Back contact solar cell module and manufacturing method thereof

Abstract

The invention belongs to the field of solar cells, and particularly relates to a back contact solar cell module and a manufacturing method thereof, and the method comprises the steps: enabling an interconnection strip to be attached to the back surface of a cell, enabling the cells to be connected into a string, laying photovoltaic glass, a first packaging glue layer, the cell string and a glass fiber surface mat from bottom to top, and then carrying out the lamination, and obtaining a cell module prefabricated part, the front surface of the cell faces the glass, the gram weight of the first packaging adhesive layer is 80-150g / m < 2 >, non-pre-crosslinked packaging adhesive is adopted, and the lamination condition is controlled to enable the interconnection strip to be in ohmic connection with the electrode grid line on the back surface of the cell and enable the first packaging adhesive to be bonded with the glass fiber surfacing mat through the gap of the cell string; a second packaging glue layer and a back plate are sequentially laid on the battery assembly prefabricated part, then lamination is carried out, the battery assembly is obtained, the lamination condition is controlled, so that second packaging glue of the second packaging glue layer is bonded with the back surface of the battery string through the glass fiber surface felt, and virtual connection or disconnection between the interconnection strip and the battery grid line is avoided.

Description

Technical Field

[0001] The 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 packaged into a back-contact solar cell module has no light-receiving side blocked by the battery electrode, which not only has a high conversion rate but is also 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 panel, rear film, battery string, front film, and front panel in sequence, and laminating to bond the front back panel, front and rear films, and battery strings together to form a solar cell module.

[0004] In the process of making a cell string of a back-contact solar cell module, a traditional thermal welding process or a low-temperature preset interconnection strip stringing process is usually used. However, when the thermal welding process is used, since all the electrodes are arranged on the back of the cell, it is easy to cause serious cell warping. In the subsequent lamination process, the severely warped cell will be forcibly flattened, which is easy to increase the risk of hidden cracks in the cell. Hidden cracks are easy to cause leakage short circuit problems, and are also easy to increase the probability of desoldering between the interconnection strip and the electrode grid line, affecting the cell efficiency. When the low-temperature preset interconnection strip stringing process is used, the back-contact solar cell module produced is easy to form an open circuit between the interconnection strip and the electrode grid line of the cell, resulting in a virtual connection or a poor disconnection, affecting the 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 known technology. Summary of the invention

[0006] The purpose of the present invention is to overcome the defect that the solar cell modules manufactured by the prior art adopt the process of low-temperature preset interconnection bars to form a string, which easily forms an open circuit between the interconnection bars 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 bars are strung together, virtual connection or disconnection between the interconnection bars and the electrode grid lines can be avoided, thereby improving the battery efficiency.

[0007] In order to achieve the above objectives, in a first aspect, the present invention provides a method for manufacturing a back contact solar cell module, comprising: The interconnection strip is attached to the back of the back-contact solar cell, the battery cells are connected into a battery string, photovoltaic glass, a first packaging 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 side of the back-contact solar cell faces the photovoltaic glass, and the first packaging adhesive layer has a gram weight of 80 g / 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 strip is ohmically connected to the electrode grid line 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 gap of the battery string; A second packaging adhesive layer and a back panel 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 through the pores of the glass fiber surface felt and adheres to the back surface of the battery string.

[0008] In some preferred embodiments, the lamination pressure of the first lamination is 20 KPa to 40 KPa, the pressure holding time is 60s to 140s, and the gram weight of the glass fiber surface felt is 20g / m 2 ~100g / m 2 .

[0009] 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.

[0010] In some preferred embodiments, 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.

[0011] In some preferred embodiments, the first packaging adhesive is EVA and / or POE.

[0012] 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.

[0013] In some preferred embodiments, the second lamination conditions include: lamination pressure of 60KPa to 100KPa, lamination temperature of 150°C to 160°C, and pressure and temperature holding time of 10min to 20min.

[0014] 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.

[0015] In some preferred embodiments, the interconnection strip is adhered to the back side of the back-contact solar cell by partially applying adhesive tape and / or locally applying glue to form the cell string.

[0016] 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.

[0017] The manufacturing method of the solar cell assembly 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 of the cell string, so as to obtain a cell assembly preform in which the photovoltaic glass, the cell string, and the glass fiber surface felt are bonded together, and then lay a second packaging glue layer and a back plate for a second lamination, 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, so as to obtain a cell assembly in which the photovoltaic glass, the cell string, the glass fiber surface felt, and the back plate are bonded together. 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 assembly 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 Furthermore, the first packaging glue is a non-pre-cross-linked packaging glue. While ensuring that the first packaging glue layer passes through the gaps in 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 prevent the first packaging glue layer from overflowing excessively to the back area of ​​the battery cell and affecting the ohmic connection between the interconnection strip and the electrode grid line.

[0018] 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.

[0019] 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, so that problems can be discovered and adjusted in time, thereby improving the yield of the packaged back-contact solar cell assembly.

[0020] 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, and the cell efficiency is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 It is a schematic cross-sectional view of a back-contact solar cell module of the present invention.

[0023] Figure 2 It is an exploded view of the back contact solar cell module stack of the present invention.

[0024] Figure 3 It is a plan view schematic diagram of the stacking of cell strings, interconnection strips and glass fiber surface felt in the back contact solar cell module of the present invention.

[0025] Figure 4 It is a cross-sectional schematic diagram of a battery string, interconnection strips and glass fiber surface felt stack at the position of the positive interconnection strip of the back contact solar cell module of the present invention.

[0026] Figure 5 It is a cross-sectional schematic diagram of a battery string, interconnection strips and glass fiber surface felt stack at the position of the negative electrode interconnection strip of the back contact solar cell module of the present invention.

[0027] 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.

[0028] Figure 7 is a microscope photograph of the interconnection strip after the first lamination in Example 1 of the present invention.

[0029] 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.

[0030] Fig. 9 This is a graph showing the electroluminescence test results of the back-contact solar cell module of comparative example 4.

[0031] Fig.10 This is a graph showing the electroluminescence test results of the back-contact solar cell module of comparative example 5.

[0032] Description of Reference Numerals 1. Photovoltaic glass; 2. First packaging adhesive layer; 3. Battery string; 31. Positive electrode fine grid; 32. Negative electrode fine grid; 33. Insulating ink; 34. Main grid; 4. Interconnection strip; 5. Glass fiber surface felt; 6. Second packaging adhesive layer; 7. Back panel. DETAILED DESCRIPTION

[0033] The endpoints and any values ​​of the ranges disclosed in this article 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 endpoint values ​​of each range, the endpoint values ​​of each range and the 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 as specifically disclosed in this article.

[0034] The inventors of the present invention have discovered that, by adopting a low-temperature preset interconnection strip stringing process to form a cell string, stacking the backplane, rear film, cell string, front film, and front plane in sequence, and laminating and bonding the front backplane, front and rear films, and cell string together to form a solar cell module, an open circuit is easily formed between the interconnection strip and the fine grid of the electrode, affecting the cell efficiency.

[0035] In this regard, in a first aspect, the present invention provides a method for manufacturing a back-contact solar cell module, wherein an interconnection strip is attached to the back of a back-contact solar cell, battery cells are connected into a battery string, photovoltaic glass, a first packaging 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 packaging adhesive layer is 80 g / 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 strip is ohmically connected to the electrode grid line 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 gap of the battery string; A second packaging adhesive layer and a back panel 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 through the pores of the glass fiber surface felt and adheres to the back surface of the battery string.

[0036] The manufacturing method of the solar cell assembly of the present invention comprises the following steps: laying photovoltaic glass, a first packaging adhesive layer, a cell string and a glass fiber surface felt formed by bonding 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 passes through the gaps of the cell string and bonds to the glass fiber surface felt, and can bond the photovoltaic glass, the cell string and the glass fiber surface felt into one body, and fix the cell string and the glass fiber surface felt. Then, laying a second packaging adhesive layer and a back plate 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 passes through the pores of the glass fiber surface felt and bonds to the back surface of the cell string, and can complete the packaging of the back of the photovoltaic assembly, and obtain a cell assembly in which the photovoltaic glass, the cell string, the glass fiber surface felt and the back plate 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 gap of the battery string to bond the photovoltaic glass, the battery string, and the 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 lamination is used to encapsulate the back of the battery component, 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.

[0037] 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 ability of the battery module 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 degree, 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. 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.

[0038] 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, so that problems can be discovered and adjusted in time, thereby improving the yield of the packaged back-contact solar cell assembly.

[0039] 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 ineffective fixing of glass fiber surface felt. If it is greater than 150g / m 2 , which may easily cause the first packaging glue to penetrate between the interconnection strip and the electrode grid line, affecting the ohmic connection between the interconnection strip and the electrode grid line. If it is a pre-crosslinked packaging glue, it may easily cause the first packaging glue layer to fail to fully penetrate the gap between the battery string and bond with the glass fiber surface felt during the first lamination process, and fail to effectively fix the glass fiber surface felt. During the first lamination process, the glass fiber surface felt may deviate, and the deviation of the glass fiber surface felt may affect the aforementioned three aspects. The non-pre-crosslinked packaging glue of the present invention refers to a packaging glue film that has not been pre-treated and has a crosslinking degree of less than 5%, and the initial crosslinking degree before lamination is less than 5%.

[0040] 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 .

[0041] The present invention does not limit the pressure of the first lamination, as long as the interconnection strip can be ohmically connected to the electrode grid line 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 gap of the battery string. In some preferred embodiments, 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 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 strip, which can promote the close fitting of the interconnection strip and the battery cell electrode, further ensure the ohmic connection between the interconnection strip and the electrode grid line, and can control the amount of the 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 strip and the electrode grid line, ensuring the ohmic connection between the interconnection strip 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 strip 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 pressure holding and heat preservation 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.

[0042] In some preferred embodiments of the present invention, the surface of the interconnection strip has a tin alloy layer, and the lamination temperature of the first lamination is 150°C to 170°C. Under this preferred solution, the lamination temperature of the first lamination is not less than 150°C, which is more conducive to the melting of the tin alloy layer on the surface of the interconnection strip and the electrode grid line on the back of the back contact solar cell to form an ohmic connection, and is more conducive to the curing and shaping of the first packaging adhesive film, and the battery string and the glass fiber surface felt are fixed by the first packaging adhesive; not higher than 170°C, which is more conducive to avoiding the excessive fluidity of the first packaging adhesive and excessive overflow to the back area of ​​the battery cell, thereby further avoiding the first packaging adhesive from penetrating between the interconnection strip and the electrode grid line in the edge area of ​​the battery cell, ensuring the ohmic connection between the interconnection strip and the electrode grid line, and further preferably, 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. Under this preferred solution, the tin alloy layer has the above composition, which is more conducive to the melting of the tin alloy layer on the surface of the interconnection strip and the electrode grid line on the back of the back contact solar cell to form an ohmic connection. 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.

[0043] In some preferred embodiments of the present invention, when the interconnection bar is a round wire interconnection bar, the diameter of the interconnection bar is 0.2 mm to 0.4 mm, and when the interconnection bar is a flat interconnection bar, the width of the interconnection bar is 0.5 mm to 2 mm, and the thickness is 0.08 mm to 0.27 mm. Under this preferred solution, it is more conducive to the interconnection bar and the electrode grid line to form a stable ohmic connection after the interconnection bar and the battery cell are closely attached in the first lamination process.

[0044] In some preferred embodiments of the present invention, the first encapsulation adhesive is EVA and / or POE. Under this preferred solution, it is more conducive to preventing the first encapsulation adhesive layer from overflowing too much to the back area of ​​the battery cell and affecting the ohmic connection between the interconnection strip and the electrode grid line, while ensuring that the first encapsulation adhesive layer passes through the gap of the battery string and effectively fixes the glass fiber surface felt.

[0045] In some preferred embodiments of the present invention, after the first lamination, the cell assembly preform is subjected to an electroluminescence test to check the ohmic connection effect between the interconnection strip and the electrode grid line on the back of the back contact solar cell. EL electroluminescence test is a common routine inspection method for crystalline silicon photovoltaics for poor solder joints, scratches, hidden cracks, etc. When the electroluminescence graph is visually inspected to have many black areas, it means that the ohmic connection effect is poor. According to the actual situation, you can choose to replace the sheet, re-press it, cut off the glass fiber felt on the back to check the position of the interconnection strip, replace it with a small piece of glass fiber felt, and laminate again.

[0046] In some preferred embodiments of the present invention, the conditions of the second lamination include: lamination pressure of 60KPa to 100KPa, lamination temperature of 150℃ to 160℃, and pressure holding and heat preservation time of 10min to 20min. Under this preferred scheme, it is more conducive to the second packaging adhesive layer to fully penetrate and fill the gaps of the glass fiber surface felt and the steps of the edge of the welding strip, and bond with the back of the battery cell to improve the packaging effect of 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 preservation time can be, for example, 10min, 12min, 14min, 16min, 18min and 20min. The lamination pressure refers to the absolute pressure of the upper chamber.

[0047] In some preferred embodiments of the present invention, during the first lamination and / or the second lamination, the air pressure in the lower chamber of the laminator is lower than 30 Pa. Under this preferred solution, it is more conducive to ensuring that the gas generated during the lamination process is discharged in time to avoid lamination bubbles in the assembly. The air pressure in the lower chamber refers to the absolute pressure.

[0048] In some preferred embodiments of the present invention, the interconnection strip is adhered to the back side of the back-contact solar cell by partially applying adhesive tape and / or locally applying glue to form the cell string.

[0049] In some preferred embodiments of the present invention, during the first lamination, a piece of Teflon high-temperature cloth is covered on the glass fiber surface felt, which is more conducive to preventing the first packaging glue layer from overflowing onto the upper cavity silicone plate or the upper cavity high-temperature cloth of the laminator.

[0050] The present invention does not limit the type of back-contact solar cells, and for example, it may be a heterojunction back-contact solar cell.

[0051] 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. The battery of the battery module of the present invention has a significantly reduced probability of being torn by tensile stress, and the battery module has significantly improved resistance to external impact and battery efficiency.

[0052] The embodiments of the present invention are described in detail below, which are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0053] Example 1 A back contact solar cell module, referring to Figure 1~Figure 5 The manufacturing method specifically comprises the following steps: S1: the interconnection strip is attached to the back of the back contact solar cell monomer by locally sticking glue, and the back contact solar cell monomer is connected into a battery string, wherein the interconnection strip 4 is a copper flat interconnection strip with a tin alloy layer on the surface, the width of the interconnection strip is 1 mm, the thickness of the interconnection strip 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 strip is shown in Figure 4 and Figure 5 Taking the positive electrode interconnection 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, the interconnection bar 4 overlaps the main grid 34, and the main overlap position is the main grid 34 above the insulating ink 33. The area where the interconnection bar 4 forms ohmic contact with the main grid 34 is segmented; 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 packaging adhesive layer 2 is laid on the upper layer of the photovoltaic glass 1. The first packaging adhesive of the first packaging adhesive layer 2 is a non-pre-crosslinked EVA material. The gram weight of the first packaging 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 downward. The battery strings are connected in series and the electrodes are led out using busbars. A layer of 60 g / m2 is laid on top of the battery string. 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. The lower chamber is evacuated for 300 seconds so that the air pressure in the lower chamber is lower than 30pa. The upper chamber is inflated and pressurized. The vacuum degree of the upper chamber is set to -70Kpa (the lamination pressure is 30Kpa). After maintaining the pressure and heat for 100 seconds, a battery assembly preform covered with the high-temperature cloth is obtained. The first lamination makes the interconnection bar 4 connected to the main grid 34 ohms. After the first packaging glue 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 where the glass fiber surface felt and the first packaging glue are bonded. The photovoltaic glass, the first packaging glue layer, the battery string, the interconnection bar and the glass fiber surface felt are bonded as a whole. 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 the back plate 7 is covered to obtain a second stack, and the second stack is sent to the laminator for the second lamination. The lamination temperature is 155°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 inflated and pressurized, and the vacuum degree of the upper chamber is set to -20Kpa (the lamination pressure is 80Kpa). After maintaining the 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.

[0054] 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 in 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 strip 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.

[0055] Example 2 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).

[0056] Example 3 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).

[0057] Example 4 The method of Example 1 is referred to, except that in step S2, the holding time of the first lamination is 40 seconds.

[0058] Example 5 The method of Example 1 is referred to, except that in step S2, the lamination temperature of the first lamination is 140°C.

[0059] Example 6 The method of Example 1 is referred to, except that in step S3, the lamination temperature of the second lamination is 140°C.

[0060] Example 7 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).

[0061] Example 8 The method of Example 1 is referred to, except that in step S3, the pressure holding and heat preservation time of the second lamination is 8 minutes.

[0062] Comparative Example 1 The method of Example 1 is followed, except that in step S2, the weight of the first encapsulation adhesive layer is 70 g / m 2 .

[0063] Comparative Example 2 The method of Example 1 is followed, except that in step S2, the weight of the first packaging adhesive layer is 200 g / m 2 .

[0064] Comparative Example 3 The method of Example 1 is referred to, except that in step S2, the first packaging glue is a pre-cross-linked EVA material.

[0065] Comparative Example 4 The method of Example 1 is followed, 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 back plate are directly laid, and then laminated to obtain a back-contact solar cell module.

[0066] Comparative Example 5 The method of Example 1 is referred to, except that after obtaining the first stack, a second encapsulation adhesive layer and a back sheet are sequentially laid directly on the first stack, and then laminated to obtain a back-contact solar cell module.

[0067] Test Case IV tests were performed on the back-contact solar cell modules of Examples 1 to 8 and Comparative Examples 1 to 5, and the test conditions were STC. The maximum power Pmax, open circuit voltage Voc, short circuit current Isc, and fill factor FF in the test results were extracted for comparison. 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 Fig. 9 , the test results of comparative example 5 are shown in Fig.10 In the battery assembly of Example 1, the interconnection strips and the battery electrodes have good contact, and the EL brightness is uniform. In the battery assembly of Comparative Example 4, the ohmic connection between the interconnection strips and the battery electrodes fails, and the EL has serious uneven brightness. In the battery assembly of Comparative Example 5, the ohmic connection between the local interconnection strips and the battery electrodes fails, and the EL has local uneven brightness.

[0068] Table 1

[0069] Comparative Example 1 and Comparative Example 2, the weight of the first packaging glue is not less than 80 g / m 2 , can effectively fix the glass fiber surface felt during the first lamination, and improve the maximum power, open circuit voltage and filling 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. Comparing 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. Comparing 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 backplane, and then laminating, laying the glass fiber surface felt above the battery string and performing a secondary 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. Comparing Example 5, compared with laying the second encapsulation glue layer and the backplane in sequence directly above the first stack after obtaining the first stack, and then laminating, the two-time 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.

[0070] Comparing Example 1 with Example 2-3, the lamination pressure of the first lamination is 20KPa-40KPa, which is more conducive to the ohmic connection between the interconnection strip and the electrode grid line, and improves the maximum power P maxand 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 strip and the electrode grid line, 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 strip and the electrode grid line, 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 improving 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 improving 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 improving the maximum power, short circuit current and open circuit voltage.

[0071] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope 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, photovoltaic glass, a first packaging 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 side of the back-contact solar cell faces the photovoltaic glass, and the first packaging adhesive layer has a gram weight of 80 g / 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 strip is ohmically connected to the electrode grid line 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 gap of the battery string; A second packaging adhesive layer and a back panel 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 through the pores of the glass fiber surface felt and adheres to the back surface of the battery string.

2. The manufacturing method according to claim 1, characterized in that: 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 .

3. The manufacturing method according to claim 1, characterized in that: 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.

4. 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.

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

6. The manufacturing method according to claim 1, characterized in that: After the first lamination, the cell assembly preform is subjected to an electroluminescence test 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.

7. The manufacturing method according to claim 1, characterized in that: The second lamination conditions include: lamination pressure of 60KPa to 100KPa, lamination temperature of 150°C to 160°C, and pressure and temperature holding time of 10min to 20min.

8. 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 made lower than 30 Pa.

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

10. A back contact solar cell module, characterized in that: It is produced by the production method according to any one of claims 1 to 9.

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