IEC TS 62727:2012

IEC/TS 62727 ®
Edition 1.0 2012-05
TECHNICAL
SPECIFICATION
colour
inside
Photovoltaic systems – Specifications for solar trackers

IEC/TS 62727:2012(E)
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IEC/TS 62727 ®
Edition 1.0 2012-05
TECHNICAL
SPECIFICATION
colour
inside
Photovoltaic systems – Specifications for solar trackers

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
U
ICS 27.160 ISBN 978-2-83220-122-0

– 2 – TS 62727 © IEC:2012(E)
CONTENTS
FOREWORD . 5
1 Scope and object . 7
2 Terms and definitions . 7
2.1 Photovoltaics (PV) . 7
2.2 Concentrating photovoltaics (CPV) . 7
2.3 Concentrator module (CPV module) . 7
2.4 Concentrator assembly . 8
3 Specifications for solar trackers for PV applications . 8
3.1 Specification template . 8
4 Tracker definitions and taxonomy . 10
4.1 General . 10
4.2 Payload types . 10
4.2.1 Standard photovoltaic (PV) module trackers . 10
4.2.2 Concentrated photovoltaic (CPV) module trackers . 11
4.3 Rotational axes . 11
4.3.1 Single axis trackers . 11
4.3.2 Dual axis trackers . 12
4.4 Actuation and control . 14
4.4.1 Architecture . 14
4.4.2 Drive types . 14
4.5 Types of tracker control . 15
4.5.1 Passive control . 15
4.5.2 Active control. 15
4.5.3 Backtracking . 15
4.6 Structural characteristics . 16
4.6.1 Vertical supports. 16
4.6.2 Foundation types . 16
4.6.3 Tracker positions . 17
4.6.4 Stow time . 17
4.7 Energy consumption . 17
4.7.1 Daily energy consumption . 17
4.7.2 Stow energy consumption . 18
4.8 External elements and interfaces . 18
4.8.1 Foundation . 18
4.8.2 Foundation interface . 18
4.8.3 Payload . 18
4.8.4 Payload interface . 18
4.8.5 Payload mechanical interface . 18
4.8.6 Payload electrical interface . 18
4.8.7 Grounding interface . 18
4.8.8 Installation effort . 18
4.8.9 Control interface . 19
4.9 Internal tolerances . 19
4.9.1 Primary axis tolerance . 19
4.9.2 Secondary axis tolerance . 20
4.10 Tracker system elements . 20

TS 62727 © IEC:2012(E) – 3 –
4.10.1 Mechanical structure . 20
4.10.2 Tracker controller . 20
4.10.3 Sensors . 20
4.11 Reliability terminology . 20
4.11.1 Mean time between failures (MTBF) . 20
4.11.2 Mean time between critical failures (MTBCF) . 21
4.11.3 Mean time to repair (MTTR) . 21
4.12 Environmental conditions . 21
4.12.1 Operating temperature range . 21
4.12.2 Survival temperature range . 21
4.12.3 Maximum wind during operation . 21
4.12.4 Maximum wind during stow . 21
4.12.5 Snow load . 21
4.13 Functional tests . 22
4.13.1 Static load test . 22
4.13.2 Moment testing . 22
4.13.3 Limit switch operation . 22
4.13.4 Manual operation . 22
5 Tracker accuracy characterization . 22
5.1 Overview . 22
5.2 Pointing error (instantaneous) . 22
5.3 Measurement . 23
5.3.1 Overview . 23
5.3.2 Example of experimental method to measure pointing error . 23
5.3.3 Calibration of pointing error measurement tool . 24
5.4 Calculation of tracker accuracy . 24
5.4.1 Overview . 24
5.4.2 Data collection . 25
5.4.3 Data binning by wind speed . 25
5.4.4 Data filtering . 26
5.4.5 Data quantity . 26
5.4.6 Accuracy calculations . 26
6 Mechanical characterization . 27
6.1 General . 27
6.2 Backlash . 27
6.3 Stiffness . 27
7 Reliability testing . 28
7.1 Corrosion . 28
7.2 Component durability. 28
7.3 Extreme conditions tests . 28
8 Additional optional accuracy calculations . 28
8.1 Typical tracking accuracy range . 28
8.2 Tracking error histogram . 29
8.3 Percent of available irradiance as a function of pointing error . 29

Figure 1 – θ = Altitude angle = 0° (zenith angle = 90°) occurs when a vector normal to
the module face is pointing to the horizon. Altitude angle = 90° (zenith angle = 0°)
occurs when the module is facing the sky . 13
Figure 2 – Illustration of primary axis tolerance for a polar tracking axis . 19

– 4 – TS 62727 © IEC:2012(E)
Figure 3 – General illustration of pointing error . 23
Figure 4 – Two flat parallel plates at a specified distance, one having a pin hole for
sunlight to be tracked on specified-diameter circles that ultimately measure 0,1°, 0,2°,
and 0,3° accuracy rings (more if necessary) . 24
Figure 5 – Pointing error frequency distribution for the entire test period . 29
Figure 6 – Available irradiance as a function of pointing error . 30
Figure 7 – Available irradiance as a function
...