Back contact photovoltaic module and photovoltaic system

Abstract

The invention discloses a back contact photovoltaic module and a photovoltaic system, and relates to the technical field of solar cells. The back contact photovoltaic module comprises a plurality of battery strings which are arranged in the first direction and electrically connected, each battery string comprises a plurality of battery pieces which are arranged in the second direction and electrically connected, and the first direction and the second direction are arranged in a crossed mode; in the same battery string, two adjacent battery pieces are partially overlapped to form an inter-piece overlapping area; and in the second direction, the ratio of the width of the inter-piece overlapping region to the length of a single battery piece is 0.25%-3.5%. According to the back contact photovoltaic module, the risks of subfissure, light leakage and edge collision of the battery piece in the packaging process can be reduced, and the module power is improved to the maximum extent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a back contact photovoltaic module and a photovoltaic system. BACKGROUND

[0002] In the technical field of photovoltaic modules, back contact photovoltaic modules have shown significant advantages in improving photoelectric conversion efficiency due to their unique electrode structure design, and have become one of the key development directions in the industry. A back contact photovoltaic module is usually composed of an array of back contact cell pieces, which includes a plurality of back contact cell strings.

[0003] In the preparation process of a conventional back contact cell string, two adjacent back contact cell pieces are usually arranged in a spaced manner, i.e., there is a fixed piece spacing. Although this design is convenient for operation in early production processes, as the photovoltaic industry continues to improve the power generation per unit area of the module, the disadvantages of this design have become increasingly apparent: the existence of the piece spacing directly occupies the effective light receiving area of the module, resulting in a limited coverage area of the cell pieces per unit area, which in turn restricts the improvement of the power generation of the module.

[0004] To solve the above problems, the industry has gradually formed a technical improvement trend of "stacked piece arrangement" - by partially stacking adjacent back contact cell pieces in a photovoltaic module, the piece spacing in the conventional spaced arrangement is eliminated. This technical solution can increase the effective light receiving area of the module, and under the same module size, it can increase the coverage ratio of the cell pieces, thereby directly improving the power generation per unit area of the photovoltaic module.

[0005] However, the present inventors have found in actual production that although the use of the stacked piece arrangement can solve the inherent defects of the conventional spaced arrangement, new technical problems arise in the subsequent lamination process of the module: due to the stacking thickness of the cell pieces in the stacked area, the pressure distribution inside the module during lamination is uneven, the local pressure in the stacked area is higher than that in the non-stacked area, which causes the stacked back contact cell pieces to be prone to hidden cracks during the lamination process, and the unreasonable overlapping method also causes quality problems such as light leakage and edge damage (i.e., "edge damage") between the cell pieces. Therefore, how to further optimize the overlapping method of the back contact cell pieces to reduce the hidden cracks, light leakage and edge damage caused during the lamination process has become a key technical problem that needs to be solved in the industry. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a back contact photovoltaic module that can reduce the hidden cracks, light leakage and edge damage caused by the lamination process in the stacked area, and maximize the improvement of the power of the module.

[0007] Another technical problem to be solved by the present application is to provide a photovoltaic system capable of reducing the hidden crack defect and edge chipping defect caused by the packaging process to the lamination area and maximizing the power of the assembly.

[0008] To solve the above technical problems, the present application provides a back contact photovoltaic assembly, comprising a plurality of cell strings arranged along a first direction and electrically connected, each of the cell strings comprising a plurality of cell pieces arranged along a second direction and electrically connected, the first direction being arranged transversely to the second direction; In the same cell string, two adjacent cell pieces are arranged partially overlapping each other, and the overlapping area is an inter-piece overlapping area; Along the second direction, the width of the inter-piece overlapping area is d1, and the length of a single cell piece is D1, wherein the ratio of d1 and D1 is 0.25% to 3.5%.

[0009] As an improvement of the above technical solution, along the second direction, the cell piece comprises parallel chamfered edges and straight edge edges, along the third direction, the cell piece has a light-receiving surface and a back surface, and the first direction, the second direction and the third direction are arranged transversely to each other; the straight edge edge is a cutting edge formed after cutting the whole cell piece.

[0010] In one embodiment, from the back surface of the cell piece, in the same cell string, the straight edge edge of one cell piece is stacked on the chamfered edge of the adjacent cell piece.

[0011] In one embodiment, from the back surface of the cell piece, in the same cell string, the chamfered edge of one cell piece is stacked on the straight edge edge of the adjacent cell piece.

[0012] As an improvement of the above technical solution, two adjacent cell strings are arranged partially overlapping each other, and the overlapping area is an inter-string overlapping area; Along the first direction, the width of the inter-string overlapping area is d2, and the width of a single cell piece is D2, and the ratio of d2 and D2 is 0.2% to 1.1%.

[0013] As an improvement of the above technical solution, along the second direction, the ratio of the width d1 of the inter-piece overlapping area and the length D1 of the cell piece is 0.4% to 2.0%.

[0014] As an improvement of the above technical solution, along the second direction, the ratio of the width d1 of the inter-piece overlapping area and the length D1 of the cell piece is 0.6% to 1.0%.

[0015] As an improvement of the above technical solution, the ratio of the width d2 of the inter-string overlapping area to the width D2 of the battery piece along the first direction is 0.3%~0.7%.

[0016] As an improvement of the above technical solution, the width d1 of the inter-piece overlapping area is 0.3mm~2.0mm.

[0017] As an improvement of the above technical solution, the width d2 of the inter-string overlapping area is 0.5mm~2.0mm.

[0018] As an improvement of the above technical solution, the chamfered edges of the battery pieces in the two adjacent battery strings face in opposite directions along the second direction.

[0019] As an improvement of the above technical solution, along the first direction, the adjacent battery pieces include a first battery piece and a second battery piece; along the second direction, the adjacent battery pieces include the first battery piece and a third battery piece. The inter-string overlapping area includes a first inter-string overlapping area formed by the overlapping of the first battery piece, the second battery piece and the third battery piece.

[0020] As an improvement of the above technical solution, the inter-string overlapping area includes a second inter-string overlapping area formed by the overlapping of the straight edge of the second battery piece and the straight edge of the third battery piece. The second inter-string overlapping area includes a third inter-string overlapping area, which is the remaining area of the second battery piece and the third battery piece overlapping area minus the first inter-string overlapping area.

[0021] As an improvement of the above technical solution, the area of the first inter-string overlapping area is S1, the area of the second inter-string overlapping area is S2, and the area of the third inter-string overlapping area is S3, S2=2*S1+S3.

[0022] As an improvement of the above technical solution, the ratio of S1 to S3 is 1:6~1:3.

[0023] As an improvement of the above technical solution, the shape of the first inter-string overlapping area is a triangle, and the shape of the third inter-string overlapping area is a hexagon.

[0024] In an embodiment, the battery string includes at least one first battery string and at least one second battery string, and the first battery string and the second battery string are arranged alternately along the first direction. In the first battery string, the chamfered edge of one of the two adjacent battery pieces is stacked on the straight edge of the other of the two adjacent battery pieces; in the second battery string, the straight edge of one of the two adjacent battery pieces is stacked on the chamfered edge of the other of the two adjacent battery pieces. In the second direction, the chamfered edges of the battery pieces in the first battery string and the chamfered edges of the battery pieces in the second battery string are oppositely directed.

[0025] As an improvement of the above technical solution, the second battery string is partially stacked on the back surface of the first battery string.

[0026] As an improvement of the above technical solution, in the first direction, the chamfered edge of the battery piece is provided with a chamfer connected to the chamfered edge on each side. The width of the chamfer in the second direction is d3, and the width of the chamfer in the first direction is d4, wherein d3 is 0.8-1.5 mm, and d4 is 0.8-1.5 mm.

[0027] Correspondingly, the application also provides a photovoltaic system comprising the above-mentioned back-contact photovoltaic module.

[0028] The application has the following beneficial effects: the back-contact photovoltaic module of the application effectively eliminates the inter-piece spacing between adjacent battery pieces in the conventional back-contact photovoltaic module by using the partial overlapping structure design of the plurality of battery pieces arranged in the second direction in the battery string, increases the effective light-receiving area of the module, and improves the power generation per unit area of the photovoltaic module. Meanwhile, the ratio of the width d1 of the inter-piece overlapping area in the second direction to the length D1 of a single battery piece in the second direction is limited to 0.25%-3.5%. The appropriate inter-piece overlapping width, on the one hand, ensures the formation of a good stacking structure between adjacent battery pieces, reduces the problems of hidden cracking, light leakage and edge damage of the battery piece in the packaging process, and maximizes the improvement of the module power; on the other hand, it can ensure that the CTM value of the battery module is in a higher range, and reduce the cost of the module. If the ratio of d1 and D1 is too small, the battery pieces cannot form a good stacking structure between them, which will cause the battery pieces to crack during the lamination process, and the overlapping width of the battery pieces is not enough, which will cause the battery pieces to be displaced by the flow of the adhesive film during the lamination process, which will easily cause light leakage and edge damage of the battery pieces, resulting in a decrease in the power of the module and poor appearance; if the ratio of d1 and D1 is too large, the battery pieces in the overlapping area cannot receive light from the front, which will cause the CTM of the module to decrease and the cost of the module to increase.

[0029] In addition, by further optimizing the overlapping manner, the straight edge of the light-receiving surface of one of the two adjacent battery pieces in the battery string is laminated on the chamfered edge of the back light surface of the other adjacent battery piece, that is, from the light-receiving surface of the photovoltaic module, the straight edge of the battery piece with cutting damage is covered by the chamfered edge of the other battery piece without cutting damage, which can avoid the influence of the low conversion efficiency of the straight edge of the battery piece on the overall efficiency of the photovoltaic module, and further improve the power of the module. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic structural view of the back contact photovoltaic module on the back light surface according to an embodiment of the present application; Figure 2 is a schematic structural view of the back contact photovoltaic module on the back light surface according to another embodiment of the present application; Figure 3 is a schematic structural view of the back contact photovoltaic module on the back light surface according to another embodiment of the present application; Figure 2 is a partial enlarged view of the back contact photovoltaic module according to the embodiment shown in the figure; Figure 4 is a partial enlarged view of the back contact photovoltaic module according to the embodiment shown in the figure; Figure 2 is a schematic structural view of the back contact photovoltaic module on the back light surface according to another embodiment of the present application; Figure 5 is a partial enlarged view of the back contact photovoltaic module according to the embodiment shown in the figure; Figure 6 Figure 5 is a partial enlarged view of the back contact photovoltaic module according to the embodiment shown in the figure; In the figure: battery string 1, first battery string 11, second battery string 12, battery piece 13, inter-piece overlapping area 14, inter-string overlapping area 15, back light surface 16, chamfered edge 131, straight edge 132, chamfered 133, first inter-string overlapping area 151, second inter-string overlapping area 152, third inter-string overlapping area 153. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described in detail below in combination with the drawings and embodiments. The examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0032] ​In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "first direction", "second direction", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0033] 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 the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0034] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0035] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0036] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplifying the present application, components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0037] It should be noted that, Figures 1 to 6 In the figure, the light gray dashed area is: from the back of the photovoltaic module, the part of the cell piece is blocked; the black solid line area is: from the back of the photovoltaic module, the part of the cell piece is not blocked.

[0038] Referring to Figure 1 As shown in the figure, the embodiment provides a back contact photovoltaic module, which includes a plurality of cell strings 1 arranged along a first direction and electrically connected, each cell string 1 includes a plurality of cell pieces 13 arranged along a second direction and electrically connected, and the first direction and the second direction are cross arranged; specifically, the first direction and the second direction are perpendicular to each other. In the same cell string 1, two adjacent cell pieces 13 are arranged locally overlapped, and the overlapped area is the inter-piece overlapping area 14. Along the second direction, the width of the inter-piece overlapping area 14 is d1, and the length of a single cell piece 13 is D1, wherein the ratio of d1 and D1 is 0.25%~3.5%.

[0039] The back contact photovoltaic module of the present application effectively eliminates the inter-piece spacing between adjacent cell pieces 13 in the conventional back contact photovoltaic module by adopting the local overlapping structure design of the plurality of cell pieces 13 arranged along the second direction in the same cell string 1, increases the effective light receiving area of the module, and thus improves the unit area power generation of the photovoltaic module.

[0040] Further, in the process of increasing the effective light-receiving area to improve the power generation of the module by using the lamination structure, the ratio of the width d1 of the overlapping area 14 in the second direction to the length D1 of the single cell 13 in the second direction plays an important role in a reasonable range. If the ratio of d1 to D1 is not reasonable, it is easy to cause quality problems such as hidden cracks, light leakage, and edge damage (i.e., "edge damage") in the packaging process (especially the lamination process). Specifically, if the ratio of d1 to D1 is too small, the overlapping contact area of adjacent cells 13 is too small, it is difficult to form a stable lamination connection structure, not only easy to cause cell hidden cracks, but also the overlapping width of the cell is not enough, the glue film flow will cause the cell to move in the lamination process, which is easy to cause edge damage and light leakage at the lamination position, resulting in power reduction and appearance defects of the module; if the ratio of d1 to D1 is too large, the cell in the overlapping area cannot be directly light-receiving, which will cause the CTM (the ratio of the output power of the photovoltaic module to the theoretical total power of all cells in the module under ideal conditions) of the module to be small, and the cost of the module to increase.

[0041] The present application limits the ratio of d1 to D1 to 0.25% to 3.5% by optimizing the overlapping method. Within this range, on the one hand, it can ensure that a stable lamination structure with sufficient strength is formed between adjacent cells 13, reducing the risk of hidden cracks, light leakage, and edge damage during the packaging process, and maximizing the power of the module and reducing appearance defects; on the other hand, the ratio of d1 to D1 within the range of 0.25% to 3.5% can ensure that the CTM value (the ratio of the power of the module to the total power of the cells) of the battery module is in a higher range, thereby reducing the production cost of the photovoltaic module.

[0042] In the second direction, the cell 13 includes mutually parallel chamfered edges 131 and straight edge edges 132, and in the third direction, the cell 13 has a light-receiving surface and a back light surface 16, and the first direction, the second direction and the third direction are arranged to intersect each other; the straight edge edge is a cutting edge formed after cutting the whole cell.

[0043] It should be noted that the cell 13 of the present embodiment can be a half cell obtained by slicing a whole cell, and the four corners of the whole cell are chamfered 133. The cell 13 formed after slicing has a chamfered edge 131 at one end and a straight edge edge 132 at the other end. The chamfered edge 131 is the original side edge of the whole cell, i.e., a non-cutting edge; the straight edge edge 132 is a cutting edge formed by slicing the whole cell, and the angles on both sides are right angles, i.e., the straight edge edge 132 is a cutting edge.

[0044] In one embodiment of the present embodiment, from the back surface of the cell piece 13, in two adjacent cell pieces 13 in the same cell string 1, the straight edge 132 of one cell piece 13 is stacked on the chamfered edge 131 of the adjacent cell piece 13, so that when viewed from the light-receiving surface of the cell piece 13, the straight edge 132 of the cell piece is blocked by the chamfered edge 131 of the other cell piece 13. By further optimizing the overlapping manner, the power of the module can be further improved. Specifically, the straight edge 132 of the cell piece 13 is a cutting edge formed by laser cutting. During laser thermal cracking, the silicon wafer of the cutting edge is damaged, forming a suspended Si-H bond, causing surface recombination and reducing the efficiency of the cell piece in this area. The present embodiment optimizes the overlapping manner of the cell piece 13, so that in the same cell string, the overlapping manner of adjacent cell pieces 13 is that the straight edge 132 of one cell piece 13 is stacked on the back surface 16 of the chamfered edge 131 of the adjacent cell piece 13. This optimized design allows the chamfered edge 131 of the cell piece 13 (i.e. the non-cutting edge with complete structure and higher efficiency) to be located closer to the upper layer of the front glass plate of the module, so that it can more fully receive sunlight for photoelectric conversion; and the straight edge 132 with lower efficiency is placed on the back light side, i.e. the straight edge 132 is covered by the chamfered edge 131 and does not participate in light receiving and power generation. Therefore, the optimized design can further increase the power of the module.

[0045] In addition, by limiting the ratio of d1 to D1 to be within the range of 0.25% to 3.5%, the affected area of laser thermal cracking in the straight edge 132 can be effectively blocked, and the power of the module can be maximized. If the ratio of d1 to D1 is small, i.e. the width of the inter-sheet overlapping area is too small, it will cause the formation of an ineffective overlapping structure and poor crack transmission, and the affected area of laser thermal cracking cannot be effectively blocked, which will lead to a decrease in the power of the module. If the width of the inter-sheet overlapping area is too large, it obviously exceeds the affected area of laser thermal cracking. At this time, increasing the overlapping width will not continue to increase the power of the module, and will also cause a decrease in the CTM of the module.

[0046] It is worth noting that in the present embodiment, the overlapping manner between adjacent cell pieces in some cell strings can be selected as follows: from the back surface of the cell piece 13, in two adjacent cell pieces 13 in the same cell string 1, the straight edge 132 of one cell piece 13 is stacked on the chamfered edge 131 of the adjacent cell piece 13. In addition to this, the overlapping manner between cell pieces in all cell strings in the back contact photovoltaic module can also adopt the above-mentioned overlapping manner.

[0047] Referring to Figure 1As shown, in all the battery strings 1 of the present embodiment, the local overlapping manner between the two adjacent battery pieces 13 in the same battery string 1 is as follows: from the back of the battery piece 13, the straight edge 132 of one battery piece 13 is stacked on the chamfered edge 131 of the adjacent battery piece 13. Thus, from the light-receiving surface of the photovoltaic module, the straight edge 132 of each battery piece is covered by the chamfered edge 131 of the adjacent battery piece 13, except for the battery piece at the end of the second direction of the photovoltaic module. This overlapping manner can further improve the power of the module.

[0048] It should be noted that in the present application, the two adjacent battery pieces in the same battery string 1 can also be overlapped in the following manner: from the back of the battery piece, the chamfered edge of one battery piece is stacked on the straight edge of the adjacent battery piece, so that when viewed from the light-receiving surface of the battery piece, the straight edge is on top (i.e., the straight edge is closer to the front glass plate of the module), and the chamfered edge is on the bottom. The power of the photovoltaic module of this embodiment is lower than that of the above-mentioned embodiment, but is still within a good range, and the CTM and light leakage of the module of this embodiment are close to those of the above-mentioned embodiment.

[0049] In some embodiments, the ratio of the width d1 of the inter-piece overlapping area 14 in the second direction to the length D1 of a single battery piece 13 in the second direction can be 0.25%, 0.35%, 0.4%, 0.6%, 0.8%, 0.83%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, 3%, 3.2%, or 3.5%, but is not limited thereto.

[0050] Alternatively, in some embodiments, the ratio of the width d1 of the inter-piece overlapping area 14 to the length D1 of a single battery piece 13 in the second direction is 0.4% to 2.0%. In other embodiments, the ratio of the width d1 of the inter-piece overlapping area 14 to the length D1 of a single battery piece 13 in the second direction is 0.6% to 1.0%.

[0051] Specifically, the plurality of battery strings 1 can be electrically connected in series or in parallel, and the plurality of battery pieces 13 in the same battery string 1 can also be electrically connected in series or in parallel.

[0052] In one embodiment, the plurality of battery strings 1 can be electrically connected in parallel, and the plurality of battery pieces 13 in the same battery string 1 can be electrically connected in series. In another embodiment, the plurality of battery strings 1 can be electrically connected in series, and the plurality of battery pieces 13 in the same battery string can also be electrically connected in series.

[0053] It is worth noting that a gap with a predetermined distance can be provided between two adjacent battery strings 1 in the present application, and in addition, two adjacent battery strings 1 in the present application can also be partially overlapped. In the present embodiment, a gap with a predetermined distance is provided between two adjacent battery strings 1, and the gap between adjacent battery strings 1 can be conventionally provided in the art.

[0054] In one embodiment of the present embodiment, along the second direction, the chamfered edges of the battery pieces in the two adjacent battery strings face the same direction.

[0055] In another embodiment of the present embodiment, along the second direction, the chamfered edges of the battery pieces in the two adjacent battery strings face opposite directions.

[0056] Referring to Figure 2 As shown, another embodiment of a back contact photovoltaic module is disclosed, in which two adjacent battery strings 1 are partially overlapped, and the overlapping area is an inter-string overlapping area 15. By partially overlapping the adjacent battery strings 1, the spacing between the battery strings can be eliminated, further increasing the light receiving area of the back contact photovoltaic module, and further improving the power of the module. Along the first direction, the width of the inter-string overlapping area 15 is d2, and the width of a single battery piece 13 is D2, and the ratio of d2 to D2 is 0.2% to 1.1%. Within this range, a stable lamination structure can be formed, which can reduce the occurrence of light leakage, edge chipping and hidden cracks between the battery strings during module packaging, maximize the power of the module, and ensure the long-term operation reliability of the module; and within the range of 0.2% to 1.1% of the ratio of d2 to D2, the width of the inter-string overlapping can be avoided to be too large, which can cause waste of battery pieces 13 and reduce the CTM of the module.

[0057] Specifically, the ratio of d2 to D2 is exemplarily 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0% or 1.1%, but is not limited thereto.

[0058] More preferably, along the first direction, the ratio of the width d2 of the inter-string overlapping area 15 to the width D2 of a single battery piece 13 is 0.3% to 0.7%.

[0059] Specifically, the orientations of the chamfered edges of the adjacent cells in the two cell strings can be the same or different in the present application, and both can achieve better electrical performance.

[0060] Referring to Figures 2 to 4 In the embodiment shown, the orientations of the chamfered edges of the adjacent cells in the two cell strings are opposite.

[0061] In an embodiment, along the first direction, the adjacent cells include a first cell and a second cell; along the second direction, the adjacent cells include the first cell and a third cell. The inter-string overlap region includes a first inter-string overlap area 151 formed by the overlap of the first cell, the second cell and the third cell.

[0062] In an embodiment, the inter-string overlap region includes a second inter-string overlap area 152 formed by the overlap of the straight edge of the second cell and the straight edge of the third cell. The second inter-string overlap area 152 includes a third inter-string overlap area 153, which is the overlap area of the third cell and the second cell minus the remaining area of the first inter-string overlap area 151.

[0063] In an embodiment, the area of the first inter-string overlap area 151 is S1, the area of the second inter-string overlap area 152 is S2, and the area of the third inter-string overlap area 153 is S3, S2 = 2 * S1 + S3.

[0064] It is worth noting that in a back contact photovoltaic module, when the adjacent cell strings are arranged to overlap each other, and the adjacent cells in the same cell string are arranged to overlap each other, a composite overlap area (i.e. the first inter-string overlap area 151 described above) is formed in which the inter-cell overlap area 14 and the inter-string overlap area 15 overlap each other. In this composite overlap area, a structure of multiple layers of cells 13 stacked together is easily formed. Due to the influence of the multiple layers of cells 13 stacked together, the stress on the cells 13 in the composite overlap area is significantly higher than that in other areas of the module. During the lamination process, hidden cracks are easily generated in the composite overlap area, and in severe cases, the straight edge 132 of the cell 13 may also be damaged, which seriously affects the structural stability and photoelectric conversion performance of the back contact photovoltaic module.

[0065] The number of layers of cells in the first inter-string overlap area 151 formed by the overlapping method of the adopted embodiment is three, which avoids the formation of a four-layer cell structure in the composite overlap area, reduces the thickness of the composite overlap area, reduces the stress on the cells 13 in this area, and further reduces hidden cracks and alleviates the problem of cutting edge damage.

[0066] In an embodiment, the ratio of S1 to S3 is 1:6~1:3, which is beneficial for further reducing the hidden crack defects and mitigating the problem of cutting edge chamfering.

[0067] In an embodiment, the first inter-string overlapping region 151 is triangular in shape, and the third inter-string overlapping region 153 is hexagonal in shape.

[0068] Referring to Figure 5 and Figure 6 It is shown that another embodiment of the back contact photovoltaic module is disclosed, and in the embodiment, the cell string includes at least one first cell string 11 and at least one second cell string 12, and the first cell string 11 and the second cell string 12 are arranged alternately along a first direction; From the back light surface of the cell piece, in the first cell string, the chamfered edge of one of the two adjacent cell pieces is stacked on the straight edge of the other adjacent cell piece; in the second cell string, the straight edge of one of the two adjacent cell pieces is stacked on the chamfered edge of the other adjacent cell piece; From the back light surface of the cell piece, in the first cell string 11, the chamfered edge 131 of one of the two adjacent cell pieces 13 is stacked on the straight edge 132 of the other adjacent cell piece 13, i.e., the straight edge 132 of the cell piece 13 in the first cell string 11 is closer to the front glass plate of the module; in the second cell string 12, the straight edge 132 of one of the two adjacent cell pieces 13 is stacked on the chamfered edge 131 of the other adjacent cell piece 13, i.e., the chamfered edge 131 of the cell piece 13 in the second cell string 12 is closer to the front glass plate of the module; Meanwhile, referring to the embodiment shown in Figure 5 In an embodiment, in the second direction, the chamfered edge 131 of the cell piece 13 in the first cell string 11 and the chamfered edge 131 of the cell piece 13 in the second cell string 12 are opposite in direction, and the second cell string 12 is partially stacked on the back light surface 16 of the first cell string 11.

[0069] It should be noted that in the back contact photovoltaic module, when the adjacent cell strings are arranged to overlap each other, and the adjacent cell pieces 13 in the same cell string are arranged to overlap each other, a composite overlapping area in which the piece-to-piece overlapping area 14 and the string-to-string overlapping area 15 overlap each other is formed, and a structure in which multiple layers of cell pieces 13 are stacked is easily formed in the composite overlapping area. Due to the stacking of multiple layers of cell pieces 13, the stress borne by the cell pieces 13 in the composite overlapping area is significantly higher than that in other areas of the module, and hidden crack defects are easily generated in the composite overlapping area during the lamination process, and in severe cases, the problem of the straight edge edge 132 of the cell piece 13 being chamfered may also be caused, which seriously affects the structural stability and photoelectric conversion performance of the back contact photovoltaic module.

[0070] To solve this problem, the overlapping manner between the cell pieces 13 is further optimized in the present embodiment. In the first cell string 11, the chamfered edge 131 of one of the two adjacent cell pieces 13 is stacked on the back light surface 16 of the straight edge edge 132 of the other adjacent cell piece 13, that is, the straight edge edge 132 of the cell piece 13 in the first cell string 11 is closer to the front glass plate of the back contact photovoltaic module. In the second cell string 12, the straight edge edge 132 of one of the two adjacent cell pieces 13 is stacked on the back light surface 16 of the chamfered edge 131 of the other adjacent cell piece 13, that is, the chamfered edge 131 of the cell piece 13 in the second cell string 12 is closer to the front glass plate of the back contact photovoltaic module, and at the same time, the second cell string 12 is partially stacked on the back light surface 16 of the first cell string 11. Through the above structural design, in the composite overlapping area in which the cell strings and the cell pieces 13 overlap at the same time, at most only a structure in which three layers of cell pieces 13 are stacked can be formed. Compared with the structure in which four layers of cell pieces 13 are stacked in the composite overlapping area, the stress borne by the cell pieces 13 in the present embodiment can be reduced, the risk of hidden cracks of the cell pieces 13 can be further reduced, the problem of the cutting edge being chamfered can be avoided, and finally the photoelectric conversion performance of the back contact photovoltaic module can be stably exerted, and the power of the module can be further improved. As shown in the back contact photovoltaic module, Figure 6 The chamfered edge 131 of the cell piece 13 in the first cell string 11 and the chamfered edge 131 of the cell piece 13 in the second cell string 12 are located in the same layer, so that the composite overlapping area only forms a structure in which three layers of cell pieces 13 are stacked.

[0071] In some optional embodiments of the above embodiment, along the second direction, the width d1 of the piece-to-piece overlapping area 14 is 0.3mm-2.0mm.

[0072] In some optional embodiments of the above embodiment, along the first direction, the width d2 of the string-to-string overlapping area 15 is 0.5mm-2.0mm.

[0073] In one implementation of the above embodiment, in the first direction, both sides of the chamfered edge 131 of the cell 13 are provided with a chamfer 133 connected to the chamfered edge; The width of the chamfer 133 in the second direction is d3, and the width of the chamfer in the first direction is d4, where d3 is 0.8-1.5 mm, and d4 is 0.8-1.5 mm.

[0074] Preferably, the cell 13 is a back contact solar cell 13. The positive and negative electrodes of the back contact solar cell 13 are both arranged on the back surface of the back contact solar cell 13, which can further increase the actual light receiving area of the back contact photovoltaic module.

[0075] In some optional implementations of the above embodiment, the length D1 of a single cell is 80-110 mm, and the width D2 of a single cell is 150-250 mm. Specifically, in some implementations, the cell 13 can be a half cell obtained by slicing a whole cell, and the whole cell refers to a complete photovoltaic cell substrate that has not been subjected to slitting treatment. For example, a single crystal silicon / polycrystal silicon cell with a size of 166 mm x 166 mm, 182 mm x 182 mm, or 210 mm x 210 mm can be used, so the size of the cell 13 of the present application can be 83 mm x 166 mm, 91 mm x 182 mm, or 105 mm x 210 mm, i.e., the length D1 of a single cell can be 83 mm, 91 mm, or 105 mm, and the width D2 of a single cell can be 166 mm, 182 mm, or 210 mm.

[0076] Correspondingly, the present embodiment also provides a photovoltaic system comprising the above-described back contact photovoltaic module.

[0077] Specifically, the photovoltaic system of the present embodiment can comprise at least one back contact photovoltaic module of the above-described embodiment. In the photovoltaic system, the back contact photovoltaic modules can be electrically connected in parallel or in series, which can be selected and arranged according to actual needs.

[0078] In the embodiments of the present application, the photovoltaic system can be applied in a photovoltaic power station, such as a ground power station, a roof power station, a water surface power station, etc., and can also be applied in a device or apparatus that utilizes solar energy to generate electricity, such as a user solar power source, a solar street lamp, a solar car, a solar building, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, i.e., the photovoltaic system can be applied in all fields that need to utilize solar energy to generate electricity.

[0079] For example, a photovoltaic system can include a photovoltaic array, a combiner box and an inverter. The photovoltaic array can be an array combination of a plurality of photovoltaic components. For example, a plurality of photovoltaic components can form a plurality of photovoltaic arrays. The photovoltaic array is connected to the combiner box. The combiner box can combine the current generated by the photovoltaic array. The combined current flows through the inverter to convert it into alternating current required by the power grid, and then connects to the power grid to realize solar power supply.

[0080] The technical solutions of the present application are further illustrated by specific examples and comparative examples.

[0081] Examples 1-3 Examples 1-3 provide a back contact photovoltaic component, which includes a plurality of cell strings arranged along a first direction and electrically connected, each cell string includes a plurality of cell pieces arranged along a second direction and electrically connected; in the same cell string, two adjacent cell pieces are partially overlapped, and the overlapping area is an inter-piece overlapping area; along the second direction, the cell piece includes mutually parallel chamfered edges and straight edges; along a third direction, the cell piece has a light-receiving surface and a back surface, and the first direction, the second direction and the third direction are perpendicular to each other. In all cell strings of the back contact photovoltaic component of the present embodiment, the straight edge of the light-receiving surface of one of the two adjacent cell pieces is laminated on the chamfered edge of the back surface of the other adjacent cell piece; along the second direction, the width of the inter-piece overlapping area is d1, and the length of a single cell piece is D1. The ratio of d1 and D1 in examples 1-3 is shown in Table 1 below.

[0082] Comparative Example 1 The present comparative example provides a back contact photovoltaic component. The structure of the back contact photovoltaic component of comparative example 1 is basically the same as that of example 1, except that the ratio of d1 and D1 in comparative example 1 is 0.10%.

[0083] Comparative Example 2 The present comparative example provides a back contact photovoltaic component. The structure of the back contact photovoltaic component of comparative example 2 is basically the same as that of example 1, except that the ratio of d1 and D1 in comparative example 1 is 5.19%.

[0084] Specifically, examples 1-3 and comparative examples 1-2 are made into back contact photovoltaic components of the same size by using the same packaging process. The component CTM, component power, light transmission defect rate and hidden crack defect rate of the back contact photovoltaic components of examples 1-3 and comparative examples 1-2 are tested. The light transmission defect rate refers to the ratio of the number of photovoltaic components with light transmission defects in the overlapping area to the total number of photovoltaic component samples tested; the hidden crack defect rate refers to the ratio of the number of photovoltaic components with hidden crack defects in the overlapping area to the total number of photovoltaic component samples tested. The test results are shown in Table 1 below: Table 1 Test results

[0085] As can be seen from Table 1, by optimizing the overlapping mode and controlling the ratio of the width of the inter-string overlapping region to the length of the single cell, the present application can reduce the risk of cracks and light leakage of the assembly after the packaging process, improve the power of the assembly, ensure that the CTM of the assembly is greater than 90%, and reduce the cost of the assembly.

[0086] Examples 4-8 Examples 4-8 respectively provide a back contact photovoltaic assembly, and the back contact photovoltaic assembly of Examples 4-8 is basically the same as Example 2, except that in Examples 4-8, the two adjacent cell strings are locally overlapped, the overlapping region is an inter-string overlapping region, and the chamfered edges of the cell pieces in the two adjacent cell strings face opposite directions along the second direction; along the first direction, the width of the inter-string overlapping region is d2, the width of the single cell piece is D2, and the ratio of d2 to D2 is 0.2% to 1.1%. In Examples 4 to 8, the ratio of d2 to D2 is shown in Table 2.

[0087] Specifically, Examples 4-8 are made into back contact photovoltaic assemblies of the same size using the same packaging process, and the CTM, power, light transmission defect rate, and crack defect rate of the back contact photovoltaic assemblies of Examples 4-8 are tested. The test results are shown in Table 2. Table 2 Test results of Examples 4-8

[0088] As can be seen from Table 2, based on Example 2, by locally overlapping the two adjacent cell strings, the inter-string spacing can be eliminated, the effective light receiving area in the unit assembly area can be further increased, and the power of the assembly can be further improved. In addition, after the cell strings are locally overlapped, the simultaneous overlapping region of the strings and pieces will cause the light leakage defect rate and the crack defect rate to increase significantly due to the overlapping of multiple cell pieces. By controlling the ratio of d2 to D2 to be within the range of 0.2% to 1.1%, the present application can reduce the risk of light leakage and cracks in the inter-string overlapping region during the assembly lamination process, maximize the power of the assembly, and ensure the long-term operation reliability of the assembly; and when the ratio of d2 to D2 is within the range of 0.2% to 1.1%, the width of the inter-string overlapping can be avoided to be too large, which can increase the waste of cell pieces and reduce the CTM of the assembly.

[0089] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application, and any skilled person in the art can make some changes or modifications to the above-mentioned technical content with the prompt as equivalent embodiments of equivalent changes without departing from the technical solution of the present application. Any simple modification, equivalent change and modification of the above embodiments made according to the technical essence of the present application without departing from the technical solution of the present application still belong to the scope of the present application.

Claims

1. A back-contact photovoltaic module, characterized in that, It includes multiple battery strings arranged and electrically connected along a first direction, each battery string including multiple battery cells arranged and electrically connected along a second direction, the first direction and the second direction being intersected; In the same battery string, two adjacent battery cells are partially overlapped, and the overlapping area is called the inter-cell overlap area. Along the second direction, the width of the inter-cell overlap region is d1, and the length of a single cell is D1, wherein the ratio of d1 to D1 is 0.25% to 3.5%.

2. The back-contact photovoltaic module according to claim 1, characterized in that, Along the second direction, the solar cell includes chamfered edges and straight edges that are parallel to each other; along the third direction, the solar cell has a light-receiving surface and a backlighting surface; the first direction, the second direction and the third direction are arranged to intersect each other. The straight edge is the cut edge formed after the entire battery cell is cut.

3. The back-contact photovoltaic module according to claim 2, characterized in that, Viewed from the back of the battery cell, in two adjacent battery cells within the same battery string, the straight edge of one battery cell overlaps the chamfered edge of the adjacent battery cell.

4. The back-contact photovoltaic module according to claim 3, characterized in that, Viewed from the back of the battery cell, in two adjacent battery cells within the same battery string, the chamfered edge of one battery cell overlaps the straight edge of the adjacent battery cell.

5. The back-contact photovoltaic module according to claim 3 or 4, characterized in that, Along the second direction, the chamfered edges of the cells in two adjacent battery strings face the same direction.

6. The back-contact photovoltaic module according to claim 3 or 4, characterized in that, Along the second direction, the chamfered edges of the cells in two adjacent battery strings face opposite directions.

7. The back-contact photovoltaic module according to any one of claims 1-4, characterized in that, The battery strings are partially overlapped between two adjacent strings, and the overlapping area is the inter-string overlap area. Along the first direction, the width of the inter-string overlapping region is d2, the width of a single solar cell is D2, and the ratio of d2 to D2 is 0.2% to 1.1%.

8. The back-contact photovoltaic module according to claim 7, characterized in that, Along the first direction, adjacent solar cells include a first solar cell and a second solar cell; along the second direction, adjacent solar cells include a first solar cell and a third solar cell. The inter-string overlap region includes a first inter-string overlap region, which is formed by the overlap of a first battery cell, a second battery cell, and a third battery cell.

9. The back-contact photovoltaic module according to claim 8, characterized in that, The inter-string overlap region includes a second inter-string overlap region, which is formed by the overlap of the straight edge of the second battery cell and the straight edge of the third battery cell. The second inter-string overlap region includes a third inter-string overlap region, which is the area remaining after subtracting the first inter-string overlap region from the overlap region of the third and second battery cells.

10. The back-contact photovoltaic module according to claim 9, characterized in that, The area of ​​the first inter-string overlapping region is S1, the area of ​​the second inter-string overlapping region is S2, and the area of ​​the third inter-string overlapping region is S3, where S2 = 2*S1 + S3.

11. The back-contact photovoltaic module according to claim 10, characterized in that, The ratio of S1 to S3 is 1:6 to 1:

3.

12. The back-contact photovoltaic module according to claim 9, characterized in that, The first overlapping area between strings is triangular in shape, and the third overlapping area between strings is hexagonal in shape.

13. The back-contact photovoltaic module according to claim 1, characterized in that, The battery string includes at least one first battery string and at least one second battery string, with the first battery string and the second battery string arranged alternately along a first direction; Viewed from the backlight side of the battery cells, in the first battery string, the chamfered edge of one of two adjacent battery cells overlaps the straight edge of the other adjacent battery cell; in the second battery string, the straight edge of one of two adjacent battery cells overlaps the chamfered edge of the other adjacent battery cell. In the second direction, the chamfered edges of the cells in the first battery string and the chamfered edges of the cells in the second battery string face opposite directions.

14. The back-contact photovoltaic module according to claim 13, characterized in that, The second battery string is partially stacked on the backlight surface of the first battery string.

15. The back-contact photovoltaic module according to claim 1, characterized in that, Along the second direction, the ratio of the width d1 of the inter-cell overlap region to the length D1 of a single cell is 0.4% to 2.0%.

16. The back-contact photovoltaic module according to claim 7, characterized in that, Along the first direction, the ratio of the width d2 of the inter-string overlapping region to the width D2 of a single solar cell is 0.3% to 0.7%.

17. The back-contact photovoltaic module according to claim 1, characterized in that, Along the second direction, the width d1 of the inter-piece overlapping region is 0.3mm to 2.0mm.

18. The back-contact photovoltaic module according to claim 7, characterized in that, Along the first direction, the width d2 of the inter-string overlapping region is 0.5mm to 2.0mm.

19. The back-contact photovoltaic module according to claim 2, characterized in that, In the first direction, the two sides of the chamfered edge of the battery cell are respectively provided with chamfers connected to the chamfered edge; The width of the chamfer in the second direction is d3, and the width of the chamfer in the first direction is d4, wherein d3 is 0.8~1.5mm and d4 is 0.8~1.5mm.

20. The back-contact photovoltaic module according to claim 1, characterized in that, The length of a single solar cell in the second direction is 80mm to 110mm, and the width of a single solar cell in the first direction is 150mm to 250mm.

21. A photovoltaic system, characterized in that, Includes the back-contact photovoltaic module as described in any one of claims 1-20.

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