Half-piece photovoltaic cell string and photovoltaic module

Abstract

The utility model relates to the field of photovoltaic technology, and discloses a half-piece photovoltaic cell string and a photovoltaic assembly, and the half-piece photovoltaic cell string comprises a plurality of cell pieces and a plurality of solder strips. A plurality of battery pieces are arranged in the first direction, the cutting face of one of every two adjacent battery pieces corresponds to the isolation face of the other battery piece, the orientations of the positive electrodes and the negative electrodes of the battery pieces are kept consistent, follow-up welding operation is facilitated, every two adjacent battery pieces are connected through the same welding strip, series connection of the battery pieces is achieved, and the welding efficiency is improved. The distance L1 between the welding strip and the first intersecting line and the distance L2 between the welding strip and the second intersecting line meet the condition that L1 is larger than or equal to 2 * L2, the distance between the welding strip and the PN junction on the cutting face is far larger than the distance between the welding strip and the position corresponding to the PN junction on the isolation face, and the risk that the welding strip is too close to or makes contact with the exposed PN junction on the cutting face can be avoided. The situation of electric leakage or short circuit is improved, and the reliability of the half-piece photovoltaic cell string is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaic, in particular to a half-cell photovoltaic cell string and a photovoltaic module. Background Art

[0002] A photovoltaic cell string is a main component in a photovoltaic module, and its main function is to convert solar energy into electrical energy. The photovoltaic cell string is formed by connecting a plurality of cell pieces in series to increase the output voltage. Currently, the cell pieces applied on the module are mainly half-cells. Using half-cells in a photovoltaic module has higher conversion efficiency and lower cost. Among them, a half-cell is obtained by cutting a square or rectangular cell piece along the direction perpendicular to the cell piece electrode (main grid). After the cell is sliced, it is necessary to weld each cell piece so that a plurality of cell pieces are connected in series to form a half-cell photovoltaic cell string. Specifically, every two cell pieces are connected by a welding tape, and the welding tape is welded to the electrode on the cell piece.

[0003] Generally, there is an isolation layer around the cell piece, and the cell piece is protected by the isolation layer. However, after the cell is divided into two half-cells, there will be no isolation layer at the cut surface position, and the PN junction in the internal structure of the cell will be exposed outside. Since the welding tape is connected between the two half-cells, there is a risk that the distance between the welding tape and the PN junction at the cut surface of the half-cell is too close or in contact, which may cause leakage or short circuit, posing a great potential safety hazard. Summary of the Utility Model

[0004] In view of this, the utility model provides a half-cell photovoltaic cell string and a photovoltaic module to solve the problem that the welding tape is likely to be too close to or in contact with the PN junction at the cut surface of the half-cell.

[0005] In a first aspect, the utility model provides a half-cell photovoltaic cell string, including: a plurality of cell pieces arranged along a first direction, a first side of each cell piece along the first direction being a cut surface and a second side being an isolation surface with an isolation layer, a positive electrode being disposed on the front surface of each cell piece and a negative electrode being disposed on the back surface of each cell piece, each cell piece having a PN junction, a first intersection line being formed at the intersection of the PN junction and the cut surface, and a second intersection line being formed at the intersection of the PN junction and the isolation surface; a plurality of welding tapes, one end of each welding tape being welded to the positive electrode on one cell piece and the other end being welded to the negative electrode on another cell piece, at least part of each welding tape being located between two adjacent cell pieces, the distance between the welding tape and the first intersection line being L1, and the distance between the welding tape and the second intersection line being L2 on the shortest connection line between the first intersection line on one cell piece and the second intersection line on an adjacent other cell piece, wherein L1≥2×L2.

[0006] Beneficial effects: By arranging a plurality of solar cells in the first direction, the cutting surfaces of all the solar cells face the same direction, and the isolation surfaces of all the solar cells face the same direction and this direction is opposite to the direction of the cutting surface, ensuring that the cutting surface of one of two adjacent solar cells corresponds to the isolation surface of the other, and the orientations of the positive and negative electrodes of all the solar cells are kept consistent, which is convenient for subsequent welding operations. By welding one end of the welding strip to the positive electrode of one solar cell and the other end to the negative electrode of another solar cell, the same welding strip is used to connect two adjacent solar cells, thereby realizing the series connection of a plurality of solar cells. And by arranging it on the shortest connection line between the first intersection line formed at the intersection of the PN junction and the cutting surface on one solar cell and the second intersection line formed at the intersection of the PN junction and the isolation surface on another adjacent solar cell, and satisfying L1≥2×L2 between the distance L1 between the welding strip and the first intersection line and the distance L2 between the welding strip and the second intersection line, for a corresponding cutting surface and isolation surface, the distance from the welding strip to the PN junction on the cutting surface is much greater than the distance from the welding strip to the corresponding position of the PN junction on the isolation surface. Thus, the risk that the welding strip is too close to or in contact with the exposed PN junction on the cutting surface due to the offset of the welding strip can be avoided. Further, the design away from the exposed PN junction can avoid the occurrence of electric leakage due to the tin slag on the surface of the welding strip 2 falling or splashing onto the exposed cutting surface during the welding process, thereby improving the situation of electric leakage or short circuit and enhancing the reliability and quality of the half-cell photovoltaic cell string.

[0007] In an optional embodiment, the distance between the PN junction and the front surface of the solar cell is less than the distance between the PN junction and the back surface of the solar cell; the welding strip includes a first welding section and a second welding section, and the first welding section of each welding strip is welded to the positive electrode on one of two adjacent solar cells located on the first side, and the second welding section is welded to the negative electrode on one of two adjacent solar cells located on the second side.

[0008] Beneficial effects: By arranging the welding strip to be connected between the positive electrode of one solar cell located on the first side and the negative electrode of another solar cell located on the second side, the intersection point of the shortest connection line between the first intersection line and the second intersection line and the welding strip is closer to the solar cell located on the first side, thereby realizing that between two adjacent solar cells, on the shortest connection line between the first intersection line and the second intersection line, the distance from the welding strip between the two solar cells to the PN junction on the solar cell located on the second side is greater than the distance from the welding strip to the PN junction on the solar cell located on the first side, and further achieving the purpose of avoiding the situation of electric leakage or short circuit during the welding process.

[0009] In an alternative embodiment, along the first direction, the first end of the second welding segment is directly or indirectly connected to the second end of the first welding segment. The first end of the first welding segment is close to and spaced from the cutting surface of a cell connected thereto. The second end of the second welding segment is close to and spaced from the isolation surface of a cell connected thereto.

[0010] Advantageous effects: By setting the first end of the first welding segment close to and spaced from the cutting surface of the cell, it can not only ensure that there is sufficient welding section length between the welding tape and the positive electrode, but also avoid the welding tape overlapping on the cutting surface, thus avoiding short circuit and ensuring the reliability of welding. Similarly, by setting the second end of the second welding segment close to and spaced from the isolation surface of a cell located on the first side, it can not only ensure that there is sufficient welding length between the welding tape and the negative electrode, but also avoid wasting materials and is convenient for processing.

[0011] In an alternative embodiment, a plurality of the cells are arranged at equal intervals along the first direction. The positive electrodes of all the cells are in the same plane, and the negative electrodes of all the cells are in the same plane. At the same time, the welding tape connected to two cells is bent. The welding tape further includes a connecting segment connected between the first welding segment and the second welding segment, and the connecting segment is located in the interval between two adjacent cells.

[0012] Advantageous effects: By arranging a plurality of cells at equal intervals along the first direction and having the positive electrodes of all the cells in the same plane and the negative electrodes of all the cells in another same plane, it is convenient for the arrangement and processing of a plurality of cells. And by setting the welding tape to be bent, the connecting segment connected between the first welding segment and the second welding segment is located in the interval between two adjacent cells, realizing the series connection of a plurality of cells in sequence, and being convenient for realizing the arrangement relationship that the distance L between the welding tape and the first intersection line is greater than or equal to a multiple of the distance L between the welding tape and the second intersection line, thus ensuring the reliability and safety of the welding process.

[0013] In an alternative embodiment, two adjacent cells are arranged with zero interval, and a plurality of the cells are in a stepped shape, and the welding tape is in a straight line shape.

[0014] Advantageous effects: It reduces the size of the whole half-cell photovoltaic cell string in the first direction, saves space and reduces costs.

[0015] In an alternative embodiment, the cell is cut from a whole piece of cell. The cutting line is perpendicular to the extending direction of the electrode. The cutting position is the front or back of the cell. The cutting method combines laser cutting and heat treatment. The laser cutting forms a damaged area on the cutting surface. The damaged area is located at both ends of the cutting line. The length of the damaged area along the extending direction of the cutting line is less than 1 cm.

[0016] Advantageous effects: By setting the cutting method to combine laser cutting and heat treatment, the damaged area formed by the laser on the cutting surface is located at both ends of the cutting line, and the length of the damaged area along the extending direction of the cutting line is less than 1 cm. The damaged area only occupies a partial area of one side of the cell, which can effectively reduce the influence of the damaged area on the cell, thereby ensuring the performance of the cell.

[0017] In an alternative embodiment, the cell is formed by laser cutting a whole piece of cell. The cutting line is perpendicular to the extending direction of the electrode. A damaged area is formed on the cutting surface. The damaged area covers the entire cutting line. The cutting position is the back of the cell.

[0018] Advantageous effects: The cell is directly formed by laser cutting a whole piece of cell. The cutting method is simple, easy to operate, and has high production efficiency. At the same time, by setting the cutting position on the back of the cell, the damaged area formed by the laser cutting on the cutting surface can be as far away from the PN junction as possible, thereby reducing the influence on the PN junction and ensuring the quality of the cell.

[0019] In an alternative embodiment, both the front and back of the cell are covered with the isolation layer. The isolation layer is an insulating material with light transmittance.

[0020] Advantageous effects: By covering both the front and back of the cell with the isolation layer, all surfaces of the cell except the cutting surface are covered with the isolation layer. The isolation layer serves as a protective layer, playing roles such as protecting the internal structure of the cell, isolating the positive and negative electrodes, reducing surface defects, reducing reflection, etc., avoiding the influence of external substances on the cell function, reducing electron recombination or leakage, and thereby improving the performance of the cell.

[0021] In an alternative embodiment, the number of the positive electrodes and the negative electrodes on each cell is n, and the number of the solder tapes connected to each cell is n, where n is a positive integer greater than or equal to 8.

[0022] Advantageous effects: The connection between the cells is relatively dense, which can more effectively collect and transmit current, and improve the power generation efficiency.

[0023] Second aspect, the present utility model further provides a photovoltaic module, comprising: a frame; a laminate installed in the frame, the laminate comprising the above-mentioned half-cell photovoltaic cell string. Since the photovoltaic module comprises a half-cell photovoltaic cell string, it has the same effects as the half-cell photovoltaic cell string, which will not be elaborated herein. Description of the Drawings

[0024] In order to more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 Structural schematic diagram of a half-cell photovoltaic cell string according to an embodiment of the present utility model;

[0026] Figure 2 For Figure 1 Partial enlarged schematic diagram of A in

[0027] Figure 3 Another structural schematic diagram of a half-cell photovoltaic cell string according to an embodiment of the present utility model;

[0028] Figure 4 Structural schematic diagram of a cell according to an embodiment of the present utility model;

[0029] Figure 5 For Figure 4 Top view of the cell shown in

[0030] Figure 6 For Figure 5 Partial enlarged schematic diagram of B in

[0031] Figure 7 Another top view of a cell according to an embodiment of the present utility model;

[0032] Figure 8 Structural schematic diagram of a whole cell according to an embodiment of the present utility model;

[0033] Figure 9 Structural schematic diagram of a photovoltaic module according to an embodiment of the present utility model.

[0034] Explanation of the reference numerals:

[0035] 1. Solar cell; 101. Isolation layer; 102. P-type region; 103. N-type region; 111. Cutting surface; 112. Isolation surface; 113. Damage area; 121. Positive electrode; 122. Negative electrode; 130. PN junction; 2. Welding ribbon; 201. First welding section; 202. Second welding section; 203. Connection section; 3. Frame; 301. Upper structure; 302. Middle structure; 303. Lower structure; 4. Laminated component. Detailed implementation manners

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0037] The following combines Figures 1 to 9 , to describe the embodiments of the present utility model.

[0038] According to an embodiment of the present utility model, on the one hand, a half-cell photovoltaic cell string is provided. As Figures 1 to 7 shown, the half-cell photovoltaic cell string includes: a plurality of solar cells 1 and a plurality of welding ribbons 2. The plurality of solar cells 1 are arranged along a first direction. A first side of each solar cell 1 along the first direction is a cutting surface 111 and a second side is an isolation surface 112 having an isolation layer 101. A positive electrode 121 is provided on the front surface of each solar cell 1 and a negative electrode 122 is provided on the back surface. Each solar cell 1 has a PN junction 130. A first intersection line is formed at the intersection of the PN junction 130 and the cutting surface 111, and a second intersection line is formed at the intersection of the PN junction 130 and the isolation surface 112. One end of each welding ribbon 2 is welded to the positive electrode 121 on one solar cell 1 and the other end is welded to the negative electrode 122 on another solar cell 1. At least part of each welding ribbon 2 is located between two adjacent solar cells 1. On the shortest connection line between the first intersection line on one solar cell 1 and the second intersection line on an adjacent another solar cell 1, the distance between the welding ribbon 2 and the first intersection line is L1, and the distance between the welding ribbon 2 and the second intersection line is L2, where L1 ≥ 2 × L2.

[0039] Among them, the first direction refers to Figure 1 , Figure 3The "first direction" indicated by the arrow; the first side and the second side are opposite sides in the first direction; the connection line between the front and back sides of the battery cell 1 is perpendicular to the connection line between the cutting surface 111 and the isolation surface 112; the battery cell 1 is a half-cell photovoltaic cell, which is cut from a whole cell, and the periphery of the whole cell is surrounded by an isolation layer 101, including the upper surface, the lower surface and each side surface, so as to protect the internal structure of the battery. After cutting, the formed battery cell 1 has a cutting surface 111, and there is no isolation layer 101 on the cutting surface 111. At the cutting surface, the internal structure of the battery is exposed outside, and the exposed PN junction is prone to danger when contacting the solder strip 2; the shortest connection line between the first intersection line on one battery cell 1 and the second intersection line on an adjacent another battery cell 1 refers to the connection line located between the adjacent two battery cells 1 and perpendicular to both the first intersection line and the second intersection line at the same time.

[0040] Applying the half-cell photovoltaic cell string of this embodiment, by arranging a plurality of battery cells 1 in the first direction, and the cutting surfaces 111 of each battery cell 1 all face the same direction, the isolation surfaces 112 of each battery cell 1 all face the same direction and this direction is opposite to the orientation of the cutting surface 111, it is ensured that the cutting surface 111 of one of the adjacent two battery cells 1 corresponds to the isolation surface 112 of the other, and the orientations of the positive and negative electrodes of each battery cell 1 are kept consistent, which is convenient for subsequent welding operations. By welding one end of the solder strip 2 to the positive electrode 121 of one battery cell 1 and the other end to the negative electrode 122 of another battery cell 1, it is realized that the same solder strip 2 connects two adjacent battery cells, so as to realize the series connection of a plurality of battery cells 1. And by setting the shortest connection line between the first intersection line formed at the intersection of the PN junction 130 and the cutting surface 111 on one battery cell 1 and the second intersection line formed at the intersection of the PN junction 130 and the isolation surface 112 on an adjacent another battery cell 1, and satisfying L1≥2×L2 between the distance L1 between the solder strip 2 and the first intersection line and the distance L2 between the solder strip 2 and the second intersection line, for a corresponding cutting surface 111 and isolation surface 112, the distance from the solder strip 2 to the PN junction 130 on the cutting surface 111 is much greater than the distance from the solder strip 2 to the corresponding position of the PN junction 130 on the isolation surface 112. Thus, the risk of the solder strip 2 being too close to or contacting the exposed PN junction 130 on the cutting surface 111 due to the offset of the solder strip 2 can be avoided. Further, the design away from the exposed PN junction 130 can prevent the solder dross on the surface of the solder strip from falling or splashing onto the exposed cutting surface 111 during the welding process, thereby improving the leakage or short-circuit situation and enhancing the reliability and quality of the half-cell photovoltaic cell string.

[0041] It should be noted that the cross-sectional structure of the whole cell is as Figure 8As shown, taking an N-type battery as an example, the substrate is the N-type region 103, and the upper surface is the front side of the cell. A P-type region 102 is provided at the front side position. The interface between the N-type region 103 and the P-type region 102 forms a PN junction (PN junction, the boundary or interface between two semiconductor materials). Under the excitation of light, the positive electrode is formed on the front side of the cell, and the negative electrode is formed on the back side. The cell becomes a power source. It is worth mentioning that the PN junction 130 described in this embodiment refers to the electrode structure that has the greatest impact on the power generation ability after the cell is made into a module, that is, the space barrier region that has the greatest impact on the power generation effect. In fact, in a photovoltaic cell, there are often multiple structures similar to the PN junction, such as the concentration difference positions formed by N and N+ or P and P+, such as the formation of metal-semiconductor contacts, etc. These are not considered in this embodiment. Among them, the front side refers to the upper surface, and the upper surface refers to the surface along Figure 8 the direction of "up" indicated by the arrow in Figure 8 ; the back side refers to the lower surface, that is, the surface along the direction of "down" indicated by the arrow in

[0042] The outer surface of the whole cell has an isolation layer 101 as a protective layer. After the whole cell is cut into two half-cells, the internal materials of the cell and the PN junction 130 at the cut surface are exposed. There is a risk of short circuit or leakage due to the overlap of the solder strip 2 and the PN junction 130. If further oxidation and other operations are performed to form an insulating protection at the cell cut surface, the operation at the module end is too complicated, requiring a large amount of manpower and material resources, and the cost performance is not high. And natural oxidation is not very realistic and cannot form an effective protection. The half-cell photovoltaic cell string of this embodiment reduces the probability of the solder strip 2 being too close to or in contact with the cut surface by setting the solder strip 2 away from the PN junction exposed on the cut surface 111.

[0043] In one embodiment, the distance between the PN junction 130 and the front surface of the cell 1 is less than the distance between the PN junction 130 and the back surface of the cell 1; the solder ribbon 2 includes a first welding section 201 and a second welding section 202. The first welding section 201 of each solder ribbon 2 is welded to the positive electrode 121 on one of the two adjacent cells 1 located on the first side, and the second welding section 202 is welded to the negative electrode 122 on one of the two adjacent cells 1 located on the second side. It should be noted that the positive electrode 121 is disposed on the front surface of the cell 1, and the negative electrode 122 is disposed on the back surface of the cell 1. Among two adjacent cells 1, the isolation surface 112 on one cell 1 located on the first side is closer to the solder ribbon 2 than the cutting surface 111, and the cutting surface 111 on the cell 1 located on the second side is closer to the solder ribbon 2 than the isolation surface 112. By setting the distance between the PN junction 130 and the front surface of the cell 1 to be less than the distance between the PN junction 130 and the back surface of the cell 1, the distance between the PN junction 130 and the positive electrode 121 on the same cell 1 is less than the distance between the PN junction 130 and the negative electrode 122. By connecting the solder ribbon 2 between the positive electrode 121 of one cell 1 located on the first side and the negative electrode 122 of the other cell 1 located on the second side, the intersection point of the shortest connection line between the first intersection line and the second intersection line and the solder ribbon 2 is closer to the cell 1 located on the first side. Thus, between two adjacent cells 1, on the shortest connection line between the first intersection line and the second intersection line, the distance from the solder ribbon 2 between the two cells 1 to the PN junction 130 on the cell 1 located on the second side is greater than the distance from the solder ribbon 2 to the PN junction 130 on the cell 1 located on the first side, thereby achieving the purpose of avoiding leakage or short circuit during the welding process.

[0044] In one embodiment, along the first direction, the first end of the second welding section 202 is directly or indirectly connected to the second end of the first welding section 201. The first end of the first welding section 201 is close to the cutting surface 111 of a battery cell 1 connected thereto and is spaced apart from the cutting surface 111. The second end of the second welding section 202 is close to the isolation surface 112 of a battery cell 1 connected thereto and is spaced apart from the isolation surface 112. Herein, the first end and the second end are the two opposite ends of a welding section along the first direction. The first end refers to the end located on the first side of the first direction, and the second end refers to the end located on the second side of the first direction. When the first end of the second welding section 202 is connected to the second end of the first welding section 201, the connection location is between two adjacent battery cells 1. The first welding section 201 is welded to the positive electrode 121 of one of the two battery cells 1 located on the first side. By setting the first end of the first welding section 201 close to the cutting surface 111 of the battery cell 1 and spaced apart from the cutting surface 111, it can not only ensure that the welding tape 2 and the positive electrode 121 have sufficient welding section length, but also avoid the welding tape 2 overlapping on the cutting surface 111, thereby avoiding short circuit and ensuring the reliability of welding. Similarly, by setting the second end of the second welding section 202 close to the isolation surface 112 of a battery cell 1 located on the first side and spaced apart from the isolation surface 112, it can not only ensure that the welding tape 2 and the negative electrode 122 have sufficient welding length, but also avoid wasting materials and is convenient for processing.

[0045] In one embodiment, the first side refers to Figure 1 、 Figure 3 the side in the direction of "right" indicated by the arrow in Figure 1 、 Figure 3 and the second side refers to the side in the direction of "left" indicated by the arrow in

[0046] In one embodiment, further in combination with Figures 1 to 2As shown, a number of solar cells 1 are arranged at equal intervals along a first direction. The positive electrodes 121 of each solar cell 1 are located in the same plane, and the negative electrodes 122 of each solar cell 1 are located in the same plane. At the same time, the solder ribbon 2 connected to two solar cells 1 is bent, and the solder ribbon 2 further includes a connecting section 203 connected between the first welding section 201 and the second welding section 202. The connecting section 203 is located in the gap between two adjacent solar cells 1. It should be noted that the connecting section 203 is connected between the second end of the first welding section 201 and the first end of the second welding section 202, that is, the first end of the second welding section 202 is indirectly connected to the second end of the first welding section 201. The number of solar cells 1 are distributed at equal intervals along the first direction, so the isolation surface 112 of one of two adjacent solar cells 1 and the cutting surface 111 of the other are arranged opposite to each other. The shortest connection line between the first intersection line and the second intersection line is perpendicular to the cutting surface 111 and the isolation surface 112. The connecting section 203 on the solder ribbon 2 is located between the oppositely arranged isolation surface 112 and cutting surface 111. Since the distance from the PN junction 130 to the positive electrode 121 is less than the distance from the PN junction 130 to the negative electrode 122, the intersection point of the shortest connection line between the first intersection line and the second intersection line and the solder ribbon 2 is closer to the front side of the solar cell 1, that is, closer to the turning point where the first welding section 201 is connected to the connecting section 203. The turning point where the first welding section 201 is connected to the connecting section 203 overlaps with a solar cell 1 on the right side and corresponds to the side where the isolation surface 112 and the front side of the solar cell 1 intersect. And there is the protection of the isolation layer 101 here, so there is no risk of short circuit caused by the contact between the solder ribbon 2 and the inside of the solar cell 1. Correspondingly, the distance between the solder ribbon 2 and a solar cell 1 on the left side is relatively far, which can also reduce the probability of contact with the PN junction on the cutting surface 111.

[0047] By arranging a number of solar cells 1 at equal intervals along the first direction and making the positive electrodes 121 of each solar cell 1 located in the same plane and the negative electrodes 122 of each solar cell 1 located in another same plane, it is convenient for the arrangement and processing of a number of solar cells 1. And by setting the solder ribbon 2 to be bent, the connecting section 203 connected between the first welding section 201 and the second welding section 202 is located in the gap between two adjacent solar cells 1, realizing the sequential series connection of a number of solar cells 1, and facilitating the arrangement relationship that the distance L1 between the solder ribbon 2 and the first intersection line is greater than or equal to 2 times the distance L2 between the solder ribbon 2 and the second intersection line, thereby ensuring the reliability and safety of the welding process.

[0048] Specifically, further combined with Figure 1As shown, during the process of assembling a half-cell string, first place the rightmost solder tape 2 (the lower solder tape), and then place the first cell 1 on the rightmost side. During the placement process, ensure that the cutting surface 111 of the cell 1 faces to the right; after placing the rightmost cell 1, the PN junction 130 on the cutting surface 111 of this cell 1 is far from the lower solder tape, that is, there is no solder tape 2 at the damaged layer and the PN junction 130 in the upper right corner of this cell 1; then place the upper solder tape. The first welding section 201 on the right side of this solder tape 2 is connected to the positive electrode 121 on the front of the first cell 1, and the second welding section 202 on the left side is to be welded to the negative electrode 122 on the back of the second cell. Subsequently, place the second cell 1. The second cell 1 is placed on the second welding section 202 of the solder tape 2. And so on, place several cells 1 into the welding equipment in sequence from right to left. Finally, the right welding equipment welds each cell 1 to the welding area on the corresponding solder tape. For the half-cell string set in this way, in two adjacent cells 1, the isolation surface 112 on the cell 1 on the right side (i.e., the first cell) faces the cutting surface 111 on the cell 1 on the left side (i.e., the second cell). Then the distance L1 between the PN junction 130 on the cutting surface 111 of the second cell and the solder tape 2 will be much greater than the distance L2 between the PN junction 130 on the isolation surface 112 of the first cell and the solder tape 2.

[0049] In addition, in other embodiments, further combined with Figure 3As shown, two adjacent solar cells 1 are arranged with zero spacing, several solar cells 1 are in a stepped shape, the solder ribbon 2 is in a straight line, there is no connecting section 203 on the solder ribbon 2, and the first end of the second welding section 202 of the solder ribbon 2 is directly connected to the second end of the first welding section 201. The size of the half-cell photovoltaic cell string in the first direction as a whole is reduced, space is saved, and cost is reduced. It should be noted that the cutting surface 111 of each solar cell 1 is arranged to the right; in two adjacent solar cells 1, the isolation surface 112 of the first solar cell and the cutting surface 111 of the second solar cell are in the same plane, realizing zero-spacing arrangement of the solar cells. The shortest connection line between the first intersection line and the second intersection line is located in the plane of the isolation surface 112 of the first solar cell and the cutting surface 111 of the second solar cell and is perpendicular to the extension direction of the solder ribbon 2; the PN junction 130 is closer to the front surface of the solar cell 1, so the linear distance between the PN junction 130 and a solder ribbon 2 connected to the negative electrode of the solar cell 1 is much greater than the linear distance between the PN junction 130 and the other solder ribbon 2 connected to the positive electrode of the solar cell 1. For the same solar cell 1, the right end of a solder ribbon 2 connected to its positive electrode is spaced from the cutting surface 111 of the solar cell 1, which can reduce the influence on the cutting surface 111 during the welding process of the solder ribbon 2 and the positive electrode 121. At the same time, the other solder ribbon 2 connected to the negative electrode of the solar cell 1 is located on the back surface of the solar cell 1 and is far from the PN junction, which can also reduce the influence on the PN junction during welding; similarly, for two solar cells 1 connected to the same solder ribbon 2, the linear distance from the PN junction on the cutting surface 111 of the second solar cell on the left to the solder ribbon 2 is much greater than the linear distance from the PN junction on the isolation surface 112 of the first solar cell on the right to the solder ribbon 2. Therefore, the risk of the solder ribbon 2 being too close to or in contact with the exposed PN junction 130 on the cutting surface 111 can be avoided, thereby improving the situation of leakage or short circuit.

[0050] In one embodiment, further in combination with Figures 5 to 6 As shown, the solar cell 1 is cut from a whole piece of cell, the cutting line is perpendicular to the extension direction of the electrode (main grid), the cutting position is the front or back surface of the solar cell 1, and the cutting method is a combination of laser cutting and heat treatment. The laser cutting forms a damaged area 113 on the cutting surface 111. The damaged area 113 is located at both ends of the cutting line, and the length of the damaged area 113 along the extension direction of the cutting line is less than 1 cm. Among them, the extension direction of the electrode is the same as Figure 5 the "first direction" indicated by the arrow in Figure 5It extends in the "second direction" indicated by the arrow in the figure, and the second direction is perpendicular to the first direction. By setting the cutting method to a combination of laser cutting and heat treatment, the damage area 113 formed by the laser on the cutting surface 111 is located at both ends of the cutting line, and the length of the damage area 113 along the extension direction of the cutting line is less than 1 cm. The damage area 113 only occupies a partial area of one side of the battery cell, which can effectively reduce the influence of the damage area 113 on the battery cell, thereby ensuring the performance of the battery cell.

[0051] It should be noted that the battery cell 1 refers to a half cell, which is obtained by cutting a whole cell into two pieces. Preferably, the areas of the two battery cells 1 after cutting are equal; most of the cutting methods are laser cutting. The use of laser often causes damage to the battery cell. High-temperature damage areas often appear at the cutting surface position formed by high-temperature laser cutting. Generally, the damage depth of the damage area along the thickness direction of the battery cell is in the micron range, ranging from a few microns to dozens of microns. This kind of damage cannot be ignored for the battery cell. Among them, the thickness refers to the distance between the front and back surfaces of the battery cell, and the thickness direction refers to Figure 1 the "up and down" direction indicated by the arrow in the figure.

[0052] Specifically, the cutting method combining laser cutting and heat treatment is a non-destructive method, that is, local area laser cutting is performed at both ends of the whole cell. After cutting small incisions with a length less than 1 cm, along the connection line position of the two incisions, through the heat treatment method of heating and rapid cooling, the battery cell will naturally split along the connection line position of the two incisions. Since the length of the damage area 113 is less than 1 cm and the size is small, it can effectively reduce the influence of the damage area 113 on the battery cell. When using this method, according to the cutting requirements, it can be selected to cut on the front surface of the whole cell to form a damage area 113 as shown in Figures 5 to 6 the figure, or it can also be selected to cut on the back surface of the whole cell (not shown in the figure), without considering its influence on the main PN junction.

[0053] In addition, in other embodiments, further combined with Figure 7 as shown in the figure, the battery cell 1 is formed by laser cutting the whole cell. The cutting line is perpendicular to the extension direction of the electrode. A damage area 113 is formed on the cutting surface 111, and the damage area 113 covers the entire cutting line. The cutting position is the back surface of the battery cell 1. Among them, the extension direction of the electrode is the same as the Figure 7 "first direction" indicated by the arrow in the figure, and the cutting line extends along Figure 7extends in the "second direction" indicated by the arrow. The cell 1 is directly formed by laser cutting a whole piece of cell. The cutting method is simple, easy to operate, and has high production efficiency. At the same time, by setting the cutting position on the back of the cell 1, the damage area 113 formed by laser cutting on the cutting surface 111 can be as far away from the PN junction 130 as possible, thereby reducing the impact on the PN junction and ensuring the quality of the cell 1. It should be noted that the direct laser cutting method is a damaging cutting, that is, a line is cut in the middle of the whole piece of cell by the high temperature of the laser, so that the whole piece of cell is divided into two half cells, and there is a damage area 113 on the entire cutting surface. Therefore, it is necessary to cut at a position far from the PN junction 130, that is, to cut on the back of the cell.

[0054] In one embodiment, the cell 1 is obtained by cutting a whole piece of cell in the shape of a rectangle, a rectangle with chamfers, a square, or a square with chamfers to form two half-cell pieces.

[0055] In one embodiment, the front and back surfaces of the cell 1 are both covered with an isolation layer 101, and the isolation layer 101 is an insulating material with light transmittance. By covering the front and back surfaces of the cell 1 with the isolation layer 101, all surfaces of the cell 1 except the cutting surface 111 are covered with the isolation layer 101. The isolation layer 101 acts as a protective layer, protecting the internal structure of the cell, isolating the positive and negative electrodes, reducing surface defects, reducing reflection, etc., avoiding the influence of external substances on the cell function, reducing electron recombination or leakage, and thus improving the performance of the cell. It should be noted that the isolation layer 101 is a protective film formed on the surface of the whole piece of cell by high-temperature oxidation or coating. For the whole piece of cell, all surfaces are covered with the isolation layer 101.

[0056] In one embodiment, the isolation layer 101 is composed of one or several materials such as silicon dioxide, silicon nitride, and silicon oxynitride with good insulation and good light transmittance. The isolation substances used for the isolation layer 101 at different positions on the cell 1 can be different.

[0057] In one embodiment, the number of the positive electrode 121 and the negative electrode 122 on each cell 1 is n, and the number of the welding tapes 2 connected to each cell 1 is n, where n is a positive integer greater than or equal to 8. Correspondingly, the number of welding tapes connecting two adjacent cells 1 is greater than or equal to 8, so the connection between the cells 1 is relatively dense, which can more effectively collect and transmit current and improve the power generation efficiency.

[0058] It should be noted that currently, the diameter of the solder ribbon 2 is getting smaller and smaller (the mainstream solder ribbon has a diameter of 0.25 mm), the number of solder ribbons 2 is increasing (the mainstream is 16), the spacing between adjacent solar cells 1 is getting smaller and smaller (the mainstream is about 1.5 mm), and there is even a soldering technology with more than 30 solder ribbons. There are also a large number of cases where the spacing between solar cells is <1 mm, and even 0 spacing or negative spacing. The cross-sectional width of the solder ribbon diameter has also reached the micron level. In the use of such extremely thin and numerous solder ribbons, the PN junction 130 exposed on the non-isolated area (i.e., the cutting surface 111) of the solar cell 1 is greatly increased in the situation of forming a lap joint with the solder ribbon 2 or being too close in distance, causing a leakage risk. However, for the half-cell photovoltaic cell string of this embodiment, without adding processes, the leakage or short-circuit situation can be effectively improved.

[0059] It should be noted that the above embodiments are described by taking N-type cells as an example. In addition, this embodiment can be applied to various types of photovoltaic cells.

[0060] According to an embodiment of the present invention, on the other hand, a photovoltaic module is also provided, as Figure 9 shown. The photovoltaic module includes: a frame 3 and a laminate 4. The laminate 4 is installed in the frame 3, and the laminate 4 includes the above-mentioned half-cell photovoltaic cell string. For the photovoltaic module of this embodiment, in the soldering process of the half-cell photovoltaic cell string, by considering the structural characteristics of the solar cell 1, the solder ribbon 2 is set away from the exposed PN junction. Without adding special processes and costs, the performance after battery soldering is improved, the defects of leakage or short circuit are improved, and the reliability and quality of the photovoltaic module are improved. By integrating the cell structure, slicing process, and solder ribbon connection process, a more efficient and reliable photovoltaic module structure is achieved.

[0061] Among them, the frame 3 includes an upper structure 301, a middle structure 302, and a lower structure 303 connected in sequence along the Figure 9 "up and down" direction indicated by the arrow in the figure. The upper structure 301 has a card slot, and the laminate 4 is snap-fitted in the card slot; the laminate 4 includes a front glass plate, an encapsulant film, a photovoltaic cell, an interconnection material, a back glass plate, etc. Among them, the photovoltaic cell is the above-mentioned half-cell photovoltaic cell string. The main power generation component of the laminate 4 is the photovoltaic cell, and the main functions of other packaging materials are to transmit light and protect the photovoltaic cell. That is, on the basis of ensuring that most of the light passes through the packaging materials to reach the battery surface, the packaging materials can also protect the photovoltaic cells in the photovoltaic module and extend the life cycle of the photovoltaic module. The photovoltaic module realizes the interconnection and protection of the solar cells and realizes the long-term stable output of the photovoltaic cells.

[0062] The assembly process of the photovoltaic module is as follows:

[0063] First, each half-piece photovoltaic cell is interconnected. The assembly equipment moves from left to right along the track, driving the cell 1 to be placed from the left side, so that the left edge of each cell 1 contains the isolation layer 101, and the right edge is the cut surface 111 without the isolation layer 101. The first welding section 201 of the welding tape 2 is arranged above one cell 1 on the right side, and the second welding section 202 is arranged below the cell 1 on the left side. After several cells 1 are connected in sequence, a half-piece photovoltaic cell string is formed, and then the cell string is connected in series and parallel to form a power generation component within the module. Then, the front glass plate, the angle piece, and the back glass plate are stacked together in sequence. Next, the stacked product is placed into a laminator. Through the high temperature and vacuum pumping of the laminator, the encapsulant material melts and the gas inside the laminate is discharged. After lamination, the overflowing encapsulant and residual materials are cut. After processing, a laminate 4 is formed, and a frame installation process (framing process) is performed on the laminate 4. The framing process requires applying glue (silicone) in the cavity of a specific frame 3, and using a framing machine to clamp and fix the frame 3 and the laminate 4.

[0064] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A half-piece photovoltaic cell string, characterized in that, Including: A plurality of solar cells (1), arranged along a first direction. For each solar cell (1), a first side along the first direction is a cutting surface (111) and a second side is an isolation surface (112) having an isolation layer (101). A positive electrode (121) is disposed on the front surface of each solar cell (1) and a negative electrode (122) is disposed on the back surface. Each solar cell (1) has a PN junction (130). A first intersection line is formed at the intersection of the PN junction (130) and the cutting surface (111), and a second intersection line is formed at the intersection of the PN junction (130) and the isolation surface (112). A plurality of solder ribbons (2). One end of each solder ribbon (2) is welded to the positive electrode (121) on one solar cell (1) and the other end is welded to the negative electrode (122) on another solar cell (1). At least part of each solder ribbon (2) is located between two adjacent solar cells (1). On the shortest connection line between the first intersection line on one solar cell (1) and the second intersection line on an adjacent solar cell (1), the distance between the solder ribbon (2) and the first intersection line is L1, and the distance between the solder ribbon (2) and the second intersection line is L2, where L1 ≥ 2 × L2.

2. The half-sheet photovoltaic cell string according to claim 1, wherein, The distance between the PN junction (130) and the front surface of the solar cell (1) is less than the distance between the PN junction (130) and the back surface of the solar cell (1). The solder ribbon (2) includes a first welding section (201) and a second welding section (202). The first welding section (201) of each solder ribbon (2) is welded to the positive electrode (121) on one of the two adjacent solar cells (1) located on the first side, and the second welding section (202) is welded to the negative electrode (122) on one of the two adjacent solar cells (1) located on the second side.

3. The half-piece photovoltaic cell string according to claim 2, characterized in that, In the first direction, the first end of the second welding section (202) is directly or indirectly connected to the second end of the first welding section (201). The first end of the first welding section (201) is close to and spaced from the cutting surface (111) of a solar cell (1) connected thereto, and the second end of the second welding section (202) is close to and spaced from the isolation surface (112) of a solar cell (1) connected thereto.

4. The half-sheet photovoltaic cell string according to claim 3, wherein A plurality of the solar cells (1) are arranged at equal intervals along the first direction. The positive electrodes (121) of all the solar cells (1) are located in the same plane, and the negative electrodes (122) of all the solar cells (1) are located in the same plane. The solder ribbon (2) connected to two solar cells (1) is bent. The solder ribbon (2) further includes a connection section (203) connected between the first welding section (201) and the second welding section (202), and the connection section (203) is located in the interval between two adjacent solar cells (1).

5. The half-sheet photovoltaic cell string according to claim 3, characterized in that, Two adjacent ones of the cell pieces (1) are arranged with zero interval, and a plurality of the cell pieces (1) are in a stepped shape, and the welding tape (2) is in a straight line shape.

6. The half-piece photovoltaic cell string according to claim 2, characterized in that, The cell piece (1) is cut from a whole piece of cell. The cutting line is perpendicular to the extending direction of the electrode. The cutting position is on the front or back surface of the cell piece (1). The cutting method combines laser cutting and heat treatment. A damaged area (113) is formed on the cutting surface (111) by the laser cutting. The damaged area (113) is located at both ends of the cutting line. The length of the damaged area (113) along the extending direction of the cutting line is less than 1 cm.

7. The half-sheet photovoltaic cell string according to claim 2, wherein The cell piece (1) is cut from a whole piece of cell by laser cutting. The cutting line is perpendicular to the extending direction of the electrode. A damaged area (113) is formed on the cutting surface (111). The damaged area (113) covers the whole cutting line. The cutting position is on the back surface of the cell piece (1).

8. The half-sheet photovoltaic cell string according to claim 1, wherein, The front and back surfaces of the cell piece (1) are both covered with the isolation layer (101). The isolation layer (101) is made of an insulating material with light transmittance.

9. The half-sheet photovoltaic cell string according to any one of claims 1 to 8, characterized in that The number of the positive electrodes (121) and the negative electrodes (122) on each cell piece (1) is n, and the number of the welding tapes (2) connected to each cell piece (1) is n, where n is a positive integer greater than or equal to 8.

10. A photovoltaic module, characterized in that, Comprising: A frame (3); A laminate (4) installed in the frame (3). The laminate (4) includes the half-cell photovoltaic cell string according to any one of claims 1 to 9.

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