Low-cost back contact solar cell string and preparation method thereof
By integrating the electrode fine gate lines, insulating layer and main gate lines to the metal composite film, and bonding the cell precursor using hot melt technology, the problems of high production costs and complex processes of back contact heterojunction solar cell strings are solved, and efficient and stable preparation process and cost reduction are achieved.
Patent Information
- Application Number
- CN202510368855.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-27
- Publication Date
- 2025-07-01
AI Technical Summary
The production cost of existing back contact heterojunction solar cell strings is high, and the preparation process is complex, requiring multiple insulating ink printing and expensive string welding equipment, resulting in inefficiency.
Using the method of integrating electrode fine gate lines, insulating layer and main gate lines to metal composite film, the precursor of the cell is bonded to the metal composite film through hot melting technology, simplifying the process, reducing printing steps, and avoiding the use of string welding equipment.
It realizes efficient and stable preparation of back-contact heterojunction solar cell strings, saves at least 3 printing processes, reduces production costs, improves production efficiency, and eliminates the need for expensive string welding equipment.
Smart Images
Figure CN120239345A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of back-contact solar cells, and in particular to a low-cost back-contact solar cell string and a preparation method thereof. Background Art
[0002] At present, the back-contact heterojunction solar cell string and preparation method are generally as follows: after the silicon wafer undergoes the back-contact heterojunction solar cell process, a cell precursor (PN junction is prepared) to be made into the grid line is formed, and then silver paste grid lines, silver-copper paste grid lines, copper alloy grid lines are attached to the cell precursor through printing, coating, electroplating and other schemes, thereby forming a piece of cell with grid lines. In order to achieve higher output power, the cell pieces need to be connected in series and in parallel. The traditional solution is to weld the grid lines on the cell pieces with welding ribbons to string the cell pieces together.
[0003] The metal electrodes of back-contact heterojunction solar cells are generally divided into silver paste grid electrodes and copper alloy grid electrodes. When silver paste grid electrodes are used, the back-contact heterojunction battery consumes a lot of silver paste due to structural reasons, and the cost is high; the copper alloy grid electrode has a complex process, many steps, and high equipment introduction costs; the battery cells prepared by the above two technical solutions need to go through the string welding process to achieve string welding, and the string welding machine equipment is the most expensive equipment in the component packaging environment. In order to avoid the problem of short circuit caused by the staggered positive and negative fine grids, the back-contact heterojunction battery also needs to print insulating ink at intervals at the intersection. In order to form a PN junction on the back, an insulating channel needs to be formed by etching or laser grooving. This insulating channel is very easy to react with the acidic substances produced by the packaging film, which leads to a significant decrease in the efficiency of the battery cell, so it is necessary to print an insulating protective ink; from the process point of view, in order to achieve insulation between electrodes and the reliability of component packaging, 2-3 insulating ink printing processes are required.
[0004] Therefore, a back-contact solar cell string and a preparation method are designed to improve production efficiency and reduce production costs. Summary of the invention
[0005] In view of the above problems, the present invention provides a back-contact solar cell string and a preparation method which are simple to prepare, efficient and stable, and can effectively reduce production costs.
[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a low-cost back-contact solar cell string, including a plurality of cell precursors and a metal composite film. The cell precursors are arranged alternately along the Y-axis direction and are provided with a first electrode region and a second electrode region that are parallel and paired. A transparent conductive film layer is provided on the outer surfaces of the first electrode region and the second electrode region in the Z-axis direction. An electrode separation groove is formed in a corresponding part of the transparent conductive film layer at the junction of the first electrode region and the second electrode region. The electrode separation groove divides the transparent conductive film layer into a first transparent conductive film layer and a second transparent conductive film layer. The metal composite film is provided with a first metal fine grid line layer, a first insulating block film layer, a second metal fine grid line layer, a second insulating block film layer, a metal main grid line layer, a carrier film layer, and a composite film layer. The metal main grid line layer is located above the carrier film layer and is arranged at intervals along the X-axis direction. The composite film layer fills the hollow area of the metal main grid line layer to form an intermediate layer structure. The first metal fine grid line layer and the second metal fine grid line layer are located above the intermediate layer structure and are arranged in a one-to-one correspondence with the first electrode region and the second electrode region, and are perpendicular to the metal main grid line layer. The first metal fine grid line layer and the second metal fine grid line layer are of an intermittent design, and a first insulating block film layer and a second insulating block film layer are provided in the intermittent area. The metal main grid line layer is ohmically connected to the first metal fine grid line layer and the second metal fine grid line layer in the Z-axis direction.
[0007] Further, the cell precursor is a silicon heterojunction cell that has already been prepared with a PN junction but has not been fabricated with metal electrode grid lines. The spacing between the cell precursors is 0.8 - 1.2 mm.
[0008] Further, the first electrode region is an N-type doped layer prepared by an intrinsic amorphous silicon layer and an N-type doped amorphous silicon layer. The thickness of the intrinsic amorphous silicon layer is 10 nm, the thickness of the N-type doped amorphous silicon layer is 120 nm, and the effective doping concentration is 8e20 / cm³; the second electrode region is a P-type doped layer prepared by stacking an amorphous silicon passivation layer and a doped amorphous silicon layer. The thickness of the stacked amorphous silicon passivation layer is 10 nm, the thickness of the doped amorphous silicon layer is 20 nm, and the effective doping concentration is 8e19 / cm³.
[0009] Further, the first electrode region, the second electrode region, and the electrode separation groove extend along the X-axis direction respectively. The electrode polarities of the first electrode region and the second electrode region are opposite.
[0010] Further, the electrode separation groove is formed by grooving the transparent conductive film layer with a green laser having a wavelength of 532 nm. The width of the electrode separation groove is 60 - 120 μm.
[0011] Further, the first transparent conductive film layer and the second transparent conductive film layer are indium tin oxide with a thickness of 80 - 100 nm.
[0012] Further, the metal main grid line layer is composed of several flat copper wires. The width of the copper wire in the X-axis direction is 0.8 - 2 mm, and the thickness in the Z-axis direction is 0.2 - 0.3 mm.
[0013] Further, the carrier film layer is a transparent PET film with a thickness of 0.2 - 0.5 mm.
[0014] Further, the first metal fine grid line layer and the second metal fine grid line layer have a width of 0.05 - 0.08 mm in the Y-axis direction and a thickness of 0.02 - 0.06 mm in the Z-axis direction. The material is copper alloy, and the surface is plated with an anti-oxidation low-temperature SnPb alloy layer.
[0015] Further, the first insulating block film layer and the second insulating block film layer are transparent PET films with a thickness of 0.03 - 0.06 mm, a length of 2 - 3 mm in the X-axis direction, and a width of 0.5 - 0.8 mm in the Y-axis direction.
[0016] A method for preparing the low-cost back-contact solar cell string as described above, the method comprising the following steps:
[0017] Provide a cell precursor;
[0018] Design a metal composite film adapted to the cell precursor;
[0019] According to the electrode arrangement of the cell string, arrange several cell precursors on the metal composite film, and hot-melt the composite film layer through methods such as rolling and laminating to complete the preparation of the back-contact heterojunction solar cell string.
[0020] Further, the metal main grid line layers at both ends of the metal composite film are extended along the Y-axis direction, and the composite film layer is peeled off and removed, leaving only the metal main grid line layer.
[0021] Further, the composite film layer of the metal composite film is a polypropylene film with a thickness of 0.2 - 0.4 mm, which will fill and protect the electrode separation groove during the hot-melting process and firmly adhere to the surface of the cell precursor.
[0022] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following advantages:
[0023] In the present invention, the electrode fine grid lines, the insulating layer, and the main grid lines are integrated onto the metal composite film, which is easy to prepare. The back-contact heterojunction cell precursor and the metal composite film are directly bonded by hot melting, so that the photo-generated carriers are output through the main grid lines on the metal composite film. The preparation of the back-contact heterojunction cell string is efficient and stable, at least 3 printing processes can be saved, and there is no need to use the existing relatively expensive string welding equipment, which greatly reduces the production cost and improves the production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:
[0025] Figure 1 It is a schematic structural diagram of the back-contact heterojunction cell precursor in Embodiment 1;
[0026] Figure 2 is Figure 1 The schematic cross-sectional cell structure diagram of A-A of;
[0027] Figure 3 is Figure 1 The schematic cross-sectional cell structure diagram of B-B of;
[0028] Figure 4 It is a schematic structural diagram of the arrangement after cutting the back-contact heterojunction cell precursor in Embodiment 1;
[0029] Figure 5 It is a schematic structural diagram of the metal composite film in Embodiment 1;
[0030] Figure 6 is Figure 5 The schematic cross-sectional cell structure diagram of C-C of;
[0031] Figure 7 is Figure 5 The schematic cross-sectional cell structure diagram of D-D of;
[0032] Figure 8 It is a schematic structural diagram of a back-contact back-contact solar cell string in Embodiment 1;
[0033] Figure 9 is Figure 8 The schematic cross-sectional cell structure diagram of E-E of;
[0034] Figure 10 is Figure 8 The schematic cross-sectional cell structure diagram of F-F of;
[0035] Figure 11 The schematic structural diagram of the metal composite film in Embodiment 2 of the present invention;
[0036] Figure 12 For Figure 11 the schematic diagram of the battery structure of the G-G cross-section. Specific embodiments
[0037] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention 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 only used to explain the present invention and are not used to limit the present invention.
[0038] Embodiment 1
[0039] Referring to Figure 1 , Figure 2 , Figure 3 shown, a precursor X of a battery cell of a back-contact battery string, which is a silicon-based heterojunction solar cell with a thickness of 120 μm. A first electrode region 100 and a second electrode region 200 are provided on the back of the battery cell precursor, and the first electrode region 100 and the second electrode region 200 are arranged alternately and in parallel pairs; the first electrode region 100 is a semiconductor layer, and an N-type doping layer is obtained through an intrinsic amorphous silicon layer (with a thickness of 10 nm) and an N-type doped amorphous silicon layer (with a thickness of 120 nm and an effective doping concentration of 8e20 / cm³); the second electrode region 200 is a semiconductor layer, and a P-type doping layer is obtained through stacking an amorphous silicon passivation layer (with a thickness of 10 nm) and a doped amorphous silicon layer (with a thickness of 20 nm and an effective doping concentration of 8e19 / cm³). A first transparent conductive film layer 100-1 is provided in the Z-axis direction of the first electrode region 100; a second transparent conductive film layer 200-1 is provided on the second electrode region 200. The first transparent conductive film layer 100-1 and the second transparent conductive film layer 200-1 are indium tin oxide doped, with a thickness of 90 nm.
[0040] At the junction position between the first electrode region 100 and the second electrode region 200, an electrode separation groove 300 is provided between the first transparent conductive film layer 100-1 and the second transparent conductive film layer 200-1, and the first electrode region 100 and the second electrode region 200 have opposite electrode polarities. The first electrode region 100 forms a positive electrode 100-4, and the second electrode region 200 forms a negative electrode 200-4. The electrode separation groove 300 is formed by grooving the transparent conductive film layer with a green laser with a wavelength of 532 nm, forming the first transparent conductive film layer 100-1 and the second transparent conductive film layer 200-1, separating the first electrode region 100 from the second electrode region 200, and forming two different electrodes. The width of the electrode separation groove 300 is 80 μm.
[0041] Referring to Figure 4 shown, the battery cell precursor X of Figure 1 is cut along the X-axis direction in the central region of the Y-axis to obtainFigure 4 The shown cell precursors X1 and X2, several cell precursors X1 and X2 are arranged in an orderly manner along the Y-axis direction as Figure 4 shown, and the cell spacing is set to 1.0 mm.
[0042] Refer to Figure 5 shown, a first metal fine grid line layer 1, a first insulating block film layer 2, a second metal fine grid line layer 3, a second insulating block film layer 4, a metal main grid line layer 5, a carrier film layer 6, and a composite film layer 7 are provided on the metal composite film M; the carrier film layer 6 is a transparent PET film with a thickness of 0.2 mm, the metal main grid line layer 5 is located above the carrier film layer 6 and is arranged at intervals in the X-axis direction. The metal main grid line layer 5 is composed of several flat copper wires. The width of the copper wire in the X-axis direction is 1 mm, and the thickness in the Z-axis direction is 0.25 mm; refer to Figure 6 shown, the composite film layer 7 fills the hollow area of the metal main grid line layer 5 to form an intermediate layer structure 8. The composite film layer 7 is a polypropylene film with a thickness of 0.25 mm. The first metal fine grid line layer 1 and the second metal fine grid line layer 3 are arranged above the intermediate layer structure 8, and as Figure 8 shown, the first metal fine grid line layer 1 and the second metal fine grid line layer 3 are arranged in a one-to-one correspondence with the first electrode region 100 and the second electrode region 200, and are perpendicular to the metal main grid line layer 5. Refer to Figure 5 , Figure 6 shown, the first metal fine grid line layer 1 and the second metal fine grid line layer 3 are of an intermittent design. The metal main grid line layer 5 is ohmically connected to the first metal fine grid line layer 1 and the second metal fine grid line layer 3 in the Z-axis direction; the first metal fine grid line layer 1 and the second metal fine grid line layer 3 have a width of 0.06 mm in the Y-axis direction and a thickness of 0.05 mm in the Z-axis direction. The material is copper alloy, and the surface is plated with an anti-oxidation low-temperature SnPb alloy layer.
[0043] Refer to Figure 5 , Figure 6 , Figure 7 shown, the first insulating block film layer 2 is arranged above the intermediate layer structure 8 and is placed in the intermittent grid region of the first metal fine grid line layer 1; the second insulating block film layer 4 is arranged above the intermediate layer structure 8 and is placed in the intermittent grid region of the second metal fine grid line layer 3; the first insulating block film layer 2 and the second insulating block film layer 4 are made of a transparent PET film with a thickness of 0.05 mm, a length of 3 mm in the X-axis direction, and a width of 0.5 mm in the Y-axis direction.
[0044] Along the Y-axis direction, the metal main grid line layers at both ends of the metal composite film M are extended by 10 mm. The composite film layer 7 in the extended area is peeled off and removed, and only the metal main grid line layer 5 is retained. When fabricating components for subsequent encapsulation, this area is used for series-parallel connection and current collection between back-contact cell strings.
[0045] Place the battery cell precursors X1 and X2 shown Figure 4 on the metal composite film M shown, and hot melt paste the composite film layer 7 on the metal composite film M onto the first transparent conductive film layer 100-1, the second transparent conductive film layer 200-1, and the electrode separation groove 300 of the battery cell precursors X1 and X2 by means of roll pressing, thereby obtaining Figure 5 the back-contact solar cell string shown in Figure 8 , Figure 9 , Figure 10 ;
[0046] Refer to Figure 8 , Figure 9 , Figure 10 shown. In order to better conduct and output the photo-generated carriers generated on the battery cell precursors X1 and X2 after illumination from the first electrode region 100 and the second electrode region 200, the first electrode region 100 corresponds to the positive electrode, and the photo-generated carriers are transmitted to the metal main grid line layer 5 through the first metal fine grid line layer 1 for current output. The second electrode region 200 corresponds to the negative electrode, and the photo-generated carriers are transmitted to the metal main grid line layer 5 through the second metal fine grid line layer 3 for current output. In order to avoid short-circuit problems caused by the contact between the metal main grid line layer 5 and the first transparent conductive film layer 100-1 and the second transparent conductive film layer 200-1 on the first electrode region 100 and the second electrode region 200, a first insulating block film layer 2 and a second insulating block film layer 4 are provided.
[0047] A battery string of 12 battery cells is prepared in the above manner, and 12 battery strings are arranged in series and parallel by busbars. EVA adhesive films with a thickness of 200 g / ㎡ and 300 g / ㎡ are respectively laid on the front and back of the battery string, and laminated and encapsulated with high-transparency coated tempered glass with a thickness of 2 mm for both the front plate and the back plate, and a photovoltaic module can be encapsulated.
[0048] Example 2
[0049] It is carried out with reference to Example 1. The difference from Example 1 is that, referring to Figure 11 , Figure 12As shown in the figure, the first metal fine grid line layer 1 and the second metal fine grid line layer 3 are linearly designed. The local areas of the first metal fine grid line layer 1 and the second metal fine grid line layer 3 are placed on the first insulating block film layer 2 and the second insulating block film layer 4. The first insulating block film layer 2 and the second insulating block film layer 4 block the first metal fine grid line layer 1 and the second metal fine grid line layer 3 from the metal main grid line layer 5 in this area. In the remaining areas, the metal main grid line layer 5 is ohmically connected to the first metal fine grid line layer 1 and the second metal fine grid line layer 3 in the Z-axis direction; the carrier film layer 6 is a 0.3-mm-thick transparent PET film, which can play a certain buffering role when hot-melting and pasting the composite film layer 7 on the metal composite film M during roll pressing, ensuring good ohmic contact between the first metal fine grid line layer 1, the second metal fine grid line layer 3 and the first transparent conductive film layer 100-1 and the second transparent conductive film layer 200-1 of the cell precursors X1 and X2.
[0050] Compared with Example 1, although Example 2 can increase the collection ability of photo-generated carriers, the bifaciality of the module will be lower than that of Example 1 because the back-shaded area increases.
[0051] Example 3
[0052] It is carried out with reference to Example 1. The difference from Example 1 is that the carrier film layer 6 is replaced with a photovoltaic fluorine-containing backsheet, and at the same time, the layout preparation of multiple strings of battery strings is completed. EVA film and photovoltaic front plate are laid on the front of the cell, and then encapsulated into a single-glass module. This solution is suitable for preparing single-glass modules with lower production costs.
[0053] The present invention integrates electrode fine grid lines, insulating layers, and main grid lines onto a metal composite film, which is easy to prepare. The back-contact heterojunction cell precursor and the metal composite film are directly bonded by hot melting, so that photo-generated carriers are output through the main grid lines on the metal composite film. The preparation of back-contact heterojunction battery strings is efficient and stable, which can save at least three printing processes and does not require the use of existing relatively expensive string welding equipment, greatly reducing production costs and improving production efficiency.
[0054] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.
Claims
1. A low-cost back-contact solar cell string, characterized in that: The invention comprises a plurality of cell precursors and a metal composite film, wherein the cell precursors are alternately arranged along the Y-axis direction and are arranged in parallel with a first electrode region and a second electrode region in pairs, a transparent conductive film layer is arranged on the outer surface of the first electrode region and the second electrode region in the Z-axis direction, an electrode separation groove is opened on a portion of the transparent conductive film layer corresponding to the junction of the first electrode region and the second electrode region, and the electrode separation groove divides the transparent conductive film layer into a first transparent conductive film layer and a second transparent conductive film layer, and the metal composite film is provided with a first metal fine grid line layer, a first insulating block film layer, a second metal fine grid line layer, a second insulating block film layer, a metal main grid line layer, a carrier film layer, and a composite film. layer, the metal main grid line layer is located above the bearing film layer and is arranged at intervals along the X-axis direction, the composite film layer is filled in the hollow area of the metal main grid line layer to form an intermediate layer structure, the first metal fine grid line layer and the second metal fine grid line layer are located above the intermediate layer structure, and are arranged in a one-to-one correspondence with the first electrode area and the second electrode area, and are perpendicular to the metal main grid line layer, the first metal fine grid line layer and the second metal fine grid line layer are of discontinuous design, and the first insulating block film layer and the second insulating block film layer are arranged on the discontinuous area, and the metal main grid line layer is ohmically connected to each other in the Z-axis direction.
2. A low-cost back-contact solar cell string according to claim 1, characterized in that: The cell precursor is a silicon heterojunction cell that has been prepared with a PN junction but has not yet produced a metal electrode grid line. The cell spacing of the cell precursor is 0.8-1.2 mm.
3. A low-cost back-contact solar cell string according to claim 1, characterized in that: The first electrode region is an N-type doped layer made by an intrinsic amorphous silicon layer and an N-type doped amorphous silicon layer, the thickness of the intrinsic amorphous silicon layer is 10nm, the thickness of the N-type doped amorphous silicon layer is 120nm, and the effective doping concentration is 8e20 / cm³; the second electrode region is a P-type doped layer made by stacking an amorphous silicon passivation layer and a doped amorphous silicon layer, the thickness of the stacked amorphous silicon passivation layer is 10nm, the thickness of the doped amorphous silicon layer is 20nm, and the effective doping concentration is 8e19 / cm³.
4. A low-cost back-contact solar cell string according to claim 1, characterized in that: The first electrode region, the second electrode region, and the electrode separation groove are respectively extended along the X-axis direction, and the electrode polarities of the first electrode region and the second electrode region are opposite.
5. A low-cost back-contact solar cell string according to claim 1, characterized in that: The width of the electrode separation groove is 60-120 μm.
6. A low-cost back-contact solar cell string according to claim 1, characterized in that: The first transparent conductive film layer and the second transparent conductive film layer are tin-doped indium oxide, and have a thickness of 80-100 nm.
7. A low-cost back-contact solar cell string according to claim 1, characterized in that: The metal main grid line layer is composed of a plurality of flat copper wires, the copper wires have a width of 0.8-2 mm in the X-axis direction and a thickness of 0.2-0.3 mm in the Z-axis direction.
8. A low-cost back-contact solar cell string according to claim 1, characterized in that: The supporting film layer is a transparent PET film with a thickness of 0.2-0.5 mm.
9. A low-cost back-contact solar cell string according to claim 1, characterized in that: The first metal fine grid line layer and the second metal fine grid line layer have a width of 0.05-0.08 mm in the Y-axis direction and a thickness of 0.02-0.06 mm in the Z-axis direction. They are made of copper alloy and are coated with an oxidation-resistant low-temperature SnPb alloy layer.
10. A low-cost back-contact solar cell string according to claim 1, characterized in that: The first insulating block film layer and the second insulating block film layer are made of a transparent PET film with a thickness of 0.03-0.06 mm, a length of 2-3 mm in the X-axis direction, and a width of 0.5-0.8 mm in the Y-axis direction.
11. A method for preparing a low-cost back-contact solar cell string according to claim 1, characterized in that: The method comprises the following steps: Provide battery cell precursors; Metal composite films that are compatible with the cell precursor design; According to the electrode arrangement of the battery string, several battery cell precursors are arranged on the metal composite film, and the composite film layer is hot-melted through rolling, lamination and other schemes to complete the preparation of the back contact heterojunction solar cell string.
12. A method for preparing a low-cost back-contact solar cell string according to claim 11, characterized in that: The metal main grid line layers at the two ends of the metal composite film are extended along the Y-axis direction, and the composite film layer is peeled off and removed, leaving only the metal main grid line layer.
13. A method for preparing a low-cost back-contact solar cell string according to claim 11, characterized in that: The composite film layer of the metal composite film is a polypropylene film with a thickness of 0.2-0.4 mm, which can fill and protect the electrode separation grooves during the hot melting process and firmly adhere to the surface of the battery cell precursor.