Solar cells, battery modules, and photovoltaic power generation systems

Abstract

In the field of solar cell technology, the present invention provides solar cells, battery modules, and photovoltaic power generation systems. The solar cell comprises a silicon wafer, a first doped layer, and a second doped layer. The second doped layer is composited and in contact with the first doped layer at a predetermined position to form a leakage composite contact structure. When the reverse voltage applied to both ends of the solar cell is 17V or less, the leakage current per unit length of the leakage composite contact structure is greater than Impp / S / N. Impp is the maximum output point current of the solar cell, S is the area of ​​the solar cell, N is the length of the leakage composite contact structure per unit area in the solar cell, and N is 4.32 cm / cm². 2 The following is true: This ensures a reduction in the risk of hot spots without excessively impairing the conversion efficiency of solar cells, reduces or eliminates the requirements for managing defects in solar cells, and improves the manufacturing capacity of solar cells.

Description

[Technical Field]

[0001] The present invention relates to the field of solar cell technology, and more particularly to solar cells, battery modules, and photovoltaic power generation systems. [Background technology]

[0002] In related technologies, solar cell modules typically consist of a battery array made up of multiple battery cells. To effectively control the risk of hot spots, solar cells usually employ a low leakage current characteristic and bypass diode design to reduce the leakage current of the battery cells, thereby controlling the heat generated at the leakage point.

[0003] However, such technological proposals require controlling the leakage current of battery cells to a small value in order to suppress the risk of hotspot failures, resulting in a high level of control over leakage current. However, this is a difficult problem for the solar power industry's manufacturing capacity to overcome, as any defect introduced during the solar cell manufacturing process can cause the leakage current to exceed the control value, resulting in low anti-hotspot risk capability and reduced manufacturing capacity.

[0004] Therefore, developing new anti-hotspot technologies with high manufacturing capacity to improve the anti-hotspot risk capability of battery cells is a technical problem that engineers must address. [Overview of the Initiative]

[0005] The present invention provides solar cells, battery modules, and photovoltaic power generation systems, and aims to solve the technical problems of how to improve the manufacturing capacity of solar cells and the ability of battery cells to reduce the risk of hot spots.

[0006] The present invention is realized as follows, and a solar cell according to an embodiment of the present invention includes a silicon wafer, a first doped layer laminated on the silicon wafer, and a second doped layer laminated on the silicon wafer, wherein the second doped layer has opposite polarity to the first doped layer, and the second doped layer is combined and in contact with the first doped layer at a predetermined position to form a leakage composite contact structure, and when the reverse voltage applied to both ends of the solar cell is 17V or less, the leakage current per unit length of the leakage composite contact structure is greater than Impp / S / N, where Impp is the maximum output point current of the solar cell, S is the area of ​​the solar cell, N is the length of the leakage composite contact structure per unit area in the solar cell, and N is 4.32 cm / cm 2 The following applies:

[0007] Furthermore, N is 3.45 cm / cm 2 The following applies:

[0008] Furthermore, N is 2.59 cm / cm 2 The following applies:

[0009] Furthermore, when the reverse voltage applied across the solar cell is 9V, the leakage current per unit length of the leakage composite contact structure is greater than Impp / S / N.

[0010] Furthermore, when the reverse voltage applied across the solar cell is 6V, the leakage current per unit length of the leakage composite contact structure is greater than Impp / S / N.

[0011] Furthermore, the solar cell is a double-sided solar cell, the silicon wafer has a first surface and a second surface facing each other, the first doped layer is laminated on the first surface, the second doped layer is laminated on the second surface, and the second doped layer and the first doped layer are combined and in contact at a predetermined position on the edge of the silicon wafer to form the leakage composite contact structure.

[0012] Furthermore, the solar cell is a back-contact solar cell, and the silicon wafer has opposing front and back surfaces, with some first doping layers and some second doping layers laminated on the back surface, the some first doping layers and some second doping layers arranged alternately with spacing between them, and there is a spacing area between the first doping layers and the second doping layers, and at a predetermined position in the spacing area, the first doping layers and the second doping layers are combined and in contact to form the leakage composite contact structure.

[0013] The present invention further provides a battery module comprising a solar cell as described in any one of the above claims.

[0014] Furthermore, the battery module includes several battery strings, each battery string includes several solar cells connected in series, and bypass diodes are connected in parallel to both ends of the battery strings; Reverse bias voltage across both ends of the shielded solar cell <D×Voc×(M-1)+Lであり: The reverse bias voltage is the voltage across the shielded solar cell when the solar cell is shielded and the leakage current of the shielded solar cell reaches the maximum output point current; Voc is the open-circuit voltage of the solar cell, M is the number of solar cells in the battery string connected in parallel with the bypass diode, D is a constant less than 1, and L is the start-up voltage of the bypass diode.

[0015] Furthermore, the battery module includes several battery strings, and the battery strings include several of the solar cells connected in series; Reverse bias voltage across the shielded solar cell <D×Voc×(P-1)であり; The reverse bias voltage is a voltage across the shaded solar cell when the solar cell is shaded and the leakage current of the shaded solar cell reaches the maximum power point current; Voc is the open circuit voltage of the solar cell, P is the number of solar cells connected in series with the shaded solar cell, and D is a constant less than 1.

[0016] Further, the possible value range of D is 0.1 to 0.5.

[0017] Further, when the solar cell is shaded, the heating power of a single leakage composite contact structure in the solar cell is less than 8.85W.

[0018] Further, the number S of the leakage composite contact structures in the solar cell satisfies the following condition. [Formula] In the formula, Impp is the maximum power point current of the solar cell, and V Impp is the reverse bias voltage across the shaded solar cell when the solar cell is shaded and the leakage current of the shaded solar cell reaches the maximum power point current, and S is a positive integer.

[0019] Further, when the solar cell is shaded, within any 4cm×4cm square area of the solar cell, the leakage current I of the solar cell leak satisfies the following condition. [Formula] In the formula, I leak is the sum of leakage currents of all the leakage composite contact structures located within the 4cm×4cm square area, and V Impp is the reverse bias voltage across the shaded solar cell when the solar cell is shaded and the leakage current of the shaded solar cell reaches the maximum power point current.

[0020] Further, when the solar cell is shielded, within any 4 cm × 4 cm square area of the solar cell, the leakage current I of the solar cell leak satisfies the following condition.

Num

[0021] Further, when the solar cell is shielded, within any 4 cm × 4 cm square area of the solar cell, the leakage current I of the solar cell leak satisfies the following condition.

Num

[0022] Further, in said solar cell, the pitch between two adjacent said leakage composite contact structures is 4 cm or more.

[0023] The present invention further provides a photovoltaic power generation system comprising the above cell module.

[0024] In the solar cell, battery module, and photovoltaic power generation system according to embodiments of the present invention, by introducing a leakage composite contact structure formed by two doping layers with different polarities at predetermined locations, and by rationally designing the leakage current per unit length of the leakage composite contact structure, the leakage capacity of the solar cell can be improved, and the leakage composite contact structure can be given high reverse leakage characteristics. As a result of this improvement in leakage capacity, on the module side, when a solar cell is shielded, if the leakage current of the solar cell reaches the maximum output point current, the voltage across both ends of the shielded solar cell decreases, and the heat generated by the solar cell decreases, thereby achieving the objective of controlling the risk of hot spots. Furthermore, according to the technical proposal of the present invention, by intentionally introducing a leakage composite contact structure at predetermined locations, a protective effect against hot spots caused by defects in the silicon wafer itself can be achieved, reducing or eliminating the requirement for defect management, reducing the risk of hot spots due to defects, and improving the manufacturing capacity of solar cells. Moreover, in the present invention, by rationally designing the length of the leakage composite contact structure per unit area, excessive efficiency loss can be avoided, and the conversion efficiency of the solar cell can be guaranteed. Additional aspects and advantages of the present invention are partially described below, some of which will become apparent from the following description or will be understood through the implementation of the present invention. [Brief explanation of the drawing]

[0025] [Figure 1] This is a schematic block diagram of a photovoltaic power generation system provided in an embodiment of the present invention. [Figure 2] This is a schematic block diagram of a battery module provided in an embodiment of the present invention. [Figure 3] This is a schematic diagram of the planar structure of a back-contact solar cell provided in an embodiment of the present invention. [Figure 4] Figure 3 is a schematic cross-sectional view of a back-contact solar cell along the IV-IV line. [Figure 5] This is another schematic cross-sectional view of the back-contact solar cell along the IV-IV line in Figure 3. [Figure 6] Figure 3 shows yet another schematic cross-sectional view along the IV-IV line of the back-contact solar cell. [Figure 7] This is a schematic diagram of the planar structure of a double-sided solar cell provided in an embodiment of the present invention. [Figure 8] This is a schematic cross-sectional view of the double-sided solar cell along line VIII-VIII in Figure 7. [Figure 9] This is another schematic cross-sectional view of the bifacial solar cell along line VIII-VIII in Figure 7. [Figure 10] This diagram shows the relationship between the hotspot temperature of a solar cell and the heat generated by that temperature. [Figure 11] This is an equivalent circuit diagram of a battery module in related technologies. [Modes for carrying out the invention]

[0026] To further clarify the object, technical concept and advantages of the present invention, the present invention will be described in more detail below with reference to the drawings and embodiments. The embodiments are shown in the drawings, and throughout the drawings, the same or similar reference numerals indicate the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are illustrative and are for interpretation purposes only, and should be understood as not intended to limit the present invention. Furthermore, the specific embodiments described herein are for interpretation purposes only, and should be understood as not intended to limit the present invention.

[0027] In the description of this invention, the directions or positional relationships indicated by terms such as "length," "width," "top," "bottom," "horizontal direction," and "vertical direction" are directions or positional relationships based on the drawings and are merely for the purpose of facilitating and simplifying the description of this invention. They do not indicate or imply that the shown devices or elements have a specific direction or must be configured and operated in a specific direction, and therefore should not be understood as limitations to this invention.

[0028] Furthermore, terms such as "first," "second," etc., are used solely for descriptive purposes and should not be understood as indicating or implying relative importance, or implicitly indicating the number of technical features being referred to. Thus, features limited by "first," "second," etc., may explicitly or implicitly include one or more of the aforementioned features. In the description of the present invention, unless otherwise clearly and specifically limited, "multiple" refers to two or more.

[0029] In this description of the present invention, unless otherwise explicitly stated and limited, the terms “attachment,” “connection,” and “connection” should be interpreted broadly, for example, meaning that connections may be fixed, detachably connected, or integrally connected; mechanically connected, electrically connected, or communicating with each other; directly connected, indirectly connected via an intermediary, or internal communication between two elements or an interaction relationship between two elements. Those skilled in the art will be able to understand the specific meaning of the above terms in this invention, depending on the specific case.

[0030] In the present invention, unless otherwise explicitly stated or limited, the description of a first feature being "above" or "below" a second feature includes cases where the first and second features are in direct contact, and cases where they are in contact via another feature between them without direct contact. Furthermore, the description of a first feature being "above," "above," and "above" a second feature includes cases where the first feature is directly above or diagonally above the second feature, or simply where the horizontal height of the first feature is greater than that of the second feature. The description of a first feature being "below," "below," and "below" a second feature includes cases where the first feature is directly below or diagonally below the second feature, or simply where the horizontal height of the first feature is lower than that of the second feature.

[0031] The following invention provides many different examples or embodiments to realize different structures of the present invention. To simplify the invention, the components and installations in specific examples are described below. Of course, these are merely examples and are not intended to limit the present invention. Furthermore, for the sake of simplification and clarity, the present invention may repeatedly use reference figures and / or reference letters in different examples, and these themselves do not indicate relationships between the various embodiments and / or installations discussed. Furthermore, the present invention provides examples of various specific processes and materials, but those skilled in the art will be able to recognize the application of other processes and / or usage scenarios of other materials.

[0032] Referring to Figures 1-2, the photovoltaic power generation system 1000 according to an embodiment of the present invention may include a battery module 200 according to an embodiment of the present invention, and the battery module 200 according to an embodiment of the present invention may include a plurality of solar cells 100 according to an embodiment of the present invention. In the embodiment of the present invention, the plurality of solar cells 100 in the battery module 200 may be connected in series in sequence to form a plurality of battery strings, and each battery string can be connected in series, parallel, or series-parallel and then merge and output currents, for example, by welding solder ribbons to each battery cell, or by using busbars to connect each battery string. In some embodiments, each battery string constitutes a battery cell array, and a front plate, front adhesive film, rear adhesive film and rear plate can be packaged to form the battery module 200.

[0033] Referring to Figures 3-8, the solar cell 100 according to an embodiment of the present invention may include a silicon wafer 10, a first doping layer 20, and a second doping layer 30. The silicon wafer 10 may be a P-type silicon wafer or an N-type silicon wafer, and is not specifically limited thereto. The first doping layer 20 is provided laminated on the silicon wafer 10, and the second doping layer 30 is also provided laminated on the silicon wafer 10, and the second doping layer 30 has the opposite polarity to the first doping layer 20. Specifically, in the embodiment of the present invention, the first doping layer 20 may be an N-type doping layer and the second doping layer 30 may be a P-type doping layer, or the first doping layer 20 may be a P-type doping layer and the second doping layer 30 may be a P-type doping layer, and is not specifically limited thereto, as long as the polarities of the two are opposite.

[0034] As shown in Figures 3 and 7, in the present invention, the second doping layer 30 of the solar cell 100 is combined with and in contact with the first doping layer 20 at a predetermined position 101 to form a leakage composite contact structure 40, and when the reverse voltage applied to both ends of the solar cell 100 is 17V or less, the leakage current per unit length of the leakage composite contact structure 40 is greater than Impp / S / N.

[0035] Impp is the maximum output point current of the solar cell 100, S is the area of ​​the solar cell 100 (i.e., the area of ​​the light-receiving surface and non-light-receiving surface of the silicon wafer 10), N is the length of the leakage composite contact structure 40 per unit area in the solar cell 100, and N is 4.32 cm / cm 2 The following applies:

[0036] The maximum output point current of solar cell 100 is the current when the cell is at maximum output under standard measurement conditions. Standard measurement conditions are common and well-known standard measurement techniques in the field of solar cell technology, and therefore, an explanation is omitted here.

[0037] Referring to Figures 3 and 4, in some embodiments, the solar cell 100 may be a back-contact solar cell, in which case the silicon wafer 10 may include a back-to-back front 13 and back 14, on which some first doping layers 20 and some second doping layers 30 may be laminated on the back 14, the some first doping layers 20 and some second doping layers 30 are arranged alternately with intervals between them, and there is an interval area 50 between the first doping layers 20 and the second doping layers 30, and at a predetermined position 101 in the interval area 50, the first doping layers 20 and the second doping layers 30 are composite and in contact to form a leakage composite contact structure 40. Specifically, as shown in Figure 3, in a back-contact solar cell, some first doping layers 20 and some second doping layers 30 are arranged alternately along the lateral direction with spacing between them, and may also extend along the vertical direction, with spacing areas between adjacent first doping layers 20 and second doping layers 30.

[0038] That is, as shown in Figure 4, at a predetermined position 101, the first dope layer 20 may extend a portion of it to the spacing area 50, thereby combining and contacting the second dope layer 30 to form a leakage composite contact structure 40. Figure 4 shows only one embodiment, and it is understood that in other embodiments, at a predetermined position 101, the second dope layer 30 may extend a portion of it to the spacing area 50, thereby combining and contacting the first dope layer 20 to form a leakage composite contact structure 40. Furthermore, in some embodiments, at a predetermined position 101, both the first dope layer 20 and the second dope layer 30 may extend along the spacing area 50, thereby combining and contacting each other within the spacing area 50 to form a leakage composite contact structure 40, but this is not specifically limited here.

[0039] As shown in Figure 5, in some embodiments, the back surface 14 of the back-contact solar cell may have some spaced grooves. The first doping layer 20 and the second doping layer 30 may be laminated on a grooveless surface, and the grooves correspond to the spacing area 50, with the first doping layer 20 and the second doping layer 30 provided on both sides of the groove, and the first doping layer 20 and the second doping layer 30 being separated by the groove. Of course, in some embodiments, the width of the grooves may be set to be relatively wide, in which case the first doping layer 20 may be provided on a grooveless surface, and the second doping layer 30 may be provided in the groove, and it is understood that the groove portion between the second doping layer 30 and the first doping layer 20 becomes the spacing area 50 in the present invention.

[0040] In this invention, "the first doped layer 20 and the second doped layer 30 combine and come into contact to form a leakage composite contact structure 40" means that at a predetermined position 101, there is no insulation between the first doped layer 20 and the second doped layer 30, and the two combine at the predetermined position 101. The two may come into direct contact to form a composite contact, or a leakage point (i.e., a leakage composite contact structure 40) may be formed by realizing a composite contact via a dielectric layer, but it is preferable to realize the composite contact via a dielectric layer. For example, as shown in Figure 6, in some embodiments, for composite contact between the first doped layer 20 and the second doped layer 30, a first dielectric layer 60 is provided between them. The first dielectric layer 60 may be a film layer such as a tunnel oxide layer, or a film layer having a passivation function such as a silicon oxide film layer. At least a portion of the first dielectric layer 60 has a tunneling function, enabling composite contact between the first doped layer 20 and the second doped layer 30. As a result, the first dielectric layer 60 can achieve composite contact between the two and provide good passivation to the contact surface between them.

[0041] Furthermore, referring to Figures 4-6, in some embodiments, the back-contact solar cell may further include a second dielectric layer 70 laminated between the first doped layer 20 and the back surface 14 of the silicon wafer 10, and a third dielectric layer 80 laminated between the second doped layer 30 and the back surface 14 of the silicon wafer 10. Both the second dielectric layer 70 and the third dielectric layer 80 may be tunnel layers, such as silicon oxide tunnel layers, which are film layers having passivation and tunneling functions, and the specific type can be selected according to the actual situation and is not specifically limited here. In other words, in the solar cell 100 as a whole, if there is a location of the first doped layer 20, there is a second dielectric layer 70, and if there is a location of the second doped layer 30, there is a third dielectric layer 80. That is, when the first doped layer 20 extends to the spacing region 50, there is a second dielectric layer 70 (not shown) below the portion of the first doped layer 20 that extends to the spacing region 50, and when the second doped layer 30 extends to the spacing region 50, there is a third dielectric layer 80 (not shown) below the portion of the second doped layer 30 that extends to the spacing region 50.

[0042] As shown in Figure 3, in a back-contact solar cell, the length L of the leakage composite contact structure 40 refers to the length in the longitudinal direction (i.e., the vertical direction in Figure 3, and the direction of extension of the first dope layer 20 and the second dope layer 30) of the spacing area 50 of the leakage composite contact structure 40, that is, the length of the leakage composite contact structure 40 in the vertical direction in Figure 3, and it is easy to understand that it refers to the length in the vertical direction of the composite contact surface of the first dope layer 20 and the second dope layer 30. The "unit length of the leakage composite contact structure 40" refers to the length of the leakage composite contact structure per unit area, and refers to the ratio of the total length of all leakage composite contact structures 40 to the area of ​​the front 13 or back 14 of the silicon wafer 10 (i.e., the light-receiving area of ​​the solar cell 100). The "area of ​​the solar cell 100" refers to the orthogonal projection area of ​​the solar cell 100 in the thickness direction, and refers to the area of ​​the light-receiving surface and the non-light-receiving surface of the solar cell 100.

[0043] Referring to Figures 7 and 8, in some embodiments, the solar cell 100 may be a double-sided solar cell, such as a PERC solar cell or a Topcon solar cell.

[0044] As shown in Figure 8, in this case, the silicon wafer 10 has opposing first surfaces 11 and second surfaces 12, the first doping layer 20 is laminated on the first surface 11, and the second doping layer 30 is laminated on the second surface 12, and the second doping layer 30 and the first doping layer 20 are combined and in contact at a predetermined position 101 on the edge of the silicon wafer 10 to form a leakage composite contact structure 40.

[0045] Specifically, as shown in Figure 8, in a double-sided solar cell, the first doping layer 20 and the second doping layer 30 are each stacked on two back-to-back surfaces of the silicon wafer 10, and the first doping layer 20 and the second doping layer 30 can be combined and in contact at a predetermined position 101 on the edge of the silicon wafer 10 to form a leakage composite contact structure 40.

[0046] As shown in Figure 8, in such an embodiment, the first dope layer 20 is laminated on the first surface 11, and at a predetermined position 101 on the edge of the silicon wafer 10, the first dope layer 20 extends along the edge of the silicon wafer 10 to the second surface 12, thereby compounding and contacting the second dope layer 30 at the edge of the second surface 12 to form a leakage composite contact structure 40.

[0047] Of course, in some embodiments, the second doping layer 30 may be laminated on the second surface 12, and at a predetermined position 101 on the edge of the silicon wafer 10, the second doping layer 30 may extend along the edge of the silicon wafer 10 to the first surface 11, thereby compounding and contacting the first doping layer 20 at the edge of the first surface 11. Furthermore, in some other embodiments, the first doping layer 20 and the second doping layer 30 may extend relatively at a predetermined position 101 on the edge of the silicon wafer 10, thereby compounding and contacting the side surface of the silicon wafer 10 (i.e., the plane connecting the first surface 11 and the second surface 12), but this is not a limitation, and it is sufficient if the two are compounded and in contact in a portion of the area of ​​the edge of the silicon wafer 10.

[0048] Similarly, as shown in Figure 9, in a double-sided solar cell, the composite contact between the first doped layer 20 and the second doped layer 30 may be direct contact between them, or a fourth dielectric layer 90 may be provided between them. The material and properties of the fourth dielectric layer 90 may be the same as those of the first dielectric layer 60 described above, but this explanation is omitted here.

[0049] The double-sided solar cells shown in Figures 8 and 9 are double-sided Topcon solar cells. In such a cell, a fifth dielectric layer 110 is provided between the first doped layer 20 and the first surface 11, and a sixth dielectric layer 120 is provided between the second doped layer 30 and the second surface 12. Both the fifth dielectric layer 110 and the sixth dielectric layer 120 may be tunnel layers, such as silicon oxide tunnel layers, which are film layers having passivation and tunneling functions. The specific type can be selected according to the actual situation and is not specifically limited here.

[0050] Similarly, as shown in Figure 7, in a double-sided solar cell, the length L of the leakage composite contact structure 40 refers to the length of the orthogonal projection of the edge of the silicon wafer 10 of the leakage composite contact structure 40, that is, the length of the leakage composite contact structure 40 in the vertical or horizontal direction in Figure 7. When the leakage composite contact structure 40 is located on both the left and right edges of the silicon wafer 10, its length L is the length in the vertical direction, and when the leakage composite contact structure 40 is located on both the top and bottom edges of the silicon wafer, its length L is the length in the horizontal direction, that is, it is easily understood to be the length in the vertical or horizontal direction of the composite contact surface of the first dope layer 20 and the second dope layer 30.

[0051] "Unit length of leakage composite contact structure 40" refers to the length of the leakage composite contact structure per unit area, i.e., the ratio of the total length of all leakage composite contact structures 40 to the area of ​​the first surface 11 or second surface 12 of the silicon wafer 10 (i.e., the light-receiving area of ​​the solar cell 100). Here, the first surface 11 and the second surface 12 correspond to the front surface 13 and back surface 14 described above.

[0052] From the above, in the solar cell 100, battery module 200, and photovoltaic power generation system 1000 according to the embodiment of the present invention, the first doping layer 20 and the second doping layer 30 of the solar cell 100 are combined and in contact at a predetermined position 101 to form a leakage composite contact structure 40, and when the reverse voltage applied to both ends of the solar cell 100 is 17V or less, the leakage current per unit length of the leakage composite contact structure 40 is greater than Impp / S / N, where Impp is the maximum output point current of the solar cell 100, S is the area of ​​the solar cell 100, N is the length of the leakage composite contact structure 40 per unit area in the solar cell 100, and N is 4.32 cm / cm 2 The following applies:

[0053] In this way, by introducing a leakage composite contact structure 40 formed by two doping layers of different polarities at a predetermined position 101, and by rationally designing the leakage current per unit length of the leakage composite contact structure 40, the leakage capability of the solar cell 100 can be improved, and the leakage composite contact structure 40 can be given high reverse leakage characteristics. As the leakage capability is improved in this way, on the module side, when the solar cell 100 is shielded, when the leakage current of the solar cell 100 reaches the maximum output point current (Impp), the voltage across the shielded solar cell 100 decreases (the voltage is smaller than the sum of the voltages of other unshielded battery cells connected in series with the battery cell), the heat generated by the solar cell 100 decreases, thereby achieving the objective of controlling the risk of hot spots. Furthermore, according to the technical proposal of the present invention, by intentionally introducing a leakage composite contact structure 40 at a predetermined position 101, a protective effect against hot spots caused by defects in the silicon wafer 10 itself can be achieved (i.e., the amount of heat generated by defects can be reduced), thereby reducing or eliminating the requirement for defect management, lowering the risk of hot spots due to defects, and improving the manufacturing capacity of the solar cell 100. Moreover, in the present invention, by rationally designing the length of the leakage composite contact structure 40 per unit area, excessive efficiency loss can be avoided, and the conversion efficiency of the solar cell 100 can be guaranteed.

[0054] In other words, according to the technical proposal of the present invention, by rationally designing the leakage current per unit length and the length of the leakage current composite contact structure 40 per unit area, it is possible to balance the control of conversion efficiency and hot spot risk, thereby ensuring a reduction in hot spot risk without excessively impairing the conversion efficiency of the solar cell 100, as well as reducing or eliminating the requirements for managing defects in the solar cell 100 and improving the manufacturing capacity of the solar cell 100.

[0055] Furthermore, in the present invention, by introducing a leakage composite contact structure 40 at a predetermined position 101, the effect performed in the battery string is equivalent to that of a bypass diode. Therefore, in some embodiments, the bypass diode can be omitted in the battery module 200 to reduce costs. Of course, in some embodiments, a bypass diode may be provided in the battery module 200, and the invention is not specifically limited here.

[0056] In the embodiments of the present invention, "predetermined position 101" refers to a position where the first dope layer 20 and the second dope layer 30 come into contact and form a composite contact. For example, in a back-contact solar cell, the predetermined position 101 refers to a part or all of the spacing area 50, preferably a part of the area, and a single spacing area 50 may have one or more predetermined positions 101. In a double-sided solar cell, the predetermined position 101 refers to a part or all of the edge of the silicon wafer 10, preferably a part of the area, and each edge of the silicon wafer 10 may have one or more predetermined positions 101, but is not specifically limited here.

[0057] In the solar cell 100, the number of predetermined positions 101 may be multiple, and they may be uniformly or unevenly distributed; in fact, there are no specific limitations here.

[0058] The following describes the specific background and the specific principles of the proposed technology of this invention.

[0059] In the field of solar cell technology, conventional experience suggests that hot spots are typically controlled using a low-leakage current scheme and bypass diodes. By using bypass diodes to limit the voltage across the battery to a certain range and improving defects in the silicon wafer, the leakage current of the battery is reduced, thereby controlling the heat generated at the point of leakage due to defects. However, managing leakage current in battery cells in this way is difficult and therefore hard to implement.

[0060] Specifically, with current crystalline silicon module packaging materials and technologies, when the temperature of a hot spot exceeds 160°C, the packaging material begins to decompose and carbonize, causing cosmetic defects and creating a fire risk.

[0061] As can be seen from Figure 10, the figure shows the relationship between hotspot temperature and the heat generated by it, with the horizontal axis representing heat generated and the vertical axis representing hotspot temperature. The black curve shows the case where the leakage point pitch is large, and the blue curve shows the case where the leakage point pitch is small. In conventional technology, in order to meet the requirements of a hotspot, the hotspot is usually due to a defect point, and as shown by the black curve, the hotspot efficiency is often due to a single-point leakage, and the spacing of the leakage points is large. As can be seen from Figure 10, in order to meet the requirements of a hotspot and avoid fire due to decomposition and carbonization of the package material, the minimum requirement for the heat generated by a single point is that the heat generated must be less than 8.85W.

[0062] Furthermore, referring to Figure 11, which shows an equivalent circuit diagram of a battery module employing a low leakage current scheme in the prior art. In the current state-of-the-art production capacity of high-efficiency batteries such as IBC, TOPCon, and HJT, the open-circuit voltage is typically between 0.73 and 0.755V, with 0.74V being a typical value, and the short-circuit current density is 38-43mA / cm². 2 Therefore, 42mA / cm 2 These values ​​are used as representative values; on the other hand, on the module side, the battery's Vmpp and Jmpp values ​​are 0.634V and 39.5mA / cm², respectively. 2 Assuming the following are representative values, the battery size is 18.2cm x 9.1cm, and the model is type 72, the short-circuit current and Impp current (maximum output point current) are set to 6.95A and 6.54A, respectively.

[0063] As shown in Figure 11, when a single cell (hatched area in the lower left corner of Figure 11) is shielded, the shielded cell employs a low reverse leakage current scheme, causing the voltage across its terminals to rise to its maximum value. Specifically, in this case, as shown in Figure 11, I1 = Isc = 6.95A, and since all batteries employ a low leakage current scheme, the current flowing through them rises to a maximum of the Isc value, where Isc is the short-circuit current; If a point-like leakage current exists between the P / N junction due to a defect,

number

number

[0064] From this, it can be seen that in conventional low-leakage current solutions, the hot spot heating power P = the reverse bias voltage borne × the leakage current at the reverse bias voltage borne; however, the reverse bias voltage borne = the open-circuit voltage of the battery × (number of batteries managed by a single bypass diode - 1) + the start voltage of the bypass diode.

[0065] In conventional technical solutions, for a 72-type module, a single bypass diode manages 24 batteries; as can be seen, for different types and modules, taking the bypass diode startup voltage as 1V as an example, experimental calculations show that if there is a leakage point due to a defect in the silicon wafer, in order to satisfy a hot spot temperature < 160°C, it is necessary to ensure that the leakage current at the reverse bias voltage borne by the battery is < 8.85W / (battery open-circuit voltage × (number of batteries managed by a single bypass diode - 1) + 1V). The results are summarized in Table 1 below, which shows the electrical performance parameters of PERC, Topcon, HJT, and BC modules and the magnitude of the leakage current that needs to be managed. The borne voltage in the table is the reverse bias voltage across the battery cell when it is shielded.

[0066] [Table 1]

[0067] As can be seen from Table 1 above, taking Topcon solar cells as an example, in a 72-type module, the leakage current needs to be reduced to 0.52A with a reverse bias voltage of -17.8V to achieve the goal of suppressing the risk of hotspot failure, and even in a 54-type module, the leakage current needs to be reduced to 0.66A with a reverse bias voltage of -13.4V. This is a difficult problem to overcome given the current manufacturing capacity of the solar power industry, and any defect introduced during the production process of the battery cells could cause the leakage current to exceed the control value.

[0068] Currently, to ensure a high yield and make manufactured products cost-competitive, a -12V bias voltage is typically used to manage leakage current, keeping it below 1A or 0.5A. However, even with certain control over leakage current during the production process, there is still a high risk of hot spots. This is because there is no linear relationship between the magnitude of the reverse leakage current and the reverse bias voltage. When the reverse bias voltage is 18V, the leakage current is more than four times greater than at 12V. In other words, on the module side, if the reverse bias voltage across the shielded battery cells is 18V, the leakage current reaches 2A, and at this point, the heat generated is ~36W, which is more than four times the required level at 160°C. However, directly using the bias voltage on the module side to manage the leakage current of the battery cells results in a significantly lower yield and poor manufacturing capacity due to the extremely high quality requirements for the battery cells.

[0069] From this, it can be seen that employing low leakage current methods in conventional technology to manage leakage current is difficult to implement, has a low yield, and is a problem that is difficult to overcome given the current manufacturing capacity of the solar power generation industry.

[0070] Based on this, the inventors of the present invention have found that in a solar cell 100, if the solar cell 100 has high reverse leakage characteristics (improved leakage capability), a relatively large reverse leakage current can be obtained with a relatively small reverse voltage when the solar cell 100 is shielded. Specifically, for a solar cell 100, when the battery sheath is shielded, as the reverse leakage capability of the battery increases, the reverse leakage current increases, the voltage across the battery is maintained, and the heat generated increases. When the reverse leakage current increases to the maximum current value (Impp), the heat generated also increases to the extreme value of the power.

[0071] However, as the reverse leakage capability of the battery increases, the reverse leakage current remains at its maximum value, but the voltage across the battery decreases compared to batteries with lower leakage capability, resulting in lower heat generation compared to batteries with even lower reverse leakage capability. In other words, as the reverse leakage capability of the battery increases, the reverse leakage current increases, and there is a maximum value for heat generation. As the leakage capability increases further, the heat generation decreases, thereby suppressing the hot spot effect. In short, by improving the leakage capability of the solar cell, high reverse leakage characteristics can be achieved, and when the battery cell is shielded, the reverse leakage current of the battery cell can be brought to its maximum value (i.e., the Impp point of solar cell 100) with a relatively small reverse voltage. From another perspective, as the leakage capability improves, when the reverse leakage current reaches its maximum value, the voltage across the shielded battery decreases, and conversely, the heat generation decreases.

[0072] Furthermore, as the battery's leakage capacity improves, there are extreme values ​​in the generated power, and when the reverse leakage current increases to its maximum current value, the generated power decreases as the leakage capacity improves. When the leakage current reaches the maximum output point current of the solar cell 100, the voltage across the shielded battery is limited by the battery's own reverse current-voltage characteristics, regardless of the number of batteries connected in series. In other words, when a battery cell is shielded, the voltage across it is determined not by the number of battery cells connected in series with it, but by the battery cell's own reverse current-voltage characteristics, and as the leakage capacity improves, the reverse voltage across it decreases.

[0073] Based on this, the inventors of the present invention have discovered that by introducing a specific leakage composite contact structure 40 to the solar cell 100, the solar cell 100 can be given high reverse leakage characteristics, and the objectives of controlling the risk of hot spots and protecting against defects can be achieved. Specifically, by introducing the leakage composite contact structure 40, the reverse bias voltage of the solar cell 100 can be reduced, thereby reducing the heat generated at the heat-generating points due to defects, and further reducing the requirement for managing leakage current during the production process. In addition, considering that the introduction of the leakage composite contact structure 40 affects the efficiency of the battery cell, the desired efficiency loss should be 0.5%.

[0074] Furthermore, after detailed examination and verification, the inventors of the present invention found that in a solar cell 100, the effect of the length of the leakage composite contact structure 40 per unit area on efficiency is 0.1158%, and in an 18.2 × 18.2 solar cell 100, the effect on efficiency is 3.5 × 10 for every 1 cm increase in the length of the leakage composite contact structure 40. -4 I discovered that it is a percentage.

[0075] Therefore, in order to satisfy the requirement of controlling efficiency loss to 0.5% or less, according to the inventors of the present invention, the length N per unit area of ​​the leakage composite contact structure 40 is set to 4.32 cm / cm 2 The inventors of the present invention discovered that the following is necessary. Based on this, after research and verification, they found that in order to effectively manage hot spots by giving the solar cell 100 high reverse leakage characteristics under conditions where the impact on efficiency is 0.5% or less, and to improve manufacturing capacity by reducing leakage current management, it is necessary to ensure that when a reverse voltage of 17V or less is applied to the solar cell 100, the leakage current per unit length of the leakage composite contact structure 40 is greater than Impp / S / N, where Impp is the maximum output point current of the solar cell 100, S is the area of ​​the solar cell 100, N is the length of the leakage composite contact structure 40 per unit area in the solar cell 100, and N is 4.32 cm / cm 2The following conditions are obtained, which provide the technical solution of the present invention, namely, conditions for avoiding excessive loss of efficiency, controlling the risk of hot spots, and improving manufacturing capacity.

[0076] Furthermore, in some embodiments, in order to reduce the efficiency loss of the solar cell 100 to 0.4% or less, the above value N is set to 3.45 cm / cm 2 The following may also be used. This further reduces efficiency losses and allows the solar cell 100 to have high reverse leakage characteristics.

[0077] More preferably, in some embodiments, in order to reduce the efficiency loss of the solar cell 100 to 0.3% or less, the above value N is preferably 2.59 cm / cm 2 The following is the result: This makes it possible to further reduce efficiency losses while giving the solar cell 100 high reverse leakage characteristics.

[0078] In some embodiments, when the reverse voltage applied across the solar cell 100 is 9V, the condition that the leakage current per unit length of the leakage composite contact structure 40 is also greater than Impp / S / N is satisfied. When the reverse voltage applied across the solar cell 100 is 6V, the condition that the leakage current per unit length of the leakage composite contact structure 40 is also greater than Impp / S / N is satisfied.

[0079] In some embodiments, the battery module 200 includes several battery strings, each battery string includes several solar cells 100 connected in series, and bypass diodes are connected in parallel to both ends of the battery strings; Reverse bias voltage across both ends of the shielded solar cell 100 <D×Voc×(M-1)+Lであり: The reverse bias voltage is the voltage across the shielded solar cell 100 when the solar cell 100 is shielded and the leakage current of the shielded solar cell 100 reaches the maximum output point current; Voc is the open-circuit voltage of the solar cell 100, M is the number of solar cells 100 in the battery string connected in parallel with the bypass diode, D is a constant less than 1, and L is the starting voltage of the bypass diode.

[0080] As a result, when the battery module 200 is equipped with a bypass diode and the solar cell 100 is shielded, the reverse bias voltage at which the solar cell 100 operates at its maximum output point current satisfies the above conditions and is smaller than the reverse bias voltage in the conventional method, resulting in less heat generation and thus achieving the objective of controlling the risk of hot spots.

[0081] Specifically, in the following example, V Impp The size is determined by the high reverse leakage current characteristics and leakage capacity of the solar cell 100; the stronger the reverse leakage current, the larger the V. Impp As the reverse leakage capability decreases, the reverse bias voltage across the battery cell decreases when the leakage current of the shielded battery cell reaches the maximum output point current. In other words, according to this technical proposal, when a battery cell is shielded, the reverse voltage across its terminals is smaller than that of the conventional technical proposal. Furthermore, heat generation is reduced, the risk of hot spots due to defects is reduced, and the requirement for controlling leakage current during the production process is also reduced.

[0082] Of course, in some embodiments, the reverse bias voltage across the shielded solar cell 100 in the battery module 200 is <D×Voc×(P-1)であり; The reverse bias voltage is the voltage across the shielded solar cell 100 when the solar cell 100 is shielded and the leakage current of the shielded solar cell 100 reaches the maximum output point current; Voc is the open-circuit voltage of the solar cell 100, P is the number of solar cells 100 connected in series with the shielded solar cell 100, and D is a constant less than 1.

[0083] In other words, in such embodiments, the reverse bias voltage across the shielded solar cell 100 satisfies these conditions regardless of whether a bypass diode is connected in parallel to the battery string. This reduces the heat generated by the shielded solar cell 100, achieving the objective of controlling the risk of hot spots.

[0084] Furthermore, in the above embodiment, the range of possible values ​​for the constant D is preferably 0.1-0.5. As a result, the reverse bias voltage across the shielded solar cell 100 is significantly reduced compared to the voltage in the conventional technology, and the heat generated can be significantly reduced. In other words, by improving the leakage capacity of the solar cell 100, the shielded solar cell 100 can be made to reach its maximum output point current with a small reverse bias voltage.

[0085] In some embodiments, when the solar cell 100 is shielded in the battery module 200, the heat generated by a single leakage composite contact structure 40 is less than 8.85W.

[0086] As a result, when the solar cell 100 is shielded, the heat generated by each leakage composite contact structure 40 is less than 8.85W, thus avoiding the risk of fire caused by excessive heat generation leading to the decomposition and carbonization of the module's packaging material.

[0087] In such embodiments, the heat generated by a single leakage composite contact structure 40 is preferably less than 6.23 W.

[0088] Specifically, as shown in Figure 10, experimental verification reveals that in the solar cell 100, when the spacing of leakage points is large, the heat generated must be controlled to less than 8.85W, and when the spacing of leakage points is small, the heat generated must be controlled to less than 6.23W. Therefore, by controlling the heat generated by each leakage composite contact structure 40 to at least less than 8.85W, preferably less than 6.23W, it is possible to avoid decomposition and carbonization of the module's package material and reduce the risk of fire.

[0089] In some embodiments, the number S of the leakage composite contact structure 40 in the battery module 200 satisfies the following conditions.

number

[0090] This allows for a larger number of leakage composite contact structures 40 on the solar cell 100 to be set so that the heat generated by each leakage composite contact structure 40 does not exceed at least 8.85W. As a result, when the maximum output point current and the reverse bias voltage across the battery cell are constant, the heat generated can be distributed by providing a sufficient number of leakage composite contact structures 40, thus avoiding excessive heat generation at a single point that could cause the package material to decompose and carbonize.

[0091] Specifically, Table 2 below shows the minimum required relationship between the number of leakage current composite contact structures 40 and the total heat generation power.

[0092] [Table 2]

[0093] As can be seen from Table 2 above, in order to achieve the anti-hot spot effect through contact, the minimum number of point-distributed leakage composite contact structures 40 on the battery cell must satisfy (Impp × (V@Impp) / 8.85W or more.

[0094] In some embodiments, S is preferably (Impp × V Impp The power output should be greater than 6.23W. In this way, even if the pitch between adjacent leakage composite structures is small, the package material can be prevented from decomposing and carbonizing.

[0095] Of course, in one possible embodiment, the solar cell 100 may be designed such that the total heat generated by all leakage composite contact structures 40 is less than 8.85W when the solar cell 100 is shielded. In this way, regardless of the number of leakage composite contact structures 40, the total heat generated by all leakage composite contact structures 40 will not exceed 8.85W, and the risk of hotspot fire can be maximized.

[0096] Referring to Figures 3 and 7, in some embodiments, the pitch between two adjacent leakage composite contact structures 40 in the solar cell 100 is 4 cm or more.

[0097] This prevents the leakage current composite contact structure 40 from becoming excessively dense, which would reduce heat dissipation and cause the temperature to rise too much due to excessive heat concentration when the circuit is interrupted.

[0098] Specifically, it is easy to understand that in solar cell 100, the factors influencing the temperature at final thermal equilibrium are 1) power generation; 2) heat capacity of the material; 3) thermal conductivity; and 4) heat dissipation effect.

[0099] Currently, the material combinations for crystalline silicon batteries are relatively fixed, and experimental methods have been used to obtain a single-point heat generation power of <8.85W under certain material heat capacity, thermal conductivity, and heat dissipation conditions. However, when there are multiple heat generation points, their distribution significantly affects the heat dissipation effect. As can be seen from Figure 10, when the heat generation points are far apart, a single-point heat generation power of <8.85W is required, while when a single heat generation point is relatively close, the power requirement is reduced to <6.23W. This is because excessively close heat generation points reduce the temperature gradient around them, worsening the heat dissipation effect.

[0100] Based on this, the inventors of the present invention have found that when the nearest pitch of heating points is 4 cm, a clear effect begins to appear on the surrounding temperature gradient, reducing the heat dissipation effect. Therefore, in order to effectively control the hot spot temperature, it is necessary to control the distance between heating points, and to ensure that multiple heat dissipation points are distributed as evenly as possible on the silicon wafer 10. Based on this, the inventors of the present invention have found that by controlling the pitch between two adjacent leakage composite contact structures 40 to 4 cm or more, a better heat dissipation effect can be achieved, and excessive heat concentration and overheating can be avoided.

[0101] The statement "the pitch between two adjacent leakage composite contact structures 40 is 4 cm or more" is understood to mean that no other leakage composite contact structures 40 exist within a 4 cm radius of one leakage composite contact structure 40 in any direction.

[0102] In some embodiments, when the solar cell 100 is shielded, the leakage current I of the solar cell 100 is within any 4cm x 4cm square area of ​​the solar cell 100. leak It satisfies the following conditions:

number

[0103] This limits the total leakage current of all leakage composite contact structures 40 within a 4x4 square area as described above, preventing excessive concentration and temperature rise in the hot area. At the same time, it limits the total heat generated within the 4x4 square area to less than 8.85W, thereby preventing the package material from decomposing and carbonizing due to temperatures exceeding 160°C.

[0104] Furthermore, in some embodiments, in order to further reduce the fire risk by further reducing the temperature due to heat generation to below 130°C, when the solar cell 100 is shielded, the leakage current I of the solar cell 100 is within any 4cm x 4cm square area of ​​the solar cell 100. leak It can satisfy the following conditions:

number

[0105] Furthermore, in some embodiments, in order to further reduce the risk of fire by further reducing the temperature due to heat generation to less than 110°C, when the solar cell 100 is shielded, the leakage current I of the solar cell 100 is within any 4cm x 4cm square area of ​​the solar cell 100. leak It satisfies the following conditions:

number

[0106] In this specification, any reference terms such as “several examples,” “exemplary examples,” “examples,” “specific examples,” or “several examples” mean that the specific features, structures, materials, or characteristics described with reference to such examples are included in at least one example of the present invention. In this specification, exemplary expressions of the above terms do not necessarily mean the same examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in appropriate form in any one or more examples.

[0107] Furthermore, the above description is merely a preferred embodiment of the present invention and does not limit it. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. [Explanation of Symbols]

[0108] 1000 Solar Power Generation Systems 200 Battery Modules 100 solar cells 101 Designated position 10 silicon wafers 11 First surface 12 Second surface 13 Front 14 Back side 20. First doping layer 30. The second doping layer 40 Earth leakage composite contact structure 50 interval zones 60 First dielectric layer 70 Second dielectric layer 80 Third dielectric layer 90 Fourth dielectric layer 110 Fifth dielectric layer 120 The sixth dielectric layer.

Claims

1. A solar cell comprising a silicon wafer, a first doped layer laminated on the silicon wafer, and a second doped layer laminated on the silicon wafer, The second doping layer has the opposite polarity to the first doping layer, and the second doping layer combines and contacts with the first doping layer at a predetermined position to form a leakage composite contact structure, and when the reverse voltage applied to both ends of the solar cell is 17V or less, the leakage current per unit length of the leakage composite contact structure is greater than Impp / S / N, where Impp is the maximum output point current of the solar cell, S is the area of ​​the solar cell, N is the length of the leakage composite contact structure per unit area in the solar cell, and N is 4.32 cm / cm ２ The following are solar cells.

2. N is 3.45 cm / cm ２ The solar cell according to claim 1, wherein the following:

3. N is 2.59 cm / cm ２ The solar cell according to claim 1, wherein the following:

4. The solar cell according to claim 1, wherein when the reverse voltage applied across both ends of the solar cell is 9V, the leakage current per unit length of the leakage composite contact structure is greater than Impp / S / N.

5. The solar cell according to claim 1, wherein when the reverse voltage applied across both ends of the solar cell is 6V, the leakage current per unit length of the leakage composite contact structure is greater than Impp / S / N.

6. The solar cell according to claim 1, wherein the solar cell is a double-sided solar cell, the silicon wafer has a first surface and a second surface facing each other, the first doped layer is laminated on the first surface, the second doped layer is laminated on the second surface, and the second doped layer and the first doped layer are combined and in contact at a predetermined position on the edge of the silicon wafer to form the leakage composite contact structure.

7. The solar cell is a back-contact solar cell, the silicon wafer has opposing front and back surfaces, some of the first doping layers and some of the second doping layers are laminated on the back surface, some of the first doping layers and some of the second doping layers are arranged alternately in sequence with spacing between them, there is a spacing area between the first doping layers and the second doping layers, and at a predetermined position in the spacing area, the first doping layers and the second doping layers are combined and in contact to form the leakage composite contact structure, as described in claim 1.

8. A battery module comprising some of the solar cells described in any one of claims 1 to 7.

9. The battery module includes several battery strings, each battery string includes several solar cells connected in series, and bypass diodes are connected in parallel to both ends of the battery strings; The reverse bias voltage across both ends of the shielded solar cell is < D × Voc × (M-1) + L; The reverse bias voltage is the voltage across the shielded solar cell when the solar cell is shielded and the leakage current of the shielded solar cell reaches the maximum output point current; The battery module according to claim 8, wherein Voc is the open-circuit voltage of the solar cell, M is the number of solar cells in the battery string connected in parallel with the bypass diode, D is a constant less than 1, and L is the starting voltage of the bypass diode.

10. The battery module includes several battery strings, each of which includes several solar cells connected in series; The reverse bias voltage across the shielded solar cell is < D × Voc × (P-1); The reverse bias voltage is the voltage across the shielded solar cell when the solar cell is shielded and the leakage current of the shielded solar cell reaches the maximum output point current; The battery module according to claim 8, wherein Voc is the open-circuit voltage of the solar cell, P is the number of solar cells connected in series with the shielded solar cell, and D is a constant less than 1.

11. The battery module according to claim 9 or claim 10, wherein the range of possible values ​​for D is 0.1 to 0.

5.

12. The battery module according to claim 8, wherein when the solar cell is shielded, the heat generated by a single leakage composite contact structure in the solar cell is less than 8.85 W.

13. The number S of the leakage composite contact structures in the solar cell satisfies the following conditions: [Math 1] In the formula, Impp is the maximum output point current of the solar cell, and V Ｉｍｐｐ The battery module according to claim 8, wherein the solar cell is shielded and the leakage current of the shielded solar cell reaches the maximum output point current, and S is a positive integer.

14. When the solar cell is shielded, the leakage current I of the solar cell is within any 4cm x 4cm square area of ​​the solar cell. ｌｅａｋ The following conditions must be met: [Math 2] In the formula, I ｌｅａｋ V is the sum of the leakage currents of all the aforementioned leakage composite contact structures located within a 4cm x 4cm square area. Ｉｍｐｐ The battery module according to claim 8, wherein the solar cell is shielded and the leakage current of the shielded solar cell reaches the maximum output point current, and the voltage is the reverse bias voltage across both ends of the shielded solar cell.

15. When the solar cell is shielded, the leakage current I of the solar cell is within any 4cm x 4cm square area of ​​the solar cell. ｌｅａｋ The following conditions must be met: [Math 3] Wherein, I ｌｅａｋ is the sum of leakage currents of all said leakage composite contact structures located within the range of said square, and V Ｉｍｐｐ is the reverse bias voltage across the shaded solar cell when said solar cell is shaded and the leakage current of said shaded solar cell reaches the maximum output point current, the battery module according to claim 14.

16. When the solar cell is shielded, the leakage current I of the solar cell is within any 4cm x 4cm square area of ​​the solar cell. ｌｅａｋ The following conditions must be met: [Math 4] In the formula, I ｌｅａｋ V is the sum of the leakage currents of all the leakage composite contact structures located within the square area, Ｉｍｐｐ The battery module according to claim 15, wherein the solar cell is shielded and the leakage current of the shielded solar cell reaches the maximum output point current, wherein is the reverse bias voltage across both ends of the shielded solar cell.

17. The battery module according to claim 8, wherein the pitch between two adjacent leakage composite contact structures in the solar cell is 4 cm or more.

18. A solar power generation system comprising a battery module according to any one of claims 8 to 17.

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