Main-grid-free back contact solar cell unit

Abstract

The utility model discloses a main-grid-free back contact solar cell unit, which is formed by orderly arranging a plurality of cell single bodies without metal electrode grid lines on a metal electrode film, each cell single body is equally divided into N sub-electrode areas along the Y-axis direction, each sub-electrode is provided with a first electrode area and a second electrode area along the X-axis direction, a first isolation groove is formed between every two connected sub-electrode areas, each sub-electrode area forms a single power generation unit, a second isolation groove is formed between the first electrode area and the second electrode area which are connected, and transparent conductive film layers are arranged on the first electrode area and the second electrode area. The metal electrode film is provided with a carrier film layer, a first metal grid line, a second metal grid line and a composite adhesive film layer. The solar cells are all effectively connected in series through the fine grid lines, and a series welding machine and a printing machine are not needed in the production process, so that the equipment investment is saved, the working procedures are also saved, and the cost is greatly reduced.

Description

Technical Field

[0001] This utility model relates to the field of solar cells, and in particular to a gridless back-contact solar cell unit. Background Technology

[0002] Silicon-based back-contact solar cells have all electrodes located on the reverse side (back side) of the cell, meaning the front side is fully exposed to sunlight, thus improving light absorption efficiency. To extract photogenerated carriers from the inside of silicon-based back-contact solar cells, existing conventional technologies primarily involve printing silver paste grid lines or fabricating copper metal grid lines on the cell surface to collect the carriers generated by the photoelectric effect. These carriers are then connected to the silver paste grid lines or copper metal grid lines via tin-plated solder ribbons, thereby achieving series and parallel connections between the cells.

[0003] If only the electrode carrier film is used to replace the fine grid lines of the solar cell for current transmission, although the shading area on the back can be greatly reduced and the power generation efficiency on the back can be improved, when multiple solar cells are connected in series and packaged into a module, it will be found that the grid lines on the back are too thin. As the transmission distance increases, the transmission resistance between cells will be very large, which will cause the module efficiency to drop significantly. Therefore, the solution has many defects.

[0004] Patent CN 221041139 U (Photovoltaic Electrode of Cross-Back Contact Photovoltaic Module) proposes another solution that uses positive and negative electrode wires on the electrode carrier film to replace the traditional printed or electroplated electrodes. However, its main purpose is to solve the problems of alignment accuracy and printing repeatability in existing printing technology, as well as the inability to control the electrode thickness and low yield. Utility Model Content

[0005] To address the above problems, this utility model provides a gridless back-contact solar cell unit.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: a gridless back-contact solar cell unit, which is composed of several solar cell units without metal electrode grids arranged in an orderly manner on a metal electrode film. Each solar cell unit is divided into N sub-electrode regions (N≥2) along the Y-axis. Each sub-electrode has a first electrode region and a second electrode region along the X-axis. The first electrode region and the second electrode region are positively charged and negatively charged, respectively, and are arranged alternately and orderly. The first electrode regions and the second electrode regions of two connected sub-electrode regions have opposite polarities. A first isolation groove is provided between two connected sub-electrode regions. Each sub-electrode region forms a single power generation unit. A second isolation groove is provided between connected first electrode regions and second electrode regions. A transparent conductive thin film layer is disposed on the first electrode region and the second electrode region. A carrier film layer, a first metal grid line, a second metal grid line, and a composite adhesive film layer are disposed on the metal electrode film. The first metal grid line and the second metal grid line are arranged according to the positions of the first electrode region and the second electrode region on the sub-battery string formed by arranging the individual battery cells along the Y-axis direction, and are disposed on the upper surface of the carrier film layer. The composite adhesive film layer is also disposed on the upper surface of the carrier film layer and fills the hollow areas of the first metal grid line and the second metal grid line. The first metal grid line is arranged at both ends of the sub-battery string and extends beyond the edge of the sub-battery string. The second metal grid line is disposed across two connected sub-electrode regions and is disposed on both the first electrode region and the second electrode region.

[0007] Furthermore, when the sub-electrode region N is an even number, the individual solar cells are arranged directly along the Y-axis, with a cell spacing W of 0.2-1 mm; when the sub-electrode region N is an odd number, the individual solar cells are arranged along the Y-axis, and each cell needs to be rotated 180° before being arranged, with a cell spacing W of 0.2-1 mm.

[0008] Furthermore, the carrier film layer material has a transmittance of greater than 85%, and the material is one of PET, PEN, PCT, PC, PETG, PMMA, COC, EVA, POE, EMA, EAA, EMMA, epoxy resin, silicone resin, PMA, PU, ​​VAE, PVB, or composite films thereof.

[0009] Furthermore, the composite adhesive film layer has a transmittance of more than 85% after hot melting, and the material is one of TPO, EVA, POE, and PVB.

[0010] Furthermore, the cross-sections of the first metal grid line and the second metal grid line are one of the following: triangular, trapezoidal, semi-circular, rectangular, and square. The first metal grid line and the second metal grid line are one of the following: copper, nickel, tin, bismuth, gold, zinc, silver, palladium, cesium, lithium, potassium, sodium, lead, gallium, indium, mercury, tin-bismuth-nickel, or other composite metals with high conductivity.

[0011] Furthermore, the contact areas between the first metal gate line, the second metal gate line and the first electrode region, and the second electrode region are planar.

[0012] Furthermore, the first metal grid line consists of a collection area and a convergence area, and the second metal grid line consists of a collection area and a crossing area.

[0013] As can be seen from the above description of this utility model, compared with the prior art, this utility model has the following advantages:

[0014] 1. This utility model designs a gridless back-contact solar cell as multiple sub-electrode regions, which minimizes the current transmission path of the metal grid lines on the metal electrode film. By setting a special local amplification transmission hub on the metal grid lines, the charge carriers of the corresponding electrode region on the gridless back-contact solar cell can be quickly and fully transmitted to the next electrode region, thereby achieving series transmission through the inside of the silicon wafer. This achieves the effect of series connection with only fine grid lines, and the production process does not require the use of stringing machines or printing machines, which saves a lot of equipment investment and many traditional processes, resulting in a significant cost reduction.

[0015] 2. This utility model has no main grid line. All the solar cells are effectively connected in series through fine grid lines. The back of the module is not blocked by the main grid or the photovoltaic ribbon. This can improve the bifacial power generation efficiency of the module to more than 80%, thereby making full use of the extra power generation generated on the back to increase the power station's efficiency. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an undue limitation of the present invention. In the drawings:

[0017] Figure 1 This is a schematic diagram of the back structure of a single cell of a back-contact solar cell in Embodiment 1 of this utility model;

[0018] Figure 2 for Figure 1 A schematic diagram of the AA cross-section battery structure;

[0019] Figure 3 for Figure 1 A schematic diagram of the BB cross-section battery structure;

[0020] Figure 4 This is a schematic diagram of the arrangement of individual cells in the back-contact solar cell of Embodiment 1 of this utility model;

[0021] Figure 5This is a schematic diagram of the structure of the metal electrode film in Embodiment 1 of this utility model;

[0022] Figure 6 This is a schematic diagram of the back structure of the back contact solar cell unit according to Embodiment 1 of this utility model;

[0023] Figure 7 for Figure 5 A schematic diagram of the metal electrode film structure at the CC cross section;

[0024] Figure 8 for Figure 5 A schematic diagram of the metal electrode film structure at the DD cross section;

[0025] Figure 9 for Figure 6 A schematic diagram of the battery cell structure with EE cross section;

[0026] Figure 10 This is a schematic diagram of the back structure of a single cell of a back-contact solar cell in Embodiment 2 of this utility model.

[0027] Figure 11 for Figure 10 A schematic diagram of the FF cross-section battery structure;

[0028] Figure 12 This is a schematic diagram of the arrangement of individual cells in the back-contact solar cell in Embodiment 2 of this utility model;

[0029] Figure 13 This is a schematic diagram of the structure of the metal electrode film in Embodiment 2 of this utility model;

[0030] Figure 14 This is a schematic diagram of the back structure of the back contact solar cell unit in Embodiment 2 of this utility model. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0032] Example 1

[0033] refer to Figure 1-9A gridless back-contact solar cell unit, wherein the cell unit X is formed by an orderly arrangement of several cell cells 100 without metal electrode grids on a metal electrode film 200. Each cell cell 100 is divided into four sub-electrode regions along the Y-axis. Each sub-electrode has a first electrode region 100-1 and a second electrode region 100-2 along the X-axis, and the first electrode regions 100-1 and 100-2 are arranged alternately and orderly. The first electrode regions 100-1 and 100-2 of two connected sub-electrode regions have opposite polarities. A first isolation groove 100-3 is provided between two connected sub-electrode regions, so that each sub-electrode region forms a single power generation unit. Figure 1 As shown, there are four sub-electrode regions, numbered ①②③④. The first electrode region ①-100-1 and the second electrode region ①-100-2 on sub-electrode region ① are positively charged and negatively charged, respectively. A second isolation groove 100-4 is set in the middle of the connected sub-electrode regions.

[0034] like Figure 1 , Figure 2 As shown, the solar cell 100 is a silicon-based solar cell with a thickness of 130 μm. An anti-reflection layer 100-5 is disposed on the front side of the cell. On the back side of the solar cell 100, a first electrode region ①-100-1 and a second electrode region ①-100-2 are alternately disposed along the X-axis direction, with the first electrode region ①-100-1 and the second electrode region ①-100-2 arranged alternately. The first electrode region ①-100-1 is a semiconductor layer, consisting of an intrinsic amorphous silicon layer (10 nm thick) and an N-type doped amorphous silicon layer (10 nm thick). An N-type doped layer is formed by stacking an amorphous silicon passivation layer (10 nm thick) and a doped amorphous silicon layer (20 nm thick, with an effective doping concentration of 8e20 / cm³). A P-type doped layer is formed in the first electrode region ①-100-1 and the second electrode region ①-100-2 along the Z-axis. The conductive film is indium tin oxide (ITO) with a thickness of 110 nm. A first isolation trench 100-3 is provided between the first electrode region ①-100-1 and the second electrode region ①-100-2. This trench removes the conductive film, ensuring that the electrode polarities of the first electrode region ①-100-1 and the second electrode region ①-100-2 are independent.

[0035] like Figure 3As shown, the back of the solar cell 100 is divided into four sub-electrode regions along the Y-axis: sub-electrode region ①, sub-electrode region ②, sub-electrode region ③, and sub-electrode region ④. A second isolation trench 100-4 is provided between the connected sub-electrode regions ① and ②, ② and ③, and ③ and ④. The second isolation trench 100-4 does not have electrode polarity, ensuring that each sub-electrode region forms an independent semiconductor structure.

[0036] like Figure 4 As shown, the individual solar cells 100 are arranged along the Y-axis. The individual solar cells do not need to be rotated 180° and are arranged directly. The spacing W between the cells is 0.5 mm. After arrangement, a sub-cell string X1 is formed.

[0037] like Figure 5 , Figure 7 , Figure 8 As shown, the metal electrode film 200 is provided with a carrier film layer 200-1, a first metal grid line 200-4, a second metal grid line 200-3, and a composite adhesive film layer 200-2. The first metal grid line 200-4 and the second metal grid line 200-3 are configured according to... Figure 4 The first electrode region 100-1 and the second electrode region 100-2 on the sub-cell string X1, after the individual solar cells 100 are arranged along the Y-axis, are arranged at corresponding positions and disposed on the surface of the carrier film layer 200-1; the composite adhesive film layer 200-2 is also disposed on the surface of the carrier film layer and fills the hollow areas of the first metal grid line 200-4 and the second metal grid line 200-3. The carrier film layer 200-1 is PET with a transmittance greater than 85% and a thickness of 0.15mm; the composite adhesive film layer 200-2 has a transmittance greater than 85% after hot melting and is made of TPO soft colloid.

[0038] like Figure 5 , Figure 6 , Figure 7 As shown, Figure 5 The metal electrode film 200 is laminated with the composite adhesive film layer 200-2 by lamination or hot rolling. Figure 4 Obtained from sub-battery string X1 Figure 6 The arrangement of the metal grid lines on the metal electrode film 200 of the battery cell X shown is as follows: the first metal grid line 200-4 is arranged at both ends of the sub-cell string X1, extending beyond the edge of the sub-cell string X1; the first metal grid line 200-4 is composed of two parts: a collecting area 200-41 and a gathering area 200-42. The cross-section of the electrode grid line in the collecting area 200-41 is triangular, which is beneficial to increasing the secondary utilization of back-reflected light; the cross-section of the electrode grid line in the gathering area 200-42 is a locally enlarged rectangle (see reference). Figure 8The cross-section of the spanning region 200-32 is shown); the second metal grid line 200-3 is set across two connected sub-electrode regions, as shown. Figure 6 As shown, the second metal grid line 200-3 alternately crosses sub-electrode regions ①, ②, ③, and ④, and crosses from sub-electrode region ④ of the cell 100 to sub-electrode region ① of the next cell 100; the second metal grid line 200-3 is simultaneously arranged on the first electrode region 100-1 and the second electrode region 100-2, so that the two sub-electrode regions form a conductive connection; the second metal grid line 200-3 is composed of two parts: a collection region 200-31 and a crossing region 200-32. The cross-section of the electrode grid line in the collection region 200-31 is triangular, which is beneficial to increasing the secondary utilization of back-reflected light, such as... Figure 8 As shown, the cross-section of the electrode grid line in the crossing region 200-32 is a locally enlarged rectangle. The width of the rectangle in the X-axis direction does not exceed the width of the first electrode region 100-1 and the second electrode region 200-2. The crossing region 200-32 is a specially designed locally enlarged transmission hub in the middle region of the metal grid line, which is beneficial to improving the current conduction capability. The contact areas between the first metal grid line 200-4, the second metal grid line 200-3 and the first electrode region 100-1 and the second electrode region 200-2 are planar. The metal grid line material is a copper alloy with high conductivity, and the surface is plated with a 3-5μm indium tin alloy.

[0039] like Figure 9 As shown, the first metal grid line 200-4 forms an ohmic contact with the second electrode region 100-2 on the sub-electrode region ④, and outputs the transmitted charge carriers; the second metal grid line 200-3 forms an ohmic contact with the first electrode region 100-2 and the second electrode region 100-2 on different sub-electrode regions, respectively, and acts as a conductive bridge; while the carrier film layer 200-1 binds all the electrical structure units through the composite adhesive film layer 200-2 and arranges them in an orderly manner, thereby forming the battery unit X.

[0040] Example 2

[0041] The procedure was carried out in accordance with Example 1, except that, in Example 1, the procedure was carried out in accordance with Example 2. Figure 10 , Figure 11 As shown, the number of sub-electrode regions on the single cell 100 is odd, with a total of 3 sub-electrode regions, numbered ①②③.

[0042] like Figure 12As shown, the individual solar cells 100 are arranged along the Y-axis. In order to ensure that the polarity of the electrode arrangement of the next solar cell 100 forms an effective series connection with the previous one, the next solar cell 100 needs to be rotated 180° for arrangement. It can be seen that the sub-electrode region ③ of the next solar cell 100 is arranged immediately after the sub-electrode region ③ of the previous solar cell 100, with a cell spacing W of 0.5mm. After arrangement, a sub-cell string X1 is formed.

[0043] like Figure 13 As shown, unlike Embodiment 1, the first metal gate line 200-4 and the second metal gate line 200-3 need to be adjusted according to... Figure 12 The layout design is carried out for the X1 sub-battery string.

[0044] like Figure 14 As shown, Figure 13 The metal electrode film 200 is laminated with the composite adhesive film layer 200-2 by lamination or hot rolling. Figure 12 Obtained from sub-battery string X1 Figure 14 The battery cell X shown.

[0045] Example 3

[0046] The process is carried out with reference to Example 1. The difference from Example 1 is that the cross-section of the electrode grid line in the collection area 200-31 is trapezoidal. After the component is packaged, the bifaciality will be about 0.5% lower than that in Example 1.

[0047] Example 4

[0048] The process is carried out with reference to Example 1. The difference from Example 1 is that the cross-section of the electrode grid line in the collection area 200-31 is rectangular. After the component is packaged, the bifaciality will be about 1% lower than that in Example 1.

[0049] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A gridless back-contact solar cell unit, characterized in that: The device consists of several solar cells without metal electrode grids arranged in an orderly manner on a metal electrode film. Each solar cell is divided into N sub-electrode regions (N≥2) along the Y-axis. Each sub-electrode has a first electrode region and a second electrode region along the X-axis. The first and second electrode regions are positively charged and negatively charged, respectively, and are arranged alternately and orderly. The first and second electrode regions of two adjacent sub-electrode regions have opposite polarities. A first isolation groove is set between two adjacent sub-electrode regions. Each sub-electrode region forms a single power generation unit. A second isolation groove is set between adjacent first and second electrode regions. Transparent conductive materials are set on the first and second electrode regions. The thin film layer includes a carrier film layer, a first metal grid line, a second metal grid line, and a composite adhesive film layer on the metal electrode film. The first and second metal grid lines are arranged according to the positions of the first and second electrode areas on the sub-cell string formed by arranging the individual cells along the Y-axis direction, and are disposed on the upper surface of the carrier film layer. The composite adhesive film layer is also disposed on the upper surface of the carrier film layer and fills the hollow areas of the first and second metal grid lines. The first metal grid lines are arranged at both ends of the sub-cell string, extending beyond the edge of the sub-cell string. The second metal grid lines span two connected sub-electrode areas and are simultaneously arranged on the first and second electrode areas.

2. The gridless back-contact solar cell unit according to claim 1, characterized in that: When the sub-electrode region N is an even number, the individual solar cells are arranged directly along the Y-axis, with a cell spacing W of 0.2-1 mm; when the sub-electrode region N is an odd number, the individual solar cells are arranged along the Y-axis, and each cell needs to be rotated 180° before being arranged, with a cell spacing W of 0.2-1 mm.

3. The gridless back-contact solar cell unit according to claim 1, characterized in that: The carrier film layer has a transmittance of more than 85% and is made of one of the following materials: PET, PEN, PCT, PC, PETG, PMMA, COC, EVA, POE, EMA, EAA, EMMA, epoxy resin, silicone resin, PMA, PU, ​​VAE, PVB, or composite films thereof.

4. The gridless back-contact solar cell unit according to claim 1, characterized in that: The composite adhesive film layer has a transmittance of more than 85% after hot melting, and the material is one of TPO, EVA, POE, and PVB.

5. The gridless back-contact solar cell unit according to claim 1, characterized in that: The cross-sections of the first metal grid line and the second metal grid line are one of the following: triangular, trapezoidal, semi-circular arc, rectangular, and square.

6. The gridless back-contact solar cell unit according to claim 1, characterized in that: The contact areas between the first metal grid line, the second metal grid line and the first electrode region, and the second electrode region are planar.

7. The gridless back-contact solar cell unit according to claim 1, characterized in that: The first metal grid line consists of a collection area and a convergence area, and the second metal grid line consists of a collection area and a crossing area.

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