Back contact solar cell module and manufacturing method thereof

Abstract

The present invention belongs to the field of solar cells, and specifically relates to a back-contact solar cell module and a manufacturing method thereof, the method comprising: attaching an interconnection strip to the back of the cell, connecting the cell monomers into a string, laying photovoltaic glass, a first encapsulation adhesive layer, a cell string, and a glass fiber surface felt from bottom to top, and then laminating to obtain a cell module preform, wherein the front of the cell faces the glass, and the gram weight of the first encapsulation adhesive layer is 80g / m 2 ~150g / m 2 A non-pre-crosslinked encapsulation adhesive is used, and the lamination conditions are controlled so that the interconnection strips are ohmically connected to the electrode grid lines on the back of the battery and the first encapsulation adhesive is bonded to the glass fiber surface felt through the gaps in the battery string; a second encapsulation adhesive layer and a back plate are sequentially laid on the battery assembly preform and then laminated to obtain a battery assembly, wherein the lamination conditions are controlled so that the second encapsulation adhesive of the second encapsulation adhesive layer is bonded to the back surface of the battery string through the glass fiber surface felt, thereby avoiding virtual connection or disconnection between the interconnection strips and the battery grid lines.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a back-contact solar cell assembly and a manufacturing method thereof. Background Art

[0002] The positive and negative electrodes of the back-contact solar cell are both located on the back of the cell, that is, the non-light-receiving side. The light-receiving side is not blocked by any electrode. The back-contact solar cell module encapsulated into the back-contact solar cell has no battery electrode blocking the light-receiving side of the module, which not only has a high conversion rate but also looks more beautiful.

[0003] The manufacturing steps of back-contact solar cell modules generally include: using interconnecting strips to connect battery cells to form battery strings; welding the interconnecting strips on the battery strings to the bus bars in series and parallel to complete the bus operation; stacking the back sheet, rear film, battery string, front film, and front sheet in sequence; and laminating the front back sheet, front and rear films, and battery strings together to form a solar cell module.

[0004] In the process of manufacturing cell strings for back-contact solar cell modules, traditional thermal welding processes or low-temperature preset interconnection strip stringing processes are usually used. However, when using the thermal welding process, since all the electrodes are arranged on the back of the cell, it is easy to cause severe cell warping. The subsequent lamination process will force the severely warped cell to be flattened, which can easily lead to an increased risk of hidden cracks in the cell. Hidden cracks can easily cause leakage short circuit problems and increase the probability of desoldering between the interconnection strips and the electrode grid lines, affecting cell efficiency. When using the low-temperature preset interconnection strip stringing process, the back-contact solar cell modules produced are prone to open circuits between the interconnection strips and the cell electrode grid lines, resulting in false connections or poor disconnections, affecting cell efficiency.

[0005] It should be noted that this part of the present invention only provides background technology related to the present invention and does not necessarily constitute prior art or public known technology. Summary of the Invention

[0006] The purpose of the present invention is to overcome the defect of the prior art that the solar cell modules produced by the low-temperature preset interconnection strip stringing process are prone to open circuits between the interconnection strips and the electrode grid lines of the battery, thereby affecting the battery efficiency. A back-contact solar cell module and a manufacturing method thereof are provided. After the low-temperature preset interconnection strips are stringed together, virtual connections or disconnections between the interconnection strips and the electrode grid lines can be avoided, thereby improving the battery efficiency.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a method for manufacturing a back-contact solar cell module, comprising:

[0008] The interconnection strip is attached to the back of the back-contact solar cell, the battery cells are connected into a battery string, and photovoltaic glass, a first encapsulation adhesive layer, the battery string, and a glass fiber surface felt are laid in order from bottom to top to obtain a first laminate, and the first laminate is subjected to a first lamination to obtain a battery assembly preform, wherein the front of the back-contact solar cell faces the photovoltaic glass, and the gram weight of the first encapsulation adhesive layer is 80g / m 2 ~150g / m 2 The first encapsulation adhesive of the first encapsulation adhesive layer is a non-pre-crosslinked encapsulation adhesive, and the conditions of the first lamination are controlled so that the interconnection strips are ohmically connected to the electrode grid lines on the back side of the back-contact solar cell and the first encapsulation adhesive is bonded to the glass fiber surface felt through the gaps between the cell strings;

[0009] A second packaging adhesive layer and a back sheet are sequentially laid on the battery assembly preform to obtain a second stack, and the second stack is subjected to a second lamination to obtain the back-contact solar cell assembly, wherein the conditions of the second lamination are controlled so that the second packaging adhesive of the second packaging adhesive layer penetrates the pores of the glass fiber surface felt and adheres to the back surface of the battery string.

[0010] In some preferred embodiments, the lamination pressure of the first lamination is 20KPa to 40KPa, the holding time is 60s to 140s, and the weight of the glass fiber surface felt is 20g / m 2 ~100g / m 2 .

[0011] In some preferred embodiments, the surface of the interconnection strip has a tin alloy layer, the lamination temperature of the first lamination is 150°C to 170°C, the tin alloy layer is a tin-bismuth-silver alloy layer, and the mass ratio of tin, bismuth and silver in the tin alloy layer is 50~65:34~45:1~5.

[0012] In some preferred embodiments, when the interconnecting strip is a round wire interconnecting strip, the diameter of the interconnecting strip is 0.2 mm to 0.4 mm; when the interconnecting strip is a flat interconnecting strip, the width of the interconnecting strip is 0.5 mm to 2 mm, and the thickness is 0.08 mm to 0.27 mm.

[0013] In some preferred embodiments, the first packaging adhesive is EVA and / or POE.

[0014] In some preferred embodiments, after the first lamination, an electroluminescence test is performed on the cell assembly preform to check the ohmic connection effect between the interconnection strips and the electrode grid lines on the back side of the back contact solar cell.

[0015] In some preferred embodiments, the second lamination conditions include: a lamination pressure of 60 KPa to 100 KPa, a lamination temperature of 150° C. to 160° C., and a pressure and temperature holding time of 10 min to 20 min.

[0016] In some preferred embodiments, during the first lamination and / or the second lamination, the air pressure in the lower chamber of the laminator is lower than 30 Pa.

[0017] In some preferred embodiments, the interconnection strip is adhered to the back surface of the back-contact solar cell by partially applying adhesive tape and / or locally applying glue to form the cell string.

[0018] In a second aspect, the present invention provides a back-contact solar cell module, which is manufactured by the manufacturing method described in the first aspect.

[0019] The manufacturing method of the solar cell module of the present invention is to attach the interconnection strip to the back of the solar cell to form a cell string, lay photovoltaic glass, a first packaging glue layer, a cell string, and a glass fiber surface felt from bottom to top, and perform a first lamination, so that the interconnection strip is ohmically connected to the electrode grid line on the back of the back contact solar cell and the first packaging glue is bonded to the glass fiber surface felt through the gaps in the cell string, thereby obtaining a cell module preform in which the photovoltaic glass, cell string, and glass fiber surface felt are bonded together as one. Then, a second packaging glue layer and a backboard are laid and a second lamination is performed, so that the second packaging glue of the second packaging glue layer is bonded to the back surface of the cell string through the pores of the glass fiber surface felt, thereby obtaining a cell module in which the photovoltaic glass, cell string, glass fiber surface felt, and backboard are bonded together as one. Since the first lamination is performed in advance, the interconnection strip is ohmically connected to the electrode grid line, which can avoid the packaging glue of the second packaging glue layer on the back of the cell string from penetrating between the interconnection strip and the electrode grid line when the back of the cell module is packaged by lamination, resulting in an open circuit between the interconnection strip and the electrode grid line, and a virtual connection or disconnection between the interconnection strip and the electrode grid line, thereby improving the cell efficiency. Among them, the weight of the first packaging adhesive layer is 80g / m 2 ~150g / m 2 Moreover, the first packaging glue is a non-pre-cross-linked packaging glue. On the premise of ensuring that the first packaging glue layer passes through the gaps of the battery string, bonds the photovoltaic glass, battery string, and glass fiber surface felt into one, and fixes the battery and the glass fiber surface felt, it can avoid the first packaging glue layer from overflowing too much to the back area of ​​the battery cell, affecting the ohmic connection between the interconnection strip and the electrode grid line.

[0020] The positive and negative electrodes of the back-contact battery are all on the back, and the positive and negative electrode interconnection strips are also all on the back. The manufacturing method of the present invention lays a glass fiber surface felt on the battery string. During the double lamination process of the first lamination and the second lamination, the probability of hidden cracks in the battery can be significantly reduced, thereby significantly reducing the probability of leakage short circuit.

[0021] The first lamination of the present invention allows the interconnection strips to form an ohmic connection with the battery electrodes, so that the ohmic connection effect between the interconnection strips and the battery electrodes can be tested in advance before the back packaging of the battery assembly is completed. Problems can be discovered and adjusted in time, thereby improving the yield of the packaged back-contact solar cell assembly.

[0022] In the back-contact solar cell assembly of the present invention, the interconnection strips form a stable ohmic connection with the electrode grid lines on the back side of the back-contact solar cell, thereby significantly improving the cell efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 It is a schematic cross-sectional view of the back contact solar cell module of the present invention.

[0025] Figure 2 It is an exploded view of the back contact solar cell module stack of the present invention.

[0026] Figure 3 It is a plan view of the stacking of cell strings, interconnecting strips and glass fiber surface felt in the back contact solar cell module of the present invention.

[0027] Figure 4 It is a cross-sectional schematic diagram of the battery string, interconnection bar and glass fiber surface felt laminate at the position of the positive electrode interconnection bar of the back contact solar cell module of the present invention.

[0028] Figure 5 It is a cross-sectional schematic diagram of the battery string, interconnection bar and glass fiber surface felt laminate at the position of the negative electrode interconnection bar of the back contact solar cell module of the present invention.

[0029] Figure 6 This is a microscope photograph of the back side of the battery after the first lamination in Example 1 of the present invention with the interconnection strips removed.

[0030] Figure 7 This is a microscope photograph of the interconnection strip after the first lamination in Example 1 of the present invention.

[0031] Figure 8 This is a graph showing the electroluminescence test results of the back-contact solar cell module of Example 1 of the present invention.

[0032] Figure 9 This is a graph showing the electroluminescence test results of the back-contact solar cell module of Comparative Example 4.

[0033] Figure 10 This is a graph showing the electroluminescence test results of the back-contact solar cell module of comparative example 5.

[0034] Description of Reference Numerals

[0035] 1. Photovoltaic glass; 2. First encapsulation adhesive layer; 3. Battery string; 31. Positive electrode fine grid; 32. Negative electrode fine grid; 33. Insulation ink; 34. Main grid; 4. Interconnection bar; 5. Glass fiber surface felt; 6. Second encapsulation adhesive layer; 7. Backplane. DETAILED DESCRIPTION

[0036] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0037] The inventors of the present invention have discovered that when a solar cell module is formed by using a low-temperature preset interconnection strip stringing process, in which the backplane, rear film, cell string, front film, and front plate are stacked in sequence, and the front backplane, front and rear films, and cell string are bonded together by lamination, an open circuit is easily formed between the interconnection strip and the fine grid of the electrode, affecting the cell efficiency.

[0038] In this regard, in a first aspect, the present invention provides a method for manufacturing a back-contact solar cell module, wherein an interconnecting strip is attached to the back of a back-contact solar cell, the battery cells are connected into a battery string, photovoltaic glass, a first encapsulation adhesive layer, the battery string, and a glass fiber surface felt are laid in sequence from bottom to top to obtain a first laminate, and the first laminate is subjected to a first lamination to obtain a battery module preform, wherein the front side of the back-contact solar cell faces the photovoltaic glass, and the gram weight of the first encapsulation adhesive layer is 80g / m 2 ~150g / m 2 The first encapsulation adhesive of the first encapsulation adhesive layer is a non-pre-crosslinked encapsulation adhesive, and the conditions of the first lamination are controlled so that the interconnection strips are ohmically connected to the electrode grid lines on the back side of the back-contact solar cell and the first encapsulation adhesive is bonded to the glass fiber surface felt through the gaps between the cell strings;

[0039] A second packaging adhesive layer and a back sheet are sequentially laid on the battery assembly preform to obtain a second stack, and the second stack is subjected to a second lamination to obtain the back-contact solar cell assembly, wherein the conditions of the second lamination are controlled so that the second packaging adhesive of the second packaging adhesive layer penetrates the pores of the glass fiber surface felt and adheres to the back surface of the battery string.

[0040] The manufacturing method of the solar cell assembly of the present invention comprises the following steps: laying photovoltaic glass, a first packaging adhesive layer, and a cell string and a glass fiber surface felt formed by attaching interconnecting strips to the back of the solar cell from bottom to top, and performing a first lamination. During the first lamination process, the first packaging adhesive penetrates the gaps in the cell string and bonds to the glass fiber surface felt, thereby bonding the photovoltaic glass, the cell string, and the glass fiber surface felt into one body, fixing the cell string and the glass fiber surface felt. Thereafter, a second packaging adhesive layer and a backboard are laid on the basis of the cell assembly preform obtained by the first lamination, and performing a second lamination. The second packaging adhesive of the second packaging adhesive layer penetrates the pores in the glass fiber surface felt and bonds to the back surface of the cell string, thereby completing the packaging of the back of the photovoltaic assembly, thereby obtaining a cell assembly in which the photovoltaic glass, the cell string, the glass fiber surface felt, and the backboard are packaged as one body. During the first lamination process, the conditions of the first lamination are controlled and the gram weight of the first packaging adhesive layer is made to be 80 g / m 2 ~150g / m 2 The first packaging glue is a non-pre-crosslinked packaging glue. During the first lamination process, it is ensured that the first packaging glue layer penetrates the gaps in the battery string and bonds the photovoltaic glass, battery string, and glass fiber surface felt into one. Under the premise of fixing the battery and the glass fiber surface felt, the interconnection strip can be ohmically connected to the electrode grid line on the back of the back contact solar cell. Since the interconnection strip and the electrode grid line are ohmically connected, it can be avoided that when the back of the battery component is packaged by lamination, the packaging glue of the second packaging glue layer on the back of the battery string penetrates between the interconnection strip and the electrode grid line, resulting in an open circuit between the interconnection strip and the electrode grid line, and a virtual connection or disconnection between the interconnection strip and the electrode grid line, thereby improving the battery efficiency.

[0041] The manufacturing method of the present invention lays a glass fiber surface felt on the battery string. On the one hand, during the double lamination process of the first lamination and the second lamination, the pressure is evenly distributed and buffered, which can significantly reduce the probability of hidden cracks in the battery and thus significantly reduce the probability of battery leakage and short circuit. On the second hand, after being prepared into a back-contact solar cell module, it can avoid problems such as hidden cracks and short circuits after the back of the module is impacted, and can improve the battery module's ability to resist external force impact. On the third hand, when the photovoltaic module is subjected to a load, the module will bend, and the battery cells encapsulated inside the module will be completely bound and bend accordingly. When the bending degree reaches a certain level, it is easy to cause the battery to be torn by tensile stress. A glass fiber surface felt is arranged on the back of the battery string, and the back of the battery string is isolated by the glass fiber surface felt, which can reduce the constraint of the back packaging material on the battery string. There is free space in the battery string, which can further significantly reduce the probability of the battery being torn by tensile stress.

[0042] The first lamination of the present invention allows the interconnection strips to form an ohmic connection with the battery electrodes, so that the ohmic connection effect between the interconnection strips and the battery electrodes can be tested in advance before the back packaging of the battery assembly is completed. Problems can be discovered and adjusted in time, thereby improving the yield of the packaged back-contact solar cell assembly.

[0043] If the weight of the first packaging adhesive layer of the present invention is less than 80g / m 2 , which may cause the problem of not being able to effectively fix the glass fiber surface felt. If it is greater than 150g / m 2 , which can easily cause the first encapsulation adhesive to penetrate between the interconnects and the electrode grid lines, affecting the ohmic connection between the interconnects and the electrode grid lines. If the encapsulation adhesive is pre-crosslinked, it can easily cause the first encapsulation adhesive layer to not fully penetrate the gaps between the battery strings and adhere to the glass fiber surface mat during the first lamination process, failing to effectively fix the glass fiber surface mat. During the first lamination process, the glass fiber surface mat may deviate, and this deviation affects the performance of the aforementioned three aspects. The non-pre-crosslinked encapsulation adhesive of the present invention refers to an encapsulation adhesive film that has not been pretreated and has a crosslinking degree of less than 5%. The initial crosslinking degree before lamination is less than 5%.

[0044] The weight of the first packaging adhesive layer of the present invention can be, for example, 80 g / m 2 , 90g / m 2 , 100g / m 2 , 110g / m 2 , 120g / m 2 , 130g / m 2 , 140g / m 2 and 150g / m 2 .

[0045] The present invention does not limit the pressure of the first lamination, as long as the interconnection strips can be ohmically connected to the electrode grid lines on the back of the back-contact solar cell and the first packaging glue can be bonded to the glass fiber surface felt through the gaps in the battery string. In some preferred embodiments, the lamination pressure of the first lamination is 20KPa to 40KPa, the pressure and heat preservation time is 60s to 140s, and the gram weight of the glass fiber surface felt is 20g / m 2 ~100g / m 2 In this preferred embodiment, the lamination pressure of the first lamination is 20KPa to 40KPa, and the weight of the glass fiber surface felt is 20g / m 2 ~100g / m 2, so that the glass fiber surface felt applies a certain pressure to the interconnection bar, which can promote the close adhesion of the interconnection bar to the battery cell electrode, further ensure the ohmic connection between the interconnection bar and the electrode grid line, and can control the amount of packaging glue of the first packaging glue layer that passes through the gap of the battery string, avoiding too little first packaging glue from passing through the gap of the battery string and bonding with the glass fiber surface felt, thereby further ensuring the effective fixation of the glass fiber surface felt, avoiding excessive overflow of the first packaging glue to the back area of ​​the battery cell, thereby further avoiding the first packaging glue from penetrating between the interconnection bar and the electrode grid line, ensuring the ohmic connection between the interconnection bar and the electrode grid line, in addition, controlling the lamination pressure of the first lamination and the gram weight of the glass fiber surface felt is also more conducive to avoiding the first lamination causing hidden cracks in the battery; the pressure and heat preservation time is 60s~140s, which is more conducive to ensuring the ohmic connection between the interconnection bar and the electrode grid line, and effectively fixing the battery string and the glass fiber surface felt. The lamination pressure of the first lamination of the present invention can be, for example, 20 KPa, 25 KPa, 30 KPa, 35 KPa and 40 KPa, the holding time can be, for example, 60 s, 80 s, 100 s, 120 s and 140 s, and the gram weight of the glass fiber surface felt can be, for example, 20 g / m 2 , 40g / m 2 , 60g / m 2 , 80g / m 2 and 100g / m 2 The lamination pressure refers to the absolute pressure of the upper chamber.

[0046] In some preferred embodiments of the present invention, the interconnecting strips have a tin alloy layer on their surfaces, and the lamination temperature for the first lamination is between 150°C and 170°C. In this preferred embodiment, the lamination temperature for the first lamination is not less than 150°C, which facilitates the melting of the tin alloy layer on the surface of the interconnecting strips to form an ohmic connection with the electrode grid lines on the back of the back-contact solar cell, further facilitating the curing and shaping of the first encapsulating film, thereby securing the cell strings and the fiberglass surface mat via the first encapsulating film. The temperature is not higher than 170°C, which facilitates preventing the first encapsulating film from becoming too fluid and overflowing onto the back of the cell, thereby further preventing the first encapsulating film from penetrating between the interconnecting strips and the electrode grid lines in the edge region of the cell, ensuring an ohmic connection between the interconnecting strips and the electrode grid lines. Furthermore, preferably, the tin alloy layer is a tin-bismuth-silver alloy layer, wherein the mass ratio of tin, bismuth, and silver in the tin alloy layer is 50-65:34-45:1-5. In this preferred embodiment, the tin alloy layer having the above composition facilitates the melting of the tin alloy layer on the surface of the interconnecting strips to form an ohmic connection with the electrode grid lines on the back of the back-contact solar cell. The lamination temperature of the first lamination of the present invention may be, for example, 150°C, 155°C, 160°C, 165°C, and 170°C.

[0047] In some preferred embodiments of the present invention, when the interconnecting bars are round wires, the diameter of the bars is 0.2mm to 0.4mm; when the interconnecting bars are flat wires, the width of the bars is 0.5mm to 2mm, and the thickness is 0.08mm to 0.27mm. This preferred solution is more conducive to forming a stable ohmic connection between the interconnecting bars and the electrode grid lines after the interconnecting bars are tightly attached to the battery cells during the first lamination process.

[0048] In some preferred embodiments of the present invention, the first encapsulating adhesive is EVA and / or POE. This preferred solution is more conducive to ensuring that the first encapsulating adhesive layer penetrates the gaps between the battery strings and effectively fixes the fiberglass surface mat, while preventing the first encapsulating adhesive layer from excessively overflowing the back area of ​​the battery cell and affecting the ohmic connection between the interconnect bar and the electrode grid line.

[0049] In some preferred embodiments of the present invention, after the first lamination, the cell module preform is subjected to an electroluminescence test to inspect the ohmic connection between the interconnecting strips and the electrode grid lines on the back side of the back-contact solar cell. EL testing is a commonly used routine inspection method for crystalline silicon photovoltaics to detect defects such as cold solder joints, scratches, and hidden cracks. Visual inspection of the electroluminescence pattern reveals a large number of black areas, indicating poor ohmic connection. Depending on the actual situation, repair options include replacing the wafer, re-pressing, cutting off the backside glass mat to inspect the position of the interconnecting strips, and then replacing them with a small piece of glass mat before re-laminating.

[0050] In some preferred embodiments of the present invention, the conditions for the second lamination include: a lamination pressure of 60KPa to 100KPa, a lamination temperature of 150℃ to 160℃, and a pressure-holding and heat-insulating time of 10min to 20min. Under this preferred embodiment, it is more conducive to the second encapsulation adhesive layer to fully penetrate and fill the gaps in the glass fiber surface felt and the steps at the edge of the welding strip, and to adhere to the back of the battery cell, thereby improving the encapsulation effect on the back of the photovoltaic module. The lamination pressure of the second lamination of the present invention can be, for example, 60KPa, 70KPa, 80KPa, 90KPa and 100KPa, the lamination temperature can be, for example, 150℃, 152℃, 154℃, 156℃, 158℃ and 160℃, and the pressure-holding and heat-insulating time can be, for example, 10min, 12min, 14min, 16min, 18min and 20min. The lamination pressure refers to the absolute pressure of the upper chamber.

[0051] In some preferred embodiments of the present invention, during the first and / or second lamination steps, the pressure in the lower chamber of the laminator is maintained below 30 Pa. This preferred embodiment further ensures the timely discharge of gases generated during the lamination process, preventing lamination bubbles in the assembly. The lower chamber pressure refers to absolute pressure.

[0052] In some preferred embodiments of the present invention, the interconnection strip is adhered to the back surface of the back-contact solar cell by partially applying adhesive tape and / or locally applying glue to form the cell string.

[0053] In some preferred embodiments of the present invention, during the first lamination, a Teflon high-temperature cloth is covered on the glass fiber surface felt, which is more conducive to preventing the first packaging adhesive layer from overflowing onto the upper cavity silicone plate or upper cavity high-temperature cloth of the laminator.

[0054] The present invention does not limit the type of back-contact solar cells, and for example, it can be a heterojunction back-contact solar cell.

[0055] In a second aspect, the present invention provides a back-contact solar cell module manufactured by the manufacturing method described in the first aspect. The cells of the cell module of the present invention have a significantly reduced probability of being torn by tensile stress, and the cell module has significantly improved resistance to external impact and cell efficiency.

[0056] The embodiments of the present invention are described in detail below, which are exemplary and only used to explain the present invention, and are not to be construed as limiting the present invention.

[0057] Example 1

[0058] A back contact solar cell module, referring to Figures 1 to 5 The manufacturing method specifically includes the following steps: S1: Adhere the interconnection bar to the back side of the back contact solar cell monomer by locally applying glue, and connect the back contact solar cell monomer into a battery string, wherein the interconnection bar 4 is a flat interconnection bar made of copper with a tin alloy layer on the surface, the width of the interconnection bar is 1 mm, the thickness of the interconnection bar is 0.23 mm, the tin alloy layer is a tin-bismuth-silver alloy layer, and the mass ratio of tin, bismuth and silver is 60:38:2. The connection method of the interconnection bar is shown in FIG. Figure 4 and Figure 5 Taking the positive electrode interconnect bar as an example, the negative electrode fine grid 32 of the battery cell is covered with insulating ink 33, the positive electrode fine grid 31 of the battery cell is connected to the main grid 34, and the interconnect bar 4 overlaps with the main grid 34, mainly overlapping the main grid 34 above the insulating ink 33. The area where the interconnect bar 4 forms ohmic contact with the main grid 34 is segmented;

[0059] S2: The photovoltaic glass 1 is placed at the bottom layer of the stack as the light-receiving surface of the photovoltaic module. The first encapsulation adhesive layer 2 is laid on the upper layer of the photovoltaic glass 1. The first encapsulation adhesive of the first encapsulation adhesive layer 2 is a non-pre-crosslinked EVA material. The gram weight of the first encapsulation adhesive layer 2 is 100g / m 2 The battery string 3 obtained in step S1 is laid flat on the first packaging adhesive layer 2 with the light incident surface facing downwards. The battery strings are connected in series and the electrodes are led out using busbars. A layer of 60g / m2 of 2The glass fiber surface felt 5 is formed to obtain a first laminate, and a Teflon high-temperature cloth is additionally covered on the first laminate. The first laminate covered with the high-temperature cloth is sent to a laminator for the first lamination. The lamination temperature is 160°C, and the lower chamber is evacuated for 300s so that the air pressure in the lower chamber is lower than 30pa. The upper chamber is then inflated and pressurized, and the vacuum degree of the upper chamber is set to -70Kpa (lamination pressure is 30Kpa). After maintaining the pressure and heat for 100s, a battery assembly preform covered with high-temperature cloth is obtained. The first lamination makes the interconnection bar 4 connected to the main grid 34 ohm. After the first packaging adhesive layer is melted, it is bonded to the glass fiber surface felt through the gap of the battery string under the action of the lamination pressure. The battery string is confined in the frame bonded to the glass fiber surface felt and the first packaging adhesive. The photovoltaic glass, the first packaging adhesive layer, the battery string, the interconnection bar and the glass fiber surface felt are bonded as one.

[0060] S3: After the battery component preform covered with the high-temperature cloth is cooled, the covering Teflon high-temperature cloth is peeled off, and the second packaging adhesive layer 6 is laid flat on the battery component preform, and then covered with the backboard 7 to obtain a second stack. The second stack is sent to the laminator for a second lamination. The lamination temperature is 155°C. The lower chamber is vacuumed for 300s so that the air pressure in the lower chamber is lower than 30pa. The upper chamber is inflated and pressurized, and the vacuum degree of the upper chamber is set to -20Kpa (lamination pressure is 80Kpa). After maintaining pressure and heat for 10 minutes, a back-contact solar cell assembly is obtained. The second lamination allows the second packaging adhesive of the second packaging adhesive layer to penetrate and fill the pores of the glass fiber surface felt and the steps at the edge of the welding strip to bond with the back surface of the battery string.

[0061] Step S2 After the first lamination, tear off the interconnection strip 4 and observe the back of the battery with a microscope. See the microscope photo for details. Figure 6 At the position corresponding to the main grid 34 above the insulating ink 33, there is an alloy that forms an ohmic connection between the interconnection bar 4 and the main grid 34, as shown by the circle mark position. The surface of the interconnection bar 4 is observed under a microscope. Figure 7 , there are segmented marks on the interconnection bar 4 that form an ohmic connection with the main grid 34. Figure 7 The distance between the segment marks on the interconnection strip 4 is 0.906 mm. Figure 6 The insulating ink position of the main grid 34 corresponds to that of the main grid 34.

[0062] Example 2

[0063] The method of Example 1 is referred to, except that in step S2, the vacuum degree of the upper chamber of the first lamination is set to -85 KPa (the lamination pressure is 15 KPa).

[0064] Example 3

[0065] The method of Example 1 is referred to, except that in step S2, the vacuum degree of the upper chamber of the first lamination is set to -50 KPa (the lamination pressure is 50 KPa).

[0066] Example 4

[0067] The method of Example 1 is referred to, except that in step S2, the holding time of the first lamination is 40 seconds.

[0068] Example 5

[0069] The method of Example 1 is referred to, except that in step S2, the lamination temperature of the first lamination is 140°C.

[0070] Example 6

[0071] The method of Example 1 is referred to, except that in step S3, the lamination temperature of the second lamination is 140°C.

[0072] Example 7

[0073] The method of Example 1 is referred to, except that in step S3, the vacuum degree of the upper chamber of the second lamination is set to -50 KPa (the lamination pressure is 50 KPa).

[0074] Example 8

[0075] The method of Example 1 is referred to, except that in step S3, the holding time of the second lamination is 8 minutes.

[0076] Comparative Example 1

[0077] The method of Example 1 is carried out with reference to the method of Example 1, except that in step S2, the weight of the first encapsulating adhesive layer is 70 g / m 2 .

[0078] Comparative Example 2

[0079] The method of Example 1 is carried out with reference to the method of Example 1, except that in step S2, the weight of the first encapsulating adhesive layer is 200 g / m 2 .

[0080] Comparative Example 3

[0081] The method of Example 1 is referred to, except that in step S2, the first packaging glue is a pre-crosslinked EVA material.

[0082] Comparative Example 4

[0083] The method of Example 1 is referred to, except that the glass fiber surface felt 5 is not laid on the top of the battery string. After the photovoltaic glass, the first packaging adhesive layer and the battery string are laid, the second packaging adhesive layer and the backboard are directly laid, and then laminated to obtain a back-contact solar cell module.

[0084] Comparative Example 5

[0085] The method of Example 1 is referred to, except that after obtaining the first stack, the second encapsulation adhesive layer and the back sheet are sequentially laid directly on the first stack, and then laminated to obtain a back-contact solar cell module.

[0086] Test Case

[0087] IV tests were performed on the back-contact solar cell modules of Examples 1 to 8 and Comparative Examples 1 to 5 under STC conditions. The maximum power Pmax, open circuit voltage Voc, short circuit current Isc, and fill factor FF in the test results were extracted and compared. The results are shown in Table 1. Electroluminescence tests (EL tests) were performed on the back-contact solar cell modules of Examples 1 to 8 and Comparative Examples 1 to 5. The test results of Example 1 are shown in Table 1. Figure 8 , the test results of Comparative Example 4 are shown in Figure 9 , the test results of comparative example 5 are shown in Figure 10 In the battery assembly of Example 1, the interconnection bars had good contact with the battery electrodes, and the EL brightness was uniform. In the battery assembly of Comparative Example 4, the ohmic connection between the interconnection bars and the battery electrodes failed, and the EL showed severe abnormal brightness and darkness unevenness. In the battery assembly of Comparative Example 5, the ohmic connection between the interconnection bars and the battery electrodes partially failed, and the EL showed local uneven brightness and darkness.

[0088] Table 1

[0089]

[0090] Comparing the embodiment and comparative example 1, the weight of the first packaging glue is not less than 80g / m 2 , can effectively fix the glass fiber surface mat during the first lamination, improve the maximum power, open circuit voltage and fill factor. Comparative Example 2 and Comparative Example 2, the weight of the first packaging glue is not more than 150g / m 2 , which can improve the ohmic connection effect between the interconnection strips and the electrode grid lines, and improve the maximum power, short-circuit current and fill factor. Comparative Example 3, the first encapsulation glue is a non-pre-crosslinked encapsulation glue, which can effectively fix the glass fiber surface felt during the first lamination, and improve the maximum power, short-circuit current and fill factor. Comparative Example 4, compared with laying the photovoltaic glass, the first encapsulation glue layer, and the battery string, directly laying the second encapsulation glue layer and the backboard, and then laminating, laying the glass fiber surface felt above the battery string and performing a second lamination, which can improve the ohmic connection effect between the interconnection strips and the electrode grid lines, and improve the maximum power, short-circuit current, open-circuit voltage and fill factor. Comparative Example 5, compared with laying the second encapsulation glue layer and the backboard in sequence directly above the first stack after obtaining the first stack, and then laminating, the two-lamination process of the present invention can improve the ohmic connection effect between the interconnection strips and the electrode grid lines, and improve the maximum power, open-circuit voltage, short-circuit current and fill factor.

[0091] Comparing Example 1 with Examples 2-3, the lamination pressure of the first lamination is 20KPa-40KPa, which is more conducive to the ohmic connection between the interconnection strips and the electrode grid lines, and improves the maximum power P max and fill factor FF; Comparing Example 1 and Example 4, the pressure holding and heat preservation time of the first lamination is 60s~140s, which is more conducive to the ohmic connection between the interconnection strips and the electrode grid lines, and improves the maximum power, open circuit voltage, short-circuit current and fill factor; Comparing Example 1 and Example 5, the lamination temperature of the first lamination is 150℃~170℃, which is more conducive to the ohmic connection between the interconnection strips and the electrode grid lines, and improves the maximum power, open circuit voltage and fill factor; Comparing Example 1 and Example 6, the lamination temperature of the second lamination is 150℃~160℃, which is more conducive to improving the packaging effect on the back of the photovoltaic module, and improves the maximum power and fill factor; Comparing Example 1 and Example 7, the lamination pressure of the first lamination is 60KPa~100Kpa, which is more conducive to improving the packaging effect on the back of the photovoltaic module, and improves the maximum power and open circuit voltage; Comparing Example 1 and Example 8, the pressure holding and heat preservation time of the second lamination is 10min~20min, which is more conducive to improving the packaging effect on the back of the photovoltaic module, and improves the maximum power, short-circuit current and open circuit voltage.

[0092] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for manufacturing a back-contact solar cell module, characterized in that: include: The interconnection strip is attached to the back of the back-contact solar cell, the battery cells are connected into a battery string, and photovoltaic glass, a first encapsulation adhesive layer, the battery string, and a glass fiber surface felt are laid in order from bottom to top to obtain a first laminate, and the first laminate is subjected to a first lamination to obtain a battery assembly preform, wherein the front of the back-contact solar cell faces the photovoltaic glass, and the gram weight of the first encapsulation adhesive layer is 80g / m 2 ~150g / m 2 The first encapsulation adhesive of the first encapsulation adhesive layer is a non-pre-crosslinked encapsulation adhesive, and the conditions of the first lamination are controlled so that the interconnection strips are ohmically connected to the electrode grid lines on the back side of the back-contact solar cell and the first encapsulation adhesive is bonded to the glass fiber surface felt through the gaps between the cell strings; sequentially laying a second encapsulating adhesive layer and a backsheet on the battery assembly preform to obtain a second laminate, and subjecting the second laminate to a second lamination to obtain the back-contact solar cell assembly, wherein the conditions of the second lamination are controlled so that the second encapsulating adhesive of the second encapsulating adhesive layer penetrates through the pores of the glass fiber surface felt and adheres to the back surface of the battery string; The lamination pressure of the first lamination is 20KPa~40KPa, the pressure and heat preservation time is 60s~140s, and the gram weight of the glass fiber surface felt is 20g / m 2 ~100g / m 2 ; The second lamination conditions include: a lamination pressure of 60 KPa to 100 KPa, a lamination temperature of 150° C. to 160° C., and a pressure and temperature holding time of 10 min to 20 min.

2. The manufacturing method according to claim 1, characterized in that The surface of the interconnection bar has a tin alloy layer, the lamination temperature of the first lamination is 150° C. to 170° C., the tin alloy layer is a tin-bismuth-silver alloy layer, and the mass ratio of tin, bismuth and silver in the tin alloy layer is 50-65:34-45:1-5.

3. The manufacturing method according to claim 1, characterized in that When the interconnection strip is a round wire interconnection strip, the diameter of the interconnection strip is 0.2 mm to 0.4 mm. When the interconnection strip is a flat interconnection strip, the width of the interconnection strip is 0.5 mm to 2 mm and the thickness is 0.08 mm to 0.27 mm.

4. The manufacturing method according to claim 1, characterized in that The first packaging adhesive is EVA and / or POE.

5. The manufacturing method according to claim 1, characterized in that After the first lamination, an electroluminescence test is performed on the cell assembly preform to check the ohmic connection effect between the interconnection strips and the electrode grid lines on the back side of the back contact solar cell.

6. The manufacturing method according to claim 1, characterized in that During the first lamination and / or the second lamination, the air pressure in the lower chamber of the laminator is set to be lower than 30 Pa.

7. The manufacturing method according to claim 1, characterized in that The interconnection strip is adhered to the back surface of the back-contact solar cell by partially applying adhesive tape and / or locally applying glue to form the cell string.

8. A back contact solar cell module, characterized in that: It is produced by the production method according to any one of claims 1 to 7.

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