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Background Statement for SEMI Draft Document 5660
New Standard: Specification for Ultra-thin Glasses Used for Photovoltaic Modules
Notice: This background statement is not part of the balloted item. It is provided solely to assist the recipient in reaching an informed decision based on the rationale of the activity that preceded the creation of this Document.
Notice: Recipients of this Document are invited to submit, with their comments, notification of any relevant patented technology or copyrighted items of which they are aware and to provide supporting documentation. In this context, “patented technology” is defined as technology for which a patent has issued or has been applied for. In the latter case, only publicly available information on the contents of the patent application is to be provided.
Background Statement:
With the rapid development of photovoltaic technology,new products and new technologies are emerging in the PV materials field. And the ultra-thin glass of PV module has recently emerged. Thinner glass is currently one of the important directions for photovoltaic glass.
Ultra-thin glass has a special tempering process. Ordinary 3.2mm tempered glass is applied in the PV industry, and strengthened particle size is generally used to characterize its tempered degree. The mechanical properties of ultra-thin glass (like 2.5mm), such as impact resistance and flexural strength, are the same as that of 3.2mm tempered glass. Because of the different processes, the particle size cannot be used to characterize the ruptured degree of ultra-thin glass. Therefore it is important to develop a standard for the “ultra-thin glass of PV modules” to promote the development of PV industry.
Review and Adjudication Information
Task Force Review / Committee AdjudicationGroup: / PV Module TF / China PV Committee
Date: / TBD / Sep. 12th, 2014
Time & Timezone: / TBD / TBD
Location: / TBD / TBD
City, State/Country: / China / Dalian, Liaoning, China
Leader(s): / Wei Zhou / Trina Solar
Jingbing Zhu/ Suntech
Liang Luo/Red Solar
Schless Ton/Sibco China / Guangchun Zhang(CanadianSolar)
Jun Liu(CESI)
Standards Staff: / Kris Shen(SEMI China)
/ Kris Shen(SEMI China)
Meeting date and time are subject to change, and additional TF reviewsessions may be scheduled if necessary. Contact the task force leaders or Standards staff for confirmation. Check for the latest schedule.
If you have any questions, please contact the ballot author at:
Taoyun Xiao/ Trina Solar
Tel:+86-519-81587381
E-mail:
SEMI Draft Document 5660
New Standard: Specification for Ultra-thin Glasses Used for Photovoltaic Modules
1 Purpose
1.1 The purpose of this standard is to standardize requirements for ultra-thin glasses for photovoltaic modules.
2 Scope
2.1 This specification covers requirements, test methods, sampling, and judgment rules for ultra-thin glass for photovoltaic modules.
2.2 Thisspecification applies to ultra-thin glass with heat-treated technology, including floatand tempered (or heat strengthened)ultra-thin glass,patternedand tempered (or heat strengthened)ultra-thin glass.
2.3 This specification applies tothe glass used for double-glass photovoltaic module, and normal module with glass and polymer back sheet.
NOTICE: SEMI Standards and Safety Guidelines do not purport to address all safety issues associated with their use. It is the responsibility of the users of the Documents to establish appropriate safety and health practices, and determine the applicability of regulatory or other limitations prior to use.
3 Limitations
3.1 None.
4 Referenced Standards and Documents
4.1 SEMIStandard
SEMI PV47 —Specification for Anti-reflective-coated Glass, Used in Crystalline Silicon Photovoltaic Modules
4.2 ASTM Standards[1]
ASTM C1279—Non-destructive Photoelastic Measurement of Edge and Surface Stresses in Annealed, Heat-strengthened, and Fully Tempered Flat Glass
4.3 EN Standards[2]
EN 572-2—Glass in Building.Basic Soda Lime Silicate Glass Products– Part 2: Float Glass
EN 572-5 —Glass in Building. Basic Soda Lime Silicate Glass Products– Part 5: Patterned Glass
EN 1096-1 — Glass in building. Coated glass – Part 1: Definitions and Classification
EN 1288-3—Glass in Building. Determination of the Bending Strength of Glass – Part 3: Test with Specimen Supported at Two Points (Four Point bending)
EN1863-1—Glass in Building. Heat Strengthened Soda Lime Silicate Glass – Part 1: Definition and Description
4.4 ISO Standards[3]
ISO 2859-1 —Sampling Procedures for Inspection by Attributes – Part 1: Sampling Schemes Indexed by Acceptance Quality Limit (AQL) for Lot-by-lot Inspection
NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.
5 Terminology
5.1 Refer to the SEMI Standards Compilation of Terms (COTs) for a list of the current Abbreviations, Acronyms, Definitions, and Symbols.
5.2 Abbreviations and Acronyms
5.2.1
5.2.1 AQL — Acceptance quality level
5.2.4 T —Thickness of ultra-thin glass
5.3 Definitions
5.3.1 ultra-thin glass used for photovoltaic module—Glass with thickness of 2~3 mm (containing 2 mm) used for photovoltaic module, as shown in Figure 1.
Figure 1
Ultra-thin Glass Used for Photovoltaic Module
5.3.2 ultra-thin heat-treated glass —ultra-thin glass with the heat-treated technology, the mechanical strength and heat shock resistance of the glass can be improved.
5.3.3 ultra-thin front glass — front glass used for thephotovoltaic module, which is ultra-white glass, including patterned and float glass, coated and uncoated glass.
5.3.4 ultra-thin rear glass — ultra-thin glass only used for the back of double-glass module, which is usuallynormal float and uncoated glass, and it can also be ultra-white glass.
6 Test Methods
6.1 Test Condition
6.1.1 Tests shall be carried in the conditions as follows:
a)Temperature:20℃±5℃;
b)Pressure:8.60×104Pa～1.06×105Pa;
c)Relative humidity:40%～80%.
6.2 Appearance
6.2.1 Appearance test of uncoated glass shall be carried according to EN 572-2 and EN 572-5.Appearance test of coated glass shall be carried according to EN 1096-1.
6.3 Size Tolerance
6.3.1 Length and width are tested by steel tape with minimum scale of 1mm. Thickness is tested on the middle spots which are 15 mm away from the glass edge by outside micrometer with 0.01mm accuracy or the equipment with the same accuracy. Thickness difference of the glass is the gap difference between maximum and minimum value.
6.4 Hole
6.4.1 Test the size of holeson the glass with appliance such asvernier caliper, whose minimum scale is 0.02 mm. Test the relative position of the holes with steel ruler or steel tape measure, whose minimum scale is 1 mm.
6.5 Edge Processed
6.5.1 Visually inspect the glass at 600mmaway from the front ofglassunder fine natural light and scattering light.
6.6 BowDegree
6.6.1 The glass shall be placed in a vertical position and supported on its longer side by two load bearing blocks at the quarter points. Put anedge ruler or metal wire close to the two sides or diagonal of the glass. And test the gap between straight line and the glass by feeler. The degree of bow is then expressed as the deformation, divided by the measured length of the edge of the glass, or diagonal.
6.6.2 Localbow shall be measured over a limited length of 300 mm by using anedge ruler or a metal line. As shown in Figure 2 (metal line) and Figure 3 (edge ruler), degree of local bow is represented by the height of the trough or crest by using a feeler. The measurement shall be carried out at room temperature.
1-Deformation of the bow; 2- Glass side or diagonal length; 3-local bow; 4-300mm length
Figure 2
Test by Metal Line
1-Edge ruler; 2-Feeler; 3-Deformation of the bow; 4-Direction of bow deformation
Figure 3
Test by Edge Ruler
6.7 Bending Strength
6.7.1 The test isperformed according to EN 1288-3.
6.8 Optical Properties
6.8.1 The test is performed according to SEMI PV47.
6.9 Iron Content
6.9.1 Iron content test is performed according to phenanthrolinespectrophotometry method.
6.10 Impact Resistance
6.10.1 Twelve glass products are selected as samples to do the test, in which six products are reserved.
6.10.2 Put the glass product on the supporting fixture, and keep theimpact surface horizontal.
6.10.3 Subject the glass product to an impact to the surface resulting from a smooth steel sphere weighing 1040 g falling through a distance of 800 mm. The impact point shall be within 25 mm of the center of the sample. Impact the glass only once to check the damage.
6.11 Surface Stress
6.11.1 For float glass, three pieces of products are selected as samples to perform the test according to ¶ 9.1 in ASTM C1279.
6.12 Heat Shock Resistance
6.12.1 Eight tempered glass samples (300 mm×300 mm) are prepared to perform the test, in whichfour samples are reserved. Samples shall be maintained for at least4 h at a temperature of 200℃±2℃in the oven. Then remove and immerse the samples vertically into the ice-water mixture immediately. Make sure that at least 1/3 of the sample is immersed in the mixture for 5 min before the inspection. Scaly peelon the glass surface and edges are not considered as damages.
6.13 Fragmentation
6.13.1 Products are selected as samples. The test sample shall be laid flat on a table. In order to prevent scattering of the fragments, the samples shall be simply held at the edges, e.g. by adhesive tape etc., so that the fragments remain interlocked after breakage yet extension of the sample is not hindered.
6.13.2 Samples shall be impacted, using a pointed steel tool, at a position 20mm in from the longest edge of the test sample at the mid-point of that edge, until breakage occurs. The radius of curvature of the pointed steel tool should be 0.2 mm±0.05 mm.
6.13.3 As for heat strengthened glass, the examination for “island” and “particle”shall be completed within 5min of fracturing the glass.“Island” and “particle” are shown in Figure 4. Samples shall be examined for its fragmentation pattern. An area of radius 100mm, centered on the impact point, and a border of 25mm, round the edge of the test sample, shall be excluded from the assessment.
1-island; 2-particle
Figure 4
“Island” and “Particle”
6.13.4 As for tempered glass, measures shall be taken to protect the particle pattern from 10s before to 3min after the impact.An area of radius 80mm, centered on the impact point, and a border of 25mm, round the edge of the test sample, shall be excluded from the assessment. The particle count shall be made in largest particle pattern by placing a mask of 50mm×50mm on the test piece. A particle cannot contain any cracks which run from one edge to another. Particles partially within the mask shall be counted as 1/2 particle.
6.14 Other
6.14.1 Scrub resistance, water resistance, acid resistance and resistance to neutral salt spray (fog) of coated glass shall be tested according to SEMI PV47.
7 Ordering Information
7.1 At a minimum ordering information shall include the following items:
7.1.1 Name, size andcertification label of the glass.
8 Requirements
8.1 Appearance
8.1.1 Appearance of uncoatedfront glass shall comply with requirements specified in EN 572-2 and EN 572-5. Appearance of coated front glass shall comply with requirements in EN 1096-1. Appearance of rear glass should be relaxed appropriately according to the agreement of both supplier and user.
8.2 Size and Tolerance
8.2.1 Tolerance of Length and Width
8.2.1.1 Tolerance of length and width of the glass shall fit the requirements in Table 1.Special requirements on tolerance shall be agreed by both supplier and user.
Table 1 Tolerance of Length and Width (mm)
Ultra-thin glass of photovoltaic module / ToleranceLength≤2000 / ±1
Length>2000 / ±2
8.2.2 Tolerance of Thickness
8.2.2.1 Tolerance shall fit the requirements shownin Table 2.Special requirements on tolerance shall be agreed by both supplierand user.
Table 2Tolerance of Thickness (mm)
T / Tolerance of thickness2.0≤T2.5 / ±0.15
2.5≤T3.0 / ±0.2
8.2.3 Thickness Difference
8.2.3.1 Thickness difference shall fit the requirements inTable 3.
Table 3Thickness Difference (mm)
T / Thickness differenceFloat glass / Patterned glass
2.0≤T2.5 / ≤0.20 / ≤0.25
2.5≤T3.0 / ≤0.25 / ≤0.30
8.2.4 Diagonal Tolerance
8.2.4.1 Diagonal tolerance of heat strengthened glass shall be smaller than 0.2% of the average length of two diagonals.Diagonal tolerance of tempered glass shall be smaller than 0.1% of the average length of two diagonals.
8.3 Hole
8.3.1 Round hole shall be according to the requirements in ¶7.4 in EN 1863-1. Other holes should be agreed by both supplier and user.
8.4 Edge Processed
8.4.1 Edge processed shall be agreed by both supplier and user.
8.5 BowDegree
8.5.1 Degree of bow shall not be larger than 0.25%; Degree of local bow shall not be larger than 0.2% in any 300mm range.
8.6 Bending Strength
8.6.1 Bending strength of ultra-thin glass shall not be smaller than 120 Mpa.
8.7 Optical Properties
8.7.1 Optical properties of ultra-thin front glass shall be according to ¶ 7.4 in SEMI PV47. No requirements on optical properties of ultra-thin rear glass.
8.8 Iron Content
8.8.1 Iron content (Fe2O3) of ultra-thin front glass shall not be larger than 0.015%. No requirements on solar direct transmittance of ultra-thin rear glass.
8.9 ImpactResistance
8.9.1 Destroyed samples in the test shall be in accordance with ¶ 10.3.
8.10 Surface Stress
8.10.1 Surface stress of float glass shallsatisfythe requirements in Table 4.
Table 4 Surface Stress of Float Glass
T(mm) / Surface stress (Mpa)2.0≤T2.5 / ≥70
2.5≤T2.8 / ≥80
2.8≤T3.0 / ≥100
8.11 Heat Shock Resistance
8.11.1 Samples shall be capable of resisting both sudden temperature changes and temperature differentials up o 200 ℃.
8.12 Fragmentation
8.12.1 For heat strengthened glass, fragment produced during the test shall be assessed as follows:
a)At least one edge of the fragment shall reach the excluded area.
b)When no edge of the fragment reaches the excluded area, either an “island” or a “particle” is produced. There shall be less than three “islands”. Area of all the “island” and “particle” shall not be larger than 500mm2.
8.12.2 For tempered glass,there shall not be less than 40 particles in every 50mm×50mm areas of the sample. A few of long particles are allowed. But the length of the long particle shall not exceed 100mm.
8.13 Other
8.13.1 Scrub resistance, water resistance, acid resistance and resistance to neutral salt spray (fog) of coated glass shall be qualified to SEMI PV47.
9 Sampling
9.1 During the normal production, products shall be selected to test in appearance, size tolerance and bow degree before sales. Other tests should be agreed by both supplier and user. When new glass product is developed, or great changes happened to the glass, such as the changes on structure, material and technology, all the test items shall beperformed. Samples shall be prepared according to the test demand.
9.2 Sampling for appearance, size tolerance and bow degree are prepared according to ISO 2859-1, with special test level of S-2, AQL is 1.5.
9.3 For other technology performance, random sampling is required in the test. Samples prepared shall be in the same technology. When the glasses are more than 1000 pieces, samplings shall be prepared from every 1000 pieces.
10 Judgment rules
10.1 Appearance, size tolerance and bow degree of the glassshall be judged according to AQL 1.5 in ISO 2859-1.
10.2 All the samples shall pass the test ofoptical property, iron content and fragmentation.
10.3 In impact resistance test, if there isno more than one damaged sample, the test is passed, while if equal or more than three samples are damaged, the test is failed. If there are two damaged samples, six reserved samples are used to test again, and the test is failed when any of the reserved samples are damaged.
10.4 Surface stress test is passed if all of the three samples are undamaged.If there are two samples damaged, the test is failed.If only two samples are undamaged,another three samples shall be tested again, and the test is failed when any of the reserved samples are damaged.
10.5 In heat shock resistance test, test is passed if all the samples are undamaged. If more than two samples are damaged, the test is failed. If there’s only one damaged sample, the test is passed when another reserved sample is undamaged. If there are two damaged samples, the test is passed when another four reserved samples are undamaged.
10.6 A batch of products is qualifiedif all the tests demanded are passed.
11 Marking, Packaging, Transportation, and Storage
11.1 Marking — Packaging marks shall comply with requirements of relevant national standards. Each packagingbox shall be labeled with marks and words such as "Upward, Handle with Care and Place Upright, Fragile, KeepDry", and labeled with the thickness of the glass, production date, certificate, factory name, factory address, ortrademark.
11.2 Packaging — The glass should be packed in a wooden box, a carton box, or a container (rack), and the box(rack) shall be convenient for handling and transportation. Preferably, each box (rack) contains the glass with thesame thickness and dimensions. Protection measures shall be taken between the glasses, between the glass and thebox (rack) to prevent the glass from being damaged, and the surface of the glass from being scratched.
11.3 Transportation —During transportation, the glass shall be tightly fixed toavoid slipping and toppling over, and shall be protected from rain.
11.4 Storage — The products shall be stored in a dry and ventilated place.
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