Evaluation method for heat and humidity resistance of packaging adhesive film

Abstract

The invention relates to a method for evaluating the humidity and heat resistance of a packaging adhesive film, and the method comprises the following steps: providing a battery piece, and testing the electrical properties and EL images of the battery piece; the method comprises the following steps: dissolving a to-be-detected packaging adhesive film and sodium salt in a solvent to obtain a mixed solution; coating the battery piece with the mixed solution, and drying to form a salt-containing adhesive film; carrying out damp-heat aging treatment on the battery piece on which the salt-containing adhesive film is formed; after the damp-heat aging treatment, removing the salt-containing adhesive film on the battery piece, and testing the electrical property and EL image of the battery piece; and evaluating the heat and humidity resistance of the packaging adhesive film according to the electrical properties of the battery piece before and after the heat and humidity aging treatment and the change of the EL image. According to the evaluation method, the damp-heat aging resistance of the packaging adhesive film can be rapidly and quantitatively evaluated, the test cost is low, the test period is short, and the efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a method for evaluating the moisture and heat resistance of encapsulating films. Background Technology

[0002] The following two methods are mainly used to evaluate the moisture and heat resistance of the encapsulating film for photovoltaic modules:

[0003] Method 1 involves using a double-glass encapsulated sample with two series-connected cells for PCT (Pressure Cooker Test) aging evaluation. The film's resistance to damp heat is assessed by comparing the blackening of the EL (Electroluminescence) images before and after PCT aging. This method has a long testing cycle, typically greater than 7 days, and the judgment of the degree of EL blackening after aging is greatly affected by subjective factors.

[0004] Method two involves conducting a damp heat aging test (DH) on photovoltaic modules encapsulated with a film. The film's resistance to damp heat is evaluated by comparing EL (electrode temperature) test results and power changes before and after aging. This method has a longer testing cycle, typically exceeding 50 days, and is more expensive, thus failing to meet the need for rapid evaluation. Summary of the Invention

[0005] Therefore, it is necessary to provide a method for evaluating the moisture and heat resistance of encapsulating films to solve the problems of long cycle and high cost of traditional moisture and heat resistance evaluation methods.

[0006] A method for evaluating the moisture and heat resistance of an encapsulating film includes the following steps:

[0007] Provide solar cells, and test the electrical performance and EL images of the solar cells;

[0008] Dissolve the encapsulating film and sodium salt to be tested in a solvent to obtain a mixed solution;

[0009] The mixed solution is coated onto the battery cell and dried to form a salt-containing adhesive film.

[0010] The battery cell with the salt-containing film formed thereon is subjected to wet heat aging treatment;

[0011] The electrical performance and EL images of the battery cells after the aforementioned damp heat aging treatment were tested.

[0012] The damp heat resistance of the encapsulating film is evaluated based on the changes in the electrical properties and EL images of the battery cells before and after the damp heat aging treatment.

[0013] In some embodiments, the ratio of the mass of the encapsulating film to the amount of sodium ions in the sodium salt is 1 g : (0.001~0.05) mol.

[0014] In some embodiments, the sodium salt is one or more of sodium nitrate, sodium bicarbonate, sodium chloride, and sodium hydroxide.

[0015] In some embodiments, the solvent is water.

[0016] In some embodiments, the step of dissolving the encapsulating film to be tested and the sodium salt in a solvent to obtain a mixed solution includes:

[0017] The encapsulation film to be tested is cut into granular films;

[0018] The particulate film is immersed in the solvent and then heated to dissolve it, thus obtaining a glue solution.

[0019] Sodium salt is added to the gel solution to obtain the mixed solution.

[0020] In some embodiments, prior to the step of dissolving the encapsulating film and sodium salt in a solvent, the method for evaluating the moisture and heat resistance of the encapsulating film further includes the following steps:

[0021] The encapsulation film to be tested is subjected to hot pressing treatment.

[0022] In some embodiments, the hot pressing treatment is performed at a temperature of 145°C to 155°C for a time of 300s to 600s.

[0023] In some embodiments, the thickness of the salt-containing film is 200 μm to 700 μm.

[0024] In some embodiments, the electrical properties include one or more of the following: photoelectric conversion efficiency, short-circuit current, open-circuit voltage, fill factor, pseudo-fill factor, series resistance, and parallel resistance.

[0025] In some embodiments, the temperature of the damp heat aging treatment is 80°C to 90°C, the humidity is 80%RH to 90%RH, and the time is 3h to 10h.

[0026] In some embodiments, evaluating the moisture resistance of the encapsulating film based on changes in the electrical properties and EL images of the battery cell before and after the moisture aging treatment includes:

[0027] If the electrical performance degradation is less than 0.5% after the damp heat aging treatment and the EL image does not turn black, the damp heat resistance of the encapsulating film is deemed qualified.

[0028] If the attenuation of the electrical performance is greater than 0.5%, and / or the EL image turns black, the moisture and heat resistance of the encapsulating film is deemed unqualified.

[0029] Compared with traditional technologies, the above-mentioned method for evaluating the moisture and heat resistance of encapsulating films has the following advantages:

[0030] The method for evaluating the damp heat resistance of the aforementioned encapsulating film involves dissolving the encapsulating film and sodium salt together, coating the resulting mixed solution onto a solar cell, and then subjecting it to damp heat aging. By adding sodium salt, sodium ions are introduced into the film, simulating the performance degradation of the solar cell caused by sodium ion precipitation in the module glass due to film hydrolysis in a damp heat environment, and accelerating the rate of performance degradation. The damp heat resistance of the encapsulating film is then evaluated based on the changes in the electrical performance and EL images of the solar cell before and after the damp heat aging treatment. Compared to traditional techniques, this evaluation method can rapidly and quantitatively assess the damp heat aging resistance of the encapsulating film, with low testing costs, short testing cycles, and improved efficiency. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating a method for evaluating the moisture and heat resistance of an encapsulating film according to one embodiment.

[0032] Figure 2 This is a schematic diagram of coating a mixed solution onto a battery cell in an embodiment of a method for evaluating the moisture and heat resistance of an encapsulating film. Detailed Implementation

[0033] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0037] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] like Figure 1 As shown, an embodiment of the method for evaluating the moisture and heat resistance of an encapsulating film includes the following steps:

[0039] Step S1: Provide a solar cell and test its electrical performance and EL image.

[0040] Step S2: Dissolve the encapsulating film and sodium salt to be tested in a solvent to obtain a mixed solution.

[0041] Step S3: Coat the solar cell with the mixed solution and dry to form a salt-containing film.

[0042] Step S4 involves subjecting the solar cell with the salt-containing film to wet heat aging treatment.

[0043] Step S5: Test the electrical performance and EL image of the solar cell after wet heat aging treatment.

[0044] Step S6: Evaluate the moisture and heat resistance of the encapsulating film based on the changes in the electrical properties and EL images of the solar cells before and after the moisture and heat aging treatment.

[0045] The method for evaluating the damp heat resistance of the aforementioned encapsulating film involves dissolving the encapsulating film and sodium salt together, coating the resulting mixed solution onto a solar cell, and then subjecting it to damp heat aging. By adding sodium salt, sodium ions are introduced into the film, simulating the performance degradation of the solar cell caused by sodium ion precipitation in the module glass due to film hydrolysis in a damp heat environment, and accelerating the rate of performance degradation. The damp heat resistance of the encapsulating film is then evaluated based on the changes in the electrical performance and EL images of the solar cell before and after the damp heat aging treatment. Compared to traditional techniques, this evaluation method can rapidly and quantitatively assess the damp heat aging resistance of the encapsulating film, with low testing costs, short testing cycles, and improved efficiency.

[0046] In step S1, the solar cell can be a crystalline silicon cell, such as a PERC cell (passivated emitter back contact cell), a TOPCon cell (tunneling oxide passivated contact cell), an HJT cell (heterojunction cell), a BC cell (back contact cell), etc.; it can also be other types of cells, such as perovskite cells; it can be a single-junction cell or a stacked cell.

[0047] In some of these examples, in step S1, the solar cell is a heterojunction cell.

[0048] In step S1, the electrical properties can be, but are not limited to, one or more of the following: photoelectric conversion efficiency, short-circuit current, open-circuit voltage, fill factor, pseudo-fill factor, series resistance, and parallel resistance.

[0049] In some examples, in step S2, the ratio of the mass of the encapsulating film to the amount of sodium ions in the sodium salt is 1 g : (0.001~0.05) mol. That is, for every 1 g of encapsulating film, the amount of sodium ions added to the sodium salt is (0.001~0.05) mol. Further, in some examples, the ratio of the mass of the encapsulating film to the amount of sodium ions in the sodium salt is 1 g : (0.01~0.05) mol.

[0050] In some examples, prior to the step of dissolving the encapsulating film and sodium salt in a solvent (step S2), the method for evaluating the moisture and heat resistance of the encapsulating film further includes the following steps:

[0051] The encapsulation film to be tested is subjected to hot pressing treatment.

[0052] In some examples, the hot-pressing temperature is 145°C to 155°C. Further, in some examples, the hot-pressing temperature is 147°C to 153°C. In some specific examples, the hot-pressing temperature is, for example, 145°C, 146°C, 147°C, 148°C, 149°C, 150°C, 151°C, 152°C, 153°C, 154°C, 155°C, etc.

[0053] In some examples, the hot-pressing time is 300s to 600s. Further, in some examples, the hot-pressing time is 400s to 500s. In some specific examples, the hot-pressing time is, for example, 300s, 350s, 400s, 450s, 300s, 550s, 600s, etc.

[0054] In some examples, the encapsulating film to be tested is cut into rectangles before hot pressing. In some examples, the side length of the rectangle is 100mm to 300mm. In some specific examples, the side length of the rectangle is one or two of the following values: 100mm, 150mm, 200mm, 250mm, 300mm, etc.

[0055] Optionally, in step S2, the added sodium salt is one or more of sodium nitrate (NaNO3), sodium bicarbonate (NaHCO3), sodium chloride (NaCl), and sodium hydroxide (NaOH).

[0056] In some of these examples, the sodium salt added in step S2 is sodium nitrate.

[0057] Optionally, in step S2, the solvent used can be, but is not limited to, water.

[0058] In some examples, water is used as the solvent in step S2. More specifically, deionized water is used as the solvent.

[0059] In some examples, the step of dissolving the encapsulating film and sodium salt to be tested in a solvent (step S2) includes:

[0060] Step S21: Cut the encapsulation film to be tested into granular films.

[0061] Step S22: Immerse the granular film in a solvent and heat it to dissolve the granular film, thus obtaining a glue solution.

[0062] Step S23: Add sodium salt to the gel solution to obtain a mixed solution.

[0063] In some of these examples, in step S21, the area of ​​the particulate film is 50 mm². 2 ~400mm 2For example, 50mm 2 100mm 2 200mm 2 300mm 2 400mm 2 The shape of the granular film can be, but is not limited to, rectangular, circular, etc. In some examples, the granular film is a square with a side length of 10 mm.

[0064] In step S22, the heating process can accelerate the dissolution of the particulate film in the solvent.

[0065] During heat treatment, it is preferable to seal the container containing the particulate film and solvent, and then place the sealed container in an oven for baking.

[0066] In some of these examples, the heat treatment temperature is 90°C to 110°C. Further, in some of these examples, the heat treatment temperature is 95°C to 105°C. In some specific examples, the heat treatment temperature is, for example, 90°C, 95°C, 100°C, 105°C, 110°C, etc.

[0067] In some examples, the heat treatment time is 24h to 72h. Further, in some examples, the heat treatment time is 30h to 66h. In some specific examples, the heat treatment time is, for example, 24h, 30h, 36h, 42h, 48h, 54h, 66h, 72h, etc.

[0068] Optionally, in step S3, the coating process of the mixed solution may be, for example, but not limited to, drop coating, spin coating, printing, inkjet printing, blade coating, printing, dip-coating, immersion, spraying, roller coating, casting, slot coating, and strip coating.

[0069] Optionally, in step S3, the mixed solution can be applied to the front side of the solar cell or the back side of the solar cell.

[0070] Optionally, in step S3, the coating of the mixed solution can be a full-surface coating or a partial coating, such as... Figure 2 As shown, for example, a mixed solution 200 is coated at several locations on the surface of the solar cell 100, with the number of coating locations being, for example, 4 to 20. The coating locations of the mixed solution 200 are located between adjacent grid lines 102.

[0071] In some of these examples, the damp heat aging process in step S4 is a DH aging process.

[0072] In some examples, the temperature of the damp heat aging treatment in step S4 is 80°C to 90°C. In some specific examples, the temperature of the damp heat aging treatment is, for example, 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, etc.

[0073] In some examples, the humidity of the damp heat aging treatment in step S4 is 80%RH~90%RH. In some specific examples, the humidity of the damp heat aging treatment is 80%RH, 82%RH, 84%RH, 86%RH, 88%RH, or 90%RH.

[0074] In some examples, the damp heat aging treatment time in step S4 is 3h to 10h. In some specific examples, the damp heat aging treatment time is 3h, 5h, 7h, 8h, 9h, 10h, etc.

[0075] In some examples, the thickness of the salt-containing adhesive film formed in step S5 is 200 μm to 700 μm. Further, in some examples, the thickness of the salt-containing adhesive film formed in step S5 is 200 μm to 700 μm. In some specific examples, the thickness of the salt-containing adhesive film formed in step S5 is, for example, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, etc.

[0076] In some examples, in step S6, if the degradation of the electrical performance of the solar cell is less than 0.5% after the damp heat aging treatment, and the EL image of the coating position of the salt-containing film does not show blackening, then the damp heat resistance of the encapsulating film is evaluated as qualified.

[0077] If the electrical performance of the solar cell degrades by more than 0.5%, and / or the EL image of the coating area of ​​the salt-containing encapsulant film turns black, the moisture and heat resistance of the encapsulant film is deemed unqualified.

[0078] It should be understood that, although Figure 1 The steps in the flowchart shown are displayed sequentially as indicated by the arrows; however, these steps are not necessarily executed in the exact order indicated by the arrows. Unless explicitly stated herein, there is no strict order constraint on the execution of these steps; they can be executed in other orders or simultaneously, as long as there is no logical contradiction. Furthermore, Figure 1At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. Their execution order is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0079] The method for evaluating the damp heat resistance of the aforementioned encapsulating film involves dissolving the encapsulating film and sodium salt together, coating the resulting mixed solution onto a solar cell, and then subjecting it to damp heat aging. By adding sodium salt, sodium ions are introduced into the film, simulating the performance degradation of the solar cell caused by sodium ion precipitation in the module glass due to film hydrolysis in a damp heat environment, and accelerating the rate of performance degradation. The damp heat resistance of the encapsulating film is then evaluated based on the changes in the electrical performance and EL images of the solar cell before and after the damp heat aging treatment. Compared to traditional techniques, this evaluation method can rapidly and quantitatively assess the damp heat aging resistance of the encapsulating film, with low testing costs, short testing cycles, and improved efficiency.

[0080] The following specific embodiments further illustrate the present invention. These specific embodiments are provided to better understand the present invention, but are not intended to limit the scope of the invention and do not constitute a limitation on its content or protection.

[0081] Example 1

[0082] This embodiment provides a method for evaluating the moisture and heat resistance of an encapsulating film, including the following steps:

[0083] Step 1: Provide a heterojunction cell and test its photoelectric conversion efficiency and EL image.

[0084] Step 2: Take the encapsulating film to be tested, cut it into rectangles with a length of 200mm and a width of 100mm, and perform hot pressing. The hot pressing temperature is 150℃, and the hot pressing time is 400s.

[0085] Step 3: Cut the heat-pressed encapsulating film into square granules with sides of 10mm. Place the granules into a beaker, add 100ml of deionized water, and seal the beaker with stretch wrap. Place the sealed beaker in an oven at 100℃ for 48 hours to fully dissolve the encapsulating film in the deionized water, obtaining the adhesive solution.

[0086] Step 4: Pour 50 ml of the above gel solution into another beaker, add 0.1318 g of sodium nitrate, and dissolve to obtain a mixed solution.

[0087] Step 5: Use a dropper to draw up the above mixed solution and drop 6 drops onto the front side of the heterojunction cell after testing the photoelectric conversion efficiency and EL image. Let it stand for 1 hour to allow the mixed solution to dry and form a salt-containing film.

[0088] Step 6: The heterojunction cell with the salt-containing film formed is placed vertically in the DH aging chamber for damp heat aging treatment. The temperature is set to 85℃, the humidity is set to 85%RH, and the treatment time is 3h.

[0089] Step 7: After the damp heat aging treatment, remove the heterojunction cell and test the photoelectric conversion efficiency and EL image of the solar cell.

[0090] Step 8: Evaluate the moisture resistance of the encapsulating film based on the changes in the photoelectric conversion efficiency and EL image of the solar cell before and after the moisture aging treatment. Specifically, after the moisture aging treatment, if the decrease in the photoelectric conversion efficiency of the solar cell is less than 0.5%, and the EL image of the coating area of ​​the salt-containing encapsulating film does not show blackening, then the moisture resistance of the encapsulating film is evaluated as qualified. If the decrease in the photoelectric conversion efficiency of the solar cell is greater than 0.5%, and / or the EL image of the coating area of ​​the salt-containing encapsulating film shows blackening, then the moisture resistance of the encapsulating film is evaluated as unqualified.

[0091] Example 2

[0092] This embodiment provides a method for evaluating the moisture and heat resistance of an encapsulating film, including the following steps:

[0093] Step 1: Provide a heterojunction cell and test its photoelectric conversion efficiency and EL image.

[0094] Step 2: Take the encapsulating film to be tested, cut it into rectangles with a length of 300mm and a width of 200mm, and perform hot pressing. The hot pressing temperature is 145℃, and the hot pressing time is 600s.

[0095] Step 3: Cut the heat-pressed encapsulating film into square granules with sides of 10mm. Place the granules into a beaker, add 100ml of deionized water, and seal the beaker with stretch wrap. Place the sealed beaker in an oven at 110℃ for 48 hours to fully dissolve the encapsulating film in the deionized water, obtaining the adhesive solution.

[0096] Step 4: Pour 50 ml of the above gel solution into another beaker, add 0.1318 g of sodium nitrate, and dissolve to obtain a mixed solution.

[0097] Step 5: Use a dropper to draw up the above mixed solution and drop 6 drops onto the front side of the heterojunction cell after testing the photoelectric conversion efficiency and EL image. Let it stand for 1 hour to allow the mixed solution to dry and form a salt-containing film.

[0098] Step 6: The heterojunction cell with the salt-containing film formed is placed vertically in the DH aging chamber for damp heat aging treatment. The temperature is set to 85℃, the humidity is set to 85%RH, and the treatment time is 3h.

[0099] Step 7: After the damp heat aging treatment, remove the heterojunction cell and test the photoelectric conversion efficiency and EL image of the solar cell.

[0100] Step 8: Evaluate the moisture resistance of the encapsulating film based on the changes in the photoelectric conversion efficiency and EL image of the solar cell before and after the moisture aging treatment. Specifically, after the moisture aging treatment, if the decrease in the photoelectric conversion efficiency of the solar cell is less than 0.5%, and the EL image of the coating area of ​​the salt-containing encapsulating film does not show blackening, then the moisture resistance of the encapsulating film is evaluated as qualified. If the decrease in the photoelectric conversion efficiency of the solar cell is greater than 0.5%, and / or the EL image of the coating area of ​​the salt-containing encapsulating film shows blackening, then the moisture resistance of the encapsulating film is evaluated as unqualified.

[0101] The evaluation method described in the above embodiments has a total process cycle of less than 4 days, which is much shorter than traditional evaluation methods. It is highly efficient and has low testing costs.

[0102] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0103] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A method for evaluating the moisture and heat resistance of an encapsulating film, characterized in that, Includes the following steps: Provide solar cells, and test the electrical performance and EL images of the solar cells; Dissolve the encapsulating film and sodium salt to be tested in a solvent to obtain a mixed solution; The mixed solution is coated onto the battery cell and dried to form a salt-containing adhesive film. The battery cell with the salt-containing film formed thereon is subjected to wet heat aging treatment; The electrical performance and EL images of the battery cells after the aforementioned damp heat aging treatment were tested. The damp heat resistance of the encapsulating film is evaluated based on the changes in the electrical properties and EL images of the battery cells before and after the damp heat aging treatment.

2. The method for evaluating the moisture and heat resistance of the encapsulating film as described in claim 1, characterized in that, The ratio of the mass of the encapsulating film to the amount of sodium ions in the sodium salt is 1 g : (0.001~0.05) mol.

3. The method for evaluating the moisture and heat resistance of the encapsulating film as described in claim 1, characterized in that, The sodium salt is one or more of sodium nitrate, sodium bicarbonate, sodium chloride, and sodium hydroxide; And / or, the solvent is water.

4. The method for evaluating the moisture and heat resistance of the encapsulating film as described in claim 1, characterized in that, The process involves dissolving the encapsulating film to be tested and the sodium salt in a solvent to obtain a mixed solution, comprising: The encapsulation film to be tested is cut into granular films; The particulate film is immersed in the solvent and then heated to dissolve it, thus obtaining a glue solution. Sodium salt is added to the gel solution to obtain the mixed solution.

5. The method for evaluating the moisture and heat resistance of the encapsulating film as described in claim 1, characterized in that, Prior to the step of dissolving the encapsulating film and sodium salt in a solvent, the method for evaluating the moisture and heat resistance of the encapsulating film further includes the following steps: The encapsulation film to be tested is subjected to hot pressing treatment.

6. The method for evaluating the moisture and heat resistance of the encapsulating film as described in claim 5, characterized in that, The hot pressing process is performed at a temperature of 145℃~155℃ for a time of 300s~600s.

7. The method for evaluating the moisture and heat resistance of the encapsulating film as described in claim 1, characterized in that, The thickness of the salt-containing adhesive film is 200μm~700μm.

8. The method for evaluating the moisture and heat resistance of the encapsulating film as described in claim 1, characterized in that, The temperature of the damp heat aging treatment is 80℃~90℃, the humidity is 80%RH~90%RH, and the time is 3h~10h.

9. The method for evaluating the moisture and heat resistance of the encapsulating film as described in claim 1, characterized in that, The electrical properties include one or more of the following: photoelectric conversion efficiency, short-circuit current, open-circuit voltage, fill factor, pseudo-fill factor, series resistance, and parallel resistance.

10. The method for evaluating the moisture and heat resistance of the encapsulating film as described in any one of claims 1 to 9, characterized in that, The evaluation of the moisture and heat resistance of the encapsulating film based on the changes in the electrical properties and EL images of the battery cells before and after the moisture and heat aging treatment includes: If the electrical performance degradation is less than 0.5% after the damp heat aging treatment and the EL image does not turn black, the damp heat resistance of the encapsulating film is deemed qualified. If the attenuation of the electrical performance is greater than 0.5%, and / or the EL image turns black, the moisture and heat resistance of the encapsulating film is deemed unqualified.

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