A back-contact solar cell and its fabrication method, and a photovoltaic module.

Abstract

This application provides a back-contact solar cell and its fabrication method, as well as a photovoltaic module, relating to the field of photovoltaic technology. The fabrication method of the back-contact solar cell includes: providing a back-contact solar cell substrate, the first surface of which has grid lines and solder joints; energizing the solder joints on the grid lines to be processed to apply a reverse bias voltage to the back-contact solar cell substrate; scanning the grid lines to be processed using a first laser to make the grid lines have a first sintered area that receives the first laser scan and a first shaded area that does not receive the first laser scan; and scanning the grid lines to be processed using a second laser to make the grid lines have a second sintered area that receives the second laser scan and a second shaded area that does not receive the second laser scan. The second laser has a different irradiation direction than the first laser, the second sintered area covers the first shaded area, and the first sintered area covers the second shaded area, thereby increasing the area of ​​the grid lines receiving laser action and improving the efficiency of the back-contact solar cell.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, specifically to a back-contact solar cell and its preparation method, and a photovoltaic module. Background Technology

[0002] In the fabrication of back-contact solar cells, laser-assisted sintering is typically performed on the grid lines to achieve good ohmic contact between the grid lines and the silicon substrate. Currently, the laser-assisted sintering process for back-contact solar cells is ineffective, negatively impacting their photoelectric conversion efficiency. Summary of the Invention

[0003] In view of this, this application provides a back-contact solar cell and its preparation method, as well as a photovoltaic module, to help solve the problem that the poor laser-assisted sintering process in the prior art affects the photoelectric conversion efficiency of the back-contact solar cell.

[0004] The first aspect of this application provides a method for fabricating a back-contact solar cell, comprising:

[0005] A back-contact solar cell substrate is provided, wherein a first surface of the back-contact solar cell substrate has grid lines and solder joints connected to the grid lines;

[0006] The solder joints on the grid lines to be processed are energized to apply a reverse bias voltage to the back contact solar cell substrate;

[0007] The grid lines to be processed are scanned using a first laser, so that the grid lines have a first sintering area that receives the first laser scan and a first shielding area that does not receive the first laser scan.

[0008] The grid lines to be processed are scanned using a second laser so that the grid lines have a second sintering area that receives the second laser scan and a second shielding area that does not receive the second laser scan. The second laser has a different irradiation direction than the first laser, the second sintering area covers the first shielding area, and the first sintering area covers the second shielding area.

[0009] In some possible implementations, the gate lines include alternating first gate lines and second gate lines, the polarity of the first gate lines being opposite to that of the second gate lines; the solder joints include a first solder joint connected to the first gate line and a second solder joint connected to the second gate line.

[0010] Methods for fabricating back-contact solar cells include:

[0011] A current is applied to the first solder joint located on the first grid line to apply a reverse bias voltage to the back contact solar cell substrate;

[0012] The first grid line is scanned using a first laser, so that the first grid line has a first sintering area that receives the first laser scan and a first shielding area that does not receive the first laser scan;

[0013] The first grid line is scanned using a second laser to give the first grid line a second sintering region that receives the second laser scan and a second shielding region that does not receive the second laser scan.

[0014] In some possible implementations, the laser-assisted sintering apparatus is used to process back-contact solar cell substrates, and the laser-assisted sintering apparatus includes a probe;

[0015] Methods for fabricating back-contact solar cells include:

[0016] When power is applied to the solder joints on the grid line to be processed, the probes are connected to the solder joints one by one.

[0017] In some possible implementations, the method for fabricating a back-contact solar cell further includes, prior to the step of energizing the solder joints on the grid lines to be processed to apply a reverse bias voltage to the back-contact solar cell substrate:

[0018] Positioning and inspection of grid lines and solder joints;

[0019] Adjust the position of the probes according to the positioning detection results so that the probes correspond one-to-one with the solder points on the grid lines to be processed.

[0020] In some possible implementations, the laser-assisted sintering apparatus further includes a laser emitter and a support stage, wherein the laser emitter, probe, and support stage are arranged along a first direction, and the probe is located between the laser emitter and the support stage;

[0021] Prior to the step of energizing the solder joints on the grid lines to be processed to apply a reverse bias voltage to the back-contact solar cell substrate, the fabrication method of the back-contact solar cell further includes:

[0022] The back-contact solar cell substrate is placed on the support platform with its first surface facing the laser emitter.

[0023] In some possible implementations, the support stage includes a first platform and a second platform spaced apart along a second direction, and the probe includes a first sub-probe and a second sub-probe spaced apart along a second direction, with the first sub-probe located on one side of the first platform along the first direction and the second sub-probe located on one side of the second platform along the first direction; the laser emitter is located between the first sub-probe and the second sub-probe along the second direction.

[0024] Methods for fabricating back-contact solar cells include:

[0025] The back-contact solar cell substrate is placed on the first platform, and the first sub-probe is connected one by one to the solder joints on the grid line to be processed, so as to apply reverse bias voltage to the back-contact solar cell substrate.

[0026] The laser emitter emits a first laser towards the first platform and scans the grating to be processed so that the grating has a first sintering zone and a first shielding zone;

[0027] The back-contact solar cell substrate is placed on the second platform, and the second sub-probe is connected one by one to the solder joints on the grid line to be processed, so as to apply reverse bias to the back-contact solar cell substrate.

[0028] The laser emitter emits a second laser towards the second platform, and the second laser scans the grating lines to be processed, so that the grating lines have a second sintering zone and a second shielding zone.

[0029] In some possible implementations, when scanning the grid lines using the first laser, the first laser scans the grid lines in an S-shaped path, and the scanning speed V1 of the first laser satisfies: 10m / s≤V1≤100m / s.

[0030] In some possible implementations, the spot diameter D1 of the first laser satisfies: 50μm≤D1≤150μm.

[0031] In some possible implementations, the wavelength λ1 of the first laser satisfies: 1000nm≤λ1≤1100nm; and / or, the power P1 of the first laser satisfies: 10w≤P1≤200w.

[0032] In some possible implementations, when scanning the grid lines using the second laser, the second laser scans the grid lines in an S-shaped path, and the scanning speed V2 of the second laser satisfies: 10m / s≤V2≤100m / s.

[0033] In some possible implementations, the spot diameter D2 of the second laser satisfies: 50μm≤D2≤150μm.

[0034] In some possible implementations, the wavelength λ2 of the second laser satisfies: 1000nm≤λ2≤1100nm; and / or, the power P2 of the second laser satisfies: 10w≤P2≤200w.

[0035] In some possible implementations, the spacing D between adjacent solder joints satisfies: 8mm ≤ D ≤ 15mm.

[0036] The second aspect of this application provides a back-contact solar cell, which is prepared by any of the back-contact solar cell preparation methods described above.

[0037] A third aspect of this application provides a photovoltaic module, including a cover plate, an encapsulation layer, and a battery string, wherein the battery string includes a plurality of back-contact solar cells as described above.

[0038] The beneficial effects of this application are: increasing the area of ​​the grid line receiving laser action, reducing the possibility of probe obstruction affecting the laser-assisted sintering effect, so as to achieve good ohmic contact between the grid line and the back contact solar cell substrate, thereby improving the photoelectric conversion efficiency of the back contact solar cell.

[0039] 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

[0040] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 A flowchart illustrating a method for fabricating a back-contact solar cell according to an embodiment of this application;

[0042] Figure 2 This is a schematic diagram of a back-contact solar cell substrate in one embodiment of this application;

[0043] Figure 3 This is a schematic diagram showing the grid lines and solder joints disposed on the first surface of the back-contact solar cell substrate in one embodiment of this application;

[0044] Figure 4 This is a schematic diagram of a laser-assisted sintering device and a back-contact solar cell substrate in one embodiment of this application;

[0045] Figure 5 This is a schematic diagram of the first laser scanning the grid lines in one embodiment of this application;

[0046] Figure 6 This is a schematic diagram of the second laser scanning the grid lines in one embodiment of this application;

[0047] Figure 7 This is a schematic diagram of a laser-assisted sintering device and a back-contact solar cell substrate in another embodiment of this application;

[0048] Figure 8 This is a schematic diagram of a first laser being emitted toward a first platform in one embodiment of this application;

[0049] Figure 9This is a schematic diagram of a second laser being emitted toward a second platform according to an embodiment of this application;

[0050] Figure 10 for Figure 3 A partial schematic diagram;

[0051] Figure 11 A partial structural schematic diagram of a back-contact solar cell provided in an embodiment of this application;

[0052] Figure 12 A partial structural schematic diagram of a back-contact solar cell provided in another embodiment of this application;

[0053] Figure 13 This is a schematic diagram of the structure of a photovoltaic module provided in an embodiment of this application.

[0054] Figure label:

[0055] 10-Back contact solar cell; 11-Back contact solar cell substrate; 111-First surface; 111a-First portion; 111b-Second portion; 112-Second surface; 113-Isolation trench; 12-Grid line; 121-First grid line; 122-Second grid line; 12a-First sintering region; 12b-First shading region; 12c-Second sintering region; 12d-Second shading region; 13-Solder joint; 131-First solder joint; 132-Second solder joint; 14-Tunneling layer; 15-First doped layer; 16-Second doped layer; 17-First passivation layer; 171-First alumina layer; 172-First silicon nitride layer; 18-Second passivation layer; 181-Second alumina layer; 182-Second silicon nitride layer; 19-First doped region;

[0056] 20 - Laser-assisted sintering apparatus; 21 - Probe; 211 - First sub-probe; 211a - First edge sub-probe; 212 - Second sub-probe; 212a - Second edge sub-probe; 22 - Laser emitter; 23 - Support stage; 231 - First platform; 232 - Second platform; 30 - First laser; 40 - Second laser;

[0057] 100 - Photovoltaic module; 101 - First cover plate; 102 - First encapsulation layer; 103 - Battery string; 104 - Second encapsulation layer; 105 - Second cover plate. Detailed Implementation

[0058] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0059] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0060] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0061] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0062] In the fabrication of back-contact solar cells, laser-assisted sintering is typically performed on the grid lines to achieve good ohmic contact between the grid lines and the silicon substrate, thereby improving the photoelectric conversion efficiency of the back-contact solar cell. Currently, laser-assisted sintering of back-contact solar cells faces challenges such as high difficulty and poor performance, impacting both the photoelectric conversion efficiency and the production efficiency of back-contact solar cells.

[0063] like Figure 1 As shown in the embodiment of this application, a method for fabricating a back-contact solar cell is provided, comprising:

[0064] S11: Provides a back-contact solar cell substrate, the first surface of which has grid lines and solder joints connected to the grid lines.

[0065] like Figure 2 As shown, the back contact solar cell substrate 11 provided in step S11 can be an N-type solar cell substrate or a P-type solar cell substrate. The N-type solar cell substrate can be a silicon substrate doped with N-type elements or an initial solar cell substrate with a passivation layer formed on an N-type silicon substrate. Specifically, the N-type element can be a pentavalent element such as phosphorus, arsenic, or antimony. The P-type solar cell substrate can be a silicon substrate doped with P-type elements or an initial solar cell substrate with a passivation layer formed on a P-type silicon substrate. Specifically, the P-type element can be a trivalent element such as boron, indium, or gallium.

[0066] The back-contact solar cell substrate 11 has a first surface 111 and a second surface 112 disposed opposite to each other along its thickness direction. The first surface 111 can be the back side of the back-contact solar cell substrate 11, that is, the surface of the back-contact solar cell substrate 11 that is not directly exposed to sunlight during use. The second surface 112 can be the front side of the back-contact solar cell substrate 11, that is, the surface of the back-contact solar cell substrate 11 that can be directly exposed to sunlight during use. Both the first surface 111 and the second surface 112 can receive sunlight and convert light energy into electrical energy.

[0067] Please also refer to Figure 2 and Figure 3 The first surface 111 is provided with a grid line 12 (i.e. a metal electrode). The grid line 12 includes an alternately arranged first grid line 121 and a second grid line 122. The polarity of the first grid line 121 is opposite to that of the second grid line 122. In other words, one of the first grid line 121 and the second grid line 122 is a positive electrode and the other is a negative electrode.

[0068] The first surface 111 is further provided with solder joints 13 connected to the gate line 12. The solder joints 13 are formed on the gate line 12 and include a first solder joint 131 connected to the first gate line 121 and a second solder joint 132 connected to the second gate line 122. The gate line 12 and the solder joints 13 can be formed by sintering a metal paste, which may include at least one of silver, copper, tin, gold, lead, or nickel.

[0069] The grid lines 12 and solder joints 13 are disposed on the first surface 111, so that the second surface 112 is not blocked by the grid lines 12 and solder joints 13. This reduces the light-shielding area of ​​the second surface 112 of the back-contact solar cell substrate 11, reduces light-shielding loss, and improves the utilization rate of incident light, thereby helping to improve the photoelectric conversion efficiency of the back-contact solar cell product.

[0070] After step S11, the back-contact solar cell substrate can be placed in a laser-assisted sintering apparatus to perform laser-assisted sintering on the grid lines. The steps of the laser-assisted sintering process will be described in detail below.

[0071] Continue as Figure 1 As shown, after step S11, the process proceeds to step S12. S12: The solder joints on the grid lines to be processed are energized to apply a reverse bias voltage to the back contact solar cell substrate.

[0072] The gate line to be processed is the gate line to be subjected to laser-assisted sintering treatment. The gate line to be subjected to laser-assisted sintering treatment can be the first gate line and / or the second gate line mentioned above.

[0073] like Figure 4As shown, the laser-assisted sintering apparatus 20 includes a probe 21 and a support stage 23. The probe 21 and the support stage 23 are electrically connected to the positive and negative terminals (not shown) of an external power supply, respectively. The probe 21 is movable relative to the support stage 23. Please also refer to... Figure 3 In step S12, the back contact solar cell substrate 11 can be placed on the support platform 23, and the probe 21 can be made in contact with the solder joint 13 to apply reverse bias to the back contact solar cell 10.

[0074] In some embodiments, all solder joints on the grid line to be processed are energized, that is, all solder joints on the grid line to be processed are in contact with the probe, so that the current is evenly distributed on the back contact solar cell substrate, reducing the possibility of excessive or insufficient local current on the back contact solar cell substrate, thereby improving the effect of laser-assisted sintering and thus improving the photoelectric conversion efficiency of the back contact solar cell product.

[0075] In some embodiments, a portion of the solder joints on the grid line to be processed are energized. Optionally, the number of solder joints on the grid line to be processed is N, and the number of solder joints that are energized and in contact with the probe is M, where M and N satisfy: 0.4 ≤ M / N ≤ 0.9. By limiting the number of energized solder joints, i.e. limiting the brush depth of the probe used in the laser-assisted sintering process, the possibility of the probe blocking the laser in subsequent laser scanning steps and affecting the laser-assisted sintering effect is reduced, while also achieving good ohmic contact between the grid line and the back-contact solar cell substrate.

[0076] In some embodiments, the reverse bias voltage A applied to the back-contact solar cell substrate satisfies: 10V ≤ A ≤ 25V, such as 10V, 12V, 14V, 16V, 18V, 20V, 22V, 24V, or 25V, or other values ​​within the above range. By limiting the value of the reverse bias voltage, the effect of laser-assisted sintering can be improved without damaging the back-contact solar cell substrate, thereby improving the photoelectric conversion efficiency of the finished back-contact solar cell.

[0077] Continue as Figure 1 As shown, after step S12, the process proceeds to step S13. S13: The gate line to be processed is scanned using a first laser to give the gate line a first sintering area that receives the first laser scan and a first blocking area that does not receive the first laser scan.

[0078] Under the irradiation of the first laser, a large number of charge carriers will be formed in the grid line and the area near the grid line. At the same time, under the action of the reverse bias voltage, the silver ions (Ag+) in the grid line can be reduced to elemental silver (Ag) to achieve good ohmic contact between the grid line and the back contact solar cell substrate, improve the fill factor and open circuit voltage, thereby improving the photoelectric conversion efficiency of the back contact solar cell product.

[0079] Please refer to Figure 5 , Figure 5 The first laser 30 is indicated by a thick dashed line, and the first obstruction area 12b of the gate line 12 is indicated by a thin diagonal line. The laser-assisted sintering apparatus 20 also includes a laser emitter 22, which emits the first laser 30 in step S13. The first laser 30 can scan the gate line 12 along its length. Since the probe 21 of the laser-assisted sintering apparatus 20 obstructs part of the structure of the gate line 12, part of the structure of the gate line 12 can be irradiated by the first laser 30, while part of the structure cannot be irradiated by the first laser 30. Thus, after being scanned by the first laser 30, the gate line 12 has a first sintering area 12a acted upon by the first laser 30 and a first obstruction area 12b not acted upon by the first laser 30.

[0080] Continue as Figure 1 As shown, after step S13, the process proceeds to step S14. S14: The gate line to be processed is scanned using a second laser so that the gate line has a second sintering area that receives the second laser scan and a second blocking area that does not receive the second laser scan. The second laser has a different irradiation direction than the first laser. The second sintering area covers the first blocking area, and the first sintering area covers the second blocking area.

[0081] Please refer to Figure 6 , Figure 6 The second laser 40 is indicated by a thick dashed line, and the second blocking region 12d of the gate line 12 is indicated by a thin diagonal line. In step S14, the second laser 40 can be emitted from the laser emitter 22. The second laser 40 has the same function as the first laser 30, which will not be described again here. The second laser 40 scans the gate line 12 along its length. Due to the blocking by the probe 21, a part of the structure of the gate line 12 can be irradiated by the second laser 40, while another part cannot be irradiated by the second laser 40. Thus, after being scanned by the second laser 40, the gate line 12 has a second sintering region 12c affected by the second laser 40 and a second blocking region 12d not affected by the second laser 40.

[0082] Please also refer to Figure 5 and Figure 6 The second laser 40 has a different irradiation direction than the first laser 30. For example, the first laser 30 and the second laser 40 can irradiate the gate line 12 from both sides of the probe 21, so that the second sintering region 12c covers the first shielding region 12b, and the first sintering region 12a covers the second shielding region 12d. In other words, the second laser 40 can irradiate the area of ​​the gate line 12 that is not irradiated by the first laser 30, and the first laser 30 can irradiate the area of ​​the gate line 12 that is not irradiated by the second laser 40.

[0083] By using lasers from different directions to scan the grid lines twice, the area of ​​the grid lines receiving laser action is increased, reducing the possibility of probe obstruction affecting the laser-assisted sintering effect. This achieves good ohmic contact between the grid lines and the back-contact solar cell substrate, thereby improving the photoelectric conversion efficiency of the back-contact solar cell.

[0084] In some embodiments, the laser emitter is provided with a galvanometer, which can adjust the direction and angle of laser irradiation to enable the first laser and the second laser to move along the length of the grid line to scan the grid line without moving the laser emitter, and to make the first laser and the second laser irradiate in different directions.

[0085] In some embodiments, the laser emitter can move relative to the back-contact solar cell substrate to irradiate the back-contact solar cell substrate with laser light in different directions, and enable the laser light to move along the length of the grid lines to scan the grid lines.

[0086] In some embodiments, the laser-assisted sintering apparatus includes probe rows, the number of which may be the same as the number of grid lines to be processed on the back-contact solar cell substrate, and the probe rows are arranged in a one-to-one correspondence with the grid lines to be processed. Each probe row has multiple probes, the number of which may be the same as the number of solder joints on the grid lines to be processed, and the probe rows are arranged in a one-to-one correspondence with the solder joints.

[0087] like Figure 3 and 4 As shown, in some possible implementations, when the solder joints 13 on the grid line 12 to be processed are energized, the probe 21 is connected to the solder joints 13 in a one-to-one correspondence, so that all the solder joints 13 on the grid line 12 to be processed can be energized at the same time, thereby achieving a uniform distribution of current on the back contact solar cell substrate 11, so as to improve the effect of laser-assisted sintering.

[0088] In some possible implementations, prior to step S12 above, the method for fabricating a back-contact solar cell further includes:

[0089] S15: Perform positioning and inspection on the grid lines and solder joints.

[0090] In step S15, detection equipment such as a vision camera can be used to obtain the position information of the grid lines and solder joints on the back-contact solar cell substrate.

[0091] After step S15, proceed to step S16. S16: Adjust the position of the probe according to the positioning detection result so that the probe corresponds one-to-one with the solder joints on the gate line to be processed.

[0092] In step S16, the probe is corrected based on the obtained position information of the grid line and solder joint to improve the accuracy of the probe position, thereby ensuring good contact between the probe and the corresponding solder joint.

[0093] like Figure 7 As shown, in some possible embodiments, the laser emitter 22, probe 21, and support stage 23 are arranged along the first direction P, with probe 21 located between the laser emitter 22 and the support stage 23. Prior to step S12, the method for fabricating a back-contact solar cell further includes:

[0094] S17: Place the back-contact solar cell substrate 11 on the support platform 23, with the first surface 111 facing the laser emitter 22.

[0095] In related technologies, during laser-assisted sintering of back-contact solar cell substrates, the first surface (i.e., the back side) of the substrate faces the support platform, meaning the grid lines and solder joints face the platform. A probe is positioned below the platform to contact the solder joints. The laser emitter is positioned above the platform, and the laser first irradiates the second surface (i.e., the front side) of the substrate before acting on the first surface. Because the first surface of the substrate faces the platform, accurate positioning of the grid lines and solder joints is difficult, increasing the difficulty of contact between the solder joints and the probe. Simultaneously, precise laser scanning of the grid lines is challenging, requiring a larger laser spot area to ensure scanning of the grid lines, increasing the requirements for spot shaping. This makes the laser-assisted sintering process difficult and hinders its large-scale application.

[0096] Compared to related technologies, such as Figure 7 As shown, in this embodiment, the first surface 111 of the back-contact solar cell substrate 11 is positioned away from the support stage 23, meaning that the grid lines and solder joints (not shown in the figure) are positioned away from the support stage 23 and towards the laser emitter 22 and probe 21. This facilitates accurate positioning of the grid lines and solder joints, thereby improving the alignment accuracy between the probe 21 and the solder joints and reducing the contact difficulty between the solder joints and the probe 21. At the same time, the laser can be directly used on the grid lines to achieve precise scanning of the grid lines. In other words, a small area of ​​light spot can be used to scan the grid lines, thereby reducing the requirements for light spot shaping and thus reducing the process difficulty of laser-assisted sintering, which is beneficial for large-scale applications.

[0097] like Figure 8 As shown, Figure 8The first laser 30 is indicated by a thick dashed line, and the centerline L of the laser emitter 22 is indicated by a thick dotted line. In some possible embodiments, the support stage 23 includes a first platform 231 and a second platform 232 spaced apart along a second direction Q. The probe 21 includes a first sub-probe 211 and a second sub-probe 212 spaced apart along the second direction Q. The first sub-probe 211 is located on one side of the first platform 231 along the first direction P and is movable relative to the first platform 231. The second sub-probe 212 is located on one side of the second platform 232 along the first direction P and is movable relative to the second platform 232. The laser emitter 22 is located between the first sub-probe 211 and the second sub-probe 212 along the second direction Q.

[0098] The laser emitter 22 has a centerline L in the first direction P. A first platform 231 and a second platform 232 are located on opposite sides of the centerline L along the second direction Q. The distance from the first platform 231 to the centerline L along the second direction Q can be the same as the distance from the second platform 232 to the centerline L along the second direction Q. A first sub-probe 211 and a second sub-probe 212 are located on opposite sides of the centerline L along the second direction Q. The first sub-probe 211 closest to the centerline L among the plurality of first sub-probes 211 is the first edge sub-probe 211a. The second sub-probe 212 closest to the centerline L among the plurality of second sub-probes 212 is the second edge sub-probe 212a. The distance from the first edge sub-probe 211a to the centerline L along the second direction Q can be the same as the distance from the second edge sub-probe 212a to the centerline L along the second direction Q.

[0099] Methods for fabricating back-contact solar cells include:

[0100] S21: Provides a back-contact solar cell substrate.

[0101] The back-contact solar cell substrate provided in step S21 is the same as the back-contact solar cell substrate provided in step S11 above, and will not be described again here.

[0102] After step S21, proceed to step S22. S22: As... Figure 3 and 8 As shown, the back contact solar cell substrate 11 is placed on the first platform 231, and the first sub-probe 211 is connected one-to-one with the solder joint 13 located on the grid line 12 to be processed, so as to apply reverse bias voltage to the back contact solar cell substrate 11.

[0103] In step S22, when the back-contact solar cell substrate 11 is placed on the first platform 231, the first surface of the back-contact solar cell substrate 11 faces the laser emitter 22.

[0104] After step S22, proceed to step S23. S23: As... Figure 5 and Figure 8 As shown, the laser emitter 22 emits a first laser 30 toward the first platform 231, and the first laser 30 scans the grid line 12 to be processed, so that the grid line 12 has a first sintering region 12a and a first shielding region 12b. After the first laser 30 completes the scan, the back contact solar cell substrate 11 on the first platform 231 is removed.

[0105] After step S23, proceed to step S24. S24: As... Figure 3 and Figure 9 As shown, the back-contact solar cell substrate 11 is placed on the second platform 232, and the second sub-probe 212 is connected one-to-one with the solder joint 13 located on the grid line 12 to be processed, so as to apply reverse bias to the back-contact solar cell substrate 11.

[0106] In step S24, when the back-contact solar cell substrate 11 is placed on the second platform 232, the first surface of the back-contact solar cell substrate 11 faces the laser emitter 22.

[0107] After step S24, proceed to step S25. S25: As... Figure 6 and Figure 9 As shown, the laser emitter 22 emits a second laser 40 toward the second platform 232, and the second laser 40 scans the gate line 12 to be processed, so that the gate line 12 has a second sintering region 12c and a second shielding region 12d.

[0108] As mentioned above, the second laser 40 and the first laser 30 have different irradiation directions, causing the second sintering region 12c to cover the first shielding region 12b, and the first sintering region 12a to cover the second shielding region 12d. By using a single laser emitter to irradiate lasers in different directions to scan the grid lines twice, the area of ​​the grid lines receiving laser action is increased, reducing the possibility of probe shielding affecting the laser-assisted sintering effect. This achieves good ohmic contact between the grid lines and the back-contact solar cell substrate, thereby improving the photoelectric conversion efficiency of the finished back-contact solar cell. Furthermore, the laser-assisted sintering device in this embodiment has a relatively simple structure, is easy to manufacture and maintain, and helps reduce the production cost of back-contact solar cells.

[0109] Please also refer to Figure 8 and Figure 9During the continuous processing of multiple back-contact solar cell substrates 11, while performing laser scanning on the back-contact solar cell substrates 11 located on the first platform 231, the back-contact solar cell substrates 11 that have already undergone laser scanning on the second platform 232 can be removed. This allows the back-contact solar cell substrates 11 on the first platform 231 to undergo laser scanning on the second platform 232 without waiting after completing the laser scanning, thereby saving processing time and improving processing efficiency.

[0110] In some possible implementations, when scanning the grid lines using the first laser, the first laser scans the grid lines in an S-shaped path, and the scanning speed V1 of the first laser satisfies: 10m / s≤V1≤100m / s.

[0111] The first laser moves in an S-shape, meaning that after scanning a grid line along its length from the beginning to the end, the first laser then scans the next adjacent grid line along its length from the end to the beginning, and so on.

[0112] The scanning speed V1 of the first laser can be 10 m / s, 20 m / s, 30 m / s, 40 m / s, 50 m / s, 60 m / s, 70 m / s, 80 m / s, 90 m / s, or 100 m / s, or other values ​​within the above range. If the first laser scanning speed is too slow, it can easily damage the back-contact solar cell substrate and grid lines, thus affecting the yield of the back-contact solar cell. If the first laser scanning speed is too fast, it can easily prevent the grid lines from forming a good contact with the back-contact solar cell substrate, thus affecting the efficiency of the back-contact solar cell. Therefore, by limiting the scanning speed of the first laser, good contact between the grid lines and the back-contact solar cell substrate can be achieved while ensuring that the grid lines and the back-contact solar cell substrate are not damaged, thereby improving the efficiency of the back-contact solar cell while ensuring its quality.

[0113] In some possible implementations, the spot diameter D1 of the first laser satisfies: 50μm ≤ D1 ≤ 150μm. For example, D1 can be 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, or 150μm, or other values ​​within the above range. By limiting the size of the spot, it is beneficial to achieve precise scanning of the grating lines by the first laser and reduce the requirements for spot shaping, thereby reducing the difficulty of laser-assisted sintering and facilitating mass production.

[0114] In some embodiments, the diameter of the first laser spot is greater than or equal to the width of the grid line, so that the first laser spot can cover the grid line. In some embodiments, the shape of the first laser spot can be circular, square, or rectangular, and can be selected according to the actual processing needs.

[0115] In some possible implementations, the wavelength λ1 of the first laser satisfies: 1000nm ≤ λ1 ≤ 1100nm. The first laser can be infrared light, and its wavelength λ1 can be 1000nm, 1010nm, 1020nm, 1030nm, 1040nm, 1050nm, 1060nm, 1064nm, 1070nm, 1080nm, 1090nm or 1100nm, or other values ​​within the above range.

[0116] The power P1 of the first laser satisfies: 10w≤P1≤200w. The power P1 can be 10w, 20w, 40w, 50w, 60w, 80w, 100w, 120w, 140w, 160w, 180w, 190w or 200w, or other values ​​within the above range.

[0117] The wavelength and power of the first laser meet the above range, so that the spot energy of the first laser is moderate, thus ensuring the effect of laser-assisted sintering.

[0118] In some possible implementations, the wavelength λ1 of the first laser satisfies: 1000nm≤λ1≤1100nm, or the power P1 of the first laser satisfies: 10w≤P1≤200w.

[0119] Optionally, the first laser can be a green laser, with a wavelength of approximately 532nm.

[0120] Optionally, the first laser can be ultraviolet light with a wavelength of approximately 355 nm.

[0121] In some possible implementations, when scanning the grid lines using the second laser, the second laser scans the grid lines in an S-shaped path, and the scanning speed V2 of the second laser satisfies: 10m / s≤V2≤100m / s.

[0122] The S-shaped scanning path has been described above and will not be repeated here. The scanning speed V1 of the second laser can be 10m / s, 20m / s, 30m / s, 40m / s, 50m / s, 60m / s, 70m / s, 80m / s, 90m / s, or 100m / s, or other values ​​within the above range. In some embodiments, the scanning speed of the second laser can be greater than or equal to the scanning speed of the first laser to reduce the possibility of damage to the back contact solar cell substrate and grid lines while ensuring the sintering effect.

[0123] In some possible implementations, the spot diameter D2 of the second laser satisfies: 50μm ≤ D2 ≤ 150μm. For example, D2 can be 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, or 150μm, or other values ​​within the above range. By limiting the spot size, it is easier to achieve precise scanning of the grating lines by the second laser, and the requirements for spot shaping are reduced, thereby reducing the difficulty of laser-assisted sintering and facilitating mass production.

[0124] In some embodiments, the diameter of the second laser spot is greater than or equal to the width of the grid line, so that the second laser spot can cover the grid line. In some embodiments, the shape of the second laser spot can be circular, square, or rectangular, and can be selected according to the actual processing needs.

[0125] In some possible implementations, the wavelength λ2 of the second laser satisfies: 1000nm ≤ λ2 ≤ 1100nm. The second laser can be infrared light, and its wavelength λ2 can be 1000nm, 1010nm, 1020nm, 1030nm, 1040nm, 1050nm, 1060nm, 1064nm, 1070nm, 1080nm, 1090nm, or 1100nm, or other values ​​within the above range.

[0126] The power P2 of the second laser satisfies: 10w≤P2≤200w. The power P2 can be 10w, 20w, 40w, 50w, 60w, 80w, 100w, 120w, 140w, 160w, 180w, 190w or 200w, or other values ​​within the above range.

[0127] The wavelength and power of the second laser meet the above range, so that the spot energy of the second laser is moderate, thus ensuring the effect of laser-assisted sintering.

[0128] In some possible implementations, the wavelength λ2 of the second laser satisfies: 1000nm≤λ2≤1100nm, or the power P2 of the second laser satisfies: 10w≤P1≤200w.

[0129] Optionally, the second laser can be a green laser, with a wavelength of approximately 532nm.

[0130] Optionally, the second laser can be ultraviolet light with a wavelength of approximately 355 nm.

[0131] In some possible implementations, the power of the second laser can be equal to or less than the power of the first laser, in order to reduce the possibility of damage to the back contact solar cell substrate and grid lines while ensuring the sintering effect.

[0132] like Figure 10 As shown, in some possible implementations, the spacing distance D between adjacent solder joints 13 satisfies: 8mm≤D≤15mm. For example, D can be 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm or 15nm, or other values ​​within the above range.

[0133] Specifically, the spacing between adjacent first solder joints 131, the spacing between adjacent second solder joints 132, and the spacing between adjacent first solder joints 131 and second solder joints 132 all satisfy the above-mentioned range.

[0134] If the density of solder joints 13 is too high, it will increase the shading area and affect the bifaciality of the back-contact solar cell. If the density of solder joints 13 is too low, there will be too few points of contact with the probe, making it difficult for the current to be evenly distributed on the back-contact solar cell substrate during laser-assisted sintering, thus affecting the sintering effect. Therefore, this embodiment limits the arrangement distance of solder joints 13 to improve the bifaciality of the back-contact solar cell while ensuring the effect of laser-assisted sintering.

[0135] In some possible implementations, the grid line to be processed is the first grid line, that is, the first grid line is subjected to laser-assisted sintering treatment. The first grid line can be the positive electrode. Based on this, the fabrication method of the back contact solar cell includes:

[0136] S31: Provides a back-contact solar cell substrate.

[0137] After step S31, proceed to step S32. S32: Power is applied to the first solder joint located on the first grid line to apply a reverse bias voltage to the back contact solar cell substrate.

[0138] After step S32, proceed to step S33. S33: Scan the first gate line using the first laser to make the first gate line have a first sintering area that receives the first laser scan and a first blocking area that does not receive the first laser scan.

[0139] After step S33, proceed to step S34. S34: Use the second laser to scan the first gate line so that the first gate line has a second sintering region that receives the second laser scan and a second blocking region that does not receive the second laser scan.

[0140] As mentioned above, the second laser has a different irradiation direction than the first laser, causing the second sintering region to cover the first shielding region, and the first sintering region to cover the second shielding region. In some embodiments of this application, laser-assisted sintering can be performed only on the positive electrode of the back-contact solar cell to achieve good ohmic contact between the positive electrode and the back-contact solar cell substrate.

[0141] In some other possible implementations, the grid line to be processed is a first grid line, which can be a negative electrode. In some embodiments of this application, only the negative electrode of the back-contact solar cell may be subjected to laser-assisted sintering to achieve good ohmic contact between the negative electrode and the back-contact solar cell substrate.

[0142] In some other possible implementations, the grid lines to be processed are a first grid line and a second grid line, where the first grid line can be the positive electrode and the second grid line can be the negative electrode. In some embodiments of this application, the positive and negative electrodes of the back-contact solar cell can be laser-assisted sintering, thereby improving the photoelectric conversion efficiency of the back-contact solar cell through good ohmic contact between the positive and negative electrodes and the back-contact solar cell substrate.

[0143] In this embodiment of the application, after the laser-assisted sintering described above, the back contact solar cell can be subjected to quality inspection to ensure the yield of the finished back contact solar cell.

[0144] The preparation method of back-contact solar cells has been described above. The structure of back-contact solar cells will be introduced below.

[0145] This application provides a back-contact solar cell, which is prepared by the back-contact solar cell preparation method described above.

[0146] like Figure 11 As shown, the back contact solar cell 10 includes a back contact solar cell substrate 11, and a first surface 111 and a second surface 112 disposed opposite to each other along its own thickness direction Z. The first surface 111 includes an alternately arranged first portion 111a and a second portion 111b.

[0147] In some embodiments, the back-contact solar cell substrate 11 can be a silicon substrate doped with N-type elements. A tunneling layer 14 and a first doped layer 15 are disposed on a first portion 111a, and a tunneling layer 14 and a second doped layer 16 are disposed on a second portion 111b. A first gate line 121 can be disposed on the first doped layer 15 and electrically connected to the first doped layer 15. A second gate line 122 can be disposed on the second doped layer 16 and electrically connected to the second doped layer 16.

[0148] The first doped layer 15 may be doped with a p-type element (e.g., boron), and may include at least one of p-type doped amorphous silicon, p-type doped polycrystalline silicon, p-type doped microcrystalline silicon, and p-type doped silicon carbide. The second doped layer 16 is doped with an n-type element (e.g., phosphorus), and may include at least one of n-type doped amorphous silicon, n-type doped polycrystalline silicon, n-type doped microcrystalline silicon, and n-type doped silicon carbide. In some embodiments, the concentration of the n-type element doped in the second doped layer 16 may be greater than the concentration of the n-type element doped in the back contact solar cell substrate 11.

[0149] The tunneling layer 14 may include at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, amorphous silicon, and polycrystalline silicon. In some embodiments, the tunneling layer 14 may include a P-type tunneling layer corresponding to the first doped layer 15 (i.e., the tunneling layer contains a P-type dopant element) and an N-type tunneling layer corresponding to the second doped layer 16 (i.e., the tunneling layer contains an N-type dopant element). Specifically, the tunneling layer 14 located on the side of the first doped layer 15 may be a P-type tunneling layer, and the tunneling layer 14 located on the side of the second doped layer 16 may be an N-type tunneling layer.

[0150] A first passivation layer 17 may also be disposed on the first surface 111. The first passivation layer 17 may be located on the side of the first doped layer 15 and the second doped layer 16 away from the back contact solar cell substrate 11. The first passivation layer 17 may include at least one of silicon oxide, silicon nitride, silicon oxynitride, titanium oxide, and aluminum oxide. A second passivation layer 18 may be disposed on the second surface 112. The first passivation layer 17 may include at least one of silicon oxide, silicon nitride, silicon oxynitride, titanium oxide, and aluminum oxide.

[0151] The first passivation layer 17 and the second passivation layer 18 can enhance the carrier concentration on the surface of the back contact solar cell 10, increase the short-circuit current and open-circuit voltage of the back contact solar cell 10, and thus improve the cell efficiency.

[0152] In some embodiments, along the thickness direction Z of the back contact solar cell 10, the distance from the first portion 111a to the second surface 112 can be greater than the distance from the second portion 111b to the second surface 112. That is, the second doped layer 16 can be closer to the second surface 112 than the first doped layer 15, so that the second doped layer 16 and the first doped layer 15 are misaligned in the thickness direction Z of the back contact solar cell 10, reducing the possibility of leakage current between the first doped layer 15 and the second doped layer 16, thereby improving the reliability of the back contact solar cell 10 and improving the photoelectric conversion efficiency and output power of the back contact solar cell 10.

[0153] In some embodiments, an isolation groove 113 recessed from the first surface 111 to the second surface 112 may be provided between adjacent first portions 111a and second portions 111b. The isolation groove 113 separates the first doped layer 15 and the second doped layer 16, reducing the possibility of leakage current between the second doped layer 16 and the first doped layer 15, thereby improving the reliability of the back contact solar cell 10 and improving the photoelectric conversion efficiency and output power of the back contact solar cell 10.

[0154] In some embodiments, the first and second portions have pyramid-shaped microstructures.

[0155] In some embodiments, the first part and the second part have a pyramid-shaped microstructure and a planar structure, respectively.

[0156] In some embodiments, the second surface has a pyramidal microstructure.

[0157] like Figure 12 As shown, in some embodiments, the first portion 111a may have a pyramidal microstructure, and the second portion 111b may have a planar structure. The back-contact solar cell 10 has a first doped region 19, which is located inside or on the back-contact solar cell substrate 11 corresponding to the first portion 111a. The first doped region 19 is doped with a P-type element (e.g., boron), and can form a PN junction with the back-contact solar cell substrate 11. A tunneling layer 14 and a second doped layer 16 are disposed on the second portion 111b. The second doped layer 16 is doped with an N-type element, and the tunneling layer 14 can be an N-type tunneling layer. The tunneling layer 14 and the second doped layer 16 have been described above and will not be repeated here. A first gate line 121 may be disposed on and connected to the first doped region 19. A second gate line 122 may be disposed on and electrically connected to the second doped layer 16.

[0158] A first passivation layer 17 is also provided on the first surface 111. The first passivation layer 17 includes a first aluminum oxide layer 171 and a first silicon nitride layer 172. The first aluminum oxide layer 171 may be located on the side of the first silicon nitride layer 172 facing the back contact solar cell substrate 11.

[0159] The second surface 112 may have a pyramidal microstructure, and a second passivation layer 18 may be disposed on the second surface 112. The second passivation layer 18 includes a second aluminum oxide layer 181 and a second silicon nitride layer 182. The second aluminum oxide layer 181 may be located on the side of the second silicon nitride layer 182 facing the back contact solar cell substrate 11. The effects of providing the first passivation layer 17 and the second passivation layer 18 have been described above and will not be repeated here.

[0160] like Figure 13 As shown, this application provides a photovoltaic module 100, including a cover plate, an encapsulation layer, and a battery string 103, wherein the battery string 103 includes a plurality of back-contact solar cells as described above.

[0161] The photovoltaic module 100 is equipped with a first cover plate 101 at the top and a second cover plate 105 at the bottom. A first encapsulation layer 102 is located between the first cover plate 101 and the battery string 103, and a second encapsulation layer 104 is located between the second cover plate 105 and the battery string 103. The first cover plate 101, first encapsulation layer 102, battery string 103, second encapsulation layer 104, and second cover plate 105 can be arranged along the thickness direction Z of the photovoltaic module 100 and laminated together. The first cover plate 101 can be a glass cover plate with high light transmittance. The first encapsulation layer 102 bonds the first cover plate 101 to the battery string 103, providing encapsulation and protection for the battery string 103. The material of the first encapsulation layer 102 can be one or more of ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), and polyvinyl butyral (PVB). The second encapsulation layer 104 connects the battery string 103 to the second cover plate 105, and also provides encapsulation and protection for the battery string 103. The material of the second encapsulation layer 104 can be one or more of the aforementioned EVA, POE, and PVB. The material of the second cover plate 105 can be glass, or the second cover plate 105 can also be composed of multiple polymer film layers.

[0162] The above are merely optional embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method of fabricating a back contact solar cell, characterized by, The application relates to a back contact solar cell substrate and a preparation method thereof. The application provides a back contact solar cell substrate, a first surface of the back contact solar cell substrate having grid lines and welding points connected with the grid lines; The welding points on the grid lines to be processed are electrified to apply a reverse bias to the back contact solar cell substrate; The first laser is used to scan the grid lines to be processed, so that the grid lines have first sintering areas receiving the first laser scanning and first shielding areas not receiving the first laser scanning and being shielded by a laser-assisted sintering device used for processing the back contact solar cell substrate; The second laser is used to scan the grid lines to be processed, so that the grid lines have second sintering areas receiving the second laser scanning and second shielding areas not receiving the second laser scanning and being shielded by the laser-assisted sintering device used for processing the back contact solar cell substrate, wherein the second laser is different from the first laser in an irradiation direction, the second sintering areas cover the first shielding areas, and the first sintering areas cover the second shielding areas.

2. The method of producing a back contact solar cell according to claim 1, wherein The grid lines comprise first grid lines and second grid lines arranged alternately, the first grid lines having a polarity opposite to that of the second grid lines; and the welding points comprise first welding points connected with the first grid lines and second welding points connected with the second grid lines. The preparation method of the back contact solar cell comprises the following steps: The first welding points on the first grid lines are electrified to apply a reverse bias to the back contact solar cell substrate; The first laser is used to scan the first grid lines to make the first grid lines have first sintering areas receiving the first laser scanning and first shielding areas not receiving the first laser scanning; The second laser is used to scan the first grid lines to make the first grid lines have second sintering areas receiving the second laser scanning and second shielding areas not receiving the second laser scanning.

3. The method of producing a back contact solar cell according to claim 1, wherein The laser-assisted sintering device comprises a probe; The preparation method of the back contact solar cell comprises the following steps: When the welding points on the grid lines to be processed are electrified, the probe is connected with the welding points one by one.

4. The method of producing a back contact solar cell according to claim 3, wherein Before the step of electrifying the welding points on the grid lines to be processed to apply a reverse bias to the back contact solar cell substrate, the preparation method of the back contact solar cell further comprises the following steps: Positioning detection is conducted on the grid lines and the welding points; According to the positioning detection result, the position of the probe is adjusted to make the probe correspond to the welding points on the grid lines to be processed one by one.

5. The method of producing a back contact solar cell according to claim 3, wherein The laser-assisted sintering device further comprises a laser emitter and a bearing table, the laser emitter, the probe and the bearing table are arranged along a first direction, and the probe is located between the laser emitter and the bearing table; Before the step of electrifying the welding points on the grid lines to be processed to apply a reverse bias to the back contact solar cell substrate, the preparation method of the back contact solar cell further comprises the following steps: The back contact solar cell substrate is placed on the bearing table, and the first surface faces the laser emitter.

6. The method of producing a back contact solar cell according to claim 5, wherein The carrier table comprises a first platform and a second platform arranged at intervals along a second direction, and the probe comprises a first sub-probe and a second sub-probe arranged at intervals along the second direction, the first sub-probe being located on one side of the first platform along the first direction, and the second sub-probe being located on one side of the second platform along the first direction; The laser emitter is located between the first sub-probe and the second sub-probe along the second direction; The preparation method of the back contact solar cell comprises: placing the back contact solar cell substrate on the first platform and connecting the first sub-probe with the soldering points on the grid lines to be processed one by one to apply a reverse bias to the back contact solar cell substrate; The laser emitter emits the first laser towards the first platform, and the first laser scans the grid lines to be processed to make the grid lines have the first sintering area and the first shielding area; placing the back contact solar cell substrate on the second platform and connecting the second sub-probe with the soldering points on the grid lines to be processed one by one to apply a reverse bias to the back contact solar cell substrate; The laser emitter emits the second laser towards the second platform, and the second laser scans the grid lines to be processed to make the grid lines have the second sintering area and the second shielding area.

7. The method of producing a back contact solar cell according to any one of claims 1 to 6, characterized in that, When the first laser scans the grid lines, the first laser scans the grid lines in an S-shaped path, and the scanning speed V1 of the first laser satisfies: 10 m / s≤V1≤100 m / s.

8. The method of producing a back contact solar cell according to claim 7, wherein The spot diameter D1 of the first laser satisfies: 50 μm≤D1≤150 μm.

9. The method of producing a back contact solar cell according to claim 8, wherein The wavelength λ1 of the first laser satisfies: 1000 nm≤λ1≤1100 nm; and / or, The power P1 of the first laser satisfies: 10 w≤P1≤200 w.

10. The method of producing a back contact solar cell according to any one of claims 1 to 6, characterized in that, When the second laser scans the grid lines, the second laser scans the grid lines in an S-shaped path, and the scanning speed V2 of the second laser satisfies: 10 m / s≤V2≤100 m / s.

11. The method of producing a back contact solar cell according to claim 10, wherein The spot diameter D2 of the second laser satisfies: 50 μm≤D2≤150 μm.

12. The method of producing a back contact solar cell according to claim 11, wherein The wavelength λ2 of the second laser satisfies: 1000 nm≤λ2≤1100 nm; and / or, The power P2 of the second laser satisfies: 10 w≤P2≤200 w.

13. The method of producing a back contact solar cell according to any one of claims 1 to 6, characterized in that, The interval distance D between adjacent soldering points satisfies: 8 mm≤D≤15 mm.

14. A back contact solar cell, characterized by The back contact solar cell is prepared by the preparation method of the back contact solar cell according to any one of claims 1 to 13.

15. A photovoltaic module, characterized by, The back contact solar cell comprises a cover plate, an encapsulation layer, and a battery string. The battery string comprises a plurality of back contact solar cells according to claim 14.

Images