Back contact cell and cell string thereof
By incorporating separator grooves and insulation layers into the back-contact cell design, the problems of microcracks and efficiency loss caused by cell breakage are solved, resulting in higher light energy conversion efficiency and effective module area, simplifying the manufacturing process and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GOLD STONE (FUJIAN) ENERGY CO LTD
- Filing Date
- 2025-07-25
- Publication Date
- 2026-07-14
AI Technical Summary
Existing technologies suffer from problems such as microcracks caused by wafer breaking, dust re-sintering, film layer obstruction, and film layer damage during silicon wafer cutting and welding processes. Furthermore, the effective power generation area of the module is limited, making it impossible to effectively improve the light energy conversion efficiency.
The back-contact cell design avoids cell breakage by setting separators and insulation in the cells. The cells are divided into multiple segments by the separators and insulation layer and connected in series by the main grid lines and fine grid lines, which simplifies the manufacturing process and increases the effective conversion area of the module.
Without changing the existing manufacturing process, this method avoids the problems caused by cell breakage, improves light energy conversion efficiency, increases the effective conversion area of the module, reduces production costs and process difficulty, and enhances the conversion efficiency of the solar cells.
Smart Images
Figure CN224503877U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of solar cells, and in particular to a back contact solar cell and its string. Background Technology
[0002] Currently, the photovoltaic industry has various high-efficiency solar cell technologies with more efficient products in mass production or under development (e.g., BC cells, perovskite cells, multilayer composite cells, etc.). In terms of mass production, promotion, compatibility, production capacity, and return on investment, the BC technology route still has significant advantages. The BC technology route achieves a larger light-receiving surface and a larger light-absorbing area in the cell, thus obtaining a relatively higher conversion efficiency. Nowadays, silicon wafer production and cutting technologies are becoming increasingly mature, and silicon wafer (N-type silicon wafers, P-type silicon wafers) manufacturers are producing larger and larger products, which also improves the power generation efficiency of downstream light energy conversion modules and the power generation capacity of power plants.
[0003] However, as silicon wafers become larger, the cells need to be divided into 2, 3, or 4 sections when made into modules, and then connected in series with solder ribbons before being packaged into modules to achieve high open-circuit voltage (Voc), reduce short-circuit current (Isc) loss, and provide safer and less loss-inducing power supply. Currently, the market typically uses laser cutting followed by cell breaking. This method is prone to damaging the film layer near the cutting line during cell breaking, causing stress effects, microcracks, dust re-sintering, film layer obstruction, and film layer damage. Breaking can also cause cell breakage, resulting in cost waste and quality risks. Furthermore, to prevent short circuits and due to limitations of current technology, a gap greater than 0.5mm must be maintained between cells, thus reducing the effective power generation area of the module.
[0004] Currently, some solutions address this issue by altering the structure of the solar cell. Specifically, pre-dividing is done on the cell, and an insulating layer is deposited at these divisions. During the coating process, the cell is designed as a series of segments to avoid cutting and achieve the effect of segmentation. While this method reduces the problems caused by slicing, manufacturing this cell requires a completely new manufacturing process, altering the distribution of the film layers, main grids, and insulating blocks. It also adds many manufacturing steps, increasing manufacturing difficulty and cost. Utility Model Content
[0005] The purpose of this utility model is to provide a back-contact solar cell and its battery string. By setting a separator groove in the solar cell and insulating it, the short-circuit voltage requirement can be achieved without breaking the cell, while also avoiding the problems caused by breaking the cell. In addition, the effective conversion area of the module is increased. Compared with the same packaged product, the connection scheme of this invention has higher conversion efficiency and improves production efficiency.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] This utility model discloses a back-contact solar cell, comprising a solar cell body having a back side and a front side. The back side of the solar cell body has alternating distributions of several first semiconductor regions and second semiconductor regions of different polarities along the Y-axis. Corresponding first and second fine grid lines are disposed on the first and second semiconductor regions. The back surface of the solar cell body has several pairs of first main grid lines and second main grid lines disposed along the X-axis. The first main grid lines are respectively connected to several first fine grid lines on the solar cell and are insulated from the second fine grid lines; the second main grid lines are respectively connected to several second fine grid lines on the solar cell and are insulated from the first fine grid lines.
[0008] The main body of the solar cell has one or two dividing grooves along the Y-axis, dividing the solar cell into two or three equal parts. The width of the dividing groove is 15um-90um, and the depth is 20%-90% of the total thickness of the solar cell. A heat-resistant filling layer for isolation and insulation is provided on the dividing groove. The length of the filling layer is 70%-100% of the dividing groove, and the width of the filling layer is 0.2mm-0.3mm.
[0009] Furthermore, in the same group of first and second main busbars, the first main busbar is located above the second main busbar. The distance between the uppermost first main busbar and the edge of the cell in the X-axis direction, the distance between the lowermost second main busbar and the edge of the cell in the X-axis direction, and the distance between the first main busbar and the second main busbar in the same group are all 3%-10% of the total Y-axis dimension of the cell; the distance between the second main busbar and the adjacent non-group first main busbar is 5%-15% of the total Y-axis dimension of the cell; the distance between the two ends of the first or second main busbar and the edge of the cell in the Y-axis direction is 0.3%-1.5% of the total X-axis dimension of the cell.
[0010] Furthermore, the first main grid line is connected to the first fine grid line respectively, and a second insulating block is provided at the intersection of the first main grid line and the second fine grid line, which is used to insulate the second fine grid line and connect the first fine grid line on the cell in series; the second main grid line is connected to the second fine grid line respectively, and a first insulating block is provided at the intersection of the second main grid line and the first fine grid line, which is used to insulate the first fine grid line and connect the second fine grid line on the cell in series.
[0011] This utility model also discloses a back-contact battery string, which includes the aforementioned back-contact battery cells, solder ribbons, and conductive wires. The solder ribbons are disposed on the main grids of the battery cells and are used to connect the main grids on both sides of the separator groove and the main grids of two adjacent battery cells in series. The conductive wires are connected to the main grid lines of the battery cells at the beginning and end of the battery string, and are used to connect each column of battery strings in series and to lead out the positive and negative electrodes.
[0012] Furthermore, the conductive wire is connected to the main grid of the battery cell via a lead wire, and the cross-sectional area of the conductive wire is 5-100 times that of the lead wire.
[0013] The advantages of this utility model are:
[0014] This invention achieves the effect of multiple solar cells without altering the manufacturing process or splitting the cells by incorporating separator grooves and insulation within the cells. Compared to existing methods that modify the cell structure, this solution retains the original manufacturing process and equipment, saving production costs and reducing process complexity. Compared to the splitting method used in existing technologies, this solution avoids problems such as microcracks, dust re-sintering, film layer obstruction, and film layer damage caused by splitting. Furthermore, it increases the effective conversion area of the module, resulting in higher conversion efficiency compared to similarly packaged products using this connection method. Attached Figure Description
[0015] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 This is a schematic diagram of the structure of the battery cell in this embodiment after omitting the fine grid.
[0017] Figure 2 yes Figure 1 A magnified view of a portion of point A in the middle.
[0018] Figure 3 This is a schematic diagram of the battery string connection in this embodiment.
[0019] Figure 4 yes Figure 3 A magnified view of a section at point B.
[0020] Explanation of key component symbols:
[0021] 1. First main grid line; 2. Second main grid line; 3. Separator groove; 4. Filler layer; 5. Solder strip; 6. Conductive wire; 7. Lead wire. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0023] In this utility model, unless otherwise stated, directional terms such as "up," "down," "left," and "right" are generally understood in conjunction with the accompanying drawings and the directions shown in actual applications.
[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.
[0025] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.
[0026] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. The terms "optional" and "discretionary" mean that they may or may not be included (or may or may not be present).
[0027] like Figure 1As shown, this embodiment discloses a back-contact solar cell, which includes a solar cell body having a back side and a front side. The back side of the solar cell body has a plurality of first semiconductor regions and second semiconductor regions of different polarities alternately distributed along the Y-axis. Corresponding first and second fine grid lines are disposed on the first and second semiconductor regions. The back surface of the solar cell body has a plurality of paired first main grid lines 1 and second main grid lines 2 disposed along the X-axis.
[0028] The first main grid line 1 is connected to a plurality of first fine grid lines on the solar cell and is insulated from the second fine grid lines; the second main grid line 2 is connected to a plurality of second fine grid lines on the solar cell and is insulated from the first fine grid lines. Specifically, in this embodiment, the first main grid line 1 is connected to the first fine grid lines, and a second insulating block is provided at the intersection of the first main grid line 1 and the second fine grid line, which is used to insulate the second fine grid lines while connecting the first fine grid lines on the solar cell in series. The second main grid line 2 is connected to the second fine grid lines, and a first insulating block is provided at the intersection of the second main grid line 2 and the first fine grid line, which is used to insulate the first fine grid lines while connecting the second fine grid lines on the solar cell in series. The fine grid lines and the insulating block are not shown in the accompanying drawings.
[0029] The solar cell body has one or two dividing grooves 3 along the Y-axis, dividing the cell into two or three equal parts. The width of the dividing grooves is 15um-90um, and the depth is 20%-90% of the total thickness of the solar cell. A heat-resistant filling layer 4 for isolation and insulation is provided on the dividing grooves 3. The material of the filling layer 4 is Teflon, PTFE, polytetrafluoroethylene, etc. The length of the filling layer 4 is 70%-100% of the dividing groove 3, and the width of the filling layer 4 is 0.2mm-0.3mm.
[0030] In this embodiment, the width of the filler layer 4 is 0.2mm-0.3mm. When the battery cells are cut and connected in strings, a spacing greater than 0.5mm must be maintained between the cells to prevent short circuits, damage to products with hard contacts, and reliability issues. Using the solution in this embodiment, firstly, compared to a 0.5mm spacing, this solution can reduce the spacing of a single battery cell by more than 0.2mm, thereby increasing the effective power generation area and reducing the non-power generation area in the series connection direction by nearly 50%. Secondly, since the battery cells are not broken apart, the process of fixing the broken cells during welding can be reduced, simplifying the process and saving production costs. Thirdly, breaking the battery cells can lead to problems such as microcracks at the breaking point, dust re-sintering, film layer obstruction, and film layer damage, resulting in battery efficiency loss or even damage. By avoiding breaking the cells and using the separator groove 3, this efficiency loss can be avoided, thereby indirectly improving battery efficiency.
[0031] In this embodiment, the battery cell is provided with a dividing groove 3, which divides the battery cell into two equal pieces.
[0032] Meanwhile, photoelectric conversion efficiency experiments were conducted on solar cells with different depths of partition groove 3 and solar cells after being split, and the photoelectric conversion efficiency was compared with that of uncut solar cells to calculate the loss difference, as shown in Table 1.
[0033] The experimental data in Table 1 show that:
[0034] The scheme with the separator 3 not split has a lower conversion efficiency loss than the scheme with the split pieces. In other words, the conversion efficiency Eff of the scheme with the separator 3 is higher than that of the scheme with the split pieces.
[0035] The depth of the separator groove 3 also affects the short-circuit current (Isc), open-circuit voltage (Voc), and fill factor (FF), thus affecting the cell's conversion efficiency (Eff). Experimental data shows that the photoelectric conversion efficiency (Eff) loss is minimized when the depth of the separator groove 3 is 55% of the total thickness of the cell.
[0036]
[0037] Specifically, such as Figure 2 As shown, to improve energy conversion efficiency, in this embodiment, the first main grid line 1 is located above the second main grid line 2 in the same group of first main grid lines 1 and second main grid lines 2. The distance b between the uppermost first main grid line 1 and the edge of the cell in the X-axis direction, the distance c between the lowermost second main grid line 2 and the edge of the cell in the X-axis direction, and the distance c between the first main grid line 1 and the second main grid line 2 in the same group are all 3%-10% of the total Y-axis dimension of the cell; the distance d between the second main grid line 2 and the adjacent non-group first main grid line is 5%-15% of the total Y-axis dimension of the cell; the distance e between the two ends of the first main grid line 1 or the second main grid line 2 and the edge of the cell in the Y-axis direction is 0.3%-1.5% of the total X-axis dimension of the cell.
[0038] like Figure 3 , Figure 4 As shown, this embodiment also discloses a back-contact battery string, which includes the aforementioned back-contact battery cells, solder ribbons 5, and conductive wires 6. The solder ribbons 5 are disposed on the main grids of the battery cells, used to connect the main grids on both sides of the separator groove 3 and the main grids of adjacent battery cells in series. The conductive wires 6 are connected to the main grid lines of the first and last battery cells in the battery string, used to connect each column of battery strings in series and to lead out the positive and negative electrodes. To enhance the current-carrying capacity, the conductive wires 6 are connected to the main grids of the battery cells through lead-out wires 7. The cross-sectional area of the conductive wires 6 is 5-100 times that of the cross-sectional area of the lead-out wires 7, which are 3mm-30mm in diameter.
[0039] Specifically, in this embodiment, taking four battery cells connected in a battery string as an example, the connection method of this scheme is described. The four battery cells are arranged in two rows and two columns, from left to right and from top to bottom as the first battery cell, the second battery cell, the third battery cell, and the fourth battery cell. The main grid line is parallel to the X-axis, the separator 3 is parallel to the Y-axis, the first main grid is the negative electrode, and the second main grid is the positive electrode.
[0040] In the first battery cell, the first main grid on the left side of the separator 3 and the second main grid on the right side of the separator 3 are connected by a solder strip 5. The second main grid on the left side of the separator 3 is connected in parallel with the conductive wire 6 through the lead wire 7 to form the positive electrode bus terminal.
[0041] The first main grid on the right side of the first cell separator 3 and the second main grid on the left side of the second cell separator 3 are connected by a welding strip 5.
[0042] The first main grid on the left side of the second cell separator 3 and the second main grid on the right side of the separator 3 are connected by a solder strip 5. The first main grid on the right side of the separator 3 is connected in parallel with the conductive wire 6 through the lead wire 7 to form the negative terminal of the cell string.
[0043] The first main grid on the left side of the third cell separator 3 forms the negative electrode busbar by connecting the lead wire 7 and the conductive wire 6 in parallel. The second main grid on the left side of the separator 3 is connected to the first main grid on the right side of the separator 3 by the solder strip 5.
[0044] The second main grid on the right side of the third cell separator 3 is connected to the first main grid on the left side of the fourth cell separator 3 via solder strip 5. The third cell is connected in series with the positive terminal of the first cell through the negative terminal.
[0045] The second main grid on the left side of the fourth cell separator 3 is connected to the first main grid on the right side of the separator 3 via a solder strip 5. The second main grid on the right side of the separator 3 is connected in parallel with the conductive wire 6 via a lead wire 7 to form the positive terminal of the battery string.
[0046] In this embodiment, in order to simplify the welding difficulty by allowing adjacent battery cells to be connected in a straight line using the solder strip 5, the second and fourth battery cells are rotated 180 degrees before being connected by the solder strip 5.
[0047] In summary, this utility model replaces cell splitting with the setting of a separator groove, which not only reduces the defects caused by cell splitting, but also improves the conversion efficiency of the cell, reduces the gap in the module, and increases the effective conversion area of the module. Compared with the same packaged product using the connection scheme of this invention, the conversion efficiency is higher.
[0048] The preferred embodiments of this utility model have been described in detail above; however, this utility model is not limited thereto. Within the scope of the technical concept of this utility model, various simple modifications can be made to the technical solution of this utility model, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed by this utility model and are all within the protection scope of this utility model.
Claims
1. A back-contact solar cell, comprising a solar cell body having a back side and a front side, wherein a plurality of first semiconductor regions and second semiconductor regions of different polarities are alternately distributed along the Y-axis direction on the back side of the solar cell body; corresponding first fine grid lines and second fine grid lines are disposed on the first semiconductor regions and the second semiconductor regions; a plurality of paired first main grid lines and second main grid lines are disposed along the X-axis direction on the back surface of the solar cell body; the first main grid lines are respectively connected to a plurality of first fine grid lines on the solar cell and are insulated from the second fine grid lines; the second main grid lines are respectively connected to a plurality of second fine grid lines on the solar cell and are insulated from the first fine grid lines. Its features are: The main body of the battery cell is provided with one or two dividing grooves along the Y-axis, which divide the battery cell into two or three equal parts. The width of the dividing groove is 15um-90um and the depth is 20%-90% of the total thickness of the battery cell. A heat-resistant filling layer for isolation and insulation is provided on the dividing groove. The length of the filling layer is 70%-100% of the dividing groove and the width of the filling layer is 0.2mm-0.3mm.
2. The back contact battery cell according to claim 1, characterized in that: In the same group of first and second main busbars, the first main busbar is located above the second main busbar; the distance between the uppermost first main busbar and the edge of the cell in the X-axis direction, the distance between the lowermost second main busbar and the edge of the cell in the X-axis direction, and the distance between the first main busbar and the second main busbar in the same group are all 3%-10% of the total cell Y-axis dimension; the distance between the second main busbar and the adjacent non-same group first main busbar is 5%-15% of the total cell Y-axis dimension; the distance between the two ends of the first or second main busbar and the edge of the cell in the Y-axis direction is 0.3%-1.5% of the total cell X-axis dimension.
3. The back contact battery cell according to claim 1, characterized in that: The first main grid line is connected to the first fine grid line respectively. A second insulating block is provided at the intersection of the first main grid line and the second fine grid line, which is used to insulate the second fine grid line and connect the first fine grid line on the cell in series. The second main grid line is connected to the second fine grid line respectively. A first insulating block is provided at the intersection of the second main grid line and the first fine grid line, which is used to insulate the first fine grid line and connect the second fine grid line on the cell in series.
4. A back-contact battery string, characterized in that: It includes the back contact battery cell, solder ribbon and conductive wire as described in claims 1 or 3. The solder ribbon is disposed on the main grid of the battery cell and is used to connect the main grids on both sides of the separator and the main grids of two adjacent battery cells in series. The conductive wire is connected to the main grid lines of the first and last battery cells of the battery string and is used to connect each column of battery strings in series and to lead out the positive and negative electrodes.
5. The back contact battery string according to claim 4, characterized in that: The conductive wire is connected to the main grid of the battery cell via a lead wire, and the cross-sectional area of the conductive wire is 5-100 times that of the lead wire.