IEC TS 62446-3:2017

Photovoltaic (PV) systems - Requirements for testing, documentation and maintenance - Part 3: Photovoltaic modules and plants - Outdoor infrared thermography

IEC TS 62446-3:2017(E) defines outdoor thermographic (infrared) inspection of PV modules and plants in operation. This inspection supports the preventive maintenance for fire protection, the availability of the system for power production, and the inspection of the quality of the PV modules. This document lays down requirements for the measurement equipment, ambient conditions, inspection procedure, inspection report, personnel qualification and a matrix for thermal abnormalities as a guideline for the inspection.

General Information

• Status: Published
• Publication Date: 14-Jun-2017
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 27.160 - Solar energy engineering
• Technical Committee: TC 82 - Solar photovoltaic energy systems
• Drafting Committee: WG 3 - TC 82/WG 3
• Current Stage: PPUB - Publication issued
• Start Date: 13-Jul-2017
• Completion Date: 15-Jun-2017

Standards Content (Sample)

IEC TS 62446-3 ®
Edition 1.0 2017-06
TECHNICAL
SPECIFICATION
colour
inside
Photovoltaic (PV) systems – Requirements for testing, documentation and
maintenance –
Part 3: Photovoltaic modules and plants – Outdoor infrared thermography

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IEC TS 62446-3 ®
Edition 1.0 2017-06
TECHNICAL
SPECIFICATION
colour
inside
Photovoltaic (PV) systems – Requirements for testing, documentation and

maintenance –
Part 3: Photovoltaic modules and plants – Outdoor infrared thermography

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-4290-2

– 2 – IEC TS 62446-3:2017 © IEC 2017
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Requirements of inspection equipment . 9
4.1 General . 9
4.2 Minimum requirements for IR-cameras used for inspecting PV plants . 9
4.3 Requirements for photo cameras for documentation of the findings . 10
4.4 Requirements for equipment to record the ambient conditions . 10
5 Inspection procedure . 11
5.1 General . 11
5.2 Visual inspection . 12
5.3 Environmental conditions . 12
5.4 Imaging procedure . 13
5.4.1 General . 13
5.4.2 Using fast carriers for IR-camera, e.g. aerial drones . 13
5.4.3 Emissivity . 14
6 Software for evaluation . 15
7 Evaluation . 15
7.1 General . 15
7.2 Evaluation of IR images . 16
7.3 Thermal abnormalities . 17
7.3.1 General . 17
7.3.2 Classes of abnormalities (CoA) . 17
7.3.3 Abnormalities of PV modules . 17
7.3.4 Abnormalities of other BOS components . 17
7.4 Projection of temperature differences to nominal irradiance . 18
7.4.1 General . 18
7.4.2 Modules . 20
7.4.3 Other BOS components . 21
8 Inspection report . 21
Annex A (normative) Inspection procedure explanations . 24
A.1 Geometric resolution of the camera . 24
A.2 Angle of view . 24
A.3 Matrix for cell identification . 25
Annex B (normative) Qualification of personnel . 27
Annex C (normative) Matrix for thermal abnormalities of PV modules . 28
Annex D (informative) Polygon measurement as a method of evaluation . 32
Annex E (informative) Beaufort scale . 34
Bibliography . 36

Figure 1 – Impact of camera moving speed . 14
Figure 2 – Dependence of the emissivity of glass on the angle of view [10]. 15
Figure 3 – Examples of influence of wind (left) and cloud movement (right) on
observed temperature pattern . 16

Figure 4 – Example infrared thermograms of a PV string combiner box with cables,
contacts, fuses and switches before (left) and after (right) maintenance on a faulty
contact . 18
Figure 5 – Graphic representation of the correction factor for temperature differences
to nominal irradiance/load conditions as a function of the relative irradiance/load . 19
Figure 6 – Example of image reporting . 23
Figure A.1 – Geometric resolution of the IR camera . 24
Figure A.2 – Angle of view . 25
Figure A.3 – View for the designation of cell position, viewed from the front of a 60-
cell module, with the junction box at the top (rear side) . 26
Figure D.1 – Arithmetic mean value by polygon measurement . 32
Figure D.2 – Arithmetic mean and spot value by polygon measurement . 33

Table 1 – Minimum requirements for IR-cameras . 9
Table 2 – Requirements for equipment to record the ambient conditions . 11
Table 3 – Required inspection conditions . 12
Table 4 – Allocation in classes of abnormalities . 17
Table 5 – Example correction factors for temperature differences to nominal load
conditions based on formula above and Figure 5 . 20
Table E.1 – Beaufort scale taken form World Meteorolgical Organization
(www.wmo.int) and Royal Meteorological Society (www.rmets.org) . 34

– 4 – IEC TS 62446-3:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC (PV) SYSTEMS –
REQUIREMENTS FOR TESTING,
DOCUMENTATION AND MAINTENANCE –

Part 3: Photovoltaic modules and plants –
Outdoor infrared thermography
FOREWORD
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