Back contact photovoltaic module

Abstract

The application relates to the field of photovoltaic technology, in particular to a back contact photovoltaic module, which comprises a cell string and a bus bar, the cell string comprises a cell piece and a solder strip, the solder strip connects adjacent cell pieces, and the bus bar connects adjacent cell strings; the back surface of the cell piece is provided with first grid lines with different polarities, the bus bar is arranged on the back surface of the cell piece, the first grid lines extend along a first direction, and the bus bar extends along a second direction; an insulating film is arranged between the bus bar and the first grid lines with one kind of polarity, and a conductive film is arranged between the bus bar and the first grid lines with another kind of polarity. In the application, the bus bar is directly connected with the first grid lines with positive polarity or the first grid lines with negative polarity, so that the solder strip does not need to be arranged between the bus bar and the first grid lines with positive polarity or the first grid lines with negative polarity, thereby the length of the solder strip can be shortened, the use amount of the solder strip can be reduced, and the production cost can be reduced. The bus bar is directly arranged on the back surface of the cell piece, the area proportion of the cell piece in the back contact photovoltaic module can be improved, and the photoelectric conversion efficiency can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaic technology, in particular to a back contact photovoltaic module. BACKGROUND

[0002] A photovoltaic module can convert solar radiation energy directly into electrical energy, mainly based on the photovoltaic effect of crystalline silicon, that is, when the light quantum of sunlight is absorbed by the semiconductor crystalline silicon, an electron-hole pair is generated, and when these electron-hole pairs reach the p-n junction composed of p-type crystalline silicon and n-type crystalline silicon, they are separated by the junction electric field to the two sides of the p-n junction, and when an external load is connected, a photoelectric current is formed, and electrical energy is output.

[0003] In a photovoltaic module, a welding strip connects adjacent cell pieces to form a cell string in series, and at the head and tail of the cell string, the welding strip is connected with a busbar to make multiple cell strings in parallel. Due to the large amount of welding strip used, the production cost of the photovoltaic module is high. SUMMARY

[0004] The present application provides a back contact photovoltaic module, which directly connects the busbar with the first grid line to reduce the amount of welding strip used in the back contact photovoltaic module and reduce the production cost of the back contact photovoltaic module.

[0005] The back contact photovoltaic module provided by the present application comprises a cell string and a busbar, the cell string comprises cell pieces and welding strips, the welding strips connect adjacent cell pieces, and the busbar connects adjacent cell strings.

[0006] The back surface of the cell piece is provided with first grid lines of different polarities, the busbar is arranged on the back surface of the cell piece, the first grid lines extend along a first direction, and the busbar extends along a second direction intersecting the first direction.

[0007] An insulating film is arranged between the busbar and the first grid lines of one polarity, and a conductive film is arranged between the busbar and the first grid lines of the other polarity, and the welding strip has no direct contact with the busbar.

[0008] In a possible design, along the first direction, the width d2 of the insulating film is greater than the width d1 of the busbar; and / or, along the first direction, the width d3 of the conductive film is greater than the width d1 of the busbar.

[0009] In a possible design, the ratio of the width d2 of the insulating film to the width d1 of the busbar satisfies: 1 < d2 / d1 ≤ 2.

[0010] In a possible design, the insulating film is provided with a bypass portion penetrating the insulating film in the thickness direction of the cell, and the conductive film is arranged in the bypass portion.

[0011] In a possible design, the bypass portion penetrates one side of the insulating film in the first direction, and the width d2 of the insulating film is equal to or greater than the size of the bypass portion in the first direction (X).

[0012] In a possible design, in the second direction, the insulating film is provided with a plurality of the conductive film is provided with a plurality of the insulating film and the conductive film are arranged alternately.

[0013] In a possible design, the width d2 of the insulating film is equal to the width d3 of the conductive film.

[0014] In a possible design, in the second direction, the length L of the conductive film satisfies: 0.2mm≤L≤1.5mm.

[0015] In a possible design, the solder strip partially overlaps the conductive film on the side of the bus bar close to the bus bar.

[0016] In a possible design, in the second direction, the conductive film partially extends to the side of the insulating film away from the cell.

[0017] In this application, when the conductive film is arranged between the bus bar and the positive first grid line, and the insulating film is arranged between the bus bar and the negative first grid line, the bus bar can be directly connected to the positive first grid line, so that the bus bar and the positive first grid line do not need to be arranged with a solder strip, thereby shortening the length of the solder strip, reducing the amount of solder strip used, and reducing the cost of the back contact photovoltaic module. Similarly, when the conductive film is arranged between the bus bar and the negative first grid line, and the insulating film is arranged between the bus bar and the positive first grid line, the bus bar can be directly connected to the negative first grid line, so that the bus bar and the negative first grid line do not need to be arranged with a solder strip, thereby shortening the length of the solder strip, reducing the amount of solder strip used, and reducing the cost of the back contact photovoltaic module.

[0018] At the same time, the bus bar is directly arranged on the back of the cell, which can improve the area ratio of the cell in the back contact photovoltaic module, and further improve the photoelectric conversion efficiency of the back contact photovoltaic module. Compared with the current method of first connecting the cell and the bus bar located on the side of the cell through a solder strip, and then folding the bus bar from the side of the cell to the back of the cell, on the one hand, the production steps of the back contact photovoltaic module are simplified, and on the other hand, there is no bent solder strip between the cell and the bus bar, which is not prone to the problem of solder strip fracture leading to disconnection of the bus bar and the cell, so the reliability of the back contact photovoltaic module is higher.

[0019] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a back-contact photovoltaic module in the prior art;

[0021] Figure 2 This is a partial structural schematic diagram of a back-contact photovoltaic module provided in this application in a specific embodiment;

[0022] Figure 3 This is a partial structural schematic diagram of a back-contact photovoltaic module provided in this application in another specific embodiment;

[0023] Figure 4 This is a partial structural schematic diagram of the back-contact photovoltaic module provided in this application in yet another specific embodiment;

[0024] Figure 5 for Figure 4 A schematic diagram of the insulating film structure in the diagram;

[0025] Figure 6 This is a schematic diagram of the back-contact photovoltaic module provided in this application.

[0026] Figure label:

[0027] 1- Battery string;

[0028] 11-Battery Cell;

[0029] 111 - First grid line;

[0030] 112 - Second grid line;

[0031] 12-Welding strip;

[0032] 2-Busbar;

[0033] 3-Insulating film;

[0034] 4-Conductive film;

[0035] 5- Front-side packaging structure;

[0036] 6-Front-side film layer;

[0037] 7-Backside film layer;

[0038] 8- Backside packaging structure.

[0039] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0040] In order to better understand the technical solutions of the present application, the embodiments of the present application are described in detail below with reference to the drawings.

[0041] It should be clear that the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0042] The terms used in the embodiments of the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0043] It should be understood that the term "and / or" used herein is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0044] It should be noted that the "up", "down", "left", "right" and other directional words described in the embodiments of the present application are described from the angle shown in the drawings, and should not be understood as a limitation on the embodiments of the present application. In addition, in the context, it should also be understood that when referring to an element connected to another element "on" or "under", it can not only be directly connected to another element "on" or "under", but also indirectly connected to another element "on" or "under" through an intermediate element.

[0045] As shown in Figure 1 The current back contact photovoltaic module includes a plurality of cell strings 1, and the bus bar 2 is connected to the head or tail of the cell string 1 through the welding strip 12, which makes the welding strip 12 need to extend to the outside of the cell sheet 11, and thus the use amount of the welding strip 12 is large.

[0046] The present application provides a back contact photovoltaic module, which comprises a cell string 1 and a bus bar 2. The cell string 1 comprises a cell sheet 11 and a welding strip 12, and the welding strip 12 connects adjacent cell sheets 11. The bus bar 2 connects adjacent cell strings 1.

[0047] The welding ribbons 12 connect adjacent battery pieces 11 to form battery strings 1 in series, and the bus bars 2 connect adjacent battery strings 1 to form battery string groups in parallel and in series between the battery string groups. For example, the back contact photovoltaic module can include three battery string groups in series, and each battery string group includes four battery strings 1 in parallel. It can be understood that the back contact photovoltaic module can also be grouped in other connection manners. For ease of description, the direction in which the welding ribbons 12 extend is defined as a first direction X, and the direction in which the bus bars 2 extend is defined as a second direction Y, and the first direction X intersects the second direction Y.

[0048] The battery piece 11 is a back contact battery, and the back contact battery has a front surface and a back surface. The front surface is a light-receiving surface of the back contact battery, and the back surface is a light-irradiating surface of the back contact battery. From the front surface to the back surface of the back contact battery, the back contact battery includes, in sequence, a front surface passivation and anti-reflection layer, a silicon substrate, a back surface tunneling layer, N-type and P-type doped regions arranged at intervals, a back surface passivation layer, and a cell electrode. The N-type and P-type doped regions are alternately arranged on a lower surface of the back surface tunneling layer. The cell electrode includes first and second grid lines 111 and 112 having different polarities. The first grid lines 111 extend along the first direction X, and the second grid lines 112 extend along the second direction Y. The second grid lines 112 of one polarity are connected to the P-type doped regions (defined as positive second grid lines 112) to collect current generated by the P-type doped regions. The second grid lines 112 of the other polarity are connected to the N-type doped regions (defined as negative second grid lines 112) to collect current generated by the N-type doped regions. The first grid lines 111 of one polarity are connected to at least part of the positive second grid lines 112 (defined as positive first grid lines 111) to collect the current collected by the positive second grid lines 112, so that the current collected by the positive second grid lines 112 can be directly or indirectly led out through the welding ribbons 12. The first grid lines 111 of the other polarity are connected to at least part of the negative second grid lines 112 (defined as negative first grid lines 111) to collect the current collected by the negative second grid lines 112, so that the current collected by the negative second grid lines 112 can be directly or indirectly led out through the welding ribbons 12.

[0049] The bus bar 2 is arranged on the back surface of the battery piece 11. An insulating film 3 is arranged between the bus bar 2 and the first grid lines 111 of one polarity, and a conductive film 4 is arranged between the bus bar 2 and the first grid lines 111 of the other polarity. The green lines in the drawing show the insulating film 3, and the orange lines show the conductive film 4.

[0050] When a conductive film 4 is provided between the busbar 2 and the positive first grid line 111, and an insulating film 3 is provided between the busbar 2 and the negative first grid line 111, the busbar 2 can be directly connected to the positive first grid line 111. This eliminates the need for a solder ribbon 12 between the busbar 2 and the positive first grid line 111, meaning that the solder ribbon 12 has no direct contact with the busbar 2. This shortens the length of the solder ribbon 12, reduces the amount of solder ribbon 12 used, and lowers the cost of the back contact photovoltaic module.

[0051] Similarly, when a conductive film 4 is provided between the busbar 2 and the negative first grid line 111, and an insulating film 3 is provided between the busbar 2 and the positive first grid line 111, the busbar 2 can be directly connected to the negative first grid line 111, so that there is no need to provide a solder ribbon 12 between the busbar 2 and the negative first grid line 111, thereby shortening the length of the solder ribbon 12, reducing the amount of solder ribbon 12 used, and reducing the cost of the back contact photovoltaic module.

[0052] Meanwhile, the busbar 2 is directly disposed on the back of the solar cell 11, which can increase the area ratio of the solar cell 11 in the back-contact photovoltaic module, thereby improving the photoelectric conversion efficiency of the back-contact photovoltaic module. Compared with the current method of first connecting the solar cell 11 and the busbar 2 located on the side of the solar cell 11 by solder ribbon 12, and then folding the busbar 2 from the side of the solar cell 11 to the back of the solar cell 11, this method simplifies the production steps of the back-contact photovoltaic module. On the other hand, the solder ribbon 12 without bending between the solar cell 11 and the busbar 2 is less likely to break and cause the busbar 2 to disconnect from the solar cell 11. Therefore, the reliability of the back-contact photovoltaic module is higher.

[0053] Specifically, such as Figure 2 As shown, along the first direction X, the width d2 of the insulating film 3 is greater than the width d1 of the busbar 2, thereby preventing the busbar 2 connected to the positive first gate line 111 from extending to the outside of the insulating film 3 and coming into contact with the negative first gate line 111 to cause a short circuit, and also preventing the busbar 2 connected to the negative first gate line 111 from extending to the outside of the insulating film 3 and coming into contact with the positive first gate line 111 to cause a short circuit.

[0054] Along the first direction X, the width d3 of the conductive film 4 is greater than the width d1 of the busbar 2, which makes the contact area between the busbar 2 and the conductive film 4 larger, and the contact area between the conductive film 4 and the first grid line 111 larger, resulting in a smaller resistance at the connection between the busbar 2 and the first grid line 111, thereby reducing the loss of electrical energy during transmission.

[0055] More specifically, the ratio of the width d2 of the insulating film 3 to the width d1 of the bus bar 2 satisfies: 1 < d2 / d1 < 2. For example, the ratio of the width d2 to the width d1 can specifically be: 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2.0, etc.

[0056] The ratio of the width d2 of the insulating film 3 to the width d1 of the bus bar 2 should not be too large or too small. If the ratio of the width d2 to the width d1 is too large (for example, d2 / d1 is greater than 2), the width of the insulating film 3 is too large, and the production cost of the back contact photovoltaic module is relatively high. If the ratio of the width d2 to the width d1 is too small (for example, d2 / d1 is equal to or less than 1), the insulating film 3 cannot effectively isolate the bus bar 2 and the cell sheet 11, and the bus bar 2 is easy to contact the cell sheet 11 to cause short circuit. Therefore, the ratio of the width d2 of the insulating film 3 to the width d1 of the bus bar 2 should be set within a reasonable range, so as to prevent the bus bar 2 from contacting the cell sheet 11 to cause short circuit while keeping the cost of the back contact photovoltaic module relatively low.

[0057] The ratio of the width d3 of the conductive film 4 to the width d1 of the bus bar 2 satisfies: 1 < d3 / d1 < 2. For example, the ratio of the width d3 to the width d1 can specifically be: 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2.0, etc.

[0058] The ratio of the width d3 of the conductive film 4 to the width d1 of the bus bar 2 should not be too large or too small. If the ratio of the width d3 to the width d1 is too large (for example, d3 / d1 is greater than 2), the width of the conductive film 4 is too large, and the production cost of the back contact photovoltaic module is relatively high. If the ratio of the width d3 to the width d1 is too small (for example, d3 / d1 is less than 1), on the one hand, the conductive film 4 is easy to disconnect from the bus bar 2 when the bus bar 2 slightly deviates from the preset position, and on the other hand, the contact area of the bus bar 2, the first grid line 111 and the conductive film 4 is relatively small, and the resistance is relatively large when the current flows, and the loss of electric energy in the transmission process is increased. Therefore, the ratio of the width d3 of the conductive film 4 to the width d1 of the bus bar 2 should be set within a reasonable range, so as to prevent the conductive film 4 from being easy to disconnect from the bus bar 2 while keeping the cost of the back contact photovoltaic module relatively low.

[0059] In an embodiment, as shown in FIG. 1, the back contact photovoltaic module comprises a plurality of cell sheets 11, a plurality of bus bars 2, a plurality of insulating films 3 and a plurality of conductive films 4. Figure 2As shown, the first gate line 111 is the main gate, and the second gate line 112 is the fine gate. The positive first gate line 111 is connected to all the positive second gate lines 112 to collect the current collected by the positive second gate line 112. The negative first gate line 111 is connected to all the negative second gate lines to collect the current collected by the negative second gate line 112. The solder ribbon 12 covers the first gate line 111 to conduct the current collected by the first gate line 111.

[0060] At the head and tail of the battery string 1 along the first direction X, the busbar 2, which is connected to the positive first grid line 111, is also connected to a portion of the positive second grid line 112. The solder ribbon 12 covering the positive first grid line 111 can abut against or partially overlap with the conductive film 4, so that the current collected by the positive second grid line 112 can flow directly to the busbar 2, flow through the positive first grid line 111 to the busbar 2, and flow through the solder ribbon 12 connected to the positive first grid line 111 to the busbar 2, thereby improving the current collection effect of the busbar 2. The solder ribbon 12 covering the positive first grid line 111 can also not contact the conductive film 4, so that the length of the solder ribbon 12 can be shorter, thereby reducing the cost of the back contact photovoltaic module.

[0061] Similarly, the busbar 2 connected to the negative first grid line 111 is also connected to part of the negative second grid line 112, and the solder strip 12 covering the negative first grid line 111 can abut against, partially overlap with or not contact the conductive film 4.

[0062] Specifically, multiple insulating films 3 and multiple conductive films 4 are provided. The insulating films 3 and conductive films 4 are arranged alternately, so that the insulating films 3 and conductive films 4 can respectively correspond to the alternately arranged positive first grid line 111 and negative first grid line 111.

[0063] In another embodiment, such as Figure 3 As shown, the first grid line 111 is the edge main grid, and the second grid line 112 is the fine grid. The edge main grid is only connected to a portion of the positive second grid line 112 or a portion of the negative second grid line 112. Compared with setting the entire main grid, the amount of paste used in the first grid line 111 is reduced, which is beneficial to reducing the production cost of the back contact photovoltaic module.

[0064] The solder ribbon 12 is connected to the positive first gate line 111 and also to the positive second gate line 112 that is not connected to the positive first gate line 111. Therefore, the solder ribbon 12 can collect all the current collected by the positive second gate line 112. The solder ribbon 12 is connected to the negative first gate line 111 and also to the negative second gate line 112 that is not connected to the negative first gate line 111. Therefore, the solder ribbon 12 can collect all the current collected by the negative second gate line 112.

[0065] At the head and tail of the battery string 1 along the first direction X, the bus bar 2 connected with the positive first grid line 111 is also connected with part of the positive second grid line 112, and the solder strip 12 covering the positive first grid line 111 can be in abutment or partially overlapped with the conductive film 4, so that the current collected by the positive second grid line 112 can partially flow to the bus bar 2 directly, partially flow to the bus bar 2 through the positive first grid line 111, and partially flow to the bus bar 2 through the solder strip 12, thereby improving the current collection effect of the bus bar 2. The solder strip 12 covering the positive first grid line 111 can also be in non-contact with the conductive film 4, so that the length of the solder strip 12 can be shorter to reduce the cost of the back contact photovoltaic module.

[0066] Similarly, the bus bar 2 connected with the negative first grid line 111 is also connected with part of the negative second grid line 112, and the solder strip 12 covering the negative first grid line 111 can be in abutment, partially overlapped, or non-contact with the conductive film 4.

[0067] Specifically, a plurality of insulating films 3 and a plurality of conductive films 4 are provided, and the insulating films 3 and the conductive films 4 are arranged alternately, so that the insulating films 3 and the conductive films 4 can correspond to the positive first grid line 111 and the negative first grid line 111 arranged alternately, respectively.

[0068] In the above embodiment, when the plurality of insulating films 3 and the plurality of conductive films 4 are arranged alternately, the width d2 of the insulating film 3 is equal to the width d3 of the conductive film 4, so that the insulating film 3 and the conductive film 4 can be cut by the same set of tooling, reducing the production cost of the insulating film 3 and the conductive film 4, and enabling the insulating film 3 and the conductive film 4 to be arranged in alignment along the second direction Y when arranged on the cell sheet 11, thereby improving the appearance consistency of the back contact photovoltaic module.

[0069] In the above embodiment, as shown in Figure 4 The insulating film 3 arranged on one cell sheet 11 can be a continuous piece, thereby reducing the number of times of placing the insulating film 3 and improving the production efficiency of the back contact photovoltaic module.

[0070] Specifically, as shown in Figure 5 The insulating film 3 is provided with an avoiding portion 31 penetrating the insulating film 3 along the thickness direction of the cell sheet 11, and the conductive film 4 is arranged in the avoiding portion 31. The thickness direction of the cell sheet 11 is perpendicular to the first direction X and the second direction Y.

[0071] When the bus bar 2 needs to be connected with the positive first grid line 111, the avoiding portion 31 on the insulating film 3 is arranged corresponding to the positive first grid line 111, so that the conductive film 4 can be in contact with the positive first grid line 111; when the bus bar 2 needs to be connected with the negative first grid line 111, the avoiding portion 31 on the insulating film 3 is arranged corresponding to the negative first grid line 111, so that the conductive film 4 can be in contact with the negative first grid line 111.

[0072] In one embodiment, the avoiding part 31 penetrates one side of the insulating film 3 along the first direction X. Optionally, the width d3 of the conductive film 4 is equal to the size of the avoiding part 31 along the first direction X, so that when the conductive film 4 is placed in the avoiding part 31, the conductive film 4 does not protrude the edge of the insulating film 3 along the first direction X, and the appearance consistency of the back contact photovoltaic module is higher. Optionally, the width d3 of the conductive film 4 is greater than the size of the avoiding part 31 along the first direction X, so that when the conductive film 4 is placed in the avoiding part 31, the conductive film 4 protrudes the edge of the insulating film 3 along the first direction X, facilitating the connection of the conductive film 4 and the first grid line 111, and increasing the connection area of the conductive film 4 and the first grid line 111 and the contact area of the conductive film 4 and the bus bar 2, thereby reducing the loss of current in the transmission process. Preferably, the width d3 of the conductive film 4 is equal to the width d2 of the insulating film 3, so that the conductive film 4 and the insulating film 3 can be cut by using a set of tooling while facilitating the connection of the conductive film 4 and the first grid line 111.

[0073] In another specific embodiment, the avoiding part 31 does not penetrate the insulating film 3 along the first direction X. Optionally, the width d3 of the conductive film 4 is equal to the size of the avoiding part 31 along the first direction X, so that the conductive film 4 can be placed in the avoiding part 31. Optionally, the width d3 of the conductive film 4 is greater than the size of the avoiding part 31 along the first direction X, so that when the conductive film 4 is placed in the avoiding part 31, a part of the conductive film 4 can extend from the side of the insulating film 3 close to the cell 11 to the space between the insulating film 3 and the cell 11, so that the conductive film 4 is connected with the first grid line 111, and the width d3 of the conductive film 4 does not make the conductive film 4 protrude the edge of the insulating film 3 along the first direction X, so that the appearance consistency of the back contact photovoltaic module is higher.

[0074] Further, the width d3 of the conductive film 4 is greater than the size of the avoiding part 31 along the first direction X, and the width d3 of the conductive film 4 is less than or equal to the width d2 of the insulating film 3, so that when the conductive film 4 is placed in the avoiding part 31, a part of the conductive film 4 can connect with the first grid line 111 by crossing the insulating film 3 from the side of the insulating film 3 close to or away from the cell 11, and the width d3 of the conductive film 4 is not too wide, which does not increase the cost of the back contact photovoltaic module too much. Preferably, the conductive film 4 can extend from the side of the insulating film 3 close to the cell 11 to the space between the insulating film 3 and the cell 11 and protrude the edge of the insulating film 3, so that the contact area of the conductive film 4 and the first grid line 111 is increased, thereby making the connection of the conductive film 4 and the first grid line 111 more reliable.

[0075] Further, along the second direction Y, the conductive film 4 partially extends to the side of the insulating film 3 away from the cell sheet 11, so that the conductive film 4 can be adhered to the insulating film 3, thereby enabling the conductive film 4 and the insulating film 3 to be placed on the cell sheet 11 together, and simplifying the production steps of the back contact photovoltaic module.

[0076] Specifically, along the second direction Y, the length L of the conductive film 4 satisfies: 0.2mm≤L≤1.5mm. For example, the length L of the conductive film 4 can be specifically 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, etc.

[0077] Along the second direction Y, the length L of the conductive film 4 should not be too large or too small. If the length L of the conductive film 4 is too small (for example, less than 0.2mm), the conductive film 4 is easy to be disconnected from the first grid line 111 when the conductive film 4 slightly deviates from the preset position, affecting the collection of the current from the first grid line 111 by the busbar 2. If the length L of the conductive film 4 is too large (for example, greater than 1.5mm), the use amount of the conductive film 4 in the back contact photovoltaic module is large, and the cost of the back contact photovoltaic module is high. Therefore, the length L of the conductive film 4 should be set within a reasonable range to prevent the conductive film 4 from being easily disconnected from the first grid line 111 while keeping the cost of the back contact photovoltaic module low.

[0078] It can be understood that, along the second direction Y, the length of the insulating film 3 is longer than the length L of the conductive film 4, so as to better isolate the first grid line 111 and the second grid line 112 of different polarities.

[0079] In the above embodiments, the insulating film 3 can be an adhesive film, and the conductive film 4 can also be an adhesive film. The insulating film 3 can also have a layered structure including an adhesive layer and an insulating layer, and the adhesive layer is arranged on the side for contacting the cell sheet 11. The conductive film 4 can also have a layered structure including a conductive adhesive layer and a conductive layer, and the conductive adhesive layer is arranged on the side for contacting the cell sheet 11.

[0080] In the above embodiments, the type of the back contact cell can be one of an interdigitated back contact (IBC) cell, a heterojunction back contact (HBC) cell, and a tunnel oxide back contact (TBC) cell.

[0081] The battery piece 11 can also be a back contact stacked battery, which includes a back contact bottom battery and a perovskite top battery, and the perovskite top battery is electrically connected to the front surface of the back contact bottom battery. The back contact bottom battery can be a back contact battery as described above. The perovskite top battery is a thin-film solar cell with perovskite material as the light active layer. The structure of the perovskite top battery mainly consists of the following key parts: a transparent conductive substrate, an electron transport layer, a perovskite light absorption layer, a hole transport layer, and a metal electrode. These components work together to enable the perovskite top battery to effectively absorb sunlight and convert it into electrical energy. The perovskite material in the perovskite light absorption layer has excellent light absorption performance, can absorb a wider spectrum of light, and effectively converts short-wavelength light, enabling the perovskite top battery to have high photoelectric conversion efficiency.

[0082] In the above embodiment, as shown in FIG. 1, the back contact photovoltaic module includes a front encapsulation structure 5, a front film layer 6, a battery string 1, a back film layer 7, and a back encapsulation structure 8. The front encapsulation structure 5, the front film layer 6, the back film layer 7, and the back encapsulation structure 8 encapsulate the battery string 1 to ensure that the back contact photovoltaic module has high mechanical strength, reduces the impact of hail impact, wind blowing, mechanical vibration, and other situations on the back contact photovoltaic module, and improves the sealing of the back contact photovoltaic module, enhancing its erosion resistance and safety. Figure 6 Specifically, the front encapsulation structure 5 and the back encapsulation structure 8 can be one of tempered glass, polyethylene terephthalate (PET), polycarbonate (PC), or one of polyvinyl fluoride (PVF), ethylene-tetra-fluoro-ethylene (ETFE), and polyvinylidene fluoride (PVDF). These materials have high light transmittance, which can improve the photoelectric conversion efficiency of the back contact photovoltaic module and ensure the power of the back contact photovoltaic module. The front film layer 6 and the back film layer 7 can be one of ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), polyvinyl butyral (PVB), EVA-POE-EVA co-extruded adhesive film (EPE), and EVA-POE co-extruded adhesive film (EP).

[0083]

[0084] ​The above descriptions are only the preferred embodiments of the present application, and are not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A back-contact photovoltaic module, characterized in that, The back-contact photovoltaic module includes a battery string (1) and a busbar (2). The battery string (1) includes a battery cell (11) and a solder strip (12). The solder strip (12) connects adjacent battery cells (11), and the busbar (2) connects adjacent battery strings (1). The back of the battery cell (11) is provided with first grid lines (111) of different polarities, and the bus bar (2) is provided on the back of the battery cell (11). The first grid lines (111) extend along a first direction (X), and the bus bar (2) extends along a second direction (Y). The second direction (Y) intersects with the first direction (X). An insulating film (3) is provided between the busbar (2) and the first grid line (111) of one polarity, and a conductive film (4) is provided between the busbar (2) and the first grid line (111) of another polarity. The solder strip (12) has no direct contact with the busbar (2). The conductive film (4) protrudes from the edge of the insulating film (3) along the first direction (X), and the solder strip (12) partially overlaps the conductive film (4) on the side near the busbar (2).

2. The back-contact photovoltaic module according to claim 1, characterized in that, Along the first direction (X), the width d2 of the insulating film (3) is greater than the width d1 of the busbar (2); And / or, along the first direction (X), the width d3 of the conductive film (4) is greater than the width d1 of the busbar (2).

3. The back-contact photovoltaic module according to claim 2, characterized in that, The ratio of the width d2 of the insulating film (3) to the width d1 of the busbar (2) satisfies: 1 < d2 / d1 ≤ 2.

4. The back-contact photovoltaic module according to claim 1, characterized in that, The insulating film (3) is provided with a clearance portion (31) that penetrates the insulating film (3) along the thickness direction of the battery cell (11), and the conductive film (4) is disposed in the clearance portion (31).

5. The back-contact photovoltaic module according to claim 4, characterized in that, The clearance portion (31) penetrates one side of the insulating film (3) along the first direction (X), and the width d2 of the insulating film (3) is equal to or greater than the size of the clearance portion (31) along the first direction (X).

6. The back-contact photovoltaic module according to claim 1, characterized in that, Along the second direction (Y), there are multiple insulating films (3) and multiple conductive films (4), and the insulating films (3) and conductive films (4) are arranged alternately.

7. The back-contact photovoltaic module according to claim 6, characterized in that, The width d2 of the insulating film (3) is equal to the width d3 of the conductive film (4).

8. The back-contact photovoltaic module according to claim 1, characterized in that, Along the second direction (Y), the length L of the conductive film (4) satisfies: 0.2mm≤L≤1.5mm.

9. The back-contact photovoltaic module according to any one of claims 2-8, characterized in that, Along the second direction (Y), the conductive film (4) extends to the side of the insulating film (3) opposite to the battery cell (11).

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