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IEC 62817
®
Edition 1.0 2014-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE colour
inside
Photovoltaic systems – Design qualification of solar trackers
Systèmes photovoltaïques – Qualification de conception des suiveurs solaires

IEC 62817:2014-08(en-fr)
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IEC 62817
®
Edition 1.0 2014-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE colour
inside
Photovoltaic systems – Design qualification of solar trackers
Systèmes photovoltaïques – Qualification de conception des suiveurs solaires
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE PRICE CODE
CODE PRIX XB
ICS 27.160 ISBN 978-2-8322-1826-6
Warning! Make sure that you obtained this publication from an authorized distributor.
Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.
® Registered trademark of the International Electrotechnical Commission

Marque déposée de la Commission Electrotechnique Internationale
–2– IEC 62817:2014 © IEC 2014
CONTENTS
FOREWORD......................................................................................................................... 6
1 Scope and object ........................................................................................................... 8
2 Normative references .................................................................................................... 8
3 Terms and definitions .................................................................................................... 9
4 Specifications for solar trackers for PV applications ........................................................ 9
5 Report ......................................................................................................................... 12
6 Tracker definitions and taxonomy ................................................................................. 13
6.1 General ............................................................................................................... 13
6.2 Payload types ..................................................................................................... 13
6.2.1 Standard photovoltaic (PV) module trackers ................................................. 13
6.2.2 Concentrator photovoltaic (CPV) module trackers ......................................... 13
6.3 Rotational axes ................................................................................................... 14
6.3.1 General ....................................................................................................... 14
6.3.2 Single-axis trackers ...................................................................................... 14
6.3.3 Dual-axis trackers ........................................................................................ 15
6.4 Actuation and control .......................................................................................... 17
6.4.1 Architecture ................................................................................................. 17
6.4.2 Drive train .................................................................................................... 17
6.4.3 Drive types .................................................................................................. 17
6.4.4 Drive train torque ......................................................................................... 18
6.5 Types of tracker control ....................................................................................... 18
6.5.1 Passive control ............................................................................................ 18
6.5.2 Active control ............................................................................................... 18
6.5.3 Backtracking ................................................................................................ 19
6.6 Structural characteristics ..................................................................................... 19
6.6.1 Vertical supports .......................................................................................... 19
6.6.2 Foundation types ......................................................................................... 20
6.6.3 Tracker positions ......................................................................................... 20
6.6.4 Stow time ..................................................................................................... 21
6.7 Energy consumption ............................................................................................ 21
6.7.1 Daily energy consumption ............................................................................ 21
6.7.2 Stow energy consumption ............................................................................ 21
6.8 External elements and interfaces ......................................................................... 21
6.8.1 Foundation .................................................................................................. 21
6.8.2 Foundation interface .................................................................................... 21
6.8.3 Payload ....................................................................................................... 21
6.8.4 Payload interface ......................................................................................... 22
6.8.5 Payload mechanical interface ....................................................................... 22
6.8.6 Payload electrical interface .......................................................................... 22
6.8.7 Grounding interface ..................................................................................... 22
6.8.8 Installation effort .......................................................................................... 22
6.8.9 Control interface .......................................................................................... 22
6.9 Internal tolerances .............................................................................................. 23
6.9.1 Primary-axis tolerance ................................................................................. 23
6.9.2 Secondary axis tolerance ............................................................................. 23
6.9.3 Backlash ...................................................................................................... 23
IEC 62817:2014 © IEC 2014 –3–
6.9.4 Stiffness ...................................................................................................... 23

6.10 Tracker system elements ..................................................................................... 24
6.10.1 Mechanical structure .................................................................................... 24
6.10.2 Tracker controller ......................................................................................... 24
6.10.3 Sensors ....................................................................................................... 24
6.11 Reliability terminology ......................................................................................... 24
6.11.1 General ....................................................................................................... 24
6.11.2 Mean time between failures (MTBF) ............................................................. 24
6.11.3 Mean time between critical failures (MTBCF) ................................................ 25
6.11.4 Mean time to repair (MTTR) ......................................................................... 25
6.12 Environmental conditions .................................................................................... 25
6.12.1 Operating temperature range ........................................................................ 25
6.12.2 Survival temperature range .......................................................................... 25
6.12.3 Wind speed .................................................................................................. 25
6.12.4 Maximum wind during operation ................................................................... 26
6.12.5 Maximum wind during stow ........................................................................... 26
6.12.6 Snow load .................................................................................................... 26
7 Tracker accuracy characterization ................................................................................ 26
7.1 Overview ............................................................................................................ 26
7.2 Pointing error (instantaneous) ............................................................................. 26
7.3 Measurement ...................................................................................................... 27
7.3.1 Overview ..................................................................................................... 27
7.3.2 Example of experimental method to measure pointing error .......................... 27
7.3.3 Calibration of pointing error measurement tool .............................................. 28
7.4 Calculation of tracker accuracy ............................................................................ 28
7.4.1 Overview ..................................................................................................... 28
7.4.2 Data collection ............................................................................................. 28
7.4.3 Data binning by wind speed .......................................................................... 29
7.4.4 Data filtering ................................................................................................ 30
7.4.5 Data quantity ............................................................................................... 30
7.4.6 Accuracy calculations ................................................................................... 30
8 Tracker test procedures ............................................................................................... 31
8.1 Visual inspection ................................................................................................. 31
8.1.1 Purpose ....................................................................................................... 31
8.1.2 Procedure .................................................................................................... 31
8.1.3 Requirements .............................................................................................. 31
8.2 Functional validation tests ................................................................................... 32
8.2.1 Purpose ....................................................................................................... 32
8.2.2 Tracking limits verification ............................................................................ 32
8.2.3 Hard limit switch operation ........................................................................... 32
8.2.4 Automatic sun tracking after power outage and feedback sensor
shadowing ................................................................................................... 32
8.2.5 Manual operation ......................................................................................... 33
8.2.6 Emergency stop ........................................................................................... 33
8.2.7 Maintenance mode ....................................................................................... 33
8.2.8 Operational temperature range ..................................................................... 33
8.2.9 Wind stow .................................................................................................... 33
8.3 Performance tests ............................................................................................... 33
8.3.1 Purpose ....................................................................................................... 33
–4– IEC 62817:2014 © IEC 2014
8.3.2 Daily energy and peak power consumption ................................................... 33

8.3.3 Stow time and stow energy and power consumption ...................................... 34
8.4 Mechanical testing .............................................................................................. 34
8.4.1 Purpose ....................................................................................................... 34
8.4.2 Control/drive train pointing repeatability test ................................................. 35
8.4.3 Deflection under static load test ................................................................... 36
8.4.4 Torsional stiffness, mechanical drift, drive torque, and backlash testing ........ 38
8.4.5 Moment testing under extreme wind loading ................................................. 41
8.5 Environmental testing .......................................................................................... 43
8.5.1 Purpose ....................................................................................................... 43
8.5.2 Procedure .................................................................................................... 43
8.5.3 Requirements .............................................................................................. 45
8.6 Accelerated mechanical cycling ........................................................................... 46
8.6.1 Purpose ....................................................................................................... 46
8.6.2 Procedure .................................................................................................... 46
8.6.3 Requirements .............................................................................................. 48
9 Design qualification testing specific to tracker electronic equipment .............................. 48
9.1 General purpose ................................................................................................. 48
9.2 Sequential testing for electronic components ....................................................... 48
9.2.1 General ....................................................................................................... 48
9.2.2 Visual inspection of electronic components ................................................... 49
9.2.3 Functioning test ........................................................................................... 50
9.2.4 Protection against dust, water, and foreign bodies (IP code) ......................... 51
9.2.5 Protection against mechanical impacts (IK code) .......................................... 51
9.2.6 Robustness of terminals test ........................................................................ 52
9.2.7 Surge immunity test ..................................................................................... 53
9.2.8 Shipping vibration test .................................................................................. 53
9.2.9 Shock test .................................................................................................... 54
9.2.10 UV test ........................................................................................................ 54
9.2.11 Thermal cycling test ..................................................................................... 55
9.2.12 Humidity-freeze test ..................................................................................... 56
9.2.13 Damp heat ................................................................................................... 57
10 Additional optional accuracy calculations ..................................................................... 57
10.1 Typical tracking accuracy range .......................................................................... 57
10.2 Tracking error histogram ..................................................................................... 57
10.3 Percent of available irradiance as a function of pointing error ............................... 58
Figure 1 – Convention for elevation angle ............................................................................ 16

Figure 2 – Illustration of primary-axis tolerance for VPDAT .................................................. 23
Figure 3 – General illustration of pointing error .................................................................... 27
Figure 4 – Example of experimental method to measure pointing error ................................. 27
Figure 5 – Example measurement locations for structural deflection ..................................... 37
Figure 6 – Load configurations while the payload is in the horizontal position ....................... 37
Figure 7 – Load configuration when the payload is in the vertical position ............................ 37
Figure 8 – Moment load applied to an elevation axis ............................................................ 39
Figure 9 – Angular displacement versus applied torque to axis of rotation ............................ 39
Figure 10 – Examples of characteristic length for (a) elevation torque, (b) azimuth
torque ................................................................................................................................. 41
IEC 62817:2014 © IEC 2014 –5–
Figure 11 – Two configurations for extreme wind moment loading ........................................ 42

Figure 12 – Representation of a tracker’s discrete-movement profile .................................... 46
Figure 13 – Representation of an accelerated discrete-movement profile for testing ............. 47
Figure 14 – Test sequence for electronic components.......................................................... 49
Figure 15 – Electronic component thermal cycling test ......................................................... 55
Figure 16 – Electronic component humidity-freeze test ........................................................ 56
Figure 17 – Pointing-error frequency distribution for the entire test period ............................ 58
Figure 18 – Available irradiance as a function of pointing error ............................................ 58
Figure 19 – Available irradiance as a function of pointing error with binning by wind
speed ................................................................................................................................. 59
Table 1 – Tracker specification template ............................................................................. 10

Table 2 – Alternate tracking-accuracy reporting template ..................................................... 31
–6– IEC 62817:2014 © IEC 2014
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC SYSTEMS –
DESIGN QUALIFICATION OF SOLAR TRACKERS
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
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
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Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
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.
International Standard IEC 62817 has been prepared by IEC technical committee 82: Solar
photovoltaic energy systems.
The text of this design qualification standard is based on the following documents:
FDIS Report on voting
82/853/FDIS 82/877/RVD
Full information on the voting for the approval of this international 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.
IEC 62817:2014 © IEC 2014 –7–
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site 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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
–8– IEC 62817:2014 © IEC 2014
PHOTOVOLTAIC SYSTEMS –
DESIGN QUALIFICATION OF SOLAR TRACKERS
1 Scope and object
This International Standard is a design qualification standard applicable to solar trackers for
photovoltaic systems, but may be used for trackers in other solar applications. The standard
defines test procedures for both key components and for the complete tracker system. In
some cases, test procedures describe methods to measure and/or calculate parameters to be
reported in the defined tracker specification sheet. In other cases, the test procedure results
in a pass/fail criterion.
The objective of this design qualification standard is twofold.
First, this standard ensures the user of the said tracker that parameters reported in the
specification sheet were measured by consistent and accepted industry procedures. This
provides customers with a sound basis for comparing and selecting a tracker appropriate to
their specific needs. This standard provides industry-wide definitions and parameters for solar
trackers. Each vendor can design, build, and specify the functionality and accuracy with
uniform definition. This allows consistency in specifying the requirements for purchasing,
comparing the products from different vendors, and verifying the quality of the products.
Second, the tests with pass/fail criteria are engineered with the purpose of separating tracker
designs that are likely to have early failures from those designs that are sound and suitable
for use as specified by the manufacturer. Mechanical and environmental testing in this
standard is designed to gauge the tracker’s ability to perform under varying operating
conditions, as well as to survive extreme conditions. Mechanical testing is not intended to
certify structural and foundational designs, because this type of certification is specific to local
jurisdictions, soil types, and other local requirements.
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 60068-2-6, Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-21, Environmental testing – Part 2-21: Tests – Test U: Robustness of

terminations and integral mounting devices
IEC 60068-2-27, Environmental testing – Part 2-27: Tests – Test Ea and guidance: Shock
IEC 60068-2-75, Environmental testing – Part 2-75: Tests – Test Eh: Hammer tests
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60904-3:2008, Photovoltaic devices – Part 3: Measurement principles for terrestrial

photovoltaic (PV) solar devices with reference spectral irradiance data
IEC 61000-4-5:2005, Electromagnetic compatibility (EMC) – Part 4-5: Testing and

measurement techniques – Surge immunity test
IEC 62817:2014 © IEC 2014 –9–
IEC 62262:2002, Degrees of protection provided by enclosures for electrical equipment

against external mechanical impacts (IK code)
ISO/IEC 17025, General requirements for the competence of testing and calibration
laboratories
ISO 12103-1, Road vehicles – Test dust for filter evaluation – Part 1: Arizona test dust
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply. For additional
tracker-specific terminology, see Clause 6.
3.1
photovoltaics
PV
devices that use solar radiation to directly generate electrical energy
3.2
concentrator photovoltaics
CPV
devices that focus magnified sunlight on photovoltaics to generate electrical energy. The
sunlight could be magnified by various different methods, such as reflective or refractive
optics, in dish, trough, lens, or other configurations
3.3
concentrator module
CPV module
group of receivers (PV cells mounted in some way), optics, and other related components,
such as interconnections and mechanical enclosures, integrated together into a modular
package. The module is typically assembled in a factory and shipped to an installation site to
be installed along with other modules on a solar tracker
Note 1 to entry: The module is typically assembled in a factory and shipped to an installation site to be installed
along with other modules on a solar tracker.
Note 2 to entry: A CPV module typically does not have a field-adjustable focus point. In addition, a module could
be made of several sub-modules. The sub-module is a smaller, modular portion of the full-size module, which might
be assembled into the full module either in a factory or in the field.
3.4
concentrator assembly
concentrator assembly consisting of receivers, optics, and other related components that have
a field-adjustable focus point and are typically assembled and aligned in the field
EXAMPLE: A system that combines a single large dish with a receiver unit that is aligned with the focal point of the
disk.
Note 1 to entry: This term is used to differentiate certain CPV designs from the CPV modules mentioned above.
4 Specifications for solar trackers for PV applications
The manufacturer shall provide the test lab, as part of its product marking and documentation,
a table in the form specified below (see Table 1). The third column of Table 1 is for
information purposes regarding this standard and is not intended to be part of an actual
specification template provided to the test lab. See later clauses/subclauses of this standard
for further explanation of individual specifications.
– 10 – IEC 62817:2014 © IEC 2014
Some of the specifications within Table 1 are required to be provided by the manufacturer and
verified by the test lab, whereas others are the sole responsibility of the test lab. Still other
specifications in Table 1 are optional; however, if a tracker manufacturer chooses to include
optional information, it shall be reported and measured in the specific way shown in Table 1
(and in some cases, reporting requirements are further described in the appropriate clause of
this standard). Refer to the third column of Table 1 to determine the responsibility of the
specification or optional status (“T” indicates test lab responsibility, “M” indicates
manufacturer responsibility, and “O” indicates an optional parameter).
Table 1 – Tracker specification template
Characteristic Example Responsibility/Clause/Subclause

Manufacturer The XYZ Company (M)
Model number XX1090 (M)
Type of tracker CPV Tracker, Dual Axis (M) 6.2, 6.3
Payload characteristics
Minimum/maximum mass 100 kg/1 025 kg (M) 6.8.3
supported
Payload center of mass 0 m to 0,3 m distance perpendicular (M) 6.8.3
restrictions to mounting surface
Maximum payload surface area 30 m 2 (M) 6.8.3
Nominal payload surface area 28 m2 (M)
Maximum dynamic torques Azimuth (Θ z ):10 kN m (M) 8.4.5
allowed while moving
Θ x , Θ y : 5 kN m
[ shall provide a set of diagrams to
clarify torques and which axes they
are relative to ]
Maximum static torques allowed [ shall provide a set of diagrams ] (M) 8.4.4, 8.4.5
while in stow position
Installation characteristics
Allowable foundation Reinforced concrete (M ) 6.6.2
Foundation tolerance in primary ± 0,5° (O) 6.9
axis
Foundation tolerance in ± 0,5° ( O) 6.9
secondary axis
Installation effort 5 man-hours, 40 metric ton crane (O) 6.8.8
Payload interface flexibility The interface can be configured to (O)
mount modules from manufacturers
“A”, “B”, and “C”. Bolting
configurations “X”, “Y”, and “Z” are
allowable.
Electrical characteristics
Includes backup power? No (M) N/A
Daily energy consumption 1,5 kWh (T) 6.7.1
Stow energy consumption 1 kWh (T) 6.7.2
Input power requirements AC, 100 V to 240 V, 50 Hz to 60 Hz, (M) No specifics defined
5A
Effective (and apparent) peak 500 W (550 VA) (T) 8.3.2
power consumption tracking
Effective (and apparent) peak 50 W (55 VA) (T) 8.3.2
power consumption non-tracking
Effective (and apparent) peak 1 000 W (1 100 VA) (T) 8.3.3
power consumption stow
positioning.
IEC 62817:2014 © IEC 2014 – 11 –

Tracking accuracy
Accuracy, typical 0,1° (T) 7.4.6
(low wind, min deflect point)
(low wind, max deflect point)
Accuracy, 95 th percentile 0,5° (T) 7.4.6
(low wind, min deflect point)
(low wind, max deflect point)
Mean wind speed during the “low 3,1 m/s (T) 7.4.6
wind” test conditions
(high wind, min deflect point)
(high wind, max deflect point)
(high wind, min deflect point)
(high wind, max deflect point)
Mean wind speed during the “high 5,2 m/s (T) 7.4.6
wind” test conditions
Weight and area of payload 500 kg payload evenly distributed (T) 7.4.2.1
installed during testing over a 50 m 2 area
Payload center of mass installed Payload center of mass 0,2 m above (T) 7.4.2.1
during testing the module mounting surface
Control characteristics
Control algorithm Hybrid (M) 6.5
Control interface None (M) 6.8.9
External communication interface Ethernet/TCP-IP (M) No specific description
Emergency stow provided? Yes, at wind speeds 14 m/s (M) 6.6.3.1
Stow time 4 min (M) 6.6.4
Clock accuracy 1 s per year (M) N/A
Hard limit switches Not included (M) 7.2.3
Mechanical design
Actuation type Distributed (M) 6.4.1
Drive type Electric (M) 6.4.3
Actuators DC motor, 185 W (M) No specific description
Range of motion, primary axis ± 160° azimuth (M) 6.6.3.3
Range of motion, secondary axis 10° to 90° elevation (M) 6.6.3.3

System stiffness See test lab report on measurement (T),(O) 6.9.4, 8.4.3
locations, applied loads, and
measured deflections
Drive train torsional stiffness See plot of angular displacement (T) 8.4.4, Figure 9
versus applied torque
Backlash 0,1° maximum (T) 6.9.3, 8.4.4
Environmental conditions
Maximum allowable wind speed 14 m/s (M) 6.12.4
during tracking
– 12 – IEC 62817:2014 © IEC 2014
Maximum allowable wind speed in 40 m/s (M) 6.12.5

stow
Temperature operational range –20 °C to +50 °C (M) 6.12.1
Temperature survival range –40 °C to +60 °C (M) 6.12.2
Snow rating Up to 20 kg/m 2 of snow load allowed (M) 6.12.6

Maintenance and Reliability
Maintenance schedule Grease application every 12 months (O)
(0,75 man-hours required)
Drive train fluid change every 3 years
(1,25 man-hours required)
MTBF 3,5 years (O) 6.11.2
MTTR 2 h (azimuth or elevation motor) (O) 6.11.4
(list components that are expected to
need repair or replacement within a
10-year period)
For an alternate template for the presentation of accuracy specifications, see Table 2.
5 Report
A certified report of the qualification tests, with measured performance characteristics and
details of any failures and re-tests, shall be prepared by the test agency in accordance with
ISO/IEC 17025. The report shall contain the specification sheet per Table 1. 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 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 tested;
f) characterization and condition of the test item;
g) date of receipt of test item and date(s) of test, where appropriate;
h) identification of test method used;
i) reference to sampling procedure, where relevant;
j) any deviations from, additions to, or exclusions from, the test method and any other
information relevant to a specific test;
k) measurements, examinations and derived results supported by tables, graphs, sketches,
and photographs as appropriate, and any failures observed;
l) a statement of the estimated uncertainty of the test results (where relevant);
m) 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;
n) where relevant, a statement to the effect that the results relate only to the items tested;
o) a statement that the certificate or report shall not be reproduced except in full, without the
written approval of the laboratory.
A copy of this report shall be kept by the manufacturer for reference purposes.
IEC 62817:2014 © IEC 2014 – 13 –
6 Tracker definitions and taxonomy
6.1 General
Solar trackers are mechanical devices used to track or follow the sun across the sky on a
daily basis. Although a solar tracker can be used for many purposes, the scope of this
standard is focused on solar trackers for photovoltaic (PV) applications. In PV applications,
the primary purpose of the tracker is to enhance the capture of available solar irradiance to be
converted to electricity. Photovoltaic trackers can be classified into two types: standard PV
trackers and concentrator photovoltaic (CPV) trackers. Each of these tracker types can be
further categorized by the number and orientation of their axes, their actuation architecture
and drive type, their intended applications, and their vertical supports and foundation type.
6.2 Payload types
6.2.1 Standard photovoltaic (PV) module trackers
6.2.1.1 Uses
Standard PV trackers are used to minimize the angle of incidence between incoming light and
a PV module. This increases the amount of energy produced from a fixed amount of power-
generating capacity.
6.2.1.2 Type of light accepted
Photovoltaic modules accept both direct and diffuse light from all angles. This means that
systems implementing standard PV trackers produce energy even when not directly pointed at
the sun. Tracking in standard PV systems is used to increase the amount of energy produced
by the direct component of the incoming light.
6.2.1.3 Accuracy requirements
In standard PV systems, the energy contributed by the direct beam drops off with the cosine
of the angle between the incoming light and the module. Thus, trackers that have accuracies
of ± 5° can deliver 99,6 % of the energy supplied by the direct beam. As a result, high-
accuracy tracking is not typically used.
6.2.2 Concentrator photovoltaic (CPV) module trackers
6.2.2.1 Uses
Concentrator photovoltaic trackers are used to enable the optics used in CPV systems. These
trackers typically align CPV optical elements with the sun’s direct beam with a higher degree
of accuracy than standard PV trackers.
6.2.2.2 Type of light accepted
Direct solar radiation, as opposed to diffuse solar radiation, is the primary energy source for
CPV modules. Optics are designed specifically to focus the direct radiation on PV cells. If this
focus is not maintained, power output drops substantially.
If the CPV module concentrates in one dimension, then single-axis tracking is required. If the
CPV module concentrates in two dimensions, then two-axis tracking is required.
6.2.2.3 Accuracy requirements
In concentrator modules, tracking accuracy requirements are typically related to energy

production through the module acceptance angle. When the sun-pointing error is less than the
acceptance angle, the modules will typically deliver 90 % or more of the rated power output.
– 14 – IEC 62817:2014 © IEC 2014
6.3 Rotational axes
6.3.1 General
Photovoltaic trackers can be grouped into classes by the number axes and orientation of the
primary axis.
6.3.2 Single-axis trackers
6.3.2.1 General
Single-axis trackers have one degree of freedom that acts as an axis of rotation.
6.3.2.2 Single-axis tracker implementations
6.3.2.2.1 General
There are several common implementations of single-axis trackers. These include horizontal
single-axis trackers, vertical single-axis trackers, and inclined single-axis trackers.
6.3.2.2.2 Horizontal single-axis tracker (HSAT)
The axis of rotation for a horizontal single-axis tracker is horizontal with respect to the
ground.
IEC
6.3.2.2.3 Vertical single-axis tracker (VSAT)
The axis of rotation for vertical single-axis trackers is vertical with respect to the ground.
These trackers rotate from east to west over the course of the day.
IEC
6.3.2.2.4 Inclined single-axis tracker (ISAT)
All trackers with axes of rotation between horizontal and vertical are considered inclined
single-axis trackers. Tracker inclination angles are often limited to reduce the wind profile and
decrease the elevated end’s height off the ground.
IEC 62817:2014 © IEC 2014 – 15 –
The polar-inclined single-axis tracker (PISAT) is a specific version of the inclined single-axis
tracker. In this particular implementation, the inclination angle is equal to the latitude of the
installation. This aligns the tracker’s axis of rotation with the Earth’s axis of rotation.
IEC
6.3.2.3 Orientation – cardinal direction
The axis of rotation of single-axis trackers is typically aligned along a true north meridian. It is
possible to align them in any cardinal direction with advanced tracking algorithms.
6.3.2.4 Module orientation with respect to rotational axis
The orientation of the module with respect to the tracker axis is important when modelling
performance.
Horizontal and inclined single-axis trackers typically have the face of the module oriented
parallel to the axis of rotation. As a module tracks, it sweeps a cylinder that is rotationally
symmetric around the axis of rotation.
Vertical single-axis trackers typically have the face of the module oriented at an angle with
respect to the axis of rotation. As a module tracks, it sweeps a cone that is rotationally
symmetric around the axis of rotation.
6.3.3 Dual-axis trackers
6.3.3.1 General
Dual-axis trackers have two degrees of freedom that act as axes of rotation. These axes are
typically normal to one another. The axis that is fixed with respect to the ground can be
considered the primary axis. The axis that is referenced to the primary axis can be considered
the secondary axis.
6.3.3.2 Dual-axis tracker implementations
6.3.3.2.1 General
There are several common implementations of dual-axis trackers. They are classified by the
orientation of their primary axes with respect to the ground. One common implementation is a
vertical primary dual-axis tracker (VPDAT) (also called azimuth-elevation).
A convention for azimuth angle is “degrees east of north” (e.g., 0° azimuth is pointing north,
and 90° azimuth is pointing east).
A convention for elevation angle is “degrees up from the horizon,” as illustrated below in
Figure 1. Zenith angle is the complement of elevation angle (zenith = 90° – elevation).
– 16 – IEC 62817:2014 © IEC 2014
θ = 0°
θ = 90°
IEC
NOTE θ = elevation angle = 0° (zenith angle = 90°) occurs when a vector normal to the module face is pointing to
the horizon. Elevation angle = 90° (zenith angle = 0°) occurs when the module is facing the sky.
Figure 1 – Convention for elevation angle
The above sign conventions are assumed to be the ones used to describe angles, but a
different convention can be used as long as it is described. For example, the range of motion
of a tracker could be described as “azimuth from +20° to +340°” or alternately, “azimuth
± 160° from south”.
6.3.3.2.2 Horizontal primary dual-axis tracker
A horizontal primary dual-axis tracker (HPDAT) has its primary axis horizontal to the ground.
The secondary axis is then typically normal to the primary axis.
IEC
6.3.3.2.3 Vertical primary dual-axis tracker
A vertical primary dual-axis tracker (VPDAT) has its primary axis vertical to the ground. The
secondary axis is then typically normal to the primary axis.
IEC 62817:2014 © IEC 2014 – 17 –
IEC
6.3.3.2.4 Inclined primary dual-axis tracker
An inclined primary dual-axis tracker (IPDAT) has its primary axis between vertical and
horizontal. The secondary axis is then typically normal to the primary axis.
6.3.3.3 Orientation – cardinal direction
The axes of rotation of horizontal primary dual-axis trackers are typically aligned either along
a true north meridian or an east-west line of latitude. It is possible to align them in any
cardinal direction with advanced tracking algorithms.
6.3.3.4 Module orientation with respect to rotational axes
The orientation of the module with respect to the tracker axis is important when modelling
performance. Dual-axis trackers typically have modules oriented parallel to the secondary
axis of rotation.
6.4 Actuation and control
6.4.1 Architecture
6.4.1.1 General
There are two common actuation and control architectures: distributed actuation and ganged
actuation. These are implemented in many ways.
6.4.1.2 Distributed actuation
In a distributed actuation architecture, each tracker and each axis of rotation is independently
actuated and controlled.
6.4.1.3 Ganged actuation
In a ganged actuation architecture, many axes of rotation are simultaneously driven with a
single actuation system. This can be multiple axes on a single tracker or multiple trackers in
an array.
6.4.2 Drive train
The drive train includes all components of the tracker system that transfer mechanical motion
to the payload interfaces, including all axes of rotation. Typically, this would include gears,
motors, actuators, hydraulic/pneumatic rams, transmission, and linkages. The drive train does
not include the electronic controls or the payload interface.
6.4.3 Drive types
6.4.3.1 General
There are three typical drive types used with solar trackers.

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Photovoltaic systems – Design qualification of solar trackers

Systèmes photovoltaïques – Qualification de conception des suiveurs solaires

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Photovoltaic systems – Design qualification of solar trackers

Systèmes photovoltaïques – Qualification de conception des suiveurs solaires

® Registered trademark of the International Electrotechnical Commission

–2– IEC 62817:2014 © IEC 2014

IEC 62817:2014 © IEC 2014 –3–

6.9.4 Stiffness ...................................................................................................... 23

–4– IEC 62817:2014 © IEC 2014

8.3.2 Daily energy and peak power consumption ................................................... 33

Figure 1 – Convention for elevation angle ............................................................................ 16

IEC 62817:2014 © IEC 2014 –5–

Figure 11 – Two configurations for extreme wind moment loading ........................................ 42

Table 1 – Tracker specification template ............................................................................. 10

–6– IEC 62817:2014 © IEC 2014

INTERNATIONAL ELECTROTECHNICAL COMMISSION

FDIS Report on voting

IEC 62817:2014 © IEC 2014 –7–

–8– IEC 62817:2014 © IEC 2014

1 Scope and object

The objective of this design qualification standard is twofold.

IEC 60068-2-21, Environmental testing – Part 2-21: Tests – Test U: Robustness of

IEC 60529, Degrees of protection provided by enclosures (IP Code)

IEC 60904-3:2008, Photovoltaic devices – Part 3: Measurement principles for terrestrial

IEC 61000-4-5:2005, Electromagnetic compatibility (EMC) – Part 4-5: Testing and

IEC 62817:2014 © IEC 2014 –9–

IEC 62262:2002, Degrees of protection provided by enclosures for electrical equipment

3 Terms and definitions

4 Specifications for solar trackers for PV applications

– 10 – IEC 62817:2014 © IEC 2014

Table 1 – Tracker specification template

Characteristic Example Responsibility/Clause/Subclause

IEC 62817:2014 © IEC 2014 – 11 –

Characteristic Example Responsibility/Clause/Subclause

Range of motion, secondary axis 10° to 90° elevation (M) 6.6.3.3

– 12 – IEC 62817:2014 © IEC 2014

Characteristic Example Responsibility/Clause/Subclause

Maximum allowable wind speed in 40 m/s (M) 6.12.5

Temperature operational range –20 °C to +50 °C (M) 6.12.1

Temperature survival range –40 °C to +60 °C (M) 6.12.2

Snow rating Up to 20 kg/m 2 of snow load allowed (M) 6.12.6

IEC 62817:2014 © IEC 2014 – 13 –

6 Tracker definitions and taxonomy

6.2 Payload types

6.2.1 Standard photovoltaic (PV) module trackers

6.2.1.2 Type of light accepted

6.2.1.3 Accuracy requirements

6.2.2 Concentrator photovoltaic (CPV) module trackers

6.2.2.2 Type of light accepted

6.2.2.3 Accuracy requirements