BSI PD IEC/TS 62788-2:2017
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Measurement procedures for materials used in photovoltaic modules – Polymeric materials. Frontsheets and backsheets
| Published By | Publication Date | Number of Pages |
| BSI | 2017 | 96 |
This part of IEC 62788 defines test methods and datasheet reporting requirements for safety and performance related properties (mechanical, electrical, thermal, optical and chemical) of non-rigid polymeric materials intended for use in terrestrial photovoltaic modules as polymeric frontsheets and backsheets.
The test methods in this document define how to characterize backsheet and frontsheet materials and their components in a manner representative of how they will be used in the module, which eventually includes combination with other matched components such as encapsulant or adhesives. The methods described in this document support the safety and performance related tests defined on PV module level as defined in the series IEC 61730 and IEC 61215.
This document also defines test methods for assessment of inherent material characteristics of polymeric backsheets and frontsheets or their components, which may be required in datasheet reporting or may be useful in the context of product development or design of PV modules.
Rigid polymeric sheet materials (also providing mechanical support) may require further consideration.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 2 | National foreword |
| 6 | CONTENTS |
| 10 | FOREWORD |
| 14 | 1 Scope 2 Normative references |
| 17 | 3 Terms and definitions |
| 20 | 4 Test procedures 4.1 General |
| 21 | 4.2 Mechanical characteristics 4.2.1 General 4.2.2 Thickness |
| 22 | 4.2.3 Area weight |
| 23 | 4.2.4 Tensile strength / elongation at break |
| 24 | Figures Figure 1 – Specimen type |
| 26 | 4.2.5 Curling 4.3 Adhesion testing 4.3.1 Purpose 4.3.2 General |
| 27 | 4.3.3 Sample preparation |
| 28 | 4.3.4 Sample conditioning 4.3.5 Apparatus and procedure 4.3.6 Adhesion tests for interfaces of backsheet and frontsheet |
| 29 | Tables Table 1 – Overview of adhesion tests |
| 31 | 4.3.7 Reporting requirements |
| 32 | 4.4 Thermal characteristics 4.4.1 Thermal endurance 4.4.2 Dimensional stability |
| 33 | Figure 2 – Specimen before and after shrinkage |
| 34 | 4.4.3 Relative thermal expansion (CTE) |
| 35 | 4.4.4 Thermal conductivity 4.5 Electrical characteristics 4.5.1 Breakdown voltage |
| 36 | 4.5.2 Distance through insulation (dti) |
| 38 | Figure 3 – Examples of lamination cycles Figure 4 – Schematics of test specimen for distancefor insulation before and after lamination |
| 39 | Figure 5 – Directions for sectioning (perpendicular tosolder wire position) |
| 41 | 4.5.3 Comparative Tracking Index (CTI) Figure 6 – Example of dti cross-section of a backsheetwith an E-layer as inner side material |
| 42 | 4.5.4 Volume resistivity |
| 43 | 4.6 Optical characteristics 4.6.1 General |
| 44 | 4.6.2 Specimen preparation 4.6.3 Visual Inspection |
| 45 | 4.6.4 Optical transmittance of frontsheets and backsheets |
| 46 | 4.6.5 Optical reflectance of backsheets 4.6.6 Yellowness index (YI) |
| 47 | 4.6.7 Colour measurement (L*, a*, b*) |
| 48 | 4.6.8 Surface gloss |
| 49 | 4.7 Diffusion characteristics 4.7.1 Permeability of water vapour |
| 50 | 4.7.2 Permeability of oxygen 4.8 Chemical characteristics 4.8.1 Resistance to solvents |
| 52 | 4.9 Other characteristics 4.9.1 Ignitability – Purpose 4.9.2 Flammability – Purpose 4.10 Accelerated ageing tests 4.10.1 Purpose |
| 53 | 4.10.2 Damp Heat (DH) testing at elevated heat and moisture |
| 54 | 4.10.3 Weathering at elevated levels of temperature and moisture |
| 56 | Table 2 – Overview of sample preparation for exposure ofsun-facing side of backsheet depending on intendedpost evaluation (see Table F.1) |
| 59 | 5 Uniform characterization form (UCF) 5.1 General 5.2 Layer stack description |
| 60 | 5.3 Material test results and reporting requirements |
| 61 | Table 3 – Uniform characterization form (UCF) for polymericPV frontsheet or backsheet |
| 62 | 6 Data sheet 6.1 Purpose 6.2 Reporting requirements 7 Product identification sheet (label) |
| 63 | Annex A (informative)Overview of adhesion testing of frontsheet and backsheet A.1 Type of adhesion failure Figure A.1 – Adhesive and cohesive failure type schematicsfor lap-shear (top) and T-pluck (bottom) |
| 64 | A.2 Characteristics of adhesion peel tests A.3 Characteristics of pluck and lap-shear tests |
| 65 | A.4 Cross-hatch tape testing A.5 Other caveats A.6 Overview |
| 66 | Table A.1 – Overview of various adhesion tests and their general capability oftesting polymeric frontsheet and backsheet |
| 68 | Annex B (normative)Adhesive bond strength test procedures in PV context B.1 180°peel adhesion test B.1.1 Specimens B.1.2 Procedure Figure B.1 – Example test panel (70 mm x 150 mm) and test specimen |
| 69 | B.1.3 Measurement Figure B.2 – Fixation of the sample for 180° peel (for use with flexible/flexible samples)and cross-section of the sample |
| 70 | B.2 T-peel adhesion test B.2.1 Sample preparation Figure B.3 – Single and multiple failure modes in a peel test |
| 71 | B.2.2 Procedure B.2.3 Measurement Figure B.4 – Sheet sandwich (above) from which test specimensfor T-peel are prepared |
| 72 | B.3 Dynamic tensile (T-pluck) B.3.1 Purpose B.3.2 Principle B.3.3 Specimens Figure B.5 – Dynamic tensile (pluck) schematic |
| 73 | B.3.4 Measurement procedure B.3.5 Final measurements Figure B.6 – Schematic of pluck sample (in cross-section)for a laminated backsheet test Figure B.7 – Dynamic tensile variables |
| 74 | B.4 Dynamic overlap shear B.4.1 Purpose B.4.2 Principle B.4.3 Specimens Figure B.8 – Overlap shear force schematics |
| 75 | Figure B.9 – Schematic of overlap shear specimen shown in cross-section,for a laminated backsheet coupon Figure B.10 – Details of overlap shear specimens(ISO 4587:2003, Figure 1) |
| 76 | B.4.4 Measurement procedure B.4.5 Final measurements Figure B.11 – Overview of overlap shear test conditions |
| 77 | B.5 Cross-hatch tape test B.5.1 Apparatus Figure B.12 – Dynamic overlap shear schematic |
| 78 | B.5.2 Procedure B.5.3 Final measurements Figure B.13 – Illustration of area removal by tape in cross-hatch test,with classification from 0 to 5 (from left to right) |
| 79 | Annex C (normative)DC breakdown voltage C.1 Apparatus |
| 80 | C.2 Surrounding medium C.3 Procedure Figure C.1 – Equal electrodes for dielectric strength test(taken from Figure 1b of IEC 60243-1:2013) |
| 81 | C.4 Criteria of breakdown C.5 Other characterization methods |
| 83 | Annex D (informative)Abrasion testing D.1 Purpose D.2 Methods |
| 84 | Figure D.1 – Number size distributions of saltation particles at the dune site,30 cm height, and the Gobi sites, 20 cm and 30 cm height,from 1223 to 1320 UT, 5 April 2002 [13] |
| 85 | Figure D.2 – Particle size distribution of sand from different heights Figure D.3 – Grain size distribution of surface sand and drifting sandcaptured at 20 cm high above the crest of dune [14] |
| 86 | Annex E (normative)Sampling of films E.1 Purpose E.2 Procedure |
| 87 | Annex F (normative)Sample preparation F.1 Purpose F.2 Sample constructions F.2.1 General considerations F.2.2 Materials and procedures |
| 89 | Table F.1 – Overview of sample preparation suitable for material tests |
| 91 | Bibliography |
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BSI PD IEC/TS 62788-2:2017
Measurement procedures for materials used in photovoltaic modules – Polymeric materials. Frontsheets and backsheets Published…
