure A.1 – Test flow for modules to detect and evaluate moisture ingress on PID
rate . 41

Table 1 – General schema of test procedures . 12
Table 2 – PID chamber test report table (example) (Variables are given in 5.3.2.3.3.7
and 5.3.4.1) . 38
Table 3 – PID chamber recovery test report table (example) (Variables are given in
5.3.3.4) . 38
Table B.1 – Dew point and required chamber relative humidity (RH) setpoints
depending on temperature difference between module and the chamber air . 43

– 4 – IEC TS 62804-2:2022  IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC (PV) MODULES – TEST METHODS FOR
THE DETECTION OF POTENTIAL-INDUCED DEGRADATION –

Part 2: Thin-film
FOREWORD
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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC TS 62804-2 has been prepared by IEC technical committee 82: Solar photovoltaic energy
systems. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
82/1958/DTS 82/2001A/RVDTS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.
A list of all parts in the IEC 62804 series, published under the general title Photovoltaic (PV)
modules – Test methods for the detection of potential-induced degradation, can be found on
the IEC website.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
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The committee has decided that the contents of this document will remain unchanged until the
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specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
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contents. Users should therefore print this document using a colour printer.

– 6 – IEC TS 62804-2:2022  IEC 2022
INTRODUCTION
Potential-induced degradation (PID) refers to any PV module degradation that is caused by the
stress of an electric potential between the active cell circuit and the external surfaces or parts
of the PV module.
The applied stresses, with system voltage being the principal factor in IEC 62804 series
documents, manifest themselves in different degradation modes that depend in part on the
module technology. Therefore, a series of technical specifications is being developed to define
PID tests for different PV module technologies and differing PID modes.
IEC TS 62804-1:2015, Photovoltaic (PV) modules – Test methods for the detection of potential-
induced degradation – Part 1: Crystalline silicon defines test methods for evaluating power loss
by PID in crystalline silicon PV modules.
IEC TS 62804-1-1:2020, Photovoltaic (PV) modules – Test methods for the detection of potential-
induced degradation – Part 1-1: Crystalline silicon – Delamination defines a test method for
evaluating delamination by PID associated with electrochemical processes in crystalline silicon
PV modules.
This part of IEC 62804 defines test methods for evaluating power loss by PID in thin-film PV
modules with moisture sensitive components and those which use moisture barrier
encapsulation because of such sensitivity.
A future document will be required for evaluating corrosion and delamination associated with
electrochemical processes in thin-film PV modules and modules with moisture sensitive
components with moisture barrier packaging. Further documents in the series may be
introduced in the future for emerging module technologies, mechanisms, or evaluation methods.
In addition to the IEC 62804 series, IEC 61215-2:2021 contains a PID test (MQT 21) with
methods and severities from IEC TS 62804-1: 2015 method (a) with modifications to avoid some
recognized test-specific degradation and polarization for application to various flat plate module
types. The PID test method in IEC 61215-2:2021 is shorter and simpler than those given in this
document.
Voltage potential that exists between the active circuit and the module surfaces directly or
indirectly connected to earth 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 or its surfaces, failure of adhesion at
interfaces, and corrosion of module components. Along with the factor of system voltage, these
processes are most active in wet or damp environments, and in environments prone to soiling
of modules with conductive, acidic, caustic, or ionic species that lead to increased conduction
on the module surfaces. Certain failure mechanisms may only be active with the module
electrically biased in one polarity depending on the cell construction, module materials, and
design. The testing in this document therefore specifies the evaluation of the effects of voltage
stress in both polarities for modules that may be operated in either polarity, or when applicable,
uniquely in the polarity defined by the manufacturer’s documented specifications and
installation instructions.
Considering this document is applicable to modules with a functional moisture barrier packaging,
a procedure is provided in Annex A to evaluate the functionality of the moisture barrier for the
purposes of PID evaluation. If the moisture barrier is not sufficiently functional, the moisture
ingress is likely to affect (usually increase) PID rate during accelerated testing in the
environmental chamber and largely invalidate projections that this document provides about
PID rate in the field.
There are many module designs, which span crystalline silicon, compound semiconductor, thin-
film and tandem technologies. These can exhibit differing sensitivities of the absorber layer,
differing laminate constructions and interfaces, and different mounting types with differing
ability to resist charge transfer between the laminate and ground. Based on the great variability
in acceleration factor between use condition and test, which has been measured in one instance
involving a thin-film module technology to vary between one and two orders of magnitude with

the singular change of the edge clip material holding the module [1] , a unique stress level for
accelerated testing of all module types covered by this document is not given at this time.
Instead, a protocol for evaluating the acceleration factor for PID degradation of thin film modules
with respect to climate zones is provided. Use of the acceleration factor method is therefore
motivated because considerable variability in acceleration factor has been found depending on
the thin film product and mounting [1]. Whether the phenomenon is specific to thin film products
has not been clarified.
To overcome the significant variability, this document offers procedures for evaluating the
relative rate (or acceleration) of current transfer and degradation in the chamber versus the
field, which has been found useful for evaluating thin-film technologies in the absence of the
variable of moisture ingress into the module [2-6]. The user may therefore calculate the relative
PID resistance in the chamber condition versus the field condition which to better forecast the
power degradation rate by PID in the use. Using of rate of coulomb transfer in the field and
chamber as a basis provides a platform for comparison of test results. With the understanding
of how many coulombs are transferred in the use environment per year, one can project power
loss by PID for the desired number of years in the use environment based on the measured
coulombs transferred and any observed power loss by PID in the environmental chamber, in
the absence of moisture ingress and significant power recovery if the factor of system voltage
bias is removed.
Differing module constructions transfer PID-inducing current between the cells and ground
differently as a function of extent of moisture on the surfaces and temperature. The charge
density profile of transferred coulombs across the module will vary as a function of temperature
and humidity on the module surfaces as well. To maintain representative temperatures and
humilities for the PID testing, an option to accelerate the PID testing with the factor of elevated
system voltage in the field is additionally offered in this document.
Thin-film modules may exhibit metastability and other effects, whereby the history of exposure
to factors including light and heat may influence power performance either reversibly or
irreversibly. Without attention to this, such effects can hinder the quantification of the PID
incurred in the PID stress test. To normalize for such extraneous power changes exhibited by
modules in this PID test, the power performance after a PID chamber stress test is examined
relative to any change in power of in-chamber control modules undergoing the same stress
regime excluding the factor of system voltage stress.
This document also includes options to mitigate power changes due other test-specific effects
resulting from the unrepresentative conditions of heat and darkness that IEC 61215-2 MQT 19,
Stabilization, alone will not correct. These options include application of light or forward bias
voltage before and during the PID stress test. This document additionally contains a light and
heat exposure sequence that may be optionally applied to the modules after the PID stress test
to obtain the power performance of the module after such recovery procedure. During
IEC 61215-2 MQT 19, Stabilization, the factor of system voltage is not applied, a condition that
does not normally occur in the field.
The voltage levels applied in testing are the modules’ nameplate-rated system voltage. This
results in a voltage level that is typically above that experienced in the field because:
a) voltage levels are reduced due to their elevated operating temperature under sunlight,
b) they are operated at maximum power and therefore a lower maximum power voltage than
system voltage that is associated with the open-circuit voltage of the modules,
c) most of the modules are not at the extremes of the series string, and
d) due to safety factors or other design criteria, modules may be in strings below the module
rated system voltage.
Numbers in square brackets refer to the Bibliography.

– 8 – IEC TS 62804-2:2022  IEC 2022
However, modules connected in series strings that are in open circuit and uncontrolled by a
maximum power tracker, for reasons including being disconnected from their load, may
experience uncontrolled and significantly higher voltages than experienced by the modules
maintained at the maximum power point even though system installation standards require
voltage levels to be below system voltage. The voltage levels applied in testing is thus the
modules’ nameplate-rated system voltage. This provides a small element of acceleration over
typical use conditions, while maintaining a system voltage level that modules may actually
experience in the field.
It is known that variability in manufacturing processes can affect the susceptibility of modules
to system voltage stress. Periodic retesting of modules by the test protocols contained herein
with internal quality assurance programs such as given in IEC 62941, and with external audits,
will aid in verifying not only the durability of the design of the module to system voltage stress,
but also the effects of any variability of the materials and manufacturing processes. Due to the
extended length of time required to perform the tests contained herein, it is anticipated that
module manufacturers themselves will apply them.

PHOTOVOLTAIC (PV) MODULES – TEST METHODS FOR
THE DETECTION OF POTENTIAL-INDUCED DEGRADATION –

Part 2: Thin-film
1 Scope
This part of IEC 62804 defines apparatus and procedures to test and evaluate the durability of
photovoltaic (PV) modules to power loss by the effects of high voltage stress in a damp heat
environment, referred to as potential-induced degradation (PID). This document defines a test
method that compares the coulomb transfer between the active cell circuit and ground through
the module packaging under voltage stress during accelerated stress testing with the coulomb
transfer during outdoor testing to determine an acceleration factor for the PID. It is designed
for thin-film PV modules and modules containing moisture sensitive films protected by vapour
barrier packaging, principally with one or two glass surfaces. This document tests for the
degradation mechanisms involving mobile ions influencing the electric field over the
semiconductor absorber layer or electronically interacting with the films such that module power
is affected. This document does not specifically test for electrochemical corrosion or
delamination associated with application of system voltage. This document does not contain
pass or fail criteria and it is not intended for design qualification.
The procedures contained herein, with testing in chamber in combination with in the field or
testing in the field alone are intended for use when it is desired to quantify the acceleration
provided by the applied stress levels over regular use conditions in the natural environment
using coulombs transferred between the module and ground as the index for damage incurred
by PID. The procedures for quantifying the acceleration are not recommended when coulombs
transferred are not an indicator of damage by PID to the module. The procedures are not directly
applicable when moisture ingress into the module laminate occurs affecting PID rate, and to the
extent that there is power recovery when the factor of system voltage bias is removed after
correctly applying the procedures herein, within the period of testing.
The protocols given herein give results according to the chamber stress levels applied and the
module grounding configuration used in the test. Because the stress method of testing in an
environmental chamber employs a non-condensing humidity level to serve as a conductive
pathway to electrical ground, it frequently applies relatively less stress toward the centre of the
module face. Also, the method can evaluate the effectiveness of some construction methods to
mitigate PID; for example, the use of rear rail mounts, edge clips, and insulating frames. The
test, however, does not include all the factors existing in the natural environment that can affect
the PID rate. The actual durability of modules to system voltage stress depends on the actual
environmental conditions under which they are operated.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
IEC 60068-2-78:2012, Environmental testing – Part 2-78: Tests – Test Cab: Damp heat, steady
state
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60721-2-1:2013, Classification of environmental conditions – Part 2-1: Environmental
conditions appearing in nature – Temperature and humidity
IEC 60904-1, Photovoltaic devices – Part 1: Measurement of photovoltaic current-voltage
characteristics
– 10 – IEC TS 62804-2:2022  IEC 2022
IEC 60904-3, Photovoltaic devices – Part 3: Measurement principles for terrestrial photovoltaic
(PV) solar devices with reference spectral irradiance data
IEC TS 60904-13, Photovoltaic devices – Part 13: Electroluminescence of photovoltaic modules
IEC 61215-1, Terrestrial photovoltaic (PV) modules – Design qualification and type approval –
Part 1: Test requirements
IEC 61215-2:2021, Terrestrial photovoltaic (PV) modules - Design qualification and type
approval - Part 2: Test procedures
IEC 61724-1, Photovoltaic system performance – Part 1: Monitoring
IEC 61730-1, Photovoltaic (PV) module safety qualification – Part 1: Requirements for
construction
IEC 61730-2, Photovoltaic (PV) module safety qualification – Part 2: Requirements for testing
IEC TS 61836, Solar photovoltaic energy systems – Terms, definitions and symbols
IEC 61853-1:2011, Photovoltaic (PV) module performance testing and energy rating – Part 1:
Irradiance and temperature performance measurements and power rating
IEC TS 62804-1:2015, Photovoltaic (PV) modules – Test methods for the detection of potential-
induced degradation – Part 1: Crystalline silicon
IEC TS 62804-1-1:2020, Photovoltaic (PV) modules – Test methods for the detection of
potential-induced degradation – Part 1-1: Crystalline silicon – Delamination
IEC 62941, Terrestrial photovoltaic (PV) modules – Quality system for PV module
manufacturing
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC TS 61836 apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
4 Samples
All samples for test shall be of representative and identical materials, construction process, and
characteristics. For application of the tests in either 5.2 or 5.3, procure two samples for each
polarity of the system voltage that is specified or allowed in the module documentation, along
with two samples to be used as control modules. If the polarity of the modules connected into
module strings is not specified, two replicas for each polarity are required. If the module
documentation and the nameplate specify usage of the module in strings of only one voltage
polarity with respect to ground (one terminal of the module string tied to ground), then the
modules selected for testing under system voltage bias shall be stressed only in that specified
polarity. Procure double the number of representative and identical samples for performing the
tests in both 5.2 and 5.3 or testing according to 5.2.6. If additional certainty is sought, for
example, if there are concerns of partial shading of modules leading to localized damage of the
absorber layer, the number of modules for test and for use as controls may be increased.
Sample types chosen for application of this document shall be protected by functioning vapour
barrier of the module encapsulation. Annex A is given for the evaluation of effective moisture
barrier of the module type for the purposes of PID evaluation.
The PV module samples 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 PV modules shall be complete in every detail and shall be accompanied by
the manufacturer’s handling, mounting, and connection instructions. When the PV 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 6).
When submitted to another party for testing, the submitted modules shall be complete and
accompanied by the manufacturer's handling, mounting and connection instructions, including
the maximum permissible system voltage. Markings on the module shall conform to the
requirements of IEC 61215-1 and IEC 61730-1.
The test results apply only to the module construction tested. To evaluate modules using more
than one component source, module design, cell design, process design, or differing process
set points and tolerances, then a set of modules for each permutation shall be procured for
testing. Changes of the junction box, cables, and connectors do not indicate retest unless
modifications to the module laminate for any electrical penetration of conductors through it are
made. In cases where the cell, module, or materials process variability or tolerances are large,
testing of more than two samples per polarity will be useful for improving the confidence in the
results.
If the PV module is provided with and is specified for use with a specific means for grounding,
then the grounding means shall be included and considered a part of the test sample. If the PV
module is provided with and is specified for use with means for mounting that could additionally
influence the module grounding, then the means for mounting shall be included and considered
a part of the test sample.
5 Tests
5.1 General
Measurement of current transfer between the cell circuits of modules and ground in the natural
environment is employed for evaluating the resistance of the particular design to system voltage
stress in the given environment. Tests are grouped into methods that either:
a) evaluate the relative rate (or acceleration) of current transfer and degradation in the
chamber versus the field, or
b) use of modules in the field with increased system voltage applied as an accelerant.
The schema of test procedures is shown in Table 1. In view of the potential for metastabilities
and test-specific artifacts that may vary among module types, in conjunction with Table 1,
consult with the manufacturer for information, guidance, and recommendations for selecting appropriate
test procedures.
– 12 – IEC TS 62804-2:2022  IEC 2022
Table 1 – General schema of test procedures
Environmental chamber testing procedure – Outdoor testing (only) procedure using elevated
chamber tests for leakage current determination and system voltage bias
degradation extent, for use in combination with the
outdoor testing procedure below. Select from:
For use to achieve testing with representative field
conditions of temperature and moisture, which affects
5.3.2: Test of modules in the dark and unpowered state, the electric field over the module surface, and the
for use when extent of PID is independent of illumination. See:
illumination or photocurrent.
5.2.6 Acceleration by elevated system voltage testing
-or- outdoor. This includes methods for evaluation of
linearity of leakage current, a requirement for
implementation of this method
5.3.3: Testing in chamber with current or light bias for
use when, respectively, forward bias current can
sufficiently simulate the effects of illumination, or (references 5.2.2 through 5.2.5 procedures and
illumination itself is required because of PID-sensitivity measurement methods)
to these factors.
Outdoor testing procedure – outdoor tests for leakage
current determination: 5.2.2 through 5.2.5.
For use in combination with an environmental chamber
testing procedure above.
On the left are the environmental chamber test procedures for use in combination with the outdoor testing
procedure for leakage current determination in the field. On the right is the alternative outdoor testing (only)
procedure that uses elevated system voltage bias to achieve acceleration.

5.2 Test procedures – Outdoor measurements
5.2.1 General
The test procedures described in 5.2.2 to 5.2.5 are for outdoor measurements done in
conjunction with chamber testing for determination of acceleration in chamber over the outdoor
environment. Comparison of the current leaking between the active cell circuit and ground in
the field to that in accelerated testing in chamber as obtained using the test procedures given
in 5.3 is used to quantify the acceleration provided by the accelerated stress testing over that
of the natural environment.
A method using uniquely outdoor measurements with increased system voltage to provide
acceleration is also given; for this, see 5.2.6.
NOTE Magnitude of leakage current itself is not a universal indicator of susceptibility or damage to the module. It
is however useful as relative indicator of rate of some PID mechanisms when comparing the PID stress on a given
design over various environments.
This subclause gives apparatus including two basic configurations for applying system voltage
bias, requirements for monitoring current transfer, and methods for mounting modules. Such
outdoor tests entail apparatus not within usual norms and constraints for PV systems, and as a
result, handling and access shall be limited to trained electrical workers.
Module characterization includes module diagnostics (electroluminescence, maximum power
determination at low light) as optional procedures which will aid in identifying the nature of any
power loss of the modules incurred over the duration of the testing.
5.2.2 Apparatus
5.2.2.1 Mounting
Two mounting angles are defined as follows. The configuration or configurations used in this
test may be chosen in view of the following considerations.
a) Horizontal: for modules that may be mounted horizontally in the field. This configuration is
generally considered most stressful because water may accumulate on the superstrate.
b) Latitude tilt: for modules whereby mounting them horizontally voids manufacturer warranty.

Module mounting shall be ground mount using an open rack (with free air flow around the
modules) and on ground (e.g., soil, sand, dirt) that is level (not concrete or asphalt) with an
elevation of 0,75 m to 1,00 m from ground to lowest point of the module to achieve
representative transpiration of humidity from the ground.
5.2.2.2 Electrical connections
Insulated wire rated for the intended test voltage; module manufacturer-specified or stainless-
steel hardware for electrical connection to the modules.
5.2.2.3 Method for measuring irradiance
A method for measuring global horizontal irradiance is required. Implement and mount a Class
B or Class A irradiance sensor for measuring global horizontal irradiance according to
IEC 61724-1 placed within 25,0 m of the PV modules be analysed.
5.2.2.4 Voltage bias
A method for applying module nameplate rated system voltage with tolerance of 5 % to the cell
. In conjunction
circuit of the module when global horizontal irradiance is greater than 10 W/m
with the requirements for number of samples indicated in Clause 4, the apparatus for controlling
voltage bias to modules shall include connections:
a) at nameplate rated system voltage for two modules for each polarity to be measured biased;
b) with one of the polarities connected to ground, a configuration where all modules to be
tested outdoors are unbiased and have one polarity connected to ground
• for two outdoor control modules
• for all the modules undergoing the outdoor preconditioning step (5.2.5.3).
An array of PV modules may be used for as a source for application of voltage bias if they are
measured to apply voltage bias to modules under test in a manner that meets the above
requirements of this subclause.
5.2.2.5 Method for maintaining modules mounted outdoors at maximum power
This may include load resistors, electronic maximum power trackers, or electronic loads, such
that the module power is maintained within at P optimized in the range of 200 W/m to 800
max
W/m irradiance on the plane of the module. If performing the test at low light per 5.2.6.3.2.3,
for the selected irradiance level.
then select the load to maintain within 25 % of Pmax
5.2.2.6 Method for current-voltage measurements
Method for measuring current-voltage measurements of the modules under test as described in
IEC 60904-1.
5.2.2.7 Measuring voltage bias and current transfer to ground
5.2.2.7.1 General
Requirements for measuring applied voltage and current transfer to ground are described. The
voltage measurement shall be capable of resolving the voltage bias on the module or modules
within 2,5 V. The current measurement shall be capable of resolving current from the modules
-8
under test with resolution of 1 x 10 A. The voltage bias and current measurement interval
associated with each module shall be 1 min or less. Measurement of current to ground on
unbiased modules is optional. The upper range of current measurement will be larger as system
voltages and module size increases.
-4
NOTE 1 x 10 A upper limit for current measurement between module and ground is found sufficient for presently
shipping commercial modules in most environments.
Example circuits for electrical loading, application of system voltage bias, and evaluation of the
current transfer between module and ground is shown in Figure 1 and Figure 3. The example
circuits may require modification to achieve the requirements of this document, depending on
the module type.
Optionally, sensors and data logger for recording the environmental conditions (air temperature,
relative humidity), module temperatures to an accuracy of ± 1,0 °C, of modules in 1 min or

– 14 – IEC TS 62804-2:2022  IEC 2022
lesser intervals may be employed. Temperature sensors and their wires mounted to the module
shall be electrically insulating at all applied temperatures and humidity levels so that they do
not impact the voltage bias and leakage current that is measured from the module.
5.2.2.7.2 Monitoring the ground return current
Figure 1 shows a circuit for monitoring current transfer, where current is measured on the
ground return.
In this configuration, isolated mounting as shown in Figure 1 is required. Here, the resistor R4
under solar irradiance of between 200 W/m² and 800 W/m².
shall be optimized to achieve Pmpp
Alternatively, a power optimizer to maintain Pmpp under an arbitrary solar irradiance level may
be implemented. High resistor values resulting from this range are sometimes selected to
reduce effects of shading damage. To make the test as representative as possible, choose
resistor values that lead to temperatures, leakage current, and times of wetness that mimic the
module under test in an array connected to a power optimizers (maximum power point trackers)
of a PV inverter.
Key
PV Photovoltaic module with grounding points or grounded mounting points connected to coaxial wire
C1, C2 Ceramic capacitor
R1 Metal film resistor
R2 Metal film resistor
R3 Metal film resistor
R4 Load for maintaining module within maximum power specified by this document
GDT Gaz discharge tube (Neon Lamp), overvoltage protection
F1 Fuse
HV System voltage bias supply
Equipment shall be selected for anticipated power applied.
Figure 1 – Circuit suitable for electrical loading, application of system voltage bias and
evaluation of leakage current from the
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