Coated steel plate suitable for inline thin-film photovoltaic module and manufacturing method therefor

Abstract

The present invention provides a coated steel plate suitable for an inline thin-film photovoltaic module, comprising a steel substrate and a composite insulating layer on the surface of the steel substrate. The composite insulating layer comprises an insulating base layer and a laser scribing buffer layer; one side of the insulating base layer is the steel substrate, and the other side is the laser scribing buffer layer. The laser scribing buffer layer contains at least one of the following components: Si.sub.xN.sub.y, where 0.75x:y1; and Si.sub.1-x(R).sub.xO.sub.y, where R is an element selected from Sb, Au, Cu, Sn, and Ag, and 0<x0.05, 1.9y2. Since the silicon nitride and the doped silicon dioxide used in the laser scribing buffer layer can exhibit specific colors, part of the energy of the laser can be absorbed during the laser etching process, and the damage and the loss of insulation of the insulating base layer during etching can be avoided, thereby ensuring that the coated steel plate for inline thin-film photovoltaic modules provided by the present invention has stable working performance. Additionally, the present invention further discloses a method for manufacturing the aforementioned coated steel plate.

Claims

1. A coated steel plate suitable for an inline thin-film photovoltaic module, comprising a steel substrate and a composite insulating layer on a surface of the steel substrate, wherein the composite insulating layer comprises an insulating base layer and a laser scribing buffer layer; one side of the insulating base layer is the steel substrate, and the other side is the laser scribing buffer layer; and the laser scribing buffer layer contains at least one of the following components: SixNy, where 0.75x: y1; and Si1-x(R)xOy, where R is at least one element selected from Sb, Au, Cu, Sn, and Ag, and 0<x0.05, 1.9y2.

2. The coated steel plate according to claim 1, wherein in the SixNy, 0.75<x:y<0.90.

3. The coated steel plate according to claim 1, wherein a thickness of the laser scribing buffer layer is 50 to 1,000 nm.

4. The coated steel plate according to claim 3, wherein the thickness of the laser scribing buffer layer is 100 to 500 nm.

5. The coated steel plate according to claim 1, wherein the insulating base layer contains at least one of the following components: SiO2-m, HfO2-m, Si (Hf)O2-m, and Ta2O5-2m, where 0m0.05.

6. The coated steel plate according to claim 5, wherein the insulating base layer is composed of at least one of the following components: SiO2-m, HfO2, Si (Hf)O2,and Ta2O5, where 0m0.05.

7. The coated steel plate according to claim 1, wherein the insulating base layer is of a single-layer structure or a multi-layer structure.

8. The coated steel plate according to claim 7, wherein a total thickness of the insulating base layer is 0.1 to 9 m.

9. The coated steel plate according to claim 8, wherein the total thickness of the insulating base layer is 0.25 to 6 m.

10. The coated steel plate according to claim 1, wherein: a thermal expansion coefficient of the steel substrate at 0 to 100 C. is (10 to 11)106/ C . . . ; the thermal expansion coefficient of the steel substrate at 100 to 315 C. is (10.5 to 11)106/ C . . . ; and the thermal expansion coefficient of the steel substrate at 315 to 650 C. is (11 to 11.5)106/ C.

11. The coated steel plate according to claim 10, wherein the steel substrate is a strip foil steel coil, having a thickness of 5 to 180 m.

12. The coated steel plate according to claim 11, wherein the thickness of the strip foil steel coil is 15 to 50 m.

13. The coated steel plate according to claim 10, wherein the steel substrate is a sheet-like rigid plate, having a thickness of 0.3 to 2.0 mm.

14. The coated steel plate according to claim 13, wherein the thickness of the sheet-like rigid plate is 0.4 to 1.0 mm.

15. The coated steel plate according to claim 10, wherein an arithmetic mean deviation of the profile, Ra, representing surface roughness of the steel substrate, is smaller than 0.3 m, and a maximum height of the profile, Rz, representing the surface roughness of the steel substrate, is smaller than 1 m.

16. The coated steel plate according to claim 15, wherein Ra<0.07 m, and/or Rz<0.3 m.

17. The coated steel plate according to claim 1, wherein the composite insulating layer has a back contact layer formed by depositing a metal bottom electrode on its surface; a material of the back contact layer comprises at least one of the following: Mo or Mo alloy, Cu or a Cu/C composite material, Al or Al alloy, Ag, Au, and Pt; and a thickness of the back contact layer is 20 nm to 2 m.

18. A method for manufacturing the coated steel plate according to claim 1, comprising the following steps: preprocessing a surface of the steel substrate; and depositing the insulating base layer and the laser scribing buffer layer on the surface of the steel substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) To make the above content of the present invention more clearly understandable, preferred embodiments are described below in details in conjunction with the accompanying drawings.

(2) FIG. 1 is a microstructure image of SUS430 steel substrate;

(3) FIG. 2 is a microstructure image of B430LNT steel substrate;

(4) FIG. 3 is a schematic diagram of sectional structure of the coated steel plate in Example 3;

(5) FIG. 4 is a schematic diagram of sectional structure of the coated steel plate in Example 3 after a back contact layer is formed by the deposition of a metal bottom electrode;

(6) FIG. 5 is a schematic diagram of the production process of the continuous coating line in the present invention;

(7) FIG. 6 is a three-dimensional representation of a surface of the coated steel plate with a back contact layer in Example 4 after laser scribing;

(8) FIG. 7 is a sectional profile of the back contact layer in FIG. 6;

(9) FIG. 8 is a three-dimensional representation of a surface of the comparative steel plate with a back contact layer in Comparative Example 3 after laser scribing; and

(10) FIG. 9 is a sectional profile of the back contact layer in FIG. 8.

DETAILED DESCRIPTION

(11) The implementation mode of the present invention will be illustrated below by the following specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention based on the disclosure in the description. Although the description of the present invention will be presented in conjunction with preferred embodiments, it should be understood that the features of the present invention are limited to the specific embodiments. On the contrary, the objective of presenting the present invention in conjunction with the implementation mode is to cover other selections or modifications that may be derived from the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will contain many specific details. However, the present invention can also be implemented without using these details. In addition, to avoid confusion or obscuring of the focus of the present invention, some specific details may be omitted in the description. It should be noted that, unless conflicting, the embodiments in the present invention and the features in the embodiments can be combined with each other.

Examples 1-46 and Comparative Examples 1-8

(12) The coated steel plates suitable for the inline thin-film photovoltaic modules in Embodiments 1-46 of the present invention and comparative steel plates in Comparative Examples 1-8 are manufactured using the following steps. S1: preprocessing a steel substrate: selecting two materials, i.e., an SUS430 strip foil steel coil and a B430LNT sheet-like rigid plate respectively, as the materials for the steel substrate, depending on different requirements of inline thin-film photovoltaic modules for the substrate flexibility and rigidity, as well as the different requirements for subsequent processing and serviceability of different thickness substrates. Among them, the maximum width of the SUS430 strip foil steel coil can be 1,000 mm; and the maximum width of the B430LNT can be 1,500 mm. SUS430: ferrite stainless steel according to the Japanese standard JIS G4303-2012. B430LNT: ferrite stainless steel according to the enterprise standard Q/BXS 009-2017 of Ningbo Baoxin Stainless Steel Co., Ltd.

(13) Based on the general 400-series ferrite stainless steel, B430LNT reduces the content of impurity elements such as N and S to a very low level and adds alloying elements such as Nb and Ti. Since Nb has a strong effect of fixing carbon and nitrogen and refining the grain grain size of ferrite, B430LNT has a very uniform and fine ferrite structure in an annealed state, with very little precipitation of carbonitrides at grain boundaries. Therefore, B430LNT has better corrosion resistance, formability, and wrinkle resistance than SUS430.

(14) The selected SUS430 steel strip and B430LNT steel plate have undergone the pretreatment process including at least cold rolling, bright annealing, and leveling. They both have a surface glossiness and flatness at BA (bright annealed and leveled surface) level or higher. The surface roughness of the selected SUS430 steel strip and B430LNT steel plate should be controlled as low as possible, with Ra<0.3 m and Rz<1 m. Preferably, it can be controlled that Ra<0.07 m and Rz<0.3 m. In addition, SUS430 steel strip and B430LNT steel plate, as the steel substrate materials, need to satisfy the thermal expansion performance requirements: in the temperature range of 0 to 100 C., the thermal expansion coefficient is (10 to 11)10.sup.6/ C.; in the temperature range of 100 to 315 C., the thermal expansion coefficient of (10.5 to 11)10.sup.6/ C.; and in the temperature range of 315 to 650 C., the thermal expansion coefficient is (11 to 11.5)10.sup.6/ C. After the surfaces of the two types of steel substrates are flushed by high pressure water, the surfaces of the steel substrates are quickly dried by blowing compressed air. Then, in a N.sub.2 atmosphere, the upper surface of the steel substrate strip is irradiated by a flat tube type 172 nm extreme ultraviolet (EUV) light source with an intensity of 50 mW/cm.sup.2. This process removes residual small organic molecules on the surface of the steel substrate and enhances the reactivity of the steel substrate surface. After EUV irradiation, the water contact angle on the surface of the above-mentioned two types of steel substrate strips is less than 10.

(15) S2: depositing a composite insulating layer on the surface of the steel substrate: directly depositing an insulating base layer on the surface of the steel substrate strip using a continuous roll-to-roll type or sheet-to-sheet type coating line on one surface of the above-mentioned two types of steel substrates, and then depositing a laser scribing buffer layer consisting of nitrides or oxides on the surface of the insulating base layer to manufacture the coated steel plate suitable for inline thin-film photovoltaic modules. In various examples and comparative examples of the present invention, the thickness of the entire insulating base layer is controlled within a range of 0.1 to 9 m, the thickness of the entire laser scribing buffer layer is controlled within a range of 50 to 1,000 nm. The insulating base layer and the laser scribing buffer layer on the surface of the insulating base layer together form a composite insulating layer.

(16) The insulating base layer is composed of at least one of the following components: SiO.sub.2-m, HfO.sub.2-m, Si(Hf)O.sub.2-m, and Ta.sub.2O.sub.5-2m, where 0m0.05. The insulating base layer can be of a single-layer structure or a multi-layer structure, and the components constituting each layer can be the same or different. The thickness of each single layer of the insulating base layer is controlled within a range of 0.1 to 3 m.

(17) The laser scribing buffer layer is composed of at least one of the following components: Si.sub.xN.sub.y, where 0.75x:y1; and Si.sub.1-x(R).sub.xO.sub.y, where R is an element selected from Sb, Au, Cu, Sn, and Ag, and 0<x0.05, 1.9y2. The materials and the structures of the steel base material and the composite insulating film layer in various examples and comparative examples are shown in Table 2.

(18) It should be noted that in the aforementioned step S1 of the present invention, the selection of different steel substrate materials can respectively satisfy the production requirements of flexible continuous roll-to-roll type process and sheet-to-sheet type process with a bearing function for thin-film photovoltaic modules. Specifically, the SUS430 strip foil steel coil serving as a flexible substrate further needs to be subjected to a precision rolling process to achieve a thickness of 5 to 180 m, and preferably, the thickness is controlled within a range of 15 to 50 m to achieve good flexibility. For the sheet-like rigid B430LNT stainless steel plate, the thickness is controlled between 0.3 to 2.0 mm, and preferably between 0.4 to 1.0 mm.

(19) Table 1 below lists the mass percentage of chemical components of the SUS430 and B430LNT types of steel.

(20) In the present invention, all the process parameters of Examples 1-46 are in conformity with the requirements of the steps above, while in the Comparative Examples 1-8, there are parameters that do not satisfy the process requirements of the aforementioned steps.

(21) Table 1 presents mass percentage of chemical components of the SUS430 and B430LNT types of steel.

(22) TABLE-US-00001 TABLE 1 (wt %, the balance being Fe and other inevitable impurities except for P and S) C Si Mn P S Cr N Ti Nb SUS430 0.120 0.75 1.00 0.040 0.030 16.0~18.0 B430LNT 0.020 0.60 1.00 0.040 0.015 16.0~18.0 0.020 0.30 0.30

(23) According to the method of GB/T 4339, the thermal expansion coefficients of the SUS430 and B430LNT types of steel with a size of 25 mm5 mm0.5 mm are measured by a NETZSCH DIL thermal expansion coefficient measurement instrument, with the same temperature rising speed and a temperature dropping speed of 10 C./min. The test temperature is raised from 0 C. to 700 C., holding for 1 minute, and then is dropped. The thermal expansion coefficients in temperature ranges of 0 to 100 C., 100 to 315 C., and 315 to 650 C. are analyzed and fitted by software.

(24) The measured thermal expansion coefficients of the selected SUS430 stainless steel are as follows: 10.410.sup.6/ C. in the temperature range of 0 to 100 C., 10.910.sup.6/ C. in the temperature range of 100 to 315 C., and 11.410.sup.6/ C. in the temperature range of 315 to 650 C.

(25) The measured thermal expansion coefficients of the selected B430LNT stainless steel are as follows: 10.110.sup.6/ C. in the temperature range of 0 to 100 C., 10.510.sup.6/ C. in the temperature range of 100 to 315 C., and 11.210.sup.6/ C. in the temperature range of 315 to 650 C.

(26) Table 2 presents compositions and film thicknesses of functional film systems of the coated steel plates suitable for the inline thin-film photovoltaic modules in Examples 1-46 and the comparative steel plates in Comparative Examples 1-8.

(27) TABLE-US-00002 TABLE 2 Composite Insulating Layer Insulating Base Layer Steel Substrate First Layer Second Layer Third Layer Laser Scribing Buffer Layer Thickness Ra Rz Thickness Thickness Thickness x:y or Thickness Number Steel Type (mm) (nm) (nm) Type (nm) Type (nm) Type (nm) Type x or x y or y x:y (nm) Example 1 B430LNT 0.5 60 95 SiO.sub.2 100 / / / / SixNy 3 4 0.75 200 Example 2 B430LNT 0.5 59 103 SiO.sub.2 250 / / / / SixNy 3 4 0.75 200 Example 3 B430LNT 0.8 89 205 SiO.sub.2 2000 / / / / SixNy 3 4 0.75 200 Example 4 B430LNT 1.2 100 306 SiO.sub.1.97 4000 / / / / SixNy 3 4 0.75 200 Example 5 B430LNT 1.3 134 575 SiO.sub.2 6000 / / / / SixNy 3 4 0.75 200 Example 6 B430LNT 2.0 297 863 SiO.sub.2 9000 / / / / SixNy 3 4 0.75 200 Example 7 B430LNT 0.4 59 99 SiO.sub.2 4000 / / / / SixNy 3 4 0.75 50 Example 8 B430LNT 0.5 56 102 SiO.sub.1.97 4000 / / / / SixNy 3 4 0.75 100 Example 9 B430LNT 0.5 60 173 SiO.sub.1.99 4000 / / / / SixNy 3 4 0.75 500 Example 10 B430LNT 0.7 65 136 SiO.sub.1.96 4000 / / / / SixN 3 4 0.75 1000 Example 11 B430LNT 0.9 61 256 SiO.sub.2 4000 / / / / Si.sub.1x(Sb).sub.xO.sub.y 0.0495 1.98 0.0255 200 Example 12 B430LNT 0.9 63 312 SiO.sub.2 4000 / / / / Si.sub.1x(Au).sub.xO.sub.y 0.0493 1.97 0.0250 200 Example 13 B430LNT 0.3 59 88 SiO.sub.2 4000 / / / / Si.sub.1x(Cu).sub.xO.sub.y 0.0488 1.90 0.0257 200 Example 14 B430LNT 0.5 60 99 SiO.sub.2 4000 / / / / Si.sub.1x(Sn).sub.xO.sub.y 0.0493 1.91 0.0258 200 Example 15 B430LNT 0.5 55 105 SiO.sub.2 4000 / / / / Si.sub.1x(Ag).sub.xO.sub.y 0.0496 1.95 0.0259 200 Example 16 B430LNT 0.5 48 103 SiO.sub.2 4000 / / / / Si.sub.xN.sub.y 3 3.9 0.77 200 Example 17 B430LNT 0.9 60 113 SiO.sub.2 4000 / / / / Si.sub.xN.sub.y 3 3.8 0.79 200 Example 18 B430LNT 0.5 56 97 SiO.sub.2 4000 / / / / Si.sub.xN.sub.y 1 1.17 0.85 200 Example 19 B430LNT 0.5 60 103 SiO.sub.2 4000 / / / / Si.sub.xN.sub.y 1 1.11 0.9 200 Example 20 B430LNT 0.5 55 123 HfO.sub.2 100 / / / / Si.sub.xN.sub.y 3 4 0.75 200 Example 21 B430LNT 0.5 60 153 HfO.sub.2 2000 / / / / Si.sub.xN.sub.y 3 4 0.75 200 Example 22 B430LNT 0.5 60 127 HfO.sub.2 4000 / / / / Si.sub.xN.sub.y 3 4 0.75 200 Example 23 B430LNT 0.5 55 97 Ta.sub.2O.sub.5 100 / / / / Si.sub.xN.sub.y 3 4 0.75 200 Example 24 B430LNT 0.5 60 98 Ta.sub.2O.sub.5 2000 / / / / Si.sub.xN.sub.y 3 4 0.75 200 Example 25 B430LNT 0.5 64 125 Ta.sub.2O.sub.5 4000 / / / / Si.sub.xN.sub.y 3 4 0.75 200 Example 26 B430LNT 0.5 56 95 SiO.sub.2 100 HfO.sub.2 100 / / Si.sub.xN.sub.y 3 4 0.75 200 Example 27 B430LNT 0.5 60 88 SiO.sub.2 3000 HfO.sub.2 3000 / / Si.sub.xN.sub.y 3 4 0.75 200 Example 28 B430LNT 0.5 60 99 SiO.sub.2 100 Ta.sub.2O.sub.5 100 / / Si.sub.xN.sub.y 3 4 0.75 200 Example 29 B430LNT 0.5 66 123 SiO.sub.2 3000 Ta.sub.2O.sub.5 3000 / / Si.sub.xN.sub.y 3 4 0.75 200 Example 30 B430LNT 0.5 46 99 SiO.sub.2 100 HfO.sub.2 100 SiO.sub.2 100 Si.sub.xN.sub.y 3 4 0.75 200 Example 31 B430LNT 0.5 60 135 SiO.sub.2 3000 HfO.sub.2 3000 Ta.sub.2O.sub.5 3000 Si.sub.xN.sub.y 3 4 0.75 200 Example 32 B430LNT 0.5 56 93 SiO.sub.2 100 SiO.sub.2 100 SiO.sub.2 100 Si.sub.xN.sub.y 3 4 0.75 200 Example 33 B430LNT 1.0 64 105 SiO.sub.2 3000 Ta.sub.2O.sub.5 3000 HfO.sub.2 3000 Si.sub.xN.sub.y 3 4 0.75 200 Example 34 B430LNT 0.5 63 104 SiO.sub.2 500 HfO.sub.2 500 Ta.sub.2O.sub.5 500 Si.sub.xN.sub.y 3 4 0.75 200 Example 35 B430LNT 0.5 62 113 Ta.sub.2O.sub.5 500 Ta.sub.2O.sub.5 500 Ta.sub.2O.sub.5 500 Si.sub.xN.sub.y 3 4 0.75 200 Example 36 B430LNT 0.5 60 112 Si(Hf)O.sub.2 100 / / / / Si.sub.xN.sub.y 3 4 0.75 200 Example 37 B430LNT 1.6 90 217 Si(Hf)O.sub.2 2000 / / / / Si.sub.xN.sub.y 3 4 0.75 200 Example 38 B430LNT 2.0 296 715 Si(Hf)O.sub.2 9000 / / / / Si.sub.xN.sub.y 3 4 0.75 200 Example 39 SUS430 0.18 55 137 SiO.sub.2 100 / / / / Si.sub.xN.sub.y 3 4 0.75 200 Example 40 SUS430 0.05 50 123 SiO.sub.2 500 / / / / Si.sub.xN.sub.y 3 4 0.75 200 Example 41 SUS430 0.03 56 153 SiO.sub.2 1000 / / / / Si.sub.xN.sub.y 3 4 0.75 200 Example 42 SUS430 0.15 50 137 HfO.sub.2 500 / / / / Si.sub.xN.sub.y 3 4 0.75 200 Example 43 SUS430 0.025 45 98 Ta.sub.2O.sub.5 100 SiO.sub.2 100 SiO.sub.2 100 Si.sub.xN.sub.y 3 4 0.75 200 Example 44 SUS430 0.08 50 123 SiO.sub.2 100 HfO.sub.2 100 SiO.sub.2 100 Si.sub.xN.sub.y 3 4 0.75 200 Example 45 SUS430 0.02 70 104 SiO.sub.2 200 HfO.sub.2 200 Ta.sub.2O.sub.5 200 Si.sub.xN.sub.y 3 4 0.75 200 Example 46 SUS430 0.05 50 123 SiO.sub.2 500 HfO.sub.2 500 SiO.sub.2 500 Si.sub.xN.sub.y 3 4 0.75 200 Comparative B430LNT 0.5 50 109 SiO.sub.2 50 / / / / / / / / / Example 1 Comparative B430LNT 0.5 50 105 SiO.sub.2 80 / / / / / / / / / Example 2 Comparative B430LNT 2.0 285 984 SiO.sub.2 20000 / / / / / / / / / Example 3 Comparative B430LNT 1.8 253 879 SiO.sub.2 4000 / / / / Si.sub.xN.sub.y 3 4 0.75 10 Example 4 Comparative B430LNT 1.5 267 788 SiO.sub.2 4000 / / / / Si.sub.xN.sub.y 3 4 0.75 30 Example 5 Comparative B430LNT 0.5 50 152 SiO.sub.2 30 HfO.sub.2 30 / / / / / / / Example 6 Comparative B430LNT 0.5 50 143 SiO.sub.2 20 HfO.sub.2 20 SiO.sub.2 20 / / / / / Example 7 Comparative B430LNT 0.5 65 133 SiO.sub.2 5000 HfO.sub.2 5000 Ta.sub.2O.sub.5 5000 / / / / / Example 8

(28) In Table 2, the first layer of the insulating base layer is the layer in direct contact with the steel substrate, and the third layer is the layer farthest from the steel substrate in the insulating base layer. In the present invention, the comparative steels in Comparative Examples 1-3 and Comparative Examples 6-8 only comprise the steel substrate and the insulating base layer, without the laser scribing buffer layer. Comparative Examples 4-5 satisfy the limitations of claim 1 in this invention, where the steel substrate, the insulating base layer, and the laser scribing buffer layer are present. Comparative Examples 4 and 5 are included to demonstrate the impact of the thickness of the laser scribing buffer layer falling outside the preferred range.

(29) Correspondingly, the coated steel plates suitable for inline thin-film photovoltaic modules in Examples 1-46 of the present invention all comprise a steel substrate and a composite insulating layer set on the surface of the steel substrate. The composite insulating layer comprises an insulating base layer adjacent to the steel substrate and a laser scribing buffer layer located above the insulating base layer. The insulating base layers in the coated steel plates in Examples 1-25 and Examples 36-42 is of a single-layer structure, while the insulating base layers in the coated steel plates in Examples 26-29 is of a double-layer structure, and the insulating base layers in the coated steel plates in Examples 30-35 and Examples 43-46 is of a three-layer structure.

(30) Samples of the finished products of the coated steel plates suitable for inline thin-film photovoltaic modules in Examples 1-46 and the comparative steel plates in Comparative Examples 1-8, which are obtained by the steps above, are respectively taken and tested according to the following testing methods. The evaluation of various performance parameters are conducted, and the obtained test results are listed in Table 3. Tests for evaluating various performance parameters are as follows:

(31) Adhesion test: conducted according to the one-hundred grid test specified in ASTM D3359. Scratches of 100 1 mm1 mm grids are made on the surface of the steel strip with the composite insulating layer using a blade (observe the scratch depth, the depth of the scratch should reach the surface of the steel strip but not penetrate the steel strip). Apply 3M 610 tape on the scratched portion of the grid and press it firmly by hand to ensure tight contact between the tape and the grid surface. After approximately 60 seconds, lift the end of the tape that is not stuck and rapidly pull it up at an angle as close to 1800 as possible. Use a magnifying glass to inspect if there is any detachment or peeling in the grid area.

(32) The specific evaluation criteria are as follows: : Indicates that the cut completely smooth with no detachment observed in the grid. : Indicates that there is slight detachment of the composite insulating layer at the intersections of the cuts, affecting approximately 5% of the grid area. : Indicates that there is slight detachment of the composite insulating layer at the edges and intersections of the cuts, affecting approximately 5-15% of the grid area. x: Indicates that there is obvious strip-like peeling of the strip composite insulating layer at the edges of the cuts and parts of the grid, affecting more than 15% of the grid area.

(33) Insulation performance test: on the surface of a plate strip sample with a size of 100 mm100 mm, which is provided with a composite insulating layer, a 60 mm60 mm0.03 mm double-sided copper foil tape is applied in the center is applied in the center of the surface where the composite insulating layer of the steel strip sample is located (with a 20 mm margin from the edge), and it serves as one voltage terminal. The stainless steel substrate is used as the other voltage terminal, voltages of 50V, 100V, 250V, 500V, and 1,000V are respectively applied along the thickness direction of the composite insulating layer using an insulation tester. After reaching the test voltage, the voltage is held for 1 minute, and the resistance measurement results are recorded.

(34) The specific evaluation criteria are as follows: : Indicates that the breakdown voltage is 250 V, and the measured resistance is 250 M; : Indicates that the breakdown voltage is 100 V, and the measured resistance is 100 M; : Indicates that the breakdown voltage is 50 V, and the measurement resistance is 50 M; x: Indicates that the breakdown voltage is 50 V, and there are surface defects or damage to the composite insulating layer, resulting in insulation failure.

(35) High-temperature corrosion resistance test: a steel plate strip sample with a size of 100 mm100 mm, which is provided with a composite insulating layer on the surface, is placed in a sealable heat treatment box, 50 mg of selenium (Se) powder and 50 mg of sulfur (S) powder are added into the heat treatment box. After the sealing the heat treatment box and evacuating it, Ar gas is introduced to achieve a pressure of 120 Torr. The heat treatment box is heated at a speed of 50 C./min to a 550 C. and is maintained at that temperature for 10 minutes. Afterward, it is cooled down to room temperature. Then, visual inspection and SEM (scanning electron microscope) observation are conducted to determine whether the surface of the composite insulating layer remains smooth and free of cracks.

(36) The specific evaluation criteria are as follows: : Indicates that there are no significant changes in the composite insulating layer observed visually before and after the test; and the SEM observation shows a smooth and even surface of the composite insulating layer without any surface cracks. : Indicates that there are no significant changes in the composite insulating layer observed visually before and after the test; and the SEM observation shows a smooth and even surface of the composite insulating layer with a small amount of surface cracks, affecting less than 5% of the area. : Indicates that there are no significant changes in the composite insulating layer observed visually before and after the test; and the SEM observation shows a smooth and even surface of the composite insulating layer with a certain amount of surface cracks, affecting approximately 5-15% of the area. x: Indicates that there is peeling of the composite insulating layer observed visually; and the SEM observation shows noticeable wrinkles and cracks in the composite insulating layer.

(37) Deformation resistance test: after a steel plate strip sample with a size of 100 mm100 mm, which is provided with a composite insulating layer on the surface, is stretched by 1%, a defect detection of the insulating layer on the surface is carried out using an optical method based on the color effects. Test solution: dissolve 3.0 g0.1 g of sodium nitrite in 100 mL of deionized water and add 4 mL of phenolphthalein ethanol solution (with a mass fraction of phenolphthalein at 0.5%). Power supply: direct current voltage of 24 V4 V. Test electrode: wet kitchen paper (with an area of 60 mm60 mm), placed in the center (leaving a 20 mm margin) placed in the center of the surface of the composite insulating layer of the test steel strip sample. Connect the stainless steel substrate of the steel strip sample to a negative electrode of the power supply, then connect the test electrode, i.e., the wet paper electrode, to a positive electrode of the power supply. Immerse the test electrode in the test solution and place it over the test area, ensuring no air enters. Turn on the power supply and after 2 minutes, turn it off. Within 1 minute of turning off the power supply, count the number of defects on the test electrode. Calculate the number of defects per square meter.

(38) The evaluation criteria for a surface defect rate of the deformed composite insulating layer are as follows: : Indicates defects/m.sup.22; : Indicates 2<defects/m.sup.25; : Indicates 5<defects/m.sup.210; and x: Indicates defects/m.sup.2>10.

(39) Table 3 presents various performance parameters of the coated steel plates suitable for inline thin-film photovoltaic modules in Examples 1-46 and the comparative steel plates in Comparative Examples 1-8 after sampling and testing.

(40) TABLE-US-00003 TABLE 3 High Temperature Insulation Corrosion Deformation Number Adhesion performance Resistance Resistance Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 Example 19 Example 20 Example 21 Example 22 Example 23 Example 24 Example 25 Example 26 Example 27 Example 28 Example 29 Example 30 Example 31 Example 32 Example 33 Example 34 Example 35 Example 36 Example 37 Example 38 Example 39 Example 40 Example 41 Example 42 Example 43 Example 44 Example 45 Example 46 Comparative X X Example 1 Comparative X X Example 2 Comparative X X Example 3 Comparative Example 4 Comparative Example 5 Comparative X X Example 6 Comparative X Example 7 Comparative Example 8

(41) It can be seen from Table 3 that the coated steel plates suitable for inline thin-film photovoltaic modules in Examples 1-46, manufactured using the manufacturing method of the present invention have undergone the aforementioned tests above and received ratings of or higher for all evaluated properties. This indicates that the steel strips treated with the surface treatment in the present invention possess excellent or qualified interface adhesion, insulation performance, high-temperature corrosion resistance, and deformation resistance required as base material for the inline steel-based thin-film modules.

(42) Correspondingly, after the coated steel plates in Examples 1-46 of the present invention and the comparative steel plates according to Comparative Examples 1-8 are obtained, it is possible to further deposit a metal bottom electrode as a back contact layers for different inline thin-film photovoltaic modules on the composite insulating layers. The material for the back contact layer can be one of the following: Mo or Mo alloy (for CIGS cells), Cu or Cu/C composite material (for CdTe cells), Al or Al alloy (for amorphous/microcrystalline silicon cells), and Ag, Au, or Pt (for GaAs photovoltaic cells, perovskite photovoltaic cells, and various organic semiconductor photovoltaic cells).

(43) The thickness of the back contact layer formed by deposition of the metal bottom electrode should fall within a range of 20 nm to 2 m, preferably within a range of 50 nm to 800 nm, and more preferably within a range of 50 nm to 500 nm. After the operation above is completed, a composite base plate suitable for use as the inline thin-film photovoltaic modules can be obtained. Depending on the requirements of the thin-film photovoltaic series-connected modules, the back contact layer can be processed by laser etching or mechanical scribing to obtain circuits with appropriate width and gap on the back contact layer.

(44) In the present invention, to further verify whether the steel strip with the composite insulating layer on the surface satisfies the requirements for internal series connection of the inline steel-based thin-film modules, the steel strips in Examples 1-46 and Comparative Examples 1-8 above are processed by magnetron sputtering to prepare the back contact layer formed by the deposition of the Mo bottom electrode. The thickness of the formed back contact layer is 60010 nm, and the square resistance is 1.0/. A laser scribing (P1) process in a thin-film module production process is performed on the steel strip coated with the back contact layer, and test data for various properties obtained is listed in Table 4.

(45) The evaluation of various performance parameters of the steel strip is conducted as follows: A laser scribing test is performed on the steel strip coated with the back contact layer. Unlike the method of laser passing through glass for scribing on glass substrates, the laser directly performs scribing on the side coated with the back contact layer, which avoids the accumulation of volatile impurities at the scribing edges or damage to the insulating layer beneath the back electrode.

(46) In the present invention, two types of lasers, infrared (1064 nm) and green (532 nm), are used for verification. The lasers used are commercially available lasers. The parameters of the infrared laser are: a laser wavelength of 1,064 nm, a pulse width of 15 to 30 ns, a repetition frequency of 1 to 150 kHz, and maximal single pulse energy of 0.28 mJ. The parameters of the green laser are: a laser wavelength of 532 nm, a pulse width of 6 to 18 ns, a repetition frequency of 1 to 120 kHz, and maximal single pulse energy of 0.10 mJ. The scribing length of the laser scribing (P1) process test is 80 mm, the scribing line width is controlled within at 505 m (10%), and the scribing rate is 500 mm/min.

(47) The compatibility of the steel strip with the composite insulating layer on the surface with the existing inline thin-film module series connection process is evaluated according to the laser scribing results. Controlling a lower scribing edge protrusion can avoid the impact on subsequent light absorption layer deposition and the risk of short-circuiting the inline thin-film photovoltaic modules. Controlling damage of the scribing depth to the insulating base layer ensures the insulation of the base material, preventing the risks of electric leakage and even short circuits of the module due to local insulation failure.

(48) The specific evaluation criteria are as follows: : Indicates that after laser P1 scribing, the height of the scribing edge protrusion (damage crater) is 30 nm, and the loss of insulating base layer thickness is 30 nm; : Indicates that after laser P1 scribing, the height of the scribing edge protrusion (damage crater) is greater than 30 nm and smaller than or equal to 50 nm, and the loss of insulating base layer thickness is greater than 30 nm and smaller than or equal to 50 nm; : Indicates that after laser P1 scribing, the height of the scribing edge protrusion (damage crater) is greater than 50 nm and smaller than or equal to 100 nm, and the loss of insulating base layer thickness is greater than 50 nm and smaller than or equal to 100 nm; and x: Indicates that after laser P1 scribing, the height of the scribing edge protrusion (damage crater) is greater than 100 nm, and the loss of insulating base layer thickness is greater than 100 nm, or the insulating base layer is completely penetrated.

(49) Table 4 presents the laser scribing compatibility test results for the coated steel plates/strips suitable for inline thin-film photovoltaic modules in Examples 1-46, as well as the comparative steel plates in Comparative Examples 1-8.

(50) TABLE-US-00004 TABLE 4 Steel Strip Laser Scribing Compatibility Test Infrared Laser Green Laser Insulating Insulating Scribing Edge Base Layer Scribing Edge Base Layer Protrusion Thickness Loss Protrusion Thickness Loss (nm) (nm) Rating (nm) (nm) Rating Example 1 85 50 45 30 Example 2 95 33 55 32 Example 3 80 33 48 45 Example 4 75 56 44 38 Example 5 88 45 55 46 Example 6 92 43 56 47 Example 7 90 92 56 90 Example 8 94 72 67 88 Example 9 73 12 30 10 Example 10 65 5 33 0 Example 11 83 27 45 30 Example 12 48 22 27 22 Example 13 45 27 38 26 Example 14 83 32 59 31 Example 15 43 25 33 21 Example 16 83 33 44 34 Example 17 90 45 59 48 Example 18 97 95 90 88 Example 19 98 98 88 91 Example 20 85 45 45 40 Example 21 86 50 48 43 Example 22 81 52 42 47 Example 23 78 54 45 43 Example 24 76 53 47 45 Example 25 82 54 39 49 Example 26 79 48 45 40 Example 27 88 52 49 45 Example 28 67 56 48 46 Example 29 83 33 44 34 Example 30 82 54 39 49 Example 31 79 48 45 40 Example 32 88 52 49 45 Example 33 84 54 39 49 Example 34 81 48 45 40 Example 35 85 52 49 45 Example 36 83 49 46 42 Example 37 87 49 48 48 Example 38 81 58 42 42 Example 39 85 30 45 30 Example 40 95 33 55 32 Example 41 80 33 48 45 Example 42 75 32 44 38 Example 43 88 45 55 46 Example 44 78 54 45 43 Example 45 76 53 47 45 Example 46 82 54 39 49 Comparative 3120 50 (completely X 2110 50 (completely X Example 1 penetrated) penetrated) Comparative 3120 80 (completely X 2100 80 (completely X Example 2 penetrated) penetrated) Comparative 4590 580 X 2130 485 X Example 3 Comparative 4115 573 X 2098 365 X Example 4 Comparative 4112 462 X 2104 334 X Example 5 Comparative 3123 60 (completely X 2108 60 (completely X Example 6 penetrated) penetrated) Comparative 3115 60 (completely X 2105 60 (completely X Example 7 penetrated) penetrated) Comparative 4512 2678 X 3421 2257 X Example 8

(51) It can be seen from Table 4 that the coated steel plates suitable for inline thin-film photovoltaic modules in Examples 1-46 have been tested by the commercial infrared or a green laser scriber. The evaluation ratings are at level or above. This indicates that the coated steel plates in Examples 1-46 of the present invention have good compatibility with the laser scribing series connection process used in the inline thin-film photovoltaic module production process. Therefore, they can satisfy the production requirements of the inline thin-film photovoltaic modules. In contrast, the comparative steel plates in Comparative Examples 1-3 and 6-8 lack the absorption and buffering of the residual energy of the laser by the laser scribing buffer layer in the composite insulating film layer, and the thicknesses of the laser scribing buffer layers of the comparative steel in Comparative Examples 4-5 is outside the preferred thickness range, so the insulating base materials in Comparative Examples 1-8 experienced significant damage to the insulation base material, with some even being penetrated, causing insulation failure. Additionally, volatile deposits accumulated at the scribing edges, forming protrusions several micrometers high, which directly affects the deposition of the subsequent light absorption layer and the performance of the inline thin-film photovoltaic modules.

(52) By considering Tables 1-4, it can be seen that compared to the comparative steel in Comparative Examples 1-8, the coated steel plates suitable for inline thin-film photovoltaic modules in Examples 1-46 of the present invention have excellent or qualified interface adhesion, insulation performance, high-temperature corrosion resistance, and deformation resistance required for serving as the base material for the inline steel-based thin-film modules, and they also have good compatibility with the laser scribing series connection process which is necessary during the production process of the inline thin-film photovoltaic modules.

(53) FIG. 1 is shows the microstructure of the SUS430 steel substrate. The SUS430 steel substrate exhibits an austenite structure at high temperatures, which transforms into ferrite and carbides during the cooling process. This phase transformation refines the ferrite grains, and the precipitated carbides also hinder grain growth.

(54) FIG. 2 is shows the microstructure of the B430LNT steel substrate. The B430LNT steel substrate remains in a single-phase ferrite structure at high temperatures without undergoing any phase transformation. Therefore, it can withstand high temperature. Additionally, B430LNT does not have carbides pinning grain boundaries and preventing the growth of the grains, which allows for larger grain sizes compared to SUS430.

(55) FIG. 3 is a schematic diagram of sectional structure of the coated steel plate according to Example 3. In FIG. 3, 1 represents the steel substrate, 2 represents the insulating base layer, and 3 represents the laser scribing buffer layer.

(56) FIG. 4 is a schematic diagram of sectional structure of the coated steel plate according to Example 3, after a back contact layer is formed by the deposition of a metal bottom electrode. In FIG. 4, 1 represents the steel substrate, 2 represents the insulating base layer, 3 represents the laser scribing buffer layer, and 4 represents the back contact layer.

(57) FIG. 5 is a schematic diagram of a production process of a continuous coating line of the present invention.

(58) In the present invention, for the coating of the steel substrate, production can be carried out in different production lines by using a roll-to-roll strip such as SUS430, or using a sheet-to-sheet type strip such as B430LNT. It should be pointed out that the difference between roll-to-roll type and sheet-to-sheet type coatings lies in the stepping and transmission of the roll or sheet material. However, the entire coating process and methods are similar.

(59) As mentioned above, before coating production on the surface of the steel substrate, it is necessary to first remove the residual or adsorbed dust on the surface of the steel substrate by high pressure water flushing. Subsequently, the steel substrate surface is rapidly dried by continuous blowing with high-speed compressed air. Then, plasma-assisted etching technology or extreme ultraviolet irradiation is employed to remove residual small organic molecules on the surface of the steel substrate and improve the reactivity of the surface of the steel substrate, thereby obtaining good adhesion between the insulating base layer and the steel substrate. Finally, vacuum coating systems such as magnetron sputtering, thermal evaporation, electron beam (EB) evaporation, and chemical vapor deposition (CVD) are used to deposit the insulating base layer and the laser scribing buffer layer. These processes are all prior art in the field.

(60) As shown in FIG. 5, this production line of continuous coating process can be divided into two types: roll-to-roll type continuous coating line and a sheet-to-sheet type stepping coating line. The first part of the roll-to-roll type continuous coating line is an uncoiler 7, followed by a high pressure water injection cleaning section 8, a compressed air blow-drying section 9, an extreme ultraviolet surface cleaning and activation chamber 10 filled with N.sub.2 atmosphere, and a looper vacuum transition chamber 11. The vacuum condition gradually transitions to 110.sup.4 Pa or below in the looper vacuum transition chamber 11. The looper equipment is used to control the coating rate and rolling speed switching in the roll changing process. Then, there are a series of deposition coating chambers 12 are disposed behind the looper vacuum transition chamber 11. The number of the coating chambers required can change within a range of 3 to 10 according to the coating rate and the film system structure to obtain the desired insulating base layer and the laser scribing buffer layer. A separate deposition chamber 13 for coating the metal back electrode is disposed behind the deposition coating chambers 12. After that, there are a transition chamber 14, a laser scribing equipment 15 for etching the circuit on the surface of the metal back electrode, and finally, a coiler for coiling the coated steel strip. Depending on the product requirements, it is possible to choose whether to equip a separate deposition chamber 13 for the metal back electrode and a laser scribing equipment 15. The sheet-to-sheet type stepping coating line has similar functional blocks to the roll-to-roll type continuous coating line. The stainless steel strip to be coated is placed on an object table 17 with magnetic fixation capability. The object table 17 together with the stainless steel strip placed thereon are conveyed by a conveying roller 18 arranged throughout the entire coating line. The subsequent sections include a high pressure water injection cleaning section 8, a compressed air blow-drying section 9, an extreme ultraviolet surface washing and activation chamber 10 filled with N.sub.2 atmosphere, and a vacuum transition chamber 11 for gradually transitioning to a vacuum condition of 110.sup.4 Pa or below. A series of deposition coating chambers 12 are disposed behind the vacuum transition chamber 11, and the number of the coating chambers required can change within a range of 3 to 10 depending on the coating rate and the film system structure to obtain the desired insulating base layer system and the laser scribing buffer layer. A separate deposition chamber 13 for coating the metal back electrode is disposed behind the deposition coating chambers 12 followed by a transition chamber 14, a laser scribing equipment 15 for etching the circuits on the surface of the metal back electrode, and finally, a manipulator 19 with a magnetic attraction or grabbing function. After releasing the magnetic fixation of the object table, the stainless steel strip coated with the functional film layer is transferred to a centralized blanking stacking location. Similarly, depending on the product requirements, it is possible to choose whether to equip a separate deposition chamber 13 for the metal back electrode and a laser scribing equipment 15.

(61) FIG. 6 is a three-dimensional representation of the coated steel plate with a back contact layer in Example 4 after laser scribing.

(62) FIG. 7 is a sectional profile of the back contact layer in FIG. 6.

(63) As shown in FIG. 6 and FIG. 7, in the implementation mode of Example 4, after laser scribing, the thickness loss of the insulating base layer is less than 10%, and the height of the protrusion formed at the scribing edge is less than 100 nm, which does not affect the deposition of the subsequent light absorption film layer and the performance of the inline thin-film photovoltaic modules.

(64) FIG. 8 is a three-dimensional representation of the comparative steel plate with a back contact layer in Comparative Example 3 after laser scribing.

(65) FIG. 9 is a sectional profile of the back contact layer in FIG. 8.

(66) As shown in FIG. 8 and FIG. 9, the insulating base material in the comparative steel plate in Comparative Example 3 has suffered significant damage, even penetrating through the steel substrate, resulting in insulation failure. Additionally, volatile deposits accumulated at the scribing edge, forming protrusions of several micrometers, directly affecting the deposition of the subsequent light absorption film layer and the performance of the inline thin-film photovoltaic modules.

(67) In summary, the embodiments above provided by the present invention are illustrative examples that demonstrate the principles and advantages of the present invention, rather than limiting the present invention. Those skilled in the art can make modifications or changes to the embodiments above without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes accomplished by those skilled in the art with ordinary knowledge in the technical field, within the spirit and the technical concepts disclosed by the present invention shall still be encompassed by the claims of the present invention.