Photovoltaic cell welding method and device based on induced current thermal effect

Abstract

The present invention relates to the field of photovoltaic cell welding technology, and specifically to a photovoltaic cell welding method and device based on the induced current thermal effect. A photovoltaic cell with a PN junction structure is used, and a plurality of welding strips are distributed on the P-type end and the N-type end of the photovoltaic cell, so that the welding strips are closely fitted and contacted with the grid lines on the surface of the photovoltaic cell; the P-type end and the N-type end are respectively connected to the negative pole and the positive pole of the power supply, and a reverse voltage is applied to the PN junction in the photovoltaic cell; an inducing medium is applied to the fitting area, so that the PN junction is reversely conducted, and current flows in the photovoltaic cell and the welding strip and a current thermal effect occurs, so that the fitting area reaches the welding temperature and the welding is completed. The characteristics of the PN junction of the photovoltaic cell itself are utilized, and by controlling the application of the inducing medium, the excitation of the carriers at the PN junction of the photovoltaic cell is controlled, so as to realize the control of the current on and off of the heating circuit, so that the local welding position can reach the welding temperature more easily and quickly, and the heating effect is stable and very easy to control.

Description

Technical Field

[0001] The invention relates to the technical field of photovoltaic cell welding, and in particular to a photovoltaic cell welding method and device based on the thermal effect of induced energized current. Background Art

[0002] With the development and continuous innovation of photovoltaic technology, photovoltaic companies have higher and higher requirements for welding technology. Welding technology with higher efficiency and higher yield is urgently needed in the current market.

[0003] There are two main methods for welding photovoltaic cells:

[0004] One is laser welding, that is, the laser light source directly irradiates the welding tape that is in close contact with the photovoltaic cell, so that the corresponding position absorbs the laser energy to weld the area to be welded of the photovoltaic cell to the welding tape. Some lasers will directly act on the surface of the photovoltaic cell, causing damage to the photovoltaic cell. Photovoltaic cells and welding tapes are basically bonded by applying pressure to the welding tape using a pressure needle carrier. The pressure needle is easy to stick to the welding tape, which is not conducive to maintenance and is not conducive to double-sided welding of photovoltaic cells;

[0005] The second is infrared welding. Infrared welding uses infrared rays to directly act on the soldering tape and photovoltaic cells so that they directly absorb heat for welding. A pressure needle carrier is required. The problem of the pressure needle sticking to the soldering tape still exists. At the same time, the uniformity of infrared heating is poor, the volatility is large, the temperature is uneven, the welding efficiency is low, and the welding effect at different positions of the photovoltaic cell is inconsistent. The yield of the welded battery string is not high.

[0006] Therefore, the present invention develops a photovoltaic cell welding method and device based on the thermal effect of induced energizing current to solve the problems existing in the prior art. Summary of the invention

[0007] The purpose of the present invention is to provide a photovoltaic cell welding method and device based on the thermal effect of induced current, so as to solve the problems of photovoltaic cell damage caused by laser welding in the prior art, needle adhesion and being unfavorable for double-sided welding, and at the same time solve the problems of poor heating uniformity, large fluctuation and high welding defect rate caused by infrared welding.

[0008] The technical solution of the present invention is: a photovoltaic cell welding method based on the thermal effect of induced current, comprising:

[0009] S1. Using a photovoltaic cell with a PN junction structure, a plurality of welding strips are distributed on the P-type end and the N-type end of the photovoltaic cell, so that the welding strips are closely attached to the grid lines on the surface of the photovoltaic cell;

[0010] S2, connect the P-type terminal and the N-type terminal to the negative and positive electrodes of the power supply respectively, and apply a reverse voltage to the PN junction in the photovoltaic cell;

[0011] S3, applying an inducing medium to the bonding area between the welding strip and the gate line to make the PN junction reversely conductive, so that current flows in the photovoltaic cell sheet and the welding strip and a current thermal effect occurs, so that the bonding area between the welding strip and the gate line reaches the welding temperature, and the welding is completed.

[0012] Preferably, the inducing medium is applied to any side end face of the P-type end and the N-type end of the photovoltaic cell, and any end face has a plurality of bonding areas; the inducing medium is applied to a local number of the bonding areas at a single time, each of the bonding areas is induced at least once, and the bonding areas of the entire end face gradually complete all inductions.

[0013] Preferably, in step S1, the welding ribbon and the photovoltaic cell are preheated, and the preheating temperature is between room temperature and 200°C.

[0014] Preferably, in step S1, soldering flux is applied to the area where the soldering tape and the gate line are bonded.

[0015] Preferably, in step S1, a solidified material is coated between the soldering ribbon and the photovoltaic cell, so that the soldering ribbon is pre-fixed at the P-type end and the N-type end of the photovoltaic cell.

[0016] Preferably, in step S2, the reverse voltage applied by the power supply is 5 to 25V.

[0017] Preferably, in step S3, the induction medium is emitted by an induction source, and the induction source is a light excitation induction source or a heat excitation induction source;

[0018] The induction medium emitted by the light excitation induction source includes any one of laser, LED light and halogen light, so as to excite photogenerated carriers in the photovoltaic cell.

[0019] The present application also discloses a photovoltaic cell welding device, which uses a photovoltaic cell welding method based on the thermal effect of induced current to complete welding, including:

[0020] At least one pair of conductors, each pair of the conductors is respectively connected to the welding strips distributed at the P-type end and the N-type end of the photovoltaic cell; the welding strips and the grid line bonding area on the surface of the photovoltaic cell form a welding area;

[0021] A power supply, wherein the positive and negative electrodes of the power supply are connected to the conductor through wires, so that the positive electrode of the power supply is connected to the N-type terminal and the negative electrode of the power supply is connected to the P-type terminal, so that the drift current flowing from the N-type terminal to the P-type terminal in the photovoltaic cell forms a closed loop;

[0022] The induction source emits an induction medium and acts on the area to be welded, so that the photovoltaic cell absorbs the energy carried by the induction medium to generate carriers, thereby realizing reverse conduction of the PN junction.

[0023] Preferably, it also includes a bearing assembly with non-conductive properties, and the bearing assembly is used to place welding strips and photovoltaic cells; the conductor adopts an energized probe.

[0024] Preferably, a pair of the conductors are fixedly connected to the carrier assembly and respectively abut against lower surfaces of solder strips at the P-type end and the N-type end placed on the carrier assembly.

[0025] Preferably, the conductor is not fixedly connected to the bearing assembly and is directly placed on the soldering strip, directly abutting against the upper surface of the soldering strip at the P-type end and the N-type end.

[0026] Preferably, each pair of the conductors is mounted on a pressure plate assembly and uses powered probes of different lengths; when the pressure plate assembly acts on the photovoltaic cell sheet, a pair of powered probes of different lengths respectively abut against solder strips arranged at the P-type end and the N-type end.

[0027] Preferably, each pair of said electrical conductors is mounted on a pressure plate assembly and uses energized probes of the same length;

[0028] At this time, there are two or more photovoltaic cells on the supporting component, and a transition welding strip is arranged between adjacent photovoltaic cells. The transition welding strip connects the welding strip at the P-type end of one photovoltaic cell with the welding strip at the N-type end of an adjacent photovoltaic cell, so that it is constructed as a combined welding strip arranged in a Z shape, and the powered probe is in contact with the welding strip on the same side.

[0029] Preferably, the pressing plate assembly is transparent, and comprises a rigid component and a flexible component, and the flexible component is pressed onto the photovoltaic cell sheet.

[0030] Preferably, a heating module is provided in the carrier assembly to preheat the photovoltaic cell sheet and the welding ribbon placed on the carrier assembly.

[0031] Preferably, it also includes a carrying component with conductive properties, the carrying component is used to place the welding strip and the photovoltaic cell sheet; the carrying component is constructed as a conductor, and the conductor also includes a powered probe;

[0032] The positive and negative electrodes of the power supply are connected to the bearing assembly and the powered probe respectively.

[0033] Preferably, when two or more photovoltaic cells are provided, adjacent photovoltaic cells are connected by Z-shaped combined welding strips, and the supporting components between each adjacent photovoltaic cell are not conductive.

[0034] Preferably, it also includes a plurality of conductive carrier components, each of which is provided with a welding strip and a photovoltaic cell, and the plurality of carrier components are simultaneously constructed as conductors; adjacent photovoltaic cells are connected by a Z-shaped combined welding strip.

[0035] Preferably, the induction source is a laser generator, and an optical element for beam splitting and shaping is arranged at the emission end of the light path.

[0036] Preferably, the induction source is an LED light row.

[0037] Compared with the prior art, the advantages of the present invention are:

[0038] (1) By utilizing the characteristics of the PN junction of the photovoltaic cell itself and controlling the application of the inducing medium, the excitation of the carriers at the PN junction of the photovoltaic cell is controlled, thereby realizing the control of the on-off current of the heating circuit, so that the local welding position can reach the welding temperature more easily and quickly, and the heating effect is stable and very easy to control.

[0039] (2) Different from the traditional laser welding method, the present invention can perform double-sided welding on photovoltaic cells, solving the problem that traditional laser welding can only be performed on one side. In addition, the overall temperature during welding is relatively low, and only the photovoltaic cells and the welding area of ​​the welding strip generate short-term high temperature, which effectively reduces the warping of the cells after welding. At the same time, it solves the problem of traditional laser welding damaging the cells from the root.

[0040] (3) Different from traditional infrared welding, the present invention uses electric current heating to perform welding, utilizing the thermal effect of the current-carrying conductor. The heating effect is very uniform, reliable and controllable, effectively avoiding the problem of uneven and volatile effects in traditional infrared welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0042] Figure 1 This is a schematic diagram of the structure of applying reverse voltage to the photovoltaic cell of the present invention;

[0043] Figure 2 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 1 of the present invention;

[0044] Figure 3 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 1 of the present invention in an application scenario;

[0045] Figure 4 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 2 of the present invention;

[0046] Figure 5This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 2 of the present invention in an application scenario;

[0047] Figure 6 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 3 of the present invention;

[0048] Figure 7 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 3 of the present invention in an application scenario;

[0049] Figure 8 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 4 of the present invention;

[0050] Fig. 9 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 4 of the present invention in an application scenario;

[0051] Fig.10 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 5 of the present invention;

[0052] Fig.11 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 5 of the present invention in an application scenario;

[0053] Fig.12 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 6 of the present invention in an application scenario;

[0054] Fig.13 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 6 of the present invention in another application scenario;

[0055] Fig.14 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 7 of the present invention;

[0056] Fig.15 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 7 of the present invention in an application scenario;

[0057] Fig.16 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 8 of the present invention;

[0058] Fig.17 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 8 of the present invention in an application scenario;

[0059] Fig.18 This is a schematic structural diagram of a photovoltaic cell welding device according to Embodiment 9 of the present invention in an application scenario;

[0060] Fig.19This is a schematic diagram of the LED light row described in Example 9 of the present invention.

[0061] Among them: 1. Photovoltaic cells;

[0062] 11. P-type terminal, 12. PN junction, 13. N-type terminal, 14. gate line, 15. welding strip, 151. transition welding strip, 152. combined welding strip, 16. area to be welded;

[0063] 2. Conductor;

[0064] 2a, powered probe;

[0065] 3. Power supply;

[0066] 4. Inducing source;

[0067] 41, LED lamp beads, 4a, laser generator, 4b, LED lamp row;

[0068] 5. Load bearing components;

[0069] 6. Press plate assembly;

[0070] 61. Rigid components, 62. Flexible components. DETAILED DESCRIPTION

[0071] The present invention is further described in detail below in conjunction with specific embodiments:

[0072] Combination Figure 1 As shown, a photovoltaic cell welding method based on the thermal effect of induced current flow includes:

[0073] a. A photovoltaic cell 1 having a PN junction 12 structure is used, and a plurality of welding strips 15 are distributed on the P-type end 11 and the N-type end 13 of the photovoltaic cell 1, so that the welding strips 15 are closely fitted and contacted with the grid lines 14 on the surface of the photovoltaic cell 1; in order to ensure the close fit between the welding strips 15 and the photovoltaic cell 1, a curing material can be coated between the welding strips 15 and the photovoltaic cell 1, and the curing material is cured in the fitting area at the designated position, so that the welding strips 15 are pre-fixed on the P-type end 11 and the N-type end 13 of the photovoltaic cell 1. The specific distribution method can be referred to Figure 1 shown.

[0074] Regarding the selection of curing materials, epoxy glue, silicone glue, acrylic glue, EVA glue, tape, film materials, etc. can be used; the curing method can be ultraviolet light curing, thermal curing, heat conduction, etc.

[0075] b. Apply soldering flux to the area where the soldering ribbon 15 and the gate line 14 are attached to assist heat conduction, remove oxides, reduce the surface tension of the material being welded, remove oil stains on the surface of the material being welded, increase the welding area and prevent re-oxidation, so as to improve the subsequent welding effect. Of course, a soldering ribbon with its own soldering flux can also be used, and no additional soldering flux is required in this case.

[0076] c. Preheat the soldering ribbon 15 and the photovoltaic cell 1. During preheating, the soldering ribbon 15 and the photovoltaic cell 1 can be placed on a heating platform. The preheating temperature is controlled between room temperature and 200° C. In this embodiment, the preheating temperature is set to 100° C.

[0077] d. Connect the P-type terminal 11 and the N-type terminal 13 to the negative and positive electrodes of the power source 3 respectively, and apply a reverse voltage between 5 and 25 V to the PN junction 12 in the photovoltaic cell 1, so that the drift current flowing from the N-type terminal 13 to the P-type terminal 11 in the photovoltaic cell 1 forms a closed loop.

[0078] e. Apply an induction medium to the bonding area between the welding strip 15 and the grid line 14, so that the PN junction 12 is reversely conductive, and current flows through the photovoltaic cell 1 and the welding strip 15 and generates a current thermal effect, so that the bonding area between the welding strip 15 and the grid line 14 reaches the welding temperature, and the welding is completed. The induction medium is applied to any side end face of the P-type end 11 and the N-type end 13 of the photovoltaic cell 1, and there are several bonding areas on any end face; the induction medium is applied to a local number of bonding areas at a time, and each bonding area is induced at least once, and the bonding area of ​​the entire end face is gradually fully induced.

[0079] The induction medium is emitted by the induction source 4 , and the induction source 4 is a light excitation induction source or a thermal excitation induction source; the induction medium emitted by the light excitation induction source includes any one of laser, LED light, and halogen light, so as to excite photogenerated carriers in the photovoltaic cell 1 .

[0080] When laser is used, a laser generator 4a is used, and relative movement occurs between the photovoltaic cell 1 and the laser generator 4a, so that the laser is sequentially irradiated on the bonding area. When the bonding area is induced by the induction medium, the photovoltaic cell 1, the welding strip 15 on the side of the P-type end 11, and the welding strip 15 on the side of the N-type end 13 form a closed circuit and flow an instantaneous large current. Due to the thermal effect of the energized conductor, the temperature of the area to be welded 16 continues to rise until the welding is completed. At the same time, optical elements can also be used to split and shape the laser separately. In this embodiment, the light spot formed by the laser is a square light spot divided into three, and then each split light beam is focused and irradiated to the designated area to be welded 16, and the corresponding areas to be welded 16 of the photovoltaic cell 1 are processed simultaneously, which greatly improves the welding efficiency. Of course, in other embodiments, according to the distribution of the area to be welded 16, the laser can be split into other numbers and shaped into other shapes.

[0081] When LED lights are used, LED light row 4b is used, and the LED light row 4b is controlled to flash sequentially to control the instantaneous high current flowing to different areas to be welded 16, so as to complete the welding of the areas to be welded 16. It is also possible to shield the normally-on LED lights, and only expose the LED lights of the areas to be welded 16. At this time, the areas to be welded 16 of the photovoltaic cell 1, the welding strip 15 on the side of the P-type end 11, and the welding strip 15 on the side of the N-type end 13 form a closed circuit and flow an instantaneous high current, and the ideal welding effect can also be achieved in the areas to be welded 16 due to the thermal effect of the energized conductor.

[0082] The present application also discloses a photovoltaic cell welding device, which uses a photovoltaic cell welding method based on the thermal effect of induced energized current to complete welding, and has the following implementation methods. Example 1

[0083] like Figure 2 As shown, a photovoltaic cell welding device includes a pair of conductors 2, a power source 3, an induction source 4, and a load-bearing component 5 with non-conductive properties.

[0084] In this embodiment, Figure 3 As shown, the photovoltaic cell 1 has strip-shaped welding strips 15 distributed at the P-type end 11 and the N-type end 13, and the welding strips 15 and the grid lines 14 on the surface of the photovoltaic cell 1 are bonded to form a welding area 16; when the photovoltaic cell 1 is placed horizontally, there is a height difference between the welding strips 15 at the P-type end 11 and the N-type end 13.

[0085] The conductor 2 uses a powered probe 2a, and is fixedly connected to both ends of the carrier assembly 5, respectively. A pair of conductors 2 are respectively connected to the soldering strips 15 distributed at the P-type end 11 and the N-type end 13 of the photovoltaic cell 1. At this time, since there is a height difference between the soldering strips 15 at the P-type end 11 and the N-type end 13, powered probes 2a with different lengths can be used, or powered probes 2a set at different heights but with the same length can be used.

[0086] The carrier component 5 is used to place the welding strip 15 and the photovoltaic cell 1. A heating module is arranged inside the carrier component 5 to preheat the photovoltaic cell 1 and the welding strip 15 placed on the carrier component 5, further reducing the power of the induction source 4 during welding and reducing the applied reverse voltage, while also reducing the temperature difference at various points in the welding process of the photovoltaic cell 1, reducing the risk of hidden cracks and fragments of the photovoltaic cell 1, and improving the welding quality while reducing costs.

[0087] The positive and negative electrodes of the power source 3 are electrically connected to the conductor 2 through wires, so that the positive electrode of the power source 3 is connected to the N-type terminal 13, and the negative electrode of the power source 3 is connected to the P-type terminal 11, so that the drift current flowing from the N-type terminal 13 to the P-type terminal 11 in the photovoltaic cell 1 forms a closed loop.

[0088] The induction source 4 emits an induction medium and acts on the area to be welded 16. In this embodiment, the induction source 4 adopts a laser generator 4a, and an optical element for beam splitting and shaping is set at the emission end of the light path, so that the photovoltaic cell 1 absorbs the energy carried by the induction medium to generate carriers, thereby realizing reverse conduction of the PN junction 12.

[0089] When working, Figure 3 As shown, a pair of powered probes 2a are respectively in contact with the lower surface of the soldering strip 15 placed on the P-type end 11 and the N-type end 13 of the carrier assembly 5. By applying a reverse voltage and introducing an induction source 4, the characteristics of the PN junction 12 of the cell itself and the thermal effect principle of the energized conductor are utilized to make the local welding position reach the welding temperature more easily and quickly, and the heating effect is stable and very easy to control. The thermal effect of the energized conductor refers to the fact that when the current passes through the conductor, due to the collision of free electrons, the temperature of the conductor will rise rapidly in a short period of time, and the electrical energy absorbed by the conductor is converted into thermal energy. The heat generated when the current passes through the conductor is proportional to the square of the current intensity, the resistance of the conductor itself, and the time when the current passes, satisfying Joule's law; in this application, the photovoltaic cell 1 and the soldering strip 15 act as the energized conductor in the thermal effect principle. Example 2

[0090] like Figure 4 As shown, a photovoltaic cell welding device includes a pair of conductors 2, a power source 3, an induction source 4, and a load-bearing component 5 with non-conductive properties.

[0091] The difference between this embodiment and embodiment 1 is that Figure 5 As shown, the conductor 2 is not fixedly connected to the carrier assembly 5 , and is directly placed on the soldering strip 15 , directly abutting against the upper surface of the soldering strip 15 at the P-type terminal 11 and the N-type terminal 13 .

[0092] In actual application scenarios, in order to ensure close contact between the conductor 2 and the soldering strip 15, an external force may be applied to the conductor 2. During operation, the induction source 4 is introduced by applying a reverse voltage, so that the area to be soldered 16 irradiated by the induction medium reaches the soldering temperature. Example 3

[0093] like Figure 6 As shown, a photovoltaic cell welding device includes a pair of conductors 2, a pressure plate assembly 6 for mounting the conductors 2, a power source 3, an induction source 4, and a bearing assembly 5 with non-conductive properties.

[0094] In this embodiment, Figure 7 As shown, the photovoltaic cell 1 has strip-shaped solder strips 15 distributed on the P-type end 11 and the N-type end 13 . When the photovoltaic cell 1 is placed horizontally, there is a height difference between the solder strips 15 on the P-type end 11 and the N-type end 13 .

[0095] A pair of conductors 2 are mounted on the pressure plate assembly 6, and powered probes 2a of different lengths are used; when the pressure plate assembly 6 acts on the photovoltaic cell 1, a pair of powered probes 2a of different lengths respectively abut against the soldering strips 15 arranged at the P-type end 11 and the N-type end 13.

[0096] The pressing plate assembly 6 is transparent and includes a rigid component 61 and a flexible component 62, and the flexible component 62 is pressed on the photovoltaic cell 1. The pressing plate assembly 6 not only fixes the welding strip 15, but also prevents the welding strip 15 from deforming and twisting and detaching from the welding area 16 during the welding process. In this embodiment, by installing the powered probe 2a at the edge of the pressing plate assembly 6, it mainly provides the power-on function, replacing the traditional needle pressing method, making the applied pressure more uniform and reliable, and also convenient for later maintenance.

[0097] The positive and negative electrodes of the power source 3 are electrically connected to the conductor 2 through wires, so that the drift current flowing from the N-type terminal 13 to the P-type terminal 11 in the photovoltaic cell 1 forms a closed loop.

[0098] The induction source 4 emits an induction medium and acts on the area to be welded 16 , so that the photovoltaic cell 1 absorbs the energy carried by the induction medium to generate carriers, thereby achieving reverse conduction of the PN junction 12 .

[0099] The carrier assembly 5 is used to place the soldering ribbon 15 and the photovoltaic cell 1 . A heating module is arranged inside the carrier assembly 5 to preheat the photovoltaic cell 1 and the soldering ribbon 15 placed on the carrier assembly 5 .

[0100] In this embodiment, pressure is applied to the welding ribbon 15 and the photovoltaic cell 1 by the cooperation of the pressure plate assembly 6 and the supporting assembly 5, ensuring that the pressure plate assembly 6 can apply uniform and stable pressure to make the welding ribbon 15 fit tightly with the photovoltaic cell 1. At the same time, the power probe 2a can connect the photovoltaic cell 1 and the welding ribbon 15 to the DC regulated power supply 3 to facilitate the application of voltage. Example 4

[0101] like Figure 8 As shown, a photovoltaic cell welding device includes three pairs of conductors 2, a pressure plate assembly 6 for mounting the conductors 2, a power source 3, an induction source 4, and a bearing assembly 5 with non-conductive properties. In this embodiment, only three pairs of conductors 2 are used as an example. Of course, in other embodiments, the conductors 2 can also be set to other numbers, specifically corresponding to the number of photovoltaic cells 1.

[0102] like Fig. 9 As shown, each cell has a soldering strip 15 independently arranged at the P-type end 11 and the N-type end 13 .

[0103] Three pairs of conductors 2 are arranged and fixed on the pressure plate assembly 6. Each pair of conductors 2 uses powered probes 2a of different lengths. When the pressure plate assembly 6 acts on the photovoltaic cell 1, the powered probes 2a of different lengths respectively abut against the welding strips 15 arranged on the P-type end 11 and the N-type end 13.

[0104] A power source 3 is provided to conduct a pair of conductors 2 at a time, so that the drift current flowing from the N-type terminal 13 to the P-type terminal 11 in the photovoltaic cell 1 forms a closed loop. The induction source 4 emits an induction medium and acts on the welding area 16 to achieve reverse conduction of the PN junction 12.

[0105] In actual application scenarios, the photovoltaic cells 1 at different positions can be connected to the power source 3 by moving the pressing plate assembly 6, the photovoltaic cell 1 and the supporting assembly 5, and then the welding can be completed in sequence. Example 5

[0106] like Fig.10 As shown, a photovoltaic cell welding device includes four conductors 2, a pressure plate assembly 6 for mounting the conductors 2, a power source 3, an induction source 4, and a non-conductive bearing assembly 5. In other embodiments, other numbers of conductors 2 may be provided, and two adjacent conductors 2 are configured as a pair for conducting with the power source 3.

[0107] like Fig.11 As shown, a transition welding strip 151 is arranged between adjacent photovoltaic cells 1, and the transition welding strip 151 connects the welding strip 15 of the P-type end 11 in one photovoltaic cell 1 with the welding strip 15 of the N-type end 13 in the adjacent photovoltaic cell 1, so that it is constructed into a combined welding strip 152 arranged in a Z shape; and then multiple photovoltaic cells 1 are constructed into a cell string.

[0108] Each conductor 2 is mounted on the pressure plate assembly 6 and uses a power-on probe 2 a of the same length. The power-on probe 2 a abuts against the soldering strip 15 on one side of the P-type terminal 11 .

[0109] by Fig.11 For example, at this time, the power source 3 is connected to the two rightmost conductors 2. Due to the design of the combined welding strip 152, the rightmost photovoltaic cell 1 forms a closed loop, and by applying the induction medium, the PN junction 12 in the rightmost photovoltaic cell 1 is reversely conducted, and an instantaneous large current flows. Due to the thermal effect of the energized conductor, the temperature of the area to be welded 16 continues to rise until the welding is completed. Afterwards, by sequentially moving the pressing plate assembly 6, the photovoltaic cell 1 and the bearing assembly 5, the photovoltaic cells 1 at different positions are connected to the power source 3, and then the welding is completed in sequence.

[0110] It should be noted that for the photovoltaic cell at the edge 1 ( Fig.11The photovoltaic cell on the far left in the figure) can be turned on by additional power supply, or a conductor 2 is added to the pressure plate assembly 6 to achieve conduction by connecting the power supply 3. Example 6

[0111] like Fig.12 As shown, a photovoltaic cell welding device includes four conductors 2, a pressure plate assembly 6 for mounting the conductors 2, a power source 3, an induction source 4, and a bearing assembly 5 with non-conductive properties.

[0112] The difference between this embodiment and embodiment 5 is that each conductor 2 is mounted on the pressure plate assembly 6, and uses a power-on probe 2a of the same length, which is in contact with the soldering strip 15 on the side of the N-type terminal 13. At this time, the photovoltaic cell 1 on the far right can be turned on by an additional power-on method, or another conductor 2 is added to the pressure plate assembly 6, and the conductor 2 needs to be in contact with the soldering strip 15 on the side of the P-type terminal 11, and turned on by connecting the power supply 3, as shown in the following example. Fig.13 shown. Example 7

[0113] like Fig.14 , Fig.15 As shown, a photovoltaic cell welding device includes a conductor 2, a pressure plate assembly 6 for mounting the conductor 2, a power source 3, an induction source 4, and a bearing assembly 5 with conductive properties.

[0114] The carrier assembly 5 is used to place the welding strip 15 and the photovoltaic cell 1. The carrier assembly 5 is constructed as a conductor 2, and the conductor 2 also includes a powered probe 2a. The positive and negative electrodes of the power supply 3 are respectively connected to the carrier assembly 5 and the powered probe 2a.

[0115] When two or more photovoltaic cells 1 are provided, adjacent photovoltaic cells 1 are connected by Z-shaped combined welding strips 152 , and the supporting components 5 between adjacent photovoltaic cells 1 are not conductive. Example 8

[0116] like Fig.16 , Fig.17 As shown, a photovoltaic cell welding device includes a pressing plate assembly 6, a power source 3, an induction source 4, and a plurality of carrying assemblies 5 with conductive properties.

[0117] In this embodiment, it is suitable for welding a plurality of photovoltaic cells 1 , and adjacent photovoltaic cells 1 are connected by a Z-shaped combined welding ribbon 152 .

[0118] In the application scenario, a welding strip 15 and a photovoltaic cell 1 are placed on each carrier assembly 5, and multiple carrier assemblies 5 are simultaneously constructed as conductors 2; the positive and negative electrodes of the power source 3 are connected to adjacent carrier assemblies 5. It should be noted that the photovoltaic cell 1 at the edge needs to be turned on by additional power supply. Example 9

[0119] like Fig.18 As shown, a photovoltaic cell welding device includes a conductor 2, a pressure plate assembly 6 for mounting the conductor 2, a power source 3, an induction source 4, and a bearing assembly 5 with non-conductive properties.

[0120] The difference between this embodiment and embodiment 5 is that the induction source 4 adopts an LED light row 4b; Fig.19 As shown, the LED lamp row 4b has a plurality of LED lamp beads 41 distributed in an array, and the distribution of the LED lamp beads 41 is the same as the distribution of the area to be welded 16. The light source emitted by the LED lamp beads 41 is irradiated on the area to be welded 16 to achieve induction.

[0121] In actual application scenarios, the LED lamp beads 41 can be lit up in sequence, or shielded in a constant light mode, each time only inducing a portion of the area to be welded 16 to avoid the problem of all the areas to be welded 16 being turned on at the same time and causing excessive energy to damage the photovoltaic cell 1.

[0122] In summary, by utilizing the characteristics of the PN junction of the photovoltaic cell itself and controlling the application of the inducing medium, the excitation of the carriers at the PN junction of the photovoltaic cell is controlled, thereby realizing the control of the on-off current of the heating circuit, making it easier and faster for the local welding position to reach the welding temperature, and the heating effect is stable and very easy to control.

[0123] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the scope of protection of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the attached claims rather than the above description, and it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A photovoltaic cell welding method based on the induced current thermal effect, characterized in that: include: S1. Using a photovoltaic cell (1) having a PN junction (12) structure, distributing a plurality of welding strips (15) on the P-type end (11) and the N-type end (13) of the photovoltaic cell (1), so that the welding strips (15) are in close contact with the grid lines (14) on the surface of the photovoltaic cell (1); S2, connecting the P-type terminal (11) and the N-type terminal (13) to the negative electrode and the positive electrode of the power source (3) respectively, and applying a reverse voltage to the PN junction (12) in the photovoltaic cell (1); S3, applying an induction medium to the bonding area between the welding strip (15) and the grid line (14), so that the PN junction (12) is reversely conductive, and current flows through the photovoltaic cell (1) and the welding strip (15) and generates a current thermal effect, so that the bonding area between the welding strip (15) and the grid line (14) reaches the welding temperature, and the welding is completed; The induction medium is applied to any side end face of the P-type end (11) and the N-type end (13) of the photovoltaic cell (1), and any end face has a plurality of bonding areas; the induction medium is applied to a local number of the bonding areas at a time, and each of the bonding areas is induced at least once, and the bonding areas of the entire end face are gradually induced; The induction medium is emitted by an induction source (4), and the induction source (4) is a light excitation induction source or a heat excitation induction source; The induction medium emitted by the light excitation induction source includes any one of laser, LED light and halogen light, so as to excite photogenerated carriers in the photovoltaic cell.

2. The photovoltaic cell welding method based on the induced current thermal effect according to claim 1 is characterized in that: In step S1, the welding ribbon (15) and the photovoltaic cell (1) are preheated, and the preheating temperature is between room temperature and 200°C.

3. The photovoltaic cell welding method based on the induced current thermal effect according to claim 1 is characterized in that: In step S1, soldering flux is applied to the area where the soldering strip (15) and the gate line (14) are bonded.

4. The photovoltaic cell welding method based on the induced current thermal effect according to claim 1, characterized in that: In step S1, a cured product is coated between the soldering ribbon (15) and the photovoltaic cell (1), so that the soldering ribbon (15) is pre-fixed on the P-type end (11) and the N-type end (13) of the photovoltaic cell (1).

5. The photovoltaic cell welding method based on the induced current thermal effect according to claim 1, characterized in that: In step S2, the reverse voltage applied by the power supply (3) is 5 to 25 V.

6. A photovoltaic cell welding device, characterized in that: The photovoltaic cell welding method based on the induced current thermal effect as described in any one of claims 1 to 5 is used to complete welding, comprising: At least one pair of conductors (2), each pair of the conductors (2) being respectively connected to welding strips (15) distributed at the P-type end (11) and the N-type end (13) of the photovoltaic cell (1); the welding strips (15) and the grid lines (14) on the surface of the photovoltaic cell (1) are bonded to form a to-be-welded area (16); A power source (3), wherein the positive and negative electrodes of the power source (3) are connected to the conductor (2) via wires, so that the positive electrode of the power source (3) is connected to the N-type terminal (13), and the negative electrode of the power source (3) is connected to the P-type terminal (11), so that a drift current flowing from the N-type terminal (13) to the P-type terminal (11) in the photovoltaic cell (1) forms a closed loop; An induction source (4) emits an induction medium and acts on the area to be welded (16), causing the photovoltaic cell (1) to absorb energy carried by the induction medium to generate carriers, thereby achieving reverse conduction of the PN junction (12).

7. The photovoltaic cell welding device according to claim 6, characterized in that: It also comprises a carrier assembly (5) having non-conductive properties, wherein the carrier assembly (5) is used to place a welding strip (15) and a photovoltaic cell sheet (1); and the conductor (2) adopts an energized probe (2a).

8. The photovoltaic cell welding device according to claim 7, characterized in that: A pair of the conductors (2) are fixedly connected to the carrier assembly (5) and respectively abut against the lower surfaces of the welding strips (15) placed on the P-type end (11) and the N-type end (13) of the carrier assembly (5).

9. The photovoltaic cell welding device according to claim 7, characterized in that: The conductor (2) is non-fixedly connected to the bearing assembly (5) and is directly placed on the welding strip (15), directly abutting against the upper surface of the welding strip (15) of the P-type end (11) and the N-type end (13).

10. The photovoltaic cell welding device according to claim 9, characterized in that: Each pair of the conductors (2) is mounted on a pressure plate assembly (6) and uses powered probes (2a) of different lengths; when the pressure plate assembly (6) acts on the photovoltaic cell sheet (1), a pair of powered probes (2a) of different lengths respectively abut against welding strips (15) arranged at the P-type end (11) and the N-type end (13).

11. The photovoltaic cell welding device according to claim 9, characterized in that: Each pair of the electrical conductors (2) is mounted on a pressure plate assembly (6) and uses energized probes (2a) of the same length; At this time, the carrier assembly (5) has two or more photovoltaic cells (1), and transition welding strips (151) are arranged between adjacent photovoltaic cells (1). The transition welding strips (151) connect the welding strip (15) of the P-type end (11) of one photovoltaic cell (1) with the welding strip (15) of the N-type end (13) of the adjacent photovoltaic cell (1), so that the welding strips (152) are arranged in a Z shape, and the energized probe (2a) abuts against the welding strips (15) on the same side.

12. The photovoltaic cell welding device according to claim 10 or 11, characterized in that: The pressing plate assembly (6) is transparent, and comprises a rigid component (61) and a flexible component (62); the flexible component (62) is pressed onto the photovoltaic cell sheet (1).

13. The photovoltaic cell welding device according to claim 7, characterized in that: A heating module is provided in the carrier component (5) to preheat the photovoltaic cell sheet (1) and the welding ribbon (15) placed on the carrier component (5).

14. The photovoltaic cell welding device according to claim 6, characterized in that: It also includes a carrying component (5) with conductive properties, the carrying component (5) being used to place the welding strip (15) and the photovoltaic cell sheet (1); the carrying component (5) is constructed as a conductor (2), and the conductor (2) also includes a powered probe (2a); The positive and negative electrodes of the power source (3) are respectively connected to the bearing assembly (5) and the powered probe (2a).

15. The photovoltaic cell welding device according to claim 14, characterized in that: When two or more photovoltaic cells (1) are provided, adjacent photovoltaic cells (1) are connected by a Z-shaped combined welding strip (152), and the supporting components (5) between each adjacent photovoltaic cell (1) are not conductive.

16. The photovoltaic cell welding device according to claim 6, characterized in that: It also comprises a plurality of carrying components (5) having conductive properties, each of the carrying components (5) being provided with a welding strip (15) and a photovoltaic cell sheet (1), and the plurality of carrying components (5) being simultaneously constructed as a conductor (2); adjacent photovoltaic cells (1) are connected by a Z-shaped combined welding strip (152).

17. The photovoltaic cell welding device according to claim 6, characterized in that: The induction source (4) adopts a laser generator (4a), and an optical element for beam splitting and shaping is arranged at the emission end of the light path.

18. The photovoltaic cell welding device according to claim 6, characterized in that: The induction source (4) is an LED light row (4b).

Images