IEC TS 62989:2018

IEC TS 62989 ®
Edition 1.0 2018-03
TECHNICAL
SPECIFICATION
colour
inside
Primary optics for concentrator photovoltaic systems

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IEC TS 62989 ®
Edition 1.0 2018-03
TECHNICAL
SPECIFICATION
colour
inside
Primary optics for concentrator photovoltaic systems

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-5422-6

– 2 – IEC TS 62989:2018 © IEC 2018
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Primary optics for concentrator photovoltaic systems . 9
5 Optics . 13
5.1 Source spectrum . 13
5.2 Optical material properties . 13
5.2.1 Spectral transmittance of lens material . 13
5.2.2 Spectral hemispherical reflectance of mirrors . 17
5.2.3 Dispersion: Abbe number of CPV primary lens materials . 18
5.2.4 Refractive index n of CPV primary lens materials . 19
D
5.3 Focusing characteristics: Focal length, lens efficiency, focal spot size and
uniformity . 20
5.3.1 Preliminaries . 20
5.3.2 Method A . 22
5.3.3 Method B . 23
5.3.4 Method C . 26
6 Mechanics . 29
6.1 Minimum radius . 29
6.2 Surface hardness . 29
6.3 Impact resistance (dynamic) . 29
6.3.1 Definitions . 29
6.3.2 Setup of experiments . 30
6.3.3 Procedure . 30
6.3.4 Presentation of results . 30
7 Materials . 30
8 Geometry . 31
8.1 General . 31
8.2 Definitions. 31
8.3 Fresnel lenses and Fresnel mirrors . 31
8.4 Presentation of drawing and tables . 31
8.5 Data exchange . 34
9 Visual apprearance . 34
9.1 Imperfections, blemishes . 34
9.2 Clarity and colour . 34
9.2.1 Haze (and schlieren; scorch) . 34
9.2.2 Colour . 35
Bibliography . 36

Figure 1 – Example of efficiency versus spot size – Encircled energy level of 95 % . 8
Figure 2 – Example of a primary lens parquet, set up for the hail impact test . 30
Figure 3 – Drawing of general dimensions of Fresnel lens parquet . 32
Figure 4 – Detail X from Figure 3 – Flange and lens of Fresnel lens parquet . 33

Figure 5 – Detail Y from Figure 3 – Thickness of lens substrate (glass) and superstrate
(silicone) . 33
Figure 6 – Detail Z from Figure 5 – Drawing of prism with tip radius R and groove
t
radius R . 34
g
Table 1 – Characteristics: product identification . 9
Table 2 – Characteristics: optics . 10
Table 3 – Characteristics: mechanics . 11
Table 4 – Characteristics: materials . 11
Table 5 – Characteristics: geometry . 12
Table 6 – Characteristics: visual appearance . 12
Table 7 – Methods and results of the round robin for the focal characteristics of
Fresnel lenses . 21

– 4 – IEC TS 62989:2018 © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PRIMARY OPTICS FOR CONCENTRATOR
PHOTOVOLTAIC SYSTEMS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC TS 62989, which is a technical specification, has been prepared by IEC technical
committee 82: Solar photovoltaic energy systems.

The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
82/1281/DTS 82/1376/RVDTS
Full information on the voting for the approval of this technical specification can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Di
...