IEC 61853-2:2016

• Abstract:

  IEC 61853-2:2016 defines measurement procedures for measuring the effects of angle of incidence of the irradiance on the output power of the device, determines the operating temperature of a module for a given set of ambient and mounting conditions and measure spectral responsivity of the module. A second purpose is to provide a characteristic set of parameters which will be useful for detailed energy predictions. The described measurements are required as inputs into the module energy rating procedure described in IEC 61853-3.

• Status: Published
• Publication Date: 05-Sep-2016
• 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: 06-Sep-2016
• Completion Date: 30-Sep-2016

• Revised: IEC 61853-2:2026 - Photovoltaic (PV) module performance testing and energy rating - Part 2: Spectral responsivity, incidence angle and nominal module operating temperature measurements
• Effective Date: 05-Sep-2023

Overview

IEC 61853-2:2016 is an international standard developed by the International Electrotechnical Commission (IEC) within the IEC 61853 series. This standard specifies measurement procedures for evaluating the spectral responsivity, incidence angle effects, and operating temperature of photovoltaic (PV) modules. These tests are crucial for determining the real-world energy output of PV modules, considering varying climatic and installation conditions. IEC 61853-2 provides standardized methods to produce a characteristic set of parameters that support detailed PV module energy predictions and are required inputs for PV module energy rating calculations in IEC 61853-3.

Key Topics

• Spectral Responsivity: Procedures for measuring how PV module output responds to different wavelengths of sunlight, impacting current production under varying spectral conditions.
• Incidence Angle Effects: Methods for determining how the angle of sunlight striking the module surface affects its output power, relevant for modules that operate at non-optimal tilt or azimuth angles.
• Module Operating Temperature: Guidelines for measuring the operating temperature of PV modules in specific ambient and mounting scenarios, as temperature influences module performance.
• Standardized Test Procedures:
  • Indoor and outdoor approaches for measuring incidence angle effects.
  • Use of PV reference devices, data acquisition systems, and temperature sensors.
  • Requirements for preconditioning and visual inspection prior to testing.
• Reporting Requirements: Specifies test report contents, including module identification, test methods used, environmental conditions, measurement results, uncertainties, and compliance aspects.

Applications

IEC 61853-2 provides practical value for several stakeholders in the photovoltaic industry:

• Manufacturers: Supplies a reliable framework to characterize new module designs under varying climate and installation conditions, aiding in product development and comparison.
• Testing Laboratories: Ensures consistency and repeatability in PV module performance evaluation, enabling credible third-party certification and laboratory comparisons.
• System Integrators and Designers: Offers key performance metrics, such as spectral responsivity curves and incidence angle corrections, essential for accurate energy yield modeling and design optimization.
• Investors and Insurers: Delivers detailed, standardized energy output data calculated under real-world conditions, reducing the risk associated with solar project investments.
• Standardized Energy Rating Inputs: The results of IEC 61853-2 are mandatory for the subsequent calculation of energy ratings as described in IEC 61853-3, providing the technical basis for standardized PV module energy yield predictions.

Related Standards

• IEC 61853-1: Photovoltaic module power rating procedures under various irradiance and temperature conditions.
• IEC 61853-3: Energy rating calculation methodology for PV modules, requiring inputs from IEC 61853-2 measurements.
• IEC 61853-4: Provides reference climatic profiles to support standardized energy yield assessments.
• IEC 60904 Series: Covers fundamental PV device testing, including current-voltage characteristics, spectral responsivity, and simulator requirements.
• IEC 61215 and IEC 61646: Define qualification and design approval for crystalline and thin-film terrestrial PV modules.

Summary

IEC 61853-2:2016 enhances the reliability of PV module performance by standardizing the measurement of spectral responsivity, incidence angle effects, and operating temperature. This standard supports accurate energy predictions throughout a PV module's lifecycle, fostering confidence in system modeling, performance comparison, and international market access. By aligning laboratory practices and reporting procedures, IEC 61853-2 plays a vital role in advancing PV module certification and the global solar energy industry.

IEC 61853-2 ®
Edition 1.0 2016-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Photovoltaic (PV) module performance testing and energy rating –
Part 2: Spectral responsivity, incidence angle and module operating temperature
measurements
Essais de performance et caractéristiques assignées d'énergie des modules
photovoltaïques (PV) –
Partie 2: Mesurages de réponse spectrale, d'angle d'incidence et de température
de fonctionnement des modules
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IEC 61853-2 ®
Edition 1.0 2016-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Photovoltaic (PV) module performance testing and energy rating –

Part 2: Spectral responsivity, incidence angle and module operating temperature

measurements
Essais de performance et caractéristiques assignées d'énergie des modules

photovoltaïques (PV) –
Partie 2: Mesurages de réponse spectrale, d'angle d'incidence et de température

de fonctionnement des modules
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.160 ISBN 978-2-8322-3584-3

– 2 – IEC 61853-2:2016 © IEC 2016
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 7
2 Normative references. 7
3 Sampling . 8
4 Testing . 8
5 Report . 9
6 Procedure for spectral responsivity measurement . 10
7 Procedure for the measurement of incidence angle effects . 10
7.1 Purpose . 10
7.2 Indoor test method . 11
7.2.1 General . 11
7.2.2 Apparatus . 11
7.2.3 Set-up procedure . 12
7.2.4 Measurement procedure . 12
7.3 Outdoor test method . 13
7.3.1 General . 13
7.3.2 Apparatus . 13
7.3.3 Set-up procedure . 14
7.3.4 Measurement procedure . 15
7.4 Interpolation of angular transmission τ(θ) . 16
8 Methodology for determining coefficients for calculating module operating
temperature . 17
8.1 General . 17
8.2 Testing and data processing . 17
8.3 Apparatus . 17
8.4 Test module mounting . 18
8.5 Procedure . 18
8.6 Evaluation . 19

Figure 1 – Overview of the testing cycle to be carried out in IEC 61853-2 . 9
Figure 2 – Positions for measuring the temperature of the test module behind the cells . 13

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC (PV) MODULE
PERFORMANCE TESTING AND ENERGY RATING –

Part 2: Spectral responsivity, incidence angle and
module operating temperature measurements

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61853-2 has been prepared by IEC technical committee 82: Solar
photovoltaic energy systems.
The text of this standard is based on the following documents:
FDIS Report on voting
82/1133/FDIS 82/1156/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – IEC 61853-2:2016 © IEC 2016
A list of all parts in the IEC 61853 series, published under the general title Photovoltaic (PV)
module performance testing and energy rating, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
INTRODUCTION
Photovoltaic (PV) modules are typically rated at standard test conditions (STC) of 25 °C cell
–2
temperature, 1 000 W⋅m irradiance, and air mass (AM) 1.5 global (G) spectrum. However,
the PV modules in the field operate over a range of temperatures, irradiance, and spectra. To
accurately predict the energy production of the modules under various field conditions, it is
necessary to characterize the modules at a wide range of temperatures, irradiances, angles of
incidence, and spectra.
Recognizing this issue, IEC Technical Committee 82 Working Group 2 (TC 82/WG 2) has
developed an appropriate power and energy rating standard (IEC 61853). The first part of this
four-part standard requires the generation of a 23-element maximum power (P ) matrix at
max
four different temperatures and seven different irradiance levels. The P matrix can be
max
generated using an indoor solar simulator method or outdoor natural sunlight method. The
outdoor test method introduces little/no spectral mismatch error and is much less expensive
than the indoor test method because it avoids the use of very expensive solar simulators.
However, obtaining an accurate and repeatable P matrix using the outdoor method over
max
time (several months or years) would be extremely challenging.
This standard consists of four parts:
• IEC 61853-1: Irradiance and temperature performance measurements and power rating,
which describes requirements for evaluating PV module performance in terms of power
(watts) rating over a range of irradiances and temperatures;
• IEC 61853-2: Spectral responsivity, incidence angle, and module operating temperature
measurements, which describes test procedures for measuring the effect of varying angle
of incidence and sunlight spectra as well as the estimation of module temperature from
irradiance, ambient temperature, and wind speed;
• IEC 61853-3 : Energy rating of PV modules, which describes the calculations for PV
module energy (watt-hours) ratings; and
• IEC 61853-4 : Standard reference climatic profiles, which describes the standard time
periods and weather conditions that can be used for the energy rating calculations.
Included in the IEC 61853 series of standards are: test methods designed to map module
performance over a wide range of temperature and irradiance conditions (IEC 61853-1); test
methods to determine spectral responsivity, incidence angle effects and the module operating
temperature all as functions of ambient conditions (IEC 61853-2); methods for evaluating
instantaneous and integrated power and energy results including a method for stating these
results in the form of a numerical rating (IEC 61853-3); and definition of reference irradiance
and climatic profiles (IEC 61853-4).
IEC 61853-1 describes requirements for evaluating PV module performance in terms of power
(watts) rating over a range of irradiances and temperatures. IEC 61853-2 describes
procedures for measuring the performance effect of angle of incidence, the estimation of
module temperature from irradiance, ambient temperature and wind speed, and impact of
spectral responsivity on module performance. IEC 61853-3 describes the calculations of PV
module energy (watt-hours) ratings. IEC 61853-4 describes the standard time periods and
weather conditions that can be utilized for calculating energy ratings.

____________
Under preparation: Stage at the time of publication: IEC/ACDV 61853-3:2016.
Under preparation: Stage at the time of publication: IEC/ACDV 61853-4:2016.

– 6 – IEC 61853-2:2016 © IEC 2016
IEC published the first part of the standard in January 2011. This standard specifies the
performance measurements of PV modules at 23 different sets of temperature and irradiance
conditions, using either a solar simulator (indoor) or natural sunlight (outdoor). There are
many possible indoor and outdoor techniques, and this standard allows several of them.
Validation of these techniques for repeatability over time within the same laboratory and for
reproducibility among multiple laboratories is extremely important for the successful
implementation of this standard.

PHOTOVOLTAIC (PV) MODULE
PERFORMANCE TESTING AND ENERGY RATING –

Part 2: Spectral responsivity, incidence angle and
module operating temperature measurements

1 Scope
The IEC 61853 series establishes IEC requirements for evaluating PV module performance
based on power (watts), energy (watt-hours) and performance ratio (PR). It is written to be
applicable to all PV technologies, but may not work well for any technology where the module
performance changes with time (e.g. modules change their behaviour with light or thermal
exposure), or which experience significant non-linearities in any of their characteristics used
for the modelling.
The purpose of this part of IEC 61853 is to define measurement procedures for measuring the
effects of angle of incidence of the irradiance on the output power of the device, to determine
the operating temperature of a module for a given set of ambient and mounting conditions and
measure spectral responsivity of the module. A second purpose is to provide a characteristic
set of parameters which will be useful for detailed energy predictions. The described
measurements are required as inputs into the module energy rating procedure described in
IEC 61853-3.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60410 , Sampling plans and procedures for inspection by attributes
IEC 60891, Photovoltaic devices – Procedures for temperature and irradiance corrections to
measured I-V characteristics
IEC 60904-1, Photovoltaic devices – Part 1: Measurement of photovoltaic current-voltage
characteristics
IEC 60904-2, Photovoltaic devices – Part 2: Requirements for photovoltaic reference devices
IEC 60904-5, Photovoltaic devices – Part 5: Determination of equivalent cell temperature
(ECT) of photovoltaic (PV) devices by the open-circuit voltage method
IEC 60904-8, Photovoltaic devices – Part 8: Measurement of spectral responsivity of a
photovoltaic (PV) device
IEC 60904-9, Photovoltaic devices – Part 9: Solar simulator performance requirements
IEC 60904-10, Photovoltaic devices – Part 10: Methods of linearity measurement
____________
Withdrawn.
– 8 – IEC 61853-2:2016 © IEC 2016
IEC 61215 (all parts), Terrestrial photovoltaic (PV) modules – Design qualification and type
approval
IEC 61215-2, Terrestrial photovoltaic (PV) modules – Design qualification and type approval –
Part 2: Test procedures
IEC 61646, Thin-film terrestrial photovoltaic (PV) modules – Design qualification and type
approval
IEC 61853-1:2011, Photovoltaic (PV) module performance testing and energy rating – Part 1:
Irradiance and temperature performance measurements and power rating
ISO 9059, Solar energy – Calibration of field pyrheliometers by comparison to a reference
pyrheliometer
3 Sampling
For performance qualification testing, three modules shall be selected at random from a
production batch or batches in accordance with the procedure given in IEC 60410. The
modules shall be pre-conditioned in accordance with Clause 4 of this standard to assure the
stability of the power values. One module (or equivalent reference sample) shall be used for
each of the three tests, angle of incidence, spectral responsivity and thermal performance. A
single module may be supplied if the test is to be carried out serially or three modules need to
be supplied if it is to be carried out in parallel.
The modules shall have been manufactured from specified materials and components in
accordance with the relevant drawings and process sheets and shall have been subjected to
the manufacture’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 and final assembly instructions regarding the recommended
installation of any diodes, frames, brackets, etc.
When the DUTs (device under test) are prototypes of a new design and not from production,
this fact shall be noted in the test report (see Clause 5).
4 Testing
One of the modules, or representative samples, shall be subjected to each of the testing
procedures defined in Clauses 6 to 8, i.e. the procedure for spectral responsivity (see
Clause 6), angle of incidence (see Clause 7) and module operating temperature
measurements (see Clause 8). In carrying out the tests, the manufacturer’s handling,
cleaning, mounting and connection instructions shall be observed. This can be the same
module undergoing all tests sequentially or three distinct modules undergoing the
characterisation tests in parallel. It shall be noted in the test report if a single or different
modules have been used.
If the module under test is going to be used with a frame that covers the edges of the
superstrate, then each of the tests shall be performed with a similar frame in place.
Preconditioning – Before beginning the measurements, the device under test shall be
stabilized, as specified in IEC 61215 or IEC 61646.
Figure 1 shows an overview of the testing procedure to be conducted.

Preconditioning
Visual inspection
Max power
determination
8 – Determination
6 – Spectral 7 – Angle of
of operating
responsivity incidence
temperature
Visual inspection
Max power
determination
IEC
Figure 1 – Overview of the testing cycle to be carried out in IEC 61853-2
5 Report
Following completion of the procedure, a report of the performance tests, with measured
module characteristics shall be prepared. Each certificate or test report shall include at least
the following information:
a) a title;
b) name and address of the test laboratory and location where the calibration or tests were
carried out;
c) unique identification of the certification or report and of each page;
d) name and address of client, where appropriate;
e) description and identification of the item calibrated or tested;
f) characterization and condition of the calibration or test item;
g) date of receipt of test item and date(s) of calibration or test, where appropriate;
h) identification of calibration or test method used;
i) reference to sampling procedure, where relevant;
j) any deviations from, additions to or exclusions from the calibration or test method, and
any other information relevant to a specific calibration or test, such as environmental

– 10 – IEC 61853-2:2016 © IEC 2016
conditions, including the tilt angle of the module used during the temperature test (see
8.4.1) and limits to the field of view;
k) measurements, examinations and derived results of module incidence angle effects, its
operating temperature and its spectral responsivity. The report should indicate the method
used to deal with the diffuse light component for the measurement of angle of incidence
(see 7.3.4);
l) for non-symmetric optical modules, the tilt and azimuth directions have to be specified in a
drawing;
m) a statement of the estimated uncertainty of the calibration and test result (where relevant);
n) a signature and title, or equivalent identification of the person(s) accepting responsibility
for the content of the certificate or report, and the date of issue;
o) where relevant, a statement to the effect that the results relate only to the items calibrated
or tested;
p) a statement that the certificate or report shall not be reproduced except in full, without the
written approval of the laboratory.
6 Procedure for spectral responsivity measurement
The spectral responsivity of a PV module has an impact on the amount of current produced at
any given spectral irradiance. Normally it is not necessary to measure the spectral
responsivity at all possible values of irradiance and temperature that a module encounters
during outdoor operation. A single measurement should be sufficiently accurate for all
expected operating conditions. The need for this can be verified by checking the linearity of
short circuit conditions measured in IEC 61853-1. Should a non-linearity of I with respect to
sc
irradiance or temperature larger than 3 % be observed, further investigation might be
warranted to identify if the SR changes as a function of irradiance and temperature (If the
spectral responsivity of a particular module type is a function of irradiance or temperature,
this result fact should appear in the test report).
To measure the spectral responsivity, follow the procedure as laid out in IEC 60904-8 using
the short circuit condition, 25 °C device temperature and an appropriate bias light. This
procedure should be applied to the full-sized module if possible, i.e. the module should be
characterized in its entirety. If this is not possible, a small sample equivalent in construction
and materials may be used or a single cell in the module should be characterized according to
the measurements described in IEC 60904-8.
The spectral responsivity of a solar cell changes upon encapsulation. Therefore, an
encapsulated solar cell shall be used if a full-sized module cannot be tested.
The module power shall be measured after measurement of the spectral responsivity. Any
changes shall be noted in the test report.
7 Procedure for the measurement of incidence angle effects
7.1 Purpose
The purpose of the incident angle test is to determine the effect of solar incidence angles on
module performance. The incidence angle dictates the fraction of the direct and diffuse
irradiance available for conversion into electrical energy inside the module, i.e. the
transmitted and reflected fractions of the available light. Both the external (the front surface)
reflection and internal reflections are functions of the solar incidence angle and of the module
design. Hence, the irradiance absorbed by PV devices at a particular incidence angle may
differ between module designs. Also, the orientation of the module installation has a strong
influence on the incidence angle effects.

For modules with a flat uncoated front glass plate, the relative light transmission into the
module is primarily influenced by the first glass-air interface. The test can be omitted if the
interface is flat and no antireflective coating is applied. The data of a flat glass-air interface
can be used. However, normally glasses used for solar modules are somewhat structured and
thus it is recommendable to carry out a verification measurement in either case.
Although the relative light transmission into the module is primarily influenced by the glass air
interface, the details of other optical interfaces and other measures to enhance optical
confinement might be relevant as well. If there is reason to believe that the other optical
interfaces have been significantly changed, the test should be conducted.
This document presents two unequal alternatives (indoor and outdoor approach) which might
not necessarily yield identical results but results should be equivalent within their
uncertainties. It should be noted in the test report, which method has been used.
7.2 Indoor test method
7.2.1 General
The test method for the incident angle test is based on gathering actual measured I data for
sc
the test modules over a wide range of incidence angles. If no light source with light uniformity
in the volume spanned by a full module upon rotation is available (see 7.2.2c), a smaller,
optically equivalent test module with one active cell, surrounded by non-active cells, may be
tested. In the following, the area of the active cell is referred to as measurement area and all
specification shall be met for this area only to allow realistic measurements. The area of
influence is the active cell plus one half cell dimension in all directions.
7.2.2 Apparatus
The following apparatus is required to control and measure the test conditions:
a) A PV reference device in conformance with IEC 60904-2 that is linear in output over the
range of irradiance variations of the solar simulator according to IEC 60904-10, mounted
fixed in the test plane of the simulator to monitor the total irradiance of the solar simulator.
b) Means of measuring the temperature of the ambient, the test module and the reference
device to an accuracy of ±1 °C with a repeatability of ±0,5 °C.
c) A solar simulator of class B with respect to the spatial uniformity requirements within the
measurement area and class C over the area of influence and with respect to temporal
stability according to IEC 60904-9. The solar simulator should have minimal irradiance
outside a 30° field of view. It is recommended that the solar simulator should have 95 % of
its irradiance within 10° field of view. The spatial uniformity requirement (class B) shall be
fulfilled in the volume that is covered by the active element(s) within the module during
rotation. The area of influence should maintain class C. The solid angle of the light of the
simulator should not vary by more than 1° over the active area of the test device. The
spatial uniformity of the active area and the area of influence shall be stated in the report.
NOTE The depth of the volume is determined by the highest inclinations and a detailed assessment of the
worst case needs to be carried out in advance of the measurements.
d) Equipment to measure the short circuit current of the test module to an accuracy of
–2
±0,2 % of the value at 1 000 W⋅m (see IEC 60904-1).
e) Equipment for measuring the reference device output to an accuracy of ±0,2 % of the
–2
value at 1 000 W⋅m .
f) An adjustable rack capable of accurately positioning the module at the specified angles of
incidences to an accuracy of ±1°. Care shall be taken to ensure that rotation of the test
apparatus does not change the irradiance on the reference device. The device should be
rotated around the rotational axis of the cell centre under investigation. The rotational axis
shall not change during the entire angular range of measurements.
g) Module temperature sensors, attached by solder or thermally conducive adhesive to the
backs of two solar cells near the middle of each test module, or to the back of the active

– 12 – IEC 61853-2:2016 © IEC 2016
cell if an optically equivalent mini-module is used. Alternatively, use IEC 60904-5 and its
associated equipment for determining cell temperature. The total accuracy of the module
temperature determination shall be ±1 °C.
h) A data acquisition system capable of recording the following parameters for each angle
setting:
• reference device output,
• short circuit current of the module,
• module temperature,
• reference device temperature.
The measurement of module current and reference device output shall be simultaneous.
7.2.3 Set-up procedure
The set-up procedure is as follows.
a) Make sure that the front surface of the module is clean.
It is acceptable to mechanically isolate and contact a single crystalline cell, i.e. cut
through the back sheet to access the contacts of a single cell directly. In the case of thin
film modules one would need to manufacture a specific test device with a single cell, or an
area of interest, being contacted separately and isolated for these measurements.
b) Mount the module in the test plane of the simulator so that it is normal to the centre line of
the beam within ±1°. Connect to the necessary instrumentation.
c) If the test system is equipped with temperature controls, set the controls at the desired
level. If temperature controls are not used, allow the module to stabilize within ±1 °C of
the room air temperature.
–2
d) Set the irradiance at the test plane of the simulator to 1 000 W⋅m at perpendicular
incidence using the reference device. Maintain this irradiance throughout the
–2 –2
measurements. If this is not possible, a value in the range of 700 W⋅m to 1 000 W⋅m
(see IEC 60891) is sufficient.
Care shall be taken to prevent reflection from within the room. There shall be no protrusions
to prevent full irradiance of the test module during the measurement. Reflections off the floor,
walls or ceiling or objects shall be avoided.
Some black paints are highly reflective in the infrared. It is recommended to test the reflective
properties of the paint used to assess the uncertainties of the procedure.
7.2.4 Measurement procedure
Measurements should be taken along two orthogonal angular directions with respect to the
module normal. In cases of known symmetrical reflection properties, measurements in one
axis are sufficient and the second axis may be omitted. Symmetrical behaviour is expected if
samples with similar cells and the same front glass have been shown to be symmetrical.
The following procedure assumes symmetry in the rotational axis.
NOTE There is no knowledge of a device which does not meet this requirement.
a) At 0° rotation angle position the test cell in the test area so that the center of the cell lies
in the optical axis and the axis of rotation in the middle of the cell. Rotational symmetry of
the test arrangement shall be verified at –80° and 80° rotation angle. The ratios (I , 80° /
SC
I , 0°) / cos 80° for both directions shall not differ by more than 2 %.
SC
b) Vary the angle between the module normal and the optical axis of the light source
between −60° and + 60° in steps of a maximum of 10°. Outside that range vary the angle
in steps of maximum 5°.
c) If using a steady state solar simulator, keep the module temperature close to a chosen
temperature by shading the module between taking data. Alternatively, allow for the
module to reach thermal equilibrium. Care shall be taken as less light irradiates the
module at increasing incidence angles. Temperature differences between measurements
shall be recorded and corrected for.
d) For each setting, take at least three readings of the short circuit current and module
temperature. If necessary, correct for irradiance fluctuations with the help of the reference
device. Correct to a module temperature of 25 °C using data from Table 2 of
IEC 61853-1:2011 and average to obtain I (θ).
sc
e) The relative light transmission into the module is given by:
τ(θ) = I (θ)/(cos (θ) I (0)) (1)
sc sc
Where θ corresponds to the angle of incidence with respect to the module normal.
Care has to be taken regarding low light level dependence: At high incidence angles, the
light intensity in the module plane will be strongly reduced by the cosine law. If the short
circuit current of the module has been shown to vary nonlinearly with respect to irradiance
in the measurements of Table 2 of IEC 61853-1:2011, a nonlinearity correction has to be
performed in addition to equation (1) using polynomial fit of the I data generated in
sc
IEC 61853-1.
f) If the results are not symmetrical determine if the results represent an off-set in angle or if
the module is truly not symmetrical (not the same on both sides of normal incidence). If it
is the latter, the light transmission should be stated for both tilt directions.
The module power shall be measured after measurement of the angle of incidence
responsivity. Any changes shall be noted in the test report.
7.3 Outdoor test method
7.3.1 General
The outdoor test method for the incident angle test is based on gathering measured I data
sc
for the test modules over a wide range of incidence angles, along with associated global
irradiance in the plane of the module and direct normal irradiance so that contributions to I
sc
from both the beam and diffuse components can be distinguished.

IEC
Figure 2 – Positions for measuring the temperature
of the test module behind the cells
7.3.2 Apparatus
The following apparatus is required to control and measure the test conditions:

– 14 – IEC 61853-2:2016 © IEC 2016
a) A calibrated pyranometer mounted in the test plane of the test module(s).
b) Optionally, a PV reference device in conformance with IEC 60904-2 linear in output over
the range of irradiance variations and calibrated as a function of angle incidence mounted
in the test plane of the test module. This is recommended if any site specific measurement
artifacts are expected.
c) A PV reference device in conformance with IEC 60904-2 that is linear in output over the
range of irradiance variations, mounted on a separate solar tracker to measure the global
normal irradiance.
d) A normal incidence pyrheliometer, calibrated according to ISO 9059, to measure the direct
normal component of irradiance mounted on the separate solar tracker.
e) Means of measuring the temperature of the ambient, the test module and the reference
device to an accuracy of ±1 °C with a repeatability of ±0,5 °C. The module temperature
should be measured in at least 4 places as shown in Figure 2.
f) Equipment to measure the short circuit current of the test module to an accuracy of
–2
±0,2 % of the value at 1 000 W⋅m (see IEC 60904-1). The test modules shall not be
continuously short circuited, to avoid reverse bias conditions and individual hot cells.
Rather the module should be in an open circuit or maximum power condition between
short duration I measurements.
sc
g) Equipment for measuring the reference device output to an accuracy of ±0,2 % of the
value at 1 000 W/m .
h) A two-axis tracker with an open rack mount and provision for introducing module angle-of-
incidence values in the range from − 90° to + 90°, with at least 80° achievable.
NOTE 1 A one axis tracker may also be sufficient, but the method will have to be adapted to correct for AOI
variation due to non-perpendicular sweep directions.
i) Means to determine the solar angle of incidence with an accuracy of at least ±0,5°.
Mounting a module onto a tracker may not satisfy this requirement even if the tracker is
capable of much better tracking accuracy. A verification of the tilt angle with an accuracy
better than ±1° is required. Options include using calculated sun position angles in
combination with solar tracker position angles, or digital inclinometer readings when tilt
angles are varied in only the elevation axis, or a digital protractor equipped with a sun
alignment feature.
NOTE 2 Determination of the solar angle of incidence (θ) with accuracy of at least ±0,5° is required;
otherwise at large θ values the uncertainty associated with the cos(θ) factor becomes significant.
j) A data acquisition system to record the following parameters:
• reference device(s) outputs,
• short circuit current of the device(s) under test,
• module temperatures,
• reference device temperatures (if applicable).
The measurement of module current and reference device output shall be simultaneous (no
more than 1 ms apart). Longer separation (up to 1 s) is permissible but the stability of the
irradiance shall be verified by taking a measurement of the irradiance before and after module
measurement.
7.3.3 Set-up procedure
Select a test period of less than 1 hour duration with optimum weather conditions; clear sky
near solar noon with minimal solar spectral (air mass) variation, minimal variation in the direct
–1
to global normal G /G ratio, and mild wind speed < 4 m⋅s .
dni gni
a) Ensure that the front surface of the DUT is clean.
b) Mount the DUT in the test rack of the angle-of-incidence test system. Attach temperature
sensors and connect to the necessary instrumentation.

c) If the DUT is equipped with temperature controls, set the controls at the desired level. If
temperature controls are not used, position the module normal to the sun and allow the
DUT’s temperature to stabilize for at least 15 min, and verify that the maximum range
between individual sensor temperatures is less than 5 °C.
d) Verify that the reference device and the pyrheliometer mounted on the separate tracker
are perpendicularly pointing to the sun.
e) The DUT accepts light from a very wide acceptance angle, essentially ±90°, so unwanted
reflections and shading from objects and structures within the view angle of the DUT shall
be avoided. The ground surrounding the DUT should not have an abnormally high
reflectance (albedo) and should be nominally flat in all directions surrounding the test
structure.
7.3.4 Measurement procedure
The test shall be co
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