Photovoltaic cell string, photovoltaic laminated member and photovoltaic assembly

Abstract

The invention provides a photovoltaic cell string, a photovoltaic laminated piece and a photovoltaic module, relates to the technical field of photovoltaic, and aims to solve the technical problem that a photovoltaic cell is poor in reliability on the basis of high power generation efficiency. The photovoltaic cell string comprises an insulating strip, a bus bar, a plurality of electrically connected photovoltaic cells and a plurality of solder strips arranged on the photovoltaic cells, the insulating strip is arranged on the photovoltaic cells, and the bus bar is arranged on the side, away from the photovoltaic cells, of the insulating strip; a plurality of thin grid lines with opposite polarities are arranged on the back surface of the photovoltaic battery piece, and the plurality of thin grid lines with opposite polarities are connected with the plurality of welding strips in a one-to-one correspondence manner; the insulating strip is provided with a plurality of first through holes, each welding strip connected with one of the thin grid lines with the same polarity in the plurality of welding strips is provided with a lug boss, and each lug boss penetrates through the corresponding first through hole and is connected with the bus bar; and each of the plurality of solder strips connected with the other type of homopolar fine grid line is electrically isolated from the bus bar through an insulating strip. The photovoltaic cell string can ensure the connection reliability between the bus bar and the solder strip.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a photovoltaic cell string, a photovoltaic laminate, and a photovoltaic module. Background Art

[0002] The statements in this section merely provide background art related to the present invention and do not necessarily constitute prior art.

[0003] Back-contact photovoltaic cells are different from conventional photovoltaic cells in that both the positive and negative electrodes are placed on the back of the cell, thus avoiding the optical loss on the front of conventional photovoltaic cells and improving the photoelectric conversion efficiency of the photovoltaic cell.

[0004] The periphery of the photovoltaic cell string usually requires bus bars to connect the welding strips on the photovoltaic cells to form a current collection, and the bus bars will form an invalid area on the front of the photovoltaic cells. In the related art, in order to reduce the invalid area occupied by the bus bars, the welding strips and / or bus bars are modified to the back of the photovoltaic cell string, thereby improving the power generation efficiency of the photovoltaic cells, but the product reliability of the photovoltaic cells cannot be guaranteed. Summary of the invention

[0005] The object of the present invention is to provide a photovoltaic cell string, a photovoltaic laminate, and a photovoltaic module to solve the technical problem that photovoltaic cells have poor reliability on the basis of high power generation efficiency.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a photovoltaic cell string, comprising an insulating strip, a bus bar, a plurality of electrically connected photovoltaic cells, and a plurality of welding strips arranged on the photovoltaic cells, wherein the insulating strip is arranged on the photovoltaic cell, and the bus bar is arranged on a side of the insulating strip away from the photovoltaic cell;

[0008] A plurality of thin grid lines with opposite polarities are arranged on the back of the photovoltaic cell sheet, and the plurality of thin grid lines with opposite polarities are connected to the plurality of welding strips in a one-to-one correspondence;

[0009] The insulating strip has a plurality of first through holes, and each of the plurality of welding strips connected to one of the same polarity fine grid lines has a convex portion, and each of the convex portions passes through a corresponding first through hole and is connected to the bus bar;

[0010] Each welding strip among the plurality of welding strips connected to another type of fine grid line with the same polarity is electrically isolated from the bus bar by the insulating strip.

[0011] According to at least one embodiment of the present invention, the bus bar has a plurality of second through holes corresponding to the first through holes, and each of the protrusions passes through the corresponding first through hole to the second through hole and is connected to the bus bar.

[0012] According to at least one embodiment of the present invention, an area of ​​a cross section of the first through hole is greater than or equal to an area of ​​a cross section of the second through hole.

[0013] According to at least one embodiment of the present invention, the protrusion is connected to the bus bar by welding; and / or,

[0014] The protrusion is a tin-coated protrusion; and / or,

[0015] The busbars and the welding strips are both tin-coated metal strips.

[0016] According to at least one embodiment of the present invention, the protrusion and the welding strip are formed integrally.

[0017] According to at least one embodiment of the present invention, the protrusion includes a bent structure formed by bending the welding strip; and / or,

[0018] The protrusion includes a boss structure formed on the welding strip.

[0019] According to at least one embodiment of the present invention, the top end of the protrusion is flush with or higher than the surface of the bus bar facing away from the insulating strip.

[0020] In a second aspect, the present invention further provides a photovoltaic laminate comprising a back cover and a plurality of electrically connected photovoltaic cell strings, wherein the photovoltaic cell string is the photovoltaic cell string described in the first aspect,

[0021] The back cover is arranged on the back side of the photovoltaic cell string through an adhesive film, and a plurality of recessed portions are formed on the surface of the back cover facing the photovoltaic cell string, and at least part of the recessed portions is opposite to the raised portion of the welding strip.

[0022] According to at least one embodiment of the present invention, when the back cover is photovoltaic glass, the recessed portion is a groove opened on the glass cover;

[0023] When the back cover is a photovoltaic back sheet, the recessed portion includes a groove formed by bending the photovoltaic back sheet.

[0024] In a third aspect, the present invention further provides a photovoltaic module, comprising the photovoltaic laminate according to the second aspect.

[0025] Among the one or more technical solutions provided in the exemplary embodiments of the present invention, at least one of the following beneficial effects can be achieved.

[0026] In the photovoltaic cell string of the exemplary embodiment of the present invention, a protrusion is provided on each welding strip (a welding strip connected to a thin grid line of the same polarity) to be connected to the bus bar, and the protrusion extends from the corresponding first through hole of the insulating strip to form an electrical connection with the bus bar; while no protrusion is provided for each welding strip (a welding strip connected to another thin grid line of the same polarity, which should not be electrically connected to the bus bar), and the bus bar and each welding strip (the welding strip that should not be electrically connected to the bus bar) are electrically isolated due to the insulating strip. Through the electrical isolation of the insulating strip, the bus bar can be arranged on the back of the photovoltaic cell string, which reduces the ineffective area of ​​the photovoltaic cell string and improves the power generation efficiency compared to the prior art in which the bus bar is arranged in the peripheral area of ​​the circumference of the photovoltaic cell string.

[0027] Compared with the prior art, no protrusions are provided on each welding strip to be connected to the bus bar (the welding strip connected to a thin grid line of the same polarity), and the welding connection between the bus bar and the welding strip is formed only by the tin material coated on the welding strip and / or the bus bar. Due to the molten fluidity of the tin material, it is difficult to ensure the welding reliability of the bus bar and the welding strip. The bus bar of the photovoltaic cell string of the exemplary embodiment of the present invention and the welding strip to be connected are physically abutted and welded through the protrusions. Since the protrusions have a fixed shape, the connection reliability between the bus bar and the welding strip can be guaranteed. Therefore, on the basis of improving the power generation efficiency, the reliability and qualified rate of the photovoltaic cell string and its subsequent products can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings illustrate exemplary embodiments of the present invention and together with the description serve to explain the principles of the present invention, and these drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification;

[0029] Figure 1 is a schematic structural diagram of a photovoltaic cell string array according to an embodiment of the present invention;

[0030] Figure 2 yes Figure 1 A schematic diagram of the structure of a battery string;

[0031] Figure 3 is a schematic structural diagram of a photovoltaic cell string array (with insulating strips) according to an embodiment of the present invention;

[0032] Figure 4 yes Figure 3 A schematic diagram of the structure of a battery string (with insulating strips) in FIG.

[0033] Figure 5 is a schematic structural diagram of a photovoltaic cell string array (with insulating bars / bus bars) according to an embodiment of the present invention;

[0034] Figure 6 yes Figure 5 A schematic diagram of the structure of a battery string (with insulating strips / bus bars) in FIG.

[0035] Figure 7 yes Figure 6 A schematic diagram of the structure of a battery cell (with an insulating strip / bus bar) at one end of the battery cell;

[0036] Fig. 8A yes Figure 7 AA cross-sectional structural diagram;

[0037] Figure 8B yes Figure 7 BB cross-sectional structure diagram;

[0038] Figure 8C yes Figure 7 Schematic diagram of CC cross-section structure;

[0039] Fig.8D yes Figure 7 DD cross-sectional structure diagram;

[0040] Fig. 9 yes Figure 6 A schematic diagram of a three-dimensional exploded structure of a battery cell (with an insulating strip / bus bar) at one end of the battery cell;

[0041] Fig.10 yes Figure 6 A schematic diagram of a three-dimensional exploded structure of a middle battery cell (with an insulating strip / bus bar);

[0042] Fig.11 is a schematic diagram of a three-dimensional exploded structure of a photovoltaic laminate according to an embodiment of the present invention;

[0043] Fig.12 FIG. 4 is a schematic diagram of a three-dimensional exploded structure of a photovoltaic laminate according to another embodiment of the present invention.

[0044] Reference numerals:

[0045] 100, front cover;

[0046] 200, front film;

[0047] 300, photovoltaic cell string array; 310, photovoltaic cell string; 311, welding strip; 311a, protrusion; 312, battery cell; 320, bus bar; 321, second through hole; 330, insulation strip; 331, first through hole;

[0048] 400, rear film;

[0049] 500, rear cover; 500a, recessed portion. DETAILED DESCRIPTION

[0050] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0051] The characteristic of back contact (BC) photovoltaic cells is that the positive and negative electrodes of the cell are designed on the back of the photovoltaic cell, thereby eliminating the light blocking by the front electrode, maximizing the use of incident light, reducing optical losses, and improving the photoelectric conversion efficiency of the photovoltaic cell. Back contact photovoltaic cells are highly compatible with other high-efficiency photovoltaic cell structures, including a variety of technical paths, such as interdigitated back contact cells (IBC), heterojunction back contact cells (HBC), passivated back contact cells (PBC), etc.

[0052] In the field of photovoltaic cell technology, the pursuit of lower production costs and higher photoelectric conversion efficiency is the core goal of the industry. The high-density packaging of photovoltaic modules mainly reduces the gap between photovoltaic cells / strings to maximize the proportion of cell area in photovoltaic modules. Assuming that the module power remains unchanged, high-efficiency photovoltaic modules have a smaller module area, which can save the use of main materials of photovoltaic modules and reduce the cost of photovoltaic modules.

[0053] Usually, the busbars in photovoltaic cells occupy ineffective areas at both ends and in the middle of the cell string, while the back-contact cell can reduce the ineffective area and improve power generation efficiency by flipping and folding the busbars to the back. In the related art, the back-contact photovoltaic cell flips and folds the busbars to the back, and needs to bend the welding strips (interconnection strips) and / or busbars to complete the interconnection between photovoltaic cells / strings, but the welding effect between the welding strips and the busbars cannot be guaranteed, resulting in the production yield and the reliability of subsequent products cannot be guaranteed.

[0054] Figure 1 Schematic diagram of the structure of a photovoltaic cell string array according to an embodiment of the present invention. Figure 1 As shown, the photovoltaic cell string 310 is a photovoltaic cell string formed by back contact technology. Exemplarily, the photovoltaic cell string array 300 has six photovoltaic cell strings 310 from top to bottom.

[0055] Figure 2 yes Figure 1 A schematic diagram of the structure of a battery string. Figure 2As shown, each photovoltaic cell string 310 includes three or more electrically connected photovoltaic cells 312, and each photovoltaic cell string 310 includes at least two photovoltaic cells 312 located at two ends, respectively, and one photovoltaic cell 312 located in the middle. Each photovoltaic cell 312 is electrically connected through a welding strip 311, and multiple welding strips 311 are arranged from top to bottom in the same photovoltaic cell 312. Some welding strips 311 are connected to fine grid lines with positive polarity, and other welding strips 311 are connected to fine grid lines with negative polarity, wherein the welding strips 311 connected to the fine grid lines with positive polarity and the welding strips 311 connected to the fine grid lines with negative polarity are arranged alternately in sequence from top to bottom.

[0056] It should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0057] For example, there may be a spacing between the cells 312 in the photovoltaic cell string 310, and the spacing between the cells is the same. The cells 312 in the photovoltaic cell string 310 may also be overlapped to reduce the occupied area of ​​the photovoltaic cell string 310 and improve the power generation efficiency.

[0058] Figure 5 is a schematic structural diagram of a photovoltaic cell string array (with insulating bars / bus bars) according to an embodiment of the present invention; Figure 6 yes Figure 5 A schematic diagram of the structure of a battery string (with insulating strips / bus bars) in FIG. Fig. 9 yes Figure 6 A schematic diagram of the three-dimensional exploded structure of a battery cell (with an insulating strip / bus bar) at one end of the circuit. Figure 5 , Figure 6 and Fig. 9As shown, an exemplary embodiment of the present invention provides a photovoltaic cell string, including an insulating strip 330, a bus bar 320, a plurality of electrically connected photovoltaic cell sheets 312, and a plurality of welding strips 311 arranged on the photovoltaic cell string 310, wherein the insulating strip 330 is arranged on the photovoltaic cell string 310, and the bus bar 320 is arranged on the side of the insulating strip 330 away from the photovoltaic cell string 310; a plurality of fine grid lines with opposite polarities are arranged on the back side of the photovoltaic cell sheet 312, and the plurality of fine grid lines with opposite polarities are connected to the plurality of welding strips 311 in a one-to-one correspondence; the insulating strip 330 has a plurality of first through holes 331, and each welding strip 311 connected to one of the fine grid lines of the same polarity among the plurality of welding strips 311 has a protrusion 311a, and each protrusion 311a passes through the corresponding first through hole 331 and is connected to the bus bar 320; each welding strip 311 connected to another fine grid line of the same polarity among the plurality of welding strips 311 is electrically isolated from the bus bar 320 by the insulating strip 330.

[0059] In practical applications, such as Figure 3 and Figure 4 As shown, in the photovoltaic cell string array 300, three insulating strips 330 are respectively arranged in the vertical direction, wherein one insulating strip 330 spans the back of the cell 312 at the same end of each photovoltaic cell string 310, another insulating strip 330 spans the back of the cell 312 at the other end of each photovoltaic cell string 310, and the third insulating strip 330 spans the back of the cell 312 at the middle of each photovoltaic cell string 310. Figure 3 is a schematic structural diagram of a photovoltaic cell string array (with insulating strips) according to an embodiment of the present invention; Figure 4 yes Figure 3 Schematic diagram of the structure of a battery string (with insulating strips) in.

[0060] For example, Fig. 9 and Fig.10 As shown, the first through holes 331 on the insulating strip 330 correspond one-to-one to the protrusions 311a on the corresponding welding strips 311. When the insulating strip 330 is attached to the battery cell 312, the protrusions 311a on the welding strips 311 pass through the corresponding first through holes 331 to be electrically connected to the bus bar 320 subsequently arranged on the insulating strip 330.

[0061] like Fig. 9 On the battery cell 312 shown, for example, each welding strip 311 with a protrusion 311a is connected to the positive polarity fine grid line, and each welding strip 311 without a protrusion 311a is connected to the negative polarity fine grid line, and the welding strips 311 with a protrusion 311a and the welding strips 311 without a protrusion 311a are alternately arranged. Fig.10 The electrical connection structure between the welding strip 311 and the bus bar 320 and the insulating strip 330 is Fig. 9 Similar, but different Fig.10 The cell 312 located in the middle of the photovoltaic cell string 310 is shown. Fig. 9 The photovoltaic cell 312 is located at the end of the photovoltaic cell string 310 .

[0062] like Figure 5 and Figure 6 As shown, after three insulating strips 330 are arranged on the photovoltaic cell string array 300, bus bars 320 are respectively attached to each insulating strip 330. The area of ​​the bus bar 320 can be smaller than the area of ​​the corresponding insulating strip 330, or in other words, the orthographic projection of the bus bar 320 on the surface of the insulating strip 330 is located within the surface of the insulating strip 330 to ensure that the bus bar 320 is electrically isolated from the welding strip 311 that should not be electrically connected.

[0063] When the bus bar 320 is placed behind the insulating strip 330, it can physically contact the protrusion 311a extending out of the first through hole 331 of the insulating strip 330, and the two can be electrically connected by welding. Since the protrusion 311a has a fixed shape and forms physical contact, the welding reliability between the two is high.

[0064] Figure 7 yes Figure 6 A schematic diagram of the structure of a battery cell (with an insulating strip / bus bar) at one end of the battery cell; Fig. 8A yes Figure 7 AA cross-sectional structural diagram; Figure 8B yes Figure 7 BB cross-sectional structure diagram; Figure 8C yes Figure 7 Schematic diagram of CC cross-section structure; Fig.8D yes Figure 7 DD cross-sectional structure diagram. Figure 7 and Fig. 8A As shown, the bus bar 320 is not provided in the end region of the insulating strip 330, that is, the end of the bus bar 320 is close to a welding strip 311 having a protrusion 311a; Figure 8B As shown, in the connection area between the bus bar 320 and the welding strip 311, the welding strip 311 is located on the battery cell 312, and its protrusion 311a passes through the first through hole 331 of the insulating strip 330 to form physical contact with the bus bar 320; Figure 8C As shown, in the area between adjacent welding strips 311, the bus bar 320 is electrically isolated from the battery cell 312 by the insulating strip 330; Fig.8D As shown, in the region of the soldering strip 311 without the protrusion 311 a , the bus bar 320 is electrically isolated from the soldering strip 311 without the protrusion 311 a by the insulating strip 330 .

[0065] From the above, it can be seen that the bus bar 320 can form an effective electrical connection with the welding strip 311 to be connected, while being electrically isolated from the welding strip 311 that should not be electrically connected, thereby achieving that the bus bar 320 can be set on the back side of the back-contact photovoltaic cell string, reducing the ineffective area occupied by the bus bar 320 set on the peripheral edge of the photovoltaic cell string, that is, hiding the bus bar 320, improving the power generation efficiency of the photovoltaic module, and at the same time ensuring the welding effect between the bus bar 320 and the welding strip 311, thereby ensuring the reliability and qualified rate of subsequent products.

[0066] Exemplarily, the protrusion 311a is a protrusion 311a with tin solder, and the busbar 320 can be a tin-coated metal strip. Exemplarily, the busbar 320 is a flat copper strip coated with tin solder; the welding strip 311 can also be a tin-coated metal strip, for example, it is a flat copper strip coated with tin solder.

[0067] Since the busbar 320 needs to carry a much larger current than the welding strip 311 (interconnection strip), the busbar 320 is generally a tinned flat copper strip with a larger cross-sectional area than the welding strip 311, and its cross-sectional area is generally more than 1mm 2 The busbar 320 is generally located at both ends of the photovoltaic cell string 310, and the welding strip 311 is welded to the busbar 320 at both ends of the photovoltaic cell string, which not only affects the power generation efficiency but also looks ugly.

[0068] After the busbar 320 is placed on the insulating strip 330, the protrusion 311a coated with tin solder and the busbar 320 can be welded and fixed by infrared welding. Due to the fixed shape of the protrusion 311a, the fluid tin solder can be accurately melted at the connection between the protrusion 311a and the busbar 320, thereby ensuring the welding effect.

[0069] It is understandable that the protrusion 311 a may also be made of a conductive metal material that is not coated with tin, such as copper, and the welding between the two may be completed using the tin solder coated on the bus bar 320 .

[0070] Exemplarily, the protrusion 311 a may be integrally formed with the soldering strip 311 to reduce the processing cost of the soldering strip 311 , and the protrusion 311 a is more stable on the soldering strip 311 .

[0071] For example, the protrusion 311a includes a bending structure formed by bending the welding strip 311. Since the welding strip 311 is a flat copper strip, it is suitable for forming a "J"-shaped structure through a bending device in terms of thickness and ductility. Figure 8B The structure of the protrusion 311a shown simplifies the processing technology and reduces the cost.

[0072] In an optional embodiment, the protrusion 311a includes a boss structure formed on the welding strip 311. The boss structure can be formed by stamping, or by using a mold during the molding process of the welding strip 311.

[0073] In another optional implementation, the protrusion 311 a may also be pre-fixed on the welding strip 311 by welding.

[0074] Considering the problem that the welding effect between the bus bar 320 and the welding ribbon 311 cannot be effectively verified, in the photovoltaic cell string provided by the exemplary embodiment of the present invention, the bus bar 320 has a plurality of second through holes 321 corresponding to the first through holes 331, and each protrusion 311a passes through the corresponding first through hole 331 to the second through hole 321 and is connected to the bus bar 320, such as Figure 8B , Fig. 9 and Fig.10 shown.

[0075] In practical applications, the second through hole 321 of the busbar 320 corresponds to the first through hole 331 of the insulating strip 330. The protrusion 311a can penetrate the first through hole 331, and a part of it is embedded in the second through hole 321, that is, the top of the protrusion 311a can be flush with the surface of the busbar 320 away from the insulating strip 330, and the size and shape of the second through hole 321 are adapted to the protrusion 311a. After welding, the welding effect between the busbar 320 and the protrusion 311a can be observed from above the busbar 320, for example, whether there is a cold weld. Alternatively, the welding effect between the busbar 320 and the protrusion 311a can be judged from above the busbar 320 by machine image recognition through an image acquisition device.

[0076] Compared with the prior art, the welding part between the busbar 320 and the welding strip 311 is blocked by the busbar 320, and the reliability of welding cannot be judged by visual inspection or image acquisition. In order to verify the welding reliability between the two, a destructive tensile test is required to verify the welding reliability. In the photovoltaic cell string of the exemplary embodiment of the present invention, the raised portion 311a of the welding strip 311 is extended to the second through hole 321 of the busbar 320 for welding connection. On the one hand, the physical connection and welding of the two can ensure the welding effect; on the other hand, since the welding part of the two is not blocked by the busbar 320, it can be intuitively judged whether there is a problem such as a cold solder joint between the busbar 320 and the welding strip 311, thereby ensuring the qualified rate of the back contact photovoltaic cell string product and the reliability of subsequent products.

[0077] In some embodiments, the cross-sectional area of ​​the first through hole 331 is greater than or equal to the cross-sectional area of ​​the second through hole 321. The cross-sectional area of ​​the second through hole 321 may be consistent with the cross-sectional area of ​​the protrusion 311a to maintain the welding reliability between the two. The cross-sectional area of ​​the first through hole 331 may be greater than the cross-sectional area of ​​the protrusion 311a, and the protrusion 311a may be easily led out of the first through hole 331. This is because the insulating strip 330 is generally a flexible strip. When wrinkling or the like occurs, the first through hole 331 may be misaligned with the position of the protrusion 311a of the welding strip 311, and it is not easy to extend from the first through hole 331 of the insulating strip 330.

[0078] In some embodiments, Figure 8B As shown, the top of the protrusion 311a can be flush with or higher than the surface of the busbar 320 that is away from the insulating strip 330. The top of the protrusion 311a refers to the end of the protrusion 311a that is away from the main body of the welding strip 311. When the top of the protrusion 311a is higher than the surface of the busbar 320 that is away from the insulating strip 330, it can be ensured that the protrusion 311a has enough parts to form a reliable welding connection with the busbar 320.

[0079] Fig.11 Schematic diagram of the three-dimensional exploded structure of a photovoltaic laminate according to an embodiment of the present invention. Fig.11 As shown, an exemplary embodiment of the present invention further provides a photovoltaic laminate, including a back cover and a plurality of electrically connected photovoltaic cell strings 310, the photovoltaic cell string 310 being the photovoltaic cell string in the above-mentioned embodiment, the back cover being arranged on the back side of the photovoltaic cell string 310 through an adhesive film, a plurality of recessed portions 500a being formed on the surface of the back cover facing the photovoltaic cell string 310, and at least part of the recessed portion 500a is opposite to the raised portion 311a of the welding strip 311.

[0080] A plurality of recessed portions 500a formed on the back cover are opposite to the second through hole 321 of the bus bar 320, that is, opposite to the raised portion 311a on the welding strip 311. Since the top of the raised portion 311a may be higher than the surface of the bus bar 320 facing away from the insulating strip 330, it may cause hidden cracks or breakage of the back cover. Therefore, corresponding recessed portions 500a are provided on the back cover to avoid the raised portion 311a on the welding strip 311, thereby ensuring the reliability of the photovoltaic laminate.

[0081] The photovoltaic laminate includes five layers of materials stacked together, including a front cover plate 100, a front adhesive film 200, a photovoltaic cell string array 300, a rear adhesive film 400 and a rear cover plate 500 in order from the light receiving surface (front) to the backlight surface (back). The front cover plate 100 is generally a cover plate formed of tempered glass, which has high light transmittance. The rear cover plate 500 can also be a cover plate formed of tempered glass. When the front cover plate 100 and the rear cover plate 500 are both tempered glass, the finished component formed is called a double-glass component; when the rear cover plate 500 is a photovoltaic back plate, the finished component formed is called a single-glass component.

[0082] The material of the photovoltaic backsheet can be an organic polymer material, which is usually composed of multiple layers of materials with different functions, such as polyethylene glycol terephthalate (PET) polyester film, fluorine materials: polyvinyl formal (PVF), polyvinylidene difluoride (PVDF) and adhesives. Compared with the back cover 500 being a tempered glass cover, the thickness of the photovoltaic backsheet is much thinner. Using tempered glass as the backsheet can improve the sealing, insulation, and anti-black line and anti-hidden crack performance of the finished photovoltaic module, thereby enhancing the reliability of the photovoltaic module. However, its cost is relatively high.

[0083] The front film 200 and the back film 400 can be polyethylene-polyvinyl acetate copolymer (Polyethylenevinylacetate, EVA) film, or can be one of polyolefin elastomer (Poly (ethylene-1-octene), POE) film, EVA / POE laminated film, EVA / POE / EVA laminated film or POE / EVA / POE laminated film. After the five layers of materials are stacked, they are placed in a laminator, and the front film 200 and the back film 400 are melted under the action of heat and pressure, and a strong bond is formed between the layers to form a finished photovoltaic laminate.

[0084] Exemplarily, the insulating strip 330 on the photovoltaic cell string 310 may be one or more of a PET film, a PET / EVA composite film, an EVA / PET / EVA composite film, a PET / POE composite film or a POE / PET / POE composite film.

[0085] Fig.12 FIG. 2 is a schematic diagram of a three-dimensional exploded structure of a photovoltaic laminate according to another embodiment of the present invention. Fig.12As shown, when the back cover is photovoltaic glass, the recessed portion 500a is a groove opened on the glass cover. Since the photovoltaic glass is thick, grooves corresponding to the protrusions 311a can be formed on the side of the photovoltaic glass facing the photovoltaic cell string array 300 through a thinning process, that is, the grooves correspond to the protrusions 311a one by one.

[0086] In an optional embodiment, in the process of forming the groove, in order to facilitate the thinning process, a continuous groove may be formed along the length direction of the bus bar 320 to avoid the protrusion 311 a and / or the bus bar 320 .

[0087] Since the photovoltaic backsheet is made of organic polymer material, it is relatively thin and it is difficult to form the recessed portion 500a through a thinning process like photovoltaic glass. When the back cover is a photovoltaic backsheet, the recessed portion 500a may include a groove formed by bending the photovoltaic backsheet, such as Fig.11 shown.

[0088] The photovoltaic back panel can be bent to form a plurality of continuous grooves, each of which can avoid the raised portion 311a of the welding strip 311 and / or the corresponding bus bar 320, and the bending process of the photovoltaic back panel is relatively simple and low in cost.

[0089] An exemplary embodiment of the present invention further provides a photovoltaic module, comprising the photovoltaic laminate according to the above embodiment.

[0090] After the photovoltaic laminate is laminated, a protective shell is also required to be wrapped around the edge of the photovoltaic laminate to provide mechanical support and protection. The protective shell is a frame or assembly frame, and the photovoltaic laminate with the frame or assembly frame installed forms a photovoltaic module.

[0091] The technical advantages of the above-mentioned photovoltaic laminates and photovoltaic modules over the prior art are the same as the advantages of the above-mentioned photovoltaic cell strings, which will not be elaborated here.

[0092] It should be understood by those skilled in the art that the above embodiments are only for the purpose of clearly illustrating the present invention, and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications may be made based on the above disclosure, and these changes or modifications are still within the scope of the present invention.

Claims

1. A photovoltaic cell string, characterized in that: It includes an insulating strip, a bus bar, a plurality of electrically connected photovoltaic cells and a plurality of welding strips arranged on the photovoltaic cells, wherein the insulating strip is arranged on the photovoltaic cells, and the bus bar is arranged on a side of the insulating strip away from the photovoltaic cells; A plurality of thin grid lines with opposite polarities are arranged on the back of the photovoltaic cell sheet, and the plurality of thin grid lines with opposite polarities are connected to the plurality of welding strips in a one-to-one correspondence; The insulating strip has a plurality of first through holes, and each of the plurality of welding strips connected to one of the same polarity fine grid lines has a convex portion, and each of the convex portions passes through a corresponding first through hole and is connected to the bus bar; Each welding strip among the plurality of welding strips connected to another type of fine grid line with the same polarity is electrically isolated from the bus bar by the insulating strip.

2. The photovoltaic cell string according to claim 1, characterized in that: The bus bar has a plurality of second through holes corresponding to the first through holes, and each of the protrusions passes through the corresponding first through hole to the second through hole and is connected to the bus bar.

3. The photovoltaic cell string according to claim 2, characterized in that: An area of ​​a cross section of the first through hole is greater than or equal to an area of ​​a cross section of the second through hole.

4. The photovoltaic cell string according to claim 1, characterized in that: The protrusion is welded to the bus bar; and / or, The protrusion is a tin-coated protrusion; and / or, The busbars and the welding strips are both tin-coated metal strips.

5. The photovoltaic cell string according to any one of claims 1 to 4, characterized in that: The protrusion is integrally formed with the welding strip.

6. The photovoltaic cell string according to claim 5, characterized in that: The protrusion includes a bent structure formed by bending the welding strip; and / or, The protrusion includes a boss structure formed on the welding strip.

7. The photovoltaic cell string according to any one of claims 1 to 4, characterized in that: The top end of the protrusion is flush with or higher than the surface of the bus bar facing away from the insulating strip.

8. A photovoltaic laminate, characterized in that: It comprises a back cover plate and a plurality of electrically connected photovoltaic cell strings, wherein the photovoltaic cell string is the photovoltaic cell string according to any one of claims 1 to 7, The back cover is arranged on the back side of the photovoltaic cell string through an adhesive film, and a plurality of recessed portions are formed on the surface of the back cover facing the photovoltaic cell string, and at least part of the recessed portions is opposite to the raised portion of the welding strip.

9. The photovoltaic laminate according to claim 8, characterized in that When the back cover is photovoltaic glass, the recessed portion is a groove opened on the glass cover.

10. A photovoltaic module, characterized in that: A photovoltaic laminate comprising the photovoltaic laminate of claim 8 or 9.

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