A method for fabricating a negative-pitch solar cell module

Abstract

This invention relates to the series connection of photovoltaic cells, specifically to a method for fabricating a negative-pitch solar cell module. This method addresses the shortcomings of conventional stringing processes, which cannot handle cells with inconsistent solder strip numbers, and the high stress experienced by cells in overlapping areas during lamination in stacking processes, leading to microcracks and cell failure. The method involves extending the same end of all the solder strips on the light-receiving side of each cell substrate beyond the edge of the substrate and welding a conductive strip perpendicular to the extension direction of the solder strips. An adhesive film is then applied to the backlight side solder strips in the non-overlapping backlight area of ​​the cell substrate, extending beyond the edge of the substrate and covering all welded joints between the solder strips and the conductive strip. An elastic material is then placed in the overlapping light-receiving area of ​​the cell substrate to form series units. These series units are then stacked and welded.

Description

Technical Field

[0001] This invention relates to the series connection of photovoltaic cells, and more specifically to a method for preparing a negative-pitch solar cell module. Background Technology

[0002] In the manufacturing process of photovoltaic modules, the series connection of solar cells is a crucial step in realizing the module's power generation function. Conventional stringing processes primarily connect the cells using solder ribbons to form a current path. Traditional stringing processes typically involve wrapping the solder ribbons around to the other side of the cell to ensure a consistent number of ribbons on both sides. This design works well when handling cells with a consistent number of ribbons, but it fails to achieve effective series connection when the number of ribbons is inconsistent.

[0003] With the development of photovoltaic technology and the diversification of application scenarios, the requirements for the series connection method of solar cells are becoming increasingly stringent. To meet these new demands, the stacking process has been introduced into the manufacturing of photovoltaic modules. By overlapping and connecting the edges of different solar cells, it is possible to connect solar cells with inconsistent numbers of solder strips without changing the shape and size of the cells. This innovative process solves the problem of inconsistent solder strip numbers to a certain extent and can improve the power density and material utilization of the modules.

[0004] However, because the edges of the solar cells are overlapped and connected, especially during the lamination process, the overlapping areas often experience significant mechanical stress. Excessive stress concentration during lamination can lead to microcracks in the solar cells, reducing their mechanical strength and potentially causing a decline in their electrical performance, ultimately affecting the overall reliability and lifespan of the photovoltaic module. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of conventional stringing processes in handling cells with inconsistent solder strip numbers, and the fact that cells in overlapping areas of the stacking process are subject to greater stress after lamination, which can easily lead to microcracks and cell failure. Therefore, this invention provides a method for preparing a negative-pitch solar cell module.

[0006] To address the shortcomings of the existing technology, the present invention provides the following technical solution:

[0007] A method for fabricating a negative-pitch solar cell module, characterized by the following steps:

[0008] Step 1: Set multiple parallel and equally spaced light-receiving surface solder strips on the light-receiving surface of each battery substrate, and set multiple parallel and equally spaced back-light-receiving surface solder strips on the back-light-receiving surface, so that the same end of all the light-receiving surface solder strips extends beyond the edge of the battery substrate by a mm, and the other end of all the light-receiving surface solder strips and both ends of all the back-light-receiving surface solder strips do not protrude beyond the edge of the battery substrate.

[0009] The spacing d1 between adjacent light-receiving surface solder strips of each battery substrate is greater than or equal to the spacing d2 between adjacent back-light-receiving surface solder strips; the value of a is 1 to 5 mm, and the values ​​of d1 and d2 are 0.5 to 3 mm.

[0010] Step 2: Press the conductive strip perpendicular to the extension direction of the light-receiving surface solder strip onto all the light-receiving surface solder strips extending from each battery substrate, so that the conductive strip and the battery substrate are respectively on both sides of all the light-receiving surface solder strips, and then weld the conductive strip and all the light-receiving surface solder strips.

[0011] Step 3: On the light-receiving surface of each battery substrate, a light-receiving overlap area of ​​width w is set on the side away from the conductive strip, and a backlight overlap area is set on the side away from the conductive strip on the backlight surface, and a backlight non-overlap area is set on the side closer to the conductive strip; the value of w is 0.2 to 2 mm.

[0012] An adhesive film is covered on the backlight surface solder strip of the non-overlapping area of ​​the backlight of each battery substrate, and part of the adhesive film extends out of the edge of the battery substrate to cover all the connection points between the solder strip and the conductive strip on the light-receiving surface. The adhesive film is then fixed by hot pressing. Finally, an elastic material is set in the light-receiving overlapping area of ​​each battery substrate to obtain a series unit.

[0013] Step 4: Lay out the photovoltaic glass and front film from bottom to top, then stack multiple series units with the light-receiving surface facing down, so that the conductive strip and light-receiving overlap area of ​​the next series unit overlaps on the back light overlap area of ​​the previous series unit; then weld the busbars and electrode leads, and lay out the back film and back sheet or photovoltaic glass from bottom to top on all series units to complete the series connection.

[0014] Alternatively, photovoltaic glass and back film are laid from bottom to top, and multiple series units are stacked with the light-receiving surfaces facing up, so that the back light overlap area of ​​the next series unit is superimposed on the conductive strip and light-receiving overlap area of ​​the previous series unit; after welding the busbars and electrode leads, the front film and photovoltaic glass are laid from bottom to top on all series units to complete the series connection.

[0015] Step 5: Lamination is performed on the series-connected units to make each conductive strip electrically connected to the corresponding backlight solder strip, thus completing the fabrication of the negative-pitch solar cell module.

[0016] Furthermore, in step 2, the conductive strip is a column with a coating on its surface, and its length is greater than or equal to the length of the battery substrate in the same direction;

[0017] The cross-section of the conductive strip is a circle with a diameter of 0.1 to 0.5 mm, or multiple circles with a diameter of 0.05 to 0.1 mm, or a rectangle with a width of 1.5 to 3 mm and a thickness of 0.1 to 0.2 mm.

[0018] Furthermore, in step 2, the coating of the conductive strip is a low-temperature alloy or a conductive resin;

[0019] The low-temperature alloy contains at least two of the following: tin, lead, silver, bismuth, indium, zinc, and cerium, and has a thickness of 1–30 μm.

[0020] Further, in step 1, both the light-receiving surface solder strip and the backlight surface solder strip are cylindrical bodies with a coating. The radial cross-sectional diameter D1 of the light-receiving surface solder strip is less than or equal to the radial cross-sectional diameter D2 of the backlight surface solder strip. The values ​​of D1 and D2 are 0.05 to 0.15 mm. The coating of the light-receiving surface solder strip and the backlight surface solder strip is an alloy or conductive resin.

[0021] Furthermore, in step 3, the elastic material is one of POE, UV adhesive, or silicone, with a thickness of 0.2–3 mm.

[0022] Furthermore, in step 3, the adhesive film is one of POE, EPE, and PVB.

[0023] Furthermore, in step 3, UV adhesive, silicone, or hot-pressed POE are applied to the light-receiving overlapping area of ​​the battery substrate as an elastic material.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] (1) The present invention provides a method for preparing a negative-pitch solar cell module. The method involves extending the same end of all the light-receiving surface solder strips of each cell substrate out of the edge of the cell substrate and welding a conductive strip perpendicular to the extension direction of the light-receiving surface solder strips. Then, an adhesive film is covered on the backlight surface solder strips in the non-overlapping area of ​​the backlight of the cell substrate, so that the adhesive film extends out of the edge of the cell substrate and covers the welding points of all the light-receiving surface solder strips and conductive strips. An elastic material is set in the light-receiving overlapping area of ​​the cell substrate to form a series unit. Then, the series units are stacked and welded. The present invention eliminates the cell spacing by overlapping cells, improves the module area utilization rate, improves the module power, and avoids the problem of microcracks after lamination due to excessive stress in the cell overlapping area when conventional cells are stacked in series.

[0026] (2) The present invention provides a method for preparing a negative spacing solar cell module, which can achieve effective series connection of cells when the number of solder strips is inconsistent; secondly, the adhesive film can strengthen the connection between the conductive strip and the cell substrate, and avoid the solder strip on the light-receiving surface from bending and deforming due to excessive weight of the conductive strip during transportation; finally, the elastic material softens during lamination, which can protect the edge of the cell from being crushed by the solder strip.

[0027] (3) The present invention provides a method for preparing a negative spacing solar cell module. By creating a series unit, the module can be connected in series more easily while ensuring welding reliability.

[0028] (4) The present invention provides a method for preparing a negative spacing solar cell module. By placing the conductive strip on the back side of the negative spacing solar cell module, the power generation loss caused by shading can be avoided, and the light-receiving surface has an aesthetically pleasing appearance. Attached Figure Description

[0029] Figure 1 This is a flowchart of a first embodiment of a method for preparing a negative-pitch solar cell module according to the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of each battery substrate after the adhesive film is fixed by hot pressing in step 3 of embodiment 1 of the present invention;

[0031] Figure 3 This is a schematic diagram of the structure in step 4 of embodiment one of the present invention, in which multiple series units are stacked with their light-receiving surfaces facing downwards.

[0032] Figure 4 This is a schematic diagram of the structure in step 4 of embodiment 1 of the present invention, in which multiple series units are stacked sequentially with their light-receiving surfaces facing upwards.

[0033] The annotations in the attached figures are explained as follows:

[0034] 1-Battery substrate; 21-Light-receiving surface solder strip; 22-Backlight surface solder strip; 31-Light-receiving overlapping area; 32-Backlight overlapping area; 33-Backlight non-overlapping area; 4-Conductive strip; 5-Adhesive film; 6-Elastic material. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and exemplary embodiments.

[0036] Example 1

[0037] Reference Figure 1 A method for fabricating a negative-pitch solar cell module includes the following steps:

[0038] Step 1: On the light-receiving surface of each battery substrate 1, multiple parallel and equally spaced light-receiving surface solder strips 21 are arranged, and on the back-lighting surface, multiple parallel and equally spaced back-lighting surface solder strips 22 are arranged, such that the same end of all light-receiving surface solder strips 21 extends a mm beyond the edge of the battery substrate 1, and the other end of all light-receiving surface solder strips 21 and both ends of all back-lighting surface solder strips 22 are flush with the edge of the battery substrate 1.

[0039] The spacing d1 between adjacent light-receiving surface solder strips 21 of each battery substrate 1 is greater than or equal to the spacing d2 between adjacent back-lighting surface solder strips 22; both the light-receiving surface solder strip 21 and the back-lighting surface solder strip 22 are cylindrical bodies with a coating, and the radial cross-sectional diameter D1 of the light-receiving surface solder strip 21 is less than or equal to the radial cross-sectional diameter D2 of the back-lighting surface solder strip 22.

[0040] In this embodiment, a = 3mm, d1 = 2mm, d2 = 1mm, D1 = D2 = 0.1mm. The plating of the light-receiving surface solder strip 21 and the backlight surface solder strip 22 is an alloy, specifically a tin-lead alloy. The spacing d1 between adjacent light-receiving surface solder strips 21 is greater than the spacing d2 between adjacent backlight surface solder strips 22, which can reduce the light-shielding area of ​​the light-receiving surface solder strips 21 and increase the battery power generation. In other embodiments, making the radial cross-sectional diameter D1 of the light-receiving surface solder strip 21 smaller than the radial cross-sectional diameter D2 of the backlight surface solder strip 22 can also reduce the light-shielding area of ​​the light-receiving surface and increase the battery power generation. However, it is necessary to reduce the solder strip spacing on the backlight surface to reduce the overall solder strip series resistance, increase the battery fill factor, and improve battery efficiency.

[0041] In other embodiments, the value of a can be 1 to 5 mm, the values ​​of d1 and d2 can be 0.5 to 3 mm, the values ​​of D1 and D2 can be 0.05 to 0.15 mm, and the coating of the light-receiving surface solder strip 21 and the backlight surface solder strip 22 can be an alloy or a conductive resin.

[0042] Step 2: Press the conductive strip 4 vertically onto all the light-receiving surface solder strips 21 extending from the battery substrate 1, so that the conductive strip 4 and the battery substrate 1 are respectively on both sides of all the light-receiving surface solder strips 21, and then weld the conductive strip 4 and all the light-receiving surface solder strips 21.

[0043] The conductive strip 4 is a column with a coating on its surface, and its length is greater than or equal to the length of the battery substrate 1 in the same direction. The cross-section of the conductive strip 4 is a rectangle with a width of 2 mm and a thickness of 0.15 mm. The coating is a tin-lead-bismuth alloy with a thickness of 10 μm.

[0044] In other embodiments, the cross-section of the conductive strip 4 is a circle with a diameter of 0.1 to 0.5 mm, or multiple circles with a diameter of 0.05 to 0.1 mm, or a rectangle with a width of 1.5 to 3 mm and a thickness of 0.1 to 0.2 mm. When the cross-section of the conductive strip 4 is multiple circles, the conductive strip 4 is composed of multiple thin circular solder strips with a coating on the surface. Specifically, it is a strip composed of multiple thin circular solder strips, which is more flexible than the conductive strip 4 composed of a single thick circular solder strip, and can avoid pressing on the battery surface and causing microcracks. When the cross-section of the conductive strip 4 is rectangular, in order to simultaneously meet the good contact between the conductive strip 4 and the backlight solder strip 22 of the adjacent battery substrate 1 and protect the battery from being crushed, the rectangle needs to have a large aspect ratio. However, an excessively large aspect ratio will increase the manufacturing difficulty of the conductive strip 4. For rectangles with a width of more than 1.5 mm, when the thickness is less than 0.1 mm, the production cost will increase significantly. Therefore, under the premise of ensuring that the requirements of the module series connection are met, a rectangle with a width of 1.5 to 3 mm and a thickness of 0.1 to 0.2 mm is selected.

[0045] In other embodiments, the coating of the conductive strip 4 is a low-temperature alloy or conductive resin; the low-temperature alloy includes at least two of tin, lead, silver, bismuth, indium, zinc, and cerium, and has a thickness of 1–30 μm. The coating is made as thick as possible without significantly increasing the cost of the conductive strip 4, so that it melts during lamination and is welded to the light-receiving surface solder strip 21 of the battery substrate 1 and the backlight surface solder strip 22 of the adjacent battery substrate 1. Reliable electrical connections between the conductive strip 4 and the light-receiving surface solder strip 21 and the backlight surface solder strip 22 are achieved by increasing the contact area and the coating thickness.

[0046] Step 3: On the light-receiving surface of each battery substrate 1, a light-receiving overlap area 31 with a width w is set on the side away from the conductive strip 4, where w = 1 mm. In other embodiments, the value of w can be 0.2 to 2 mm. On the backlight surface of each battery substrate 1, a backlight overlap area 32 is set on the side away from the conductive strip 4, and a backlight non-overlap area 33 is set on the side closer to the conductive strip 4. The value of w is 0.2 to 2 mm.

[0047] An adhesive film 5 is applied to the backlight surface solder strip 22 of the non-overlapping backlight area 33 of each battery substrate 1, with a portion of the adhesive film 5 extending beyond the edge of the battery substrate 1 to cover all solder strips 21 on the light-receiving surface and the solder joints of the conductive strips 4. The adhesive film 5 strengthens the connection between the conductive strips 4 and the battery substrate 1, preventing the conductive strips 4 from bending and deforming due to excessive weight during handling. The adhesive film 5 is POE. In other embodiments, the adhesive film 5 can be one of POE, EPE (Expanded Polyethylene), or PVB (Polyvinyl Butyral).

[0048] Then, the adhesive film 5 is fixed by hot pressing (100℃), as shown below. Figure 2As shown, a UV adhesive with a thickness of 0.5 mm is applied to the light-receiving overlap area 31 of each battery substrate 1 as an elastic material 6 to obtain a series unit;

[0049] In other embodiments, silicone or hot-pressed POE (Polyolefin Elastomer) with a thickness of 0.2 to 3 mm can also be applied as elastic material 6; the function of elastic material 6 can be simply to buffer, without being conductive, and can be softened during lamination to protect the battery edges from being cracked by the solder strips.

[0050] Step 4: Lay the photovoltaic glass and front-side encapsulating film from bottom to top, then stack multiple series-connected units with the light-receiving surface facing down, as shown below. Figure 3 As shown, the conductive strip 4 and the light-receiving overlap area 31 of the next series unit are stacked on the backlight overlap area 32 of the previous series unit; then, after welding the busbar and electrode lead wire, the back adhesive film and the back sheet or photovoltaic glass are laid on all series units from bottom to top to complete the series connection.

[0051] In other embodiments, photovoltaic glass and backing film can be laid sequentially from bottom to top, and then multiple series-connected units can be stacked with their light-receiving surfaces facing upwards, such as... Figure 4 As shown, the backlight overlap area 32 of the next series unit is stacked on the conductive strip 4 and the light-receiving overlap area 31 of the previous series unit; then, after welding the busbar and electrode lead wire, the front adhesive film and photovoltaic glass are laid on all series units from bottom to top to complete the series connection.

[0052] It should be noted that stacking multiple series units with the light-receiving surface facing down is suitable for both single-glass and double-glass modules, while stacking multiple series units with the light-receiving surface facing up is suitable for double-glass modules. This is because the backsheet is relatively flexible and cannot be laid first.

[0053] Step 5: Lamination is performed on the series-connected units so that each conductive strip 4 is electrically connected to the corresponding backlight solder strip 22, thus completing the fabrication of the negative-pitch solar cell module.

[0054] Example 2

[0055] In this embodiment, a = 2.5mm, d1 = 1.5mm, d2 = 1mm, D1 = D2 = 0.09mm, and the plating of the light-receiving solder strip 21 and the backlight-receiving solder strip 22 is an alloy, specifically a tin-lead alloy.

[0056] The conductive strip 4 has a cross-section of three circles with a diameter of 0.05 mm, and the plating is a tin-lead-bismuth alloy with a thickness of 2 μm; the width w of the light-receiving overlap area 31 is 1 mm.

[0057] Elastic material 6 is POE with a thickness of 0.5mm;

[0058] Film 5 is FPE;

[0059] All other settings in this embodiment are the same as in Embodiment 1.

Claims

1. A method for fabricating a negative-pitch solar cell module, characterized in that, Includes the following steps: Step 1: On the light-receiving surface of each battery substrate (1), multiple parallel and equally spaced light-receiving surface solder strips (21) are arranged, and on the back-lighting surface, multiple parallel and equally spaced back-lighting surface solder strips (22) are arranged, such that the same end of all light-receiving surface solder strips (21) extends amm beyond the edge of the battery substrate (1), and the other end of all light-receiving surface solder strips (21) and both ends of all back-lighting surface solder strips (22) do not protrude beyond the edge of the battery substrate (1). The spacing d1 between adjacent light-receiving surface solder strips (21) of each battery substrate (1) is greater than or equal to the spacing d2 between adjacent back-light surface solder strips (22); the value of a is 1 to 5 mm, and the values ​​of d1 and d2 are 0.5 to 3 mm. Step 2: Press the conductive strip (4) perpendicular to the extension direction of the light-receiving surface solder strip (21) onto all the light-receiving surface solder strips (21) extending from each battery substrate (1), so that the conductive strip (4) and the battery substrate (1) are respectively on both sides of all the light-receiving surface solder strips (21), and then weld the conductive strip (4) and all the light-receiving surface solder strips (21). Step 3: On the light-receiving surface of each battery substrate (1), a light-receiving overlap area (31) with a width w is set on the side away from the conductive strip (4), a backlight overlap area (32) is set on the side away from the conductive strip (4) on the backlight surface, and a backlight non-overlap area (33) is set on the side close to the conductive strip (4); the value of w is 0.2 to 2 mm. An adhesive film (5) is covered on the backlight surface solder strip (22) of the backlight non-overlapping area (33) of each battery substrate (1), and part of the adhesive film (5) extends out of the edge of the battery substrate (1) to cover the connection between all the light-receiving surface solder strips (21) and conductive strips (4). The adhesive film (5) is then fixed by hot pressing. Then, an elastic material (6) is set in the light-receiving overlapping area (31) of each battery substrate (1) to obtain a series unit. Step 4: Lay photovoltaic glass and front film from bottom to top, and then stack multiple series units with the light-receiving surface facing down, so that the conductive strip (4) and light-receiving overlap area (31) of the next series unit are stacked on the back light overlap area (32) of the previous series unit; then weld the busbar and electrode lead wire, and lay the back film and back sheet or photovoltaic glass from bottom to top on all series units to complete the series connection; Alternatively, photovoltaic glass and back film are laid from bottom to top, and multiple series units are stacked with their light-receiving surfaces facing upwards, so that the back light overlap area (32) of the next series unit is stacked on the conductive strip (4) and light-receiving overlap area (31) of the previous series unit; then, after welding the busbar and electrode lead wire, the front film and photovoltaic glass are laid from bottom to top on all series units to complete the series connection. Step 5: Lamination is performed on the series-connected units so that each conductive strip (4) is electrically connected to the corresponding backlight solder strip (22) to complete the fabrication of the negative pitch solar cell module.

2. The method for fabricating a negative-pitch solar cell module according to claim 1, characterized in that: In step 2, the conductive strip (4) is a column with a coating on its surface, and its length is greater than or equal to the length of the battery substrate (1) in the same direction; The cross section of the conductive strip (4) is a circle with a diameter of 0.1 to 0.5 mm, or multiple circles with a diameter of 0.05 to 0.1 mm, or a rectangle with a width of 1.5 to 3 mm and a thickness of 0.1 to 0.2 mm.

3. The method for preparing a negative-pitch solar cell module according to claim 2, characterized in that: In step 2, the coating of the conductive strip (4) is a low-temperature alloy or a conductive resin; The low-temperature alloy contains at least two of the following: tin, lead, silver, bismuth, indium, zinc, and cerium, and has a thickness of 1–30 μm.

4. A method for preparing a negative-pitch solar cell module according to any one of claims 1 to 3, characterized in that: In step 1, both the light-receiving surface solder strip (21) and the backlight surface solder strip (22) are cylindrical bodies with a coating. The radial cross-sectional diameter D1 of the light-receiving surface solder strip (21) is less than or equal to the radial cross-sectional diameter D2 of the backlight surface solder strip (22). The values ​​of D1 and D2 are 0.05 to 0.15 mm. The coating of the light-receiving surface solder strip (21) and the backlight surface solder strip (22) is an alloy or a conductive resin.

5. The method for preparing a negative-pitch solar cell module according to claim 4, characterized in that: In step 3, the elastic material (6) is one of POE, UV adhesive, and silicone, with a thickness of 0.2 to 3 mm.

6. The method for preparing a negative-pitch solar cell module according to claim 5, characterized in that: In step 3, the provision of elastic material (6) in the light-receiving overlap area (31) of the battery substrate (1) specifically involves applying UV adhesive, silicone, or hot-pressed POE to the light-receiving overlap area (31) of the battery substrate (1) as elastic material (6).

7. The method for preparing a negative-pitch solar cell module according to claim 4, characterized in that: In step 3, the adhesive film (5) is one of POE, EPE, and PVB.

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