A back contact photovoltaic module and a method of manufacturing the same

Abstract

The application relates to the field of photovoltaic technology and discloses a back contact photovoltaic module and a preparation method thereof. 10 Ω.cm) is cut, the cut insulation adhesive film is laid on the back surface of the back contact cell sheet, the insulation adhesive film covers each fine grid line on the back surface of the cell sheet, and each main grid line and a PAD point (a welding point) on the main grid line on the back surface of the cell sheet are exposed to isolate the positive and negative grid lines on the back surface of the cell sheet; the laid insulation adhesive film is pre-fixed on the back surface of the cell sheet, and the pre-fixing temperature is less than or equal to 80 DEG C; a solder strip is laid on the main grid line on the back surface of the cell sheet along the length direction of the main grid line; and the solder strip on the PAD point of the main grid line is laser welded, so that a plurality of cell sheets are serially connected to form a cell string through soldering by the solder strip. The preparation method can obtain the back contact photovoltaic module with low cost and high yield.

Description

Technical Field

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

[0002] With the development of solar cell technology, the development of high-efficiency solar cells and high-efficiency photovoltaic modules is receiving increasing attention. Among them, BC (Back Contact) cells, due to their absence of grid lines (or electrodes) on the front side, have attracted much attention from researchers at home and abroad due to their advantages such as high conversion efficiency, large short-circuit current, high fill factor, and aesthetic appeal. Currently, BC cells have become a new platform technology in the photovoltaic industry. Because the positive and negative electrodes of BC cells are both on the back of the cell, and the positive and negative electrodes are arranged alternately in an interdigitated pattern on the back of the cell, BC cell modules require the use of insulating adhesive to isolate the positive and negative electrodes.

[0003] As shown in publication CN116995109A, the existing BC photovoltaic product manufacturing method involves applying a front-side adhesive film to a front cover plate; placing a back contact cell on the front-side adhesive film; printing insulating adhesive on the back side of the back contact cell and curing it to form an insulating layer to isolate the positive and negative grid lines of the back contact cell; then printing a low-temperature electrical connection material (such as low-temperature solder paste with a melting point of 90℃~135℃) on the PAD point area of ​​the main grid lines; laying low-temperature solder ribbons (such as a tin-bismuth-silver system with a melting point of 90℃~135℃) on the pre-cured low-temperature electrical connection material; then applying a back-side adhesive film (such as a pre-crosslinked adhesive film or a PVB film with low local surface flow) and a back cover plate on the low-temperature solder ribbons, and then laminating and curing it in a laminator. This existing BC photovoltaic product manufacturing method, by printing low-temperature solder paste on the PAD point area and pre-curing it, combined with low-temperature solder ribbons, can ensure effective bonding between the weakly bonded aluminum grid lines and the low-temperature solder ribbons, achieving the effect of current collection, and naturally resulting in better bonding in the silver paste area.

[0004] However, this existing method for manufacturing BC photovoltaic products has at least the following drawbacks: 1. High equipment and material costs: Before applying the back film, it requires localized printing of insulating adhesive, printing of low-temperature solder paste, and laying of low-temperature solder ribbon. Therefore, screen printing equipment is needed at the module end to print the insulating adhesive and solder paste. Currently, the cost of screen printing equipment and both insulating adhesive and solder paste is high. Furthermore, additional processes such as printing and pre-curing of low-temperature solder paste are required, making the manufacturing process of this BC photovoltaic product complex, cumbersome, and inefficient, further increasing its production costs. 2. It uses low-temperature solder ribbon, which is welded using conventional welding methods (infrared or substrate heating, etc.). These conventional welding methods have low welding precision. When using these conventional welding methods, the insulating adhesive and low-temperature solder paste are prone to melting and flowing, causing displacement, which further affects welding precision and increases the defect rate of module-end products. In addition, conventional infrared high-temperature welding can cause cell warping due to stress (thermal expansion and contraction), which can lead to defects such as cell cracking and poor soldering, resulting in a decrease in module yield. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a back-contact photovoltaic module and its preparation method, which reduces the cost and improves the yield.

[0006] Based on this, the present invention discloses a method for preparing a back-contact photovoltaic module, comprising the following preparation steps:

[0007] Step 1: Cut the pre-crosslinked insulating film and lay the cut insulating film on the back of the back-contacting cell so that the insulating film covers each fine grid line on the back of the cell and exposes each main grid line and PAD point on the main grid line to isolate the positive and negative grid lines on the back of the cell.

[0008] The pre-crosslinked insulating film has a melting point of 60-80℃, a pre-crosslinking degree of ≥90%, and an insulation resistance of ≥1.0*10. 10 Ω.cm;

[0009] Step 2: Pre-fix the laid insulating film to the back of the battery cell, with a pre-fixing temperature ≤80℃;

[0010] Step 3: Lay solder ribbons along the length of the main busbar on the back of the cell.

[0011] Step 4: Laser welding is performed on the solder strips at the PAD points of the main busbar so that several battery cells are connected in series to form a battery string.

[0012] Preferably, in step 1, the pre-crosslinked insulating film is cut into strips according to the position and shape of the main grid line openings on the battery screen.

[0013] The pre-crosslinked insulating film is made of POE insulating film.

[0014] More preferably, in step 1, the melting point of the pre-crosslinked insulating film is 75°C and its pre-crosslinking degree is 95%.

[0015] Preferably, in step 1, when laying the insulating film, a gap of ≥0.3mm is maintained between the insulating film and the main grid line, and between the insulating film and the PAD point.

[0016] More preferably, in step 1, when laying the insulating film, a gap of 0.3-0.5 mm is maintained between the insulating film and the main grid line, and between the insulating film and the PAD point.

[0017] Preferably, in step 2, the pre-fixing method is to use the base plate of the welding platform for heating or infrared heating.

[0018] More preferably, step 2 specifically includes: treating the battery cell with the insulating film laid on it in a 70°C oven for 5 seconds and then taking it out so that the insulating film is pre-fixed on the back of the battery cell.

[0019] Preferably, in step 3, the welding strip is a flat welding strip, and its welding temperature needs to be ≥185℃.

[0020] Preferably, in step 4, the laser of one or more sets of laser heads of the laser device is positioned on the PAD point of the main grid line to perform laser welding on the solder strip at the PAD point position of the main grid line. The laser length is 3-20cm (which can be adjusted according to the height of the laser device), the laser width is 0.1-2mm (which can be adjusted according to the size of the PAD point of the battery cell), and the laser power is 1000-4000W (which can be adjusted according to the actual welding situation).

[0021] Preferably, the method for preparing a back-contact photovoltaic module of the present invention further includes step 5: applying a front encapsulating film on the front cover plate and laying the front side of the battery string on the front encapsulating film; applying a back encapsulating film and a back cover plate sequentially on the back side of the battery string and then laminating them; and installing the frame and junction box.

[0022] The present invention also discloses a back-contact photovoltaic module, which is prepared by the preparation method of a back-contact photovoltaic module described above in the present invention.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] This invention lays a pre-crosslinked POE insulating film before laying the solder strip (conventional solder strip). This POE insulating film has a low melting point (60℃~80℃), extremely low fluidity (high pre-crosslinking degree, up to 90%-100%), and high insulation resistance (≥1.0*10). 10 The POE insulating film is then pre-fixed at a low temperature (pre-fixing temperature not exceeding 80℃) to the back of the battery cell, serving to insulate and separate the positive and negative grid lines (and the distance between the pre-fixed insulating film and the main grid lines and PAD points is controlled within the range of 0.3-0.5mm), replacing the process of printing insulating adhesive and solder paste using screen printing equipment as required by CN116995109A; and combined with the more precise laser welding process for positioning welding, replacing the conventional welding process (such as infrared welding or base plate heating welding) of CN116995109A. Thus, the preparation method of the present invention has the following advantages:

[0025] On the one hand, it eliminates the need for screen printing equipment and materials such as insulating adhesive and solder paste required by CN116995109A. Compared with the low-temperature solder ribbon used in CN116995109A, the conventional solder ribbon used in this invention is cheaper, thus greatly reducing the equipment and material costs of this invention. Moreover, this invention does not require additional printing and pre-curing processes of low-temperature solder paste as CN116995109A, which can improve the efficiency of component production and further reduce the cost of component production.

[0026] On the other hand, the preparation method of the present invention involves laying a low-melting-point, highly pre-crosslinked, and highly insulating insulating film, combined with low-temperature pre-fixation (ensuring that the spacing between the pre-fixed insulating film and the main grid lines and PAD points is controlled within the range of 0.3-0.5 mm) and laser welding. Therefore, during the preparation process, the pre-fixed insulating film will not shift, ensuring its good insulation effect; the insulating film will not flow onto the PAD points, resulting in poor welding; and thermal stress will not cause product warping. Thus, the yield of back-contact photovoltaic modules can be significantly improved. Therefore, the preparation method of the present invention can obtain back-contact photovoltaic modules that combine low cost and high yield. Attached Figure Description

[0027] Figure 1 This is a partial structural diagram of the back side of the solar cell after step 1 processing, according to a method for preparing a back-contact photovoltaic module of the present invention.

[0028] Figure 2 for Figure 1 A partially enlarged structural diagram.

[0029] Figure 3 This is a schematic diagram of the laser welding process, step 4, in a method for preparing a back-contact photovoltaic module according to the present invention.

[0030] Figure 4 This is a graph showing the EL (electroluminescence) test data of the back-contact photovoltaic laminate prepared in Example 1.

[0031] Figure 5 This is a graph showing the EL test data of the back-contact photovoltaic laminate prepared in Comparative Example 2.

[0032] Explanation of reference numerals: 1. Battery cell; 11. Main grid line; 111. Positive main grid line; 112. Negative main grid line; 12. PAD point; 2. Insulating film; 3. Laser head. Detailed Implementation

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1

[0035] This embodiment describes a method for fabricating a back-contact photovoltaic module, see [link to relevant documentation]. Figure 1-3 The preparation steps include the following:

[0036] Step 1: Place the battery cell 1 on the welding platform. Cut the pre-crosslinked insulating film 2 into strips according to the position and shape of the main grid lines opening on the battery screen. Lay the cut strips of insulating film 2 on the back of the battery cell 1, so that the laid insulating film 2 covers each fine grid line on the back of the battery cell 1, and exposes each main grid line 11 and the PAD points 12 on the main grid line 11 (e.g., ...). Figure 1-2 (As shown), to isolate the positive and negative grid lines on the back of the battery cell 1.

[0037] In step 1, the battery cell 1 is a back-contact battery cell 1, meaning that both its positive and negative grid lines are located on the back side of the battery cell 1. Both the positive and negative grid lines include main grid lines 11 (such as negative main grid line 112 and positive main grid line 111) and fine grid lines (such as negative fine grid lines and positive fine grid lines). Several PAD points 12 (welding points) are distributed at intervals on the main grid lines 11. The specific arrangement of the positive and negative grid lines on the back side of the battery cell 1 is described in the prior art and will not be repeated here.

[0038] In step 1, the pre-crosslinked insulating film 2 is a POE insulating film (such as the POE insulating film provided by Foster Films). This pre-crosslinked POE insulating film has a melting point of 75℃, a pre-crosslinking degree of 95%, and an insulation resistance ≥1.0*10. 10 Ω.cm (e.g., 1.0*10) 14 Ω.cm).

[0039] In step 1, when laying the insulating film 2, it is necessary to ensure that there is a gap of 0.3-0.5mm (e.g. 0.3mm) between the insulating film 2 and the main grid line 11, and between the insulating film 2 and the PAD point 12.

[0040] Step 2: Use the base plate of the welding platform for heating or infrared heating to pre-fix the laid insulating film 2. The pre-fixing heating temperature should not exceed 80℃.

[0041] In step 2 of this embodiment, the specific process of pre-fixing the laid insulating film 2 is as follows: the battery cell 1 with the laid insulating film 2 is placed in a 70°C oven for 5 seconds and then taken out, so that the insulating film 2 is pre-fixed on the back of the battery cell 1.

[0042] Due to the low melting point, ultra-low fluidity (its pre-crosslinking degree is as high as 95%), and high insulation properties of the insulating film 2, and the fact that the pre-fixing temperature of the insulating film 2 is not higher than 80°C, the insulating film 2 will not change position during the pre-fixing process in step 2 (that is, the insulating film 2 will not shift due to melting and flow during the pre-fixing process), ensuring that the pre-fixed insulating film 2 can play a good insulating role, and ensuring that the pre-fixed insulating film 2 will not flow onto the PAD point 12 and have a negative impact on subsequent welding; moreover, the low-temperature pre-fixing of the insulating film 2 will not cause the battery cell 1 to warp.

[0043] Step 3: Along the length of the main busbar 11, flat solder strips are laid on each main busbar 11 on the back of the cell 1.

[0044] Step 4: Adjust the angle of the laser equipment so that the laser is positioned at PAD point 12 of the main grid line 11. Perform laser welding on the solder strip at PAD point 12 of the main grid line 11. Through solder strip welding, several battery cells 1 are connected in series to form a battery string.

[0045] In step 4 of this embodiment, the laser length of the laser device is 6cm, the laser width is 0.8mm, and the laser power is 2100W.

[0046] In step 4, the laser equipment can use one or more laser heads 3 to perform laser welding to precisely weld the solder strip at the PAD point 12 position of the main grid line 11 (e.g., Figure 3 (As shown). Laser welding offers more precise positioning and minimizes thermal stress, enabling precise welding of the solder strip at the PAD point 12 of the main grid line 11 without affecting other positions on the back of the solar cell 1. This ensures that the pre-fixed insulating film 2 is not affected by the laser (it will not damage the pre-fixed insulating film 2), further ensuring that the pre-fixed insulating film 2 provides better insulation and also further preventing warping of the solar cell 1.

[0047] Step 5: Apply a front encapsulating film to the front cover plate and lay the front of the battery string on the front encapsulating film; after applying a back encapsulating film and a back cover plate to the back of the battery string in sequence, laminate it in a laminator at 148°C to obtain a back contact photovoltaic laminate.

[0048] Step 6: After performing routine installation work such as frame and junction box installation on the back contact photovoltaic laminate, the back contact photovoltaic module of this embodiment is obtained.

[0049] Example 2

[0050] This embodiment describes a method for preparing a back-contact photovoltaic module. The preparation steps are specifically the same as in Embodiment 1, but the difference between the two embodiments is as follows:

[0051] In step 1 of this embodiment, the degree of pre-crosslinking of the pre-crosslinked insulating film is 90%.

[0052] Comparative Example 1

[0053] The preparation method of the back-contact photovoltaic module in this comparative example is the same as that in Example 1, except that:

[0054] In step 1 of this comparative example, the insulating film laid has a melting point above 90℃ (e.g., 95℃), a pre-crosslinking degree of less than 15% (e.g., 10%), and an insulation resistance of less than 1.0*10. 15 Ω.cm (e.g., 1.0*10) 14 POE insulating film (Ω.cm).

[0055] In step 2 of this comparative example, the battery cell with the insulating film laid on it is placed in a 100°C oven for 5 seconds and then taken out, so that the insulating film is pre-fixed on the back of the battery cell.

[0056] Comparative Example 2

[0057] The preparation method of the back-contact photovoltaic module in this comparative example is the same as that in Example 1, except that:

[0058] In step 4 of this comparative example, conventional infrared welding or base plate heating welding (such as conventional infrared welding) is used instead of laser welding in Example 1.

[0059] Comparative Examples 3-9

[0060] The preparation method of a back-contact photovoltaic module according to Comparative Examples 3-9 is specifically the same as that in Example 1, except that:

[0061] The pre-crosslinking degrees of the pre-crosslinked insulating films in step 1 of Comparative Examples 3-9 were 60%, 65%, 70%, 75%, 80%, 85%, and 88%, respectively.

[0062] Performance testing

[0063] 1. The EL (electroluminescence) test results of the back-contact photovoltaic laminates prepared in step 5 of Examples 1 and 2 show no abnormalities, the power can be tested normally, and the EL test results are passed (e.g., ...). Figure 4 (As shown).

[0064] In Comparative Example 1, after removing the solar cell from the oven in step 2, it was found that the laid insulating film had a high melting point and high fluidity (pre-crosslinking degree less than 15%). Furthermore, due to the increased pre-fixing temperature, the position of the pre-fixed insulating film changed or shifted, failing to achieve the purpose of isolating the positive and negative grid lines and thus failing to provide good insulation. Moreover, the insulating film of Comparative Example 1 flowed onto the PAD points of the main grid lines, making it impossible to carry out subsequent welding work normally. As a result, the EL test result of the back contact photovoltaic laminate of Comparative Example 1 was NG (failed).

[0065] In Comparative Example 2, due to the inability to precisely control the welding range in conventional welding processes, and the requirement that the melting point of conventional solder strips be ≥185℃, the insulating film melted under these uncontrollable conditions. This caused the original placement of the insulating film to change or shift, resulting in poor insulation performance. Furthermore, the melting affected subsequent welding, leading to an NG (Not Good) EL test result for the back-contact photovoltaic laminate in Comparative Example 2. Figure 5 (As shown).

[0066] 2. Multiple warpage tests were conducted on the solar cells of Example 1 after laser welding and the solar cells of Comparative Example 2 after conventional welding. It was found that the warpage of the solar cells of Example 1 was significantly reduced, and the test results were satisfactory. Specific warpage test data are shown in Table 1 below.

[0067] Table 1

[0068]

[0069] 3. Furthermore, the reason why this invention uses an insulating film with a low melting point, high pre-crosslinking degree, and high insulation is because:

[0070] ① The applicant's tests revealed that when solar cells are bonded to the adhesive film (pre-fixed), the critical temperature at which the cells deform and warp due to thermal stress (thermal expansion and contraction) occurs is around 80℃. If the pre-fixing temperature of the adhesive film exceeds 80℃, it leads to a mismatch in the coefficient of thermal expansion (CTE), inducing thermal stress. If this thermal stress exceeds the material's yield strength, plastic deformation or warping occurs. The lowest melting point of the particles within the adhesive film is around 60℃. When the pre-fixing temperature is below 60℃, the adhesive film is difficult to cross-link, resulting in lower adhesion and preventing proper pre-fixation to the solar cells. Therefore, a melting point between 60℃ and 80℃ for the insulating adhesive film is most suitable.

[0071] ② Furthermore, the applicant's tests revealed that the preparation method of the back-contact photovoltaic module of the present invention requires ensuring a gap of approximately 0.3-0.5 mm between the insulating film and the main grid lines, and between the insulating film and the PAD points, during the laying of the insulating film. Additionally, the insulating film must possess ultra-low flowability (≥90% pre-crosslinking degree) to ensure that it does not flow onto the main grid lines or PAD points during pre-fixation, thus affecting the welding effect. Multiple sets of tests verified that when the pre-crosslinking degree of the insulating film reaches 90% or higher, and pre-fixation is performed at temperatures of 80℃ or below, the flow distance of the insulating film will not exceed 0.3 mm. Specific test data are shown in Table 2 below.

[0072] Table 2

[0073]

[0074] Referring to Table 2, it can be seen that as the pre-crosslinking degree of the insulating film laid in Comparative Examples 3-9 and Example 2 gradually increases, the displacement distance of the insulating film after pre-fixation in step 2 on the back of the cell becomes smaller and smaller. Therefore, the insulating film after pre-fixation in Example 2 can play a better role in insulating and isolating the positive and negative grid lines, and can effectively avoid welding defects caused by the insulating film flowing to the PAD point of the main grid line, thereby greatly improving the product yield of the back contact photovoltaic module.

[0075] In summary, comparing the preparation methods of back-contact photovoltaic modules in Comparative Example 1 (high melting point, low pre-crosslinking degree insulating film + laser welding process), Comparative Example 2 (low melting point, high pre-crosslinking degree, and high insulation insulating film + conventional welding process), Comparative Examples 3-9 (low melting point, low pre-crosslinking degree, and high insulation insulating film + laser welding process), and Examples 1-2 (low melting point, high pre-crosslinking degree, and high insulation insulating film + laser welding process), it can be found that:

[0076] Only when the back-contact photovoltaic module preparation method of Examples 1-2 is adopted (the pre-fixing temperature of the insulating film does not exceed 80°C, and the spacing between the pre-fixed insulating film and the main grid line and PAD points is controlled within the range of 0.3-0.5mm, and conventional solder ribbon is used), and combined with a low-melting-point, high-pre-crosslinking, and high-insulation insulating film + laser welding process, can the technical effect of significantly reducing costs be achieved (this invention does not require the screen printing equipment and materials such as insulating adhesive and solder paste required by CN116995109A, and the conventional solder ribbon used in this invention is cheaper than low-temperature solder ribbon, greatly reducing equipment and material costs; moreover, this invention does not require the additional printing and pre-curing processes of low-temperature solder paste as in CN116995109A, which can improve module production efficiency and further reduce module production costs), and the technical effect of significantly improving the yield of back-contact photovoltaic modules be achieved, thereby obtaining a back-contact photovoltaic module with both low cost and high yield.

[0077] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0078] The technical solution provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a back-contact photovoltaic module, characterized in that, The preparation steps include the following: Step 1: Cut the pre-crosslinked insulating film and lay the cut insulating film on the back of the back-contacting cell so that the insulating film covers each fine grid line on the back of the cell and exposes each main grid line and PAD point on the main grid line to isolate the positive and negative grid lines on the back of the cell. The pre-crosslinked insulating film has a melting point of 60-80℃, a pre-crosslinking degree of ≥90%, and an insulation resistance of ≥1.0*10. 10 Ω.cm; Step 2: Pre-fix the laid insulating film to the back of the battery cell, with a pre-fixing temperature ≤80℃; Step 3: Lay solder ribbons along the length of the main busbar on the back of the cell. Step 4: Laser welding is performed on the solder strips at the PAD points of the main busbar so that several battery cells are connected in series to form a battery string.

2. The method for preparing a back-contact photovoltaic module according to claim 1, characterized in that, In step 1, the pre-crosslinked insulating film is cut into strips according to the position and shape of the main grid line openings on the battery screen. The pre-crosslinked insulating film is made of POE insulating film.

3. A method for preparing a back-contact photovoltaic module according to claim 1 or 2, characterized in that, In step 1, the melting point of the pre-crosslinked insulating film is 75°C and its pre-crosslinking degree is 95%.

4. The method for preparing a back-contact photovoltaic module according to claim 1, characterized in that, In step 1, when laying the insulating film, a gap of ≥0.3mm is maintained between the insulating film and the main grid line, and between the insulating film and the PAD point.

5. The method for preparing a back-contact photovoltaic module according to claim 4, characterized in that, In step 1, when laying the insulating film, a gap of 0.3-0.5mm should be maintained between the insulating film and the main grid line, and between the insulating film and the PAD point.

6. The method for preparing a back-contact photovoltaic module according to claim 1, characterized in that, In step 2, the pre-fixing method is to use the base plate of the welding platform for heating or infrared heating; Step 2 specifically includes: after the battery cell with the insulating film laid on it is placed in a 70°C oven for 5 seconds, it is taken out so that the insulating film is pre-fixed on the back of the battery cell.

7. The method for preparing a back-contact photovoltaic module according to claim 1, characterized in that, In step 3, the welding strip is a flat welding strip, and its welding temperature needs to be ≥185℃.

8. The method for preparing a back-contact photovoltaic module according to claim 1, characterized in that, In step 4, the laser of one or more laser heads of the laser equipment is positioned on the PAD point of the main grid line to perform laser welding on the solder strip at the PAD point position of the main grid line. The laser length is 3-20cm, the laser width is 0.1-2mm, and the laser power is 1000-4000W.

9. The method for preparing a back-contact photovoltaic module according to claim 1, characterized in that, It also includes step 5: applying a front sealing film to the front cover plate and laying the front of the battery string on the front sealing film; applying a back sealing film and a back cover plate to the back of the battery string in sequence and then laminating; and installing the frame and junction box.

10. A back-contact photovoltaic module, characterized in that, It is prepared by the method of any one of claims 1-9 for preparing a back-contact photovoltaic module.

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