Encapsulating film, methods for preparing encapsulating film, and photovoltaic modules

Abstract

This invention discloses an encapsulating film, a method for preparing the encapsulating film, and a photovoltaic module. The encapsulating film includes a film body and a stress-chromic agent. The stress-chromic agent is disposed on the film body, and reacts with the film body to produce a color change when the stress it receives exceeds a certain limit. By placing the stress-chromic agent on the film body, and allowing it to react with the film body when the stress exceeds a certain limit, relevant personnel can quickly identify the fracture state of the encapsulating film without the need for specialized testing equipment. This facilitates the monitoring and hazard identification of photovoltaic modules, improving the safety and ease of maintenance of the encapsulating film.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to an encapsulating film, a method for preparing the encapsulating film, and a photovoltaic module. Background Technology

[0002] Currently, photovoltaic modules are subject to external impacts and temperature changes during production, transportation, installation, and use. This can easily lead to localized stress concentrations inside the photovoltaic modules. When the stress exceeds a critical value, it may cause phenomena such as cell breakage and solder ribbon breakage, affecting the power generation efficiency and lifespan of the photovoltaic modules.

[0003] In related technologies, stress monitoring of photovoltaic modules mainly relies on electroluminescence detection. However, this method requires specialized equipment and is complex to operate, which not only increases equipment costs but also fails to enable rapid screening of fracture points with the naked eye. Consequently, damage cannot be dealt with in a timely manner, leading to further damage to the photovoltaic modules. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide an encapsulating film that, when the stress limit is exceeded, causes a color change reaction between the stress chromogen and the film itself. This color change reaction can be quickly identified by the naked eye, allowing for rapid remedial measures and eliminating the need for specialized equipment testing, thereby preventing further damage to photovoltaic modules.

[0005] The present invention also proposes a method for preparing an encapsulating film.

[0006] The present invention further proposes a photovoltaic module.

[0007] According to a first aspect of the present invention, an encapsulating film includes: a film body; and a stress chromogen disposed on the film body, wherein the stress chromogen reacts with the film body to produce a color change when subjected to stress exceeding a limit value.

[0008] According to an embodiment of the present invention, the encapsulating film, by placing a stress-chromic element on the film body, reacts with the film body when the stress on the stress-chromic element exceeds a limit value. This allows relevant personnel to quickly identify the fracture state of the encapsulating film without the need for professional testing equipment, thereby facilitating the monitoring and hazard investigation of photovoltaic modules and improving the safety and maintenance convenience of the encapsulating film.

[0009] According to some embodiments of the present invention, the stress-sensitive color-changing body includes: a release membrane disposed on the film body and forming an inner cavity; a photochromic compound disposed in the inner cavity, wherein the release membrane ruptures after the stress exceeds a limit value, so that the photochromic compound comes into contact with the film body and undergoes a color-developing reaction.

[0010] According to some embodiments of the present invention, the photochromic compound is one of a spiropyran compound and a spiroxazine compound; and / or the film body is one of a vinyl acetate copolymer film and a polyolefin elastomer film.

[0011] According to some embodiments of the present invention, the separating membrane is one of a polyurea membrane and a gelatin-gum arabic composite membrane.

[0012] According to some embodiments of the present invention, the isolation membrane is capsule-shaped with a particle size of L, where L satisfies the relationship: 5μm≤L≤20μm.

[0013] According to some embodiments of the present invention, the adhesive film body includes a color-changing region and a non-color-changing region, and the stress color-changing body is disposed only in the color-changing region.

[0014] According to some embodiments of the present invention, the color-changing area includes: a battery gap color-changing area, which extends along one of the length direction and the width direction of the adhesive film body, and is adapted to correspond to a battery gap; and a frame color-changing area, which extends along the other of the length direction and the width direction of the adhesive film body and is connected to the end of the battery gap color-changing area, and is adapted to correspond to a frame.

[0015] According to some embodiments of the present invention, there are multiple battery gap color-changing areas, which are distributed at intervals along the length direction and width direction of the adhesive film body; and / or there are two border color-changing areas, which are respectively connected to the two ends of the battery gap color-changing areas; and / or the width of the battery gap color-changing area is smaller than the width of the border color-changing area.

[0016] According to some embodiments of the present invention, the limit value of the stress chromatic body is P, and P satisfies the relationship: 60 MPa ≤ P ≤ 62 MPa.

[0017] A method for preparing the encapsulating film according to a second aspect of the present invention includes: preparing the stress chromosome; and casting the stress chromosome and a substrate of the encapsulating film body into a film.

[0018] According to other embodiments of the present invention, the step of preparing the stress chromatic body includes: encapsulating a photochromic compound in an isolation membrane to form the stress chromatic body.

[0019] According to other embodiments of the present invention, the step of mixing the stress chromophore and the substrate of the adhesive film body and then casting them into a film includes: laying a portion of the substrate of the adhesive film body to form a base film layer; mixing the stress chromophore and another portion of the substrate of the adhesive film body, and then casting them together with the base film layer to form a film.

[0020] According to other embodiments of the present invention, the adhesive film body includes a color-changing region and a non-color-changing region, and the step of mixing the stress-changing material and another part of the substrate of the adhesive film body and then casting it with the base film to form a film includes: mixing the stress-changing material and another part of the substrate of the adhesive film body, and then casting it with the base film in the color-changing region to form a film.

[0021] According to other embodiments of the present invention, the mass percentage of the stress chromophore and another portion of the substrate of the adhesive film body located in the chromophore area is a, where a satisfies the relationship: 0.3%≤a≤0.8%.

[0022] A photovoltaic module according to a third aspect of the present invention includes: a cover plate; a back sheet; a plurality of solar cells disposed between the cover plate and the back sheet; a first encapsulating film disposed between the cover plate and the plurality of solar cells; and a second encapsulating film disposed between the back sheet and the plurality of solar cells; wherein at least one of the first encapsulating film and the second encapsulating film is an encapsulating film according to any one of claims 1-10.

[0023] In some embodiments of the present invention, the encapsulating film includes a color-changing area, the color-changing area includes a cell gap color-changing area, the cell gap color-changing area and the gap between two adjacent cells are disposed opposite to each other in the thickness direction of the cover plate; and / or the photovoltaic module further includes a frame, the cover plate and the back plate are disposed within the frame, the color-changing area includes a frame color-changing area, the frame color-changing area and the frame are disposed opposite to each other in the thickness direction of the cover plate.

[0024] In some embodiments of the present invention, the width of the color-changing area of ​​the battery gap is greater than the width of the gap between two adjacent battery cells; and / or the thickness of the color-changing area is d1, and the thickness of the non-color-changing area is d2, wherein d1 and d2 satisfy the relationship: 0.6d1≤d2≤0.75d1.

[0025] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a partial cross-sectional view of a photovoltaic module according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the encapsulating film according to an embodiment of the present invention; Figure 3 This is a flowchart of a method for preparing an encapsulating film according to an embodiment of the present invention; Figure 4 This is a flowchart of a method for casting a film by mixing a stress chromophore and a substrate of the film body.

[0027] Figure label: 100. Encapsulating film; 10. Adhesive film body; 11. Color-changing area; 111. Color-changing area between batteries; 112. Color-changing area of ​​the edge; 12. Non-color-changing area; 20. Stress-induced color changer; 200, cover plate; 300, back plate; 400, battery cell. Detailed Implementation

[0028] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention are described in detail below.

[0029] The following is for reference. Figure 1 and Figure 2 The encapsulation film 100 according to an embodiment of the present invention is described.

[0030] like Figure 1 and Figure 2 As shown, the encapsulating film 100 according to an embodiment of the present invention includes: a film body 10 and a stress chromogenic agent 20. The stress chromogenic agent 20 is disposed on the film body 10. When the stress received by the stress exceeds a limit value, the stress chromogenic agent 20 reacts with the film body 10 to produce a color.

[0031] It is understandable that the adhesive film body 10 and the stress-sensitive color changer 20 constitute the main structure of the encapsulation adhesive film 100. The stress-sensitive color changer 20 is set on the adhesive film body 10, which makes it easy for the stress-sensitive color changer 20 to be integrated with the adhesive film body 10. This not only ensures the integrity and stability of the adhesive film body 10, but also eliminates the need to add additional complex sensing components, thereby ensuring the integrity and reliability of the encapsulation adhesive film 100.

[0032] The stress chromatic agent 20 has a critical stress value. When the stress chromatic agent 20 is subjected to a stress exceeding the critical value, the encapsulant film 10 reacts with the stress chromatic agent 20, resulting in a color change. Relevant personnel can distinguish the color change with the naked eye. This allows relevant personnel to quickly identify the fracture state of the encapsulant film 100 without the need for professional testing equipment. Moreover, the color reaction is directly triggered by stress exceeding the limit value, and the reaction is rapid and clear. This facilitates the monitoring and hazard investigation of photovoltaic modules by staff, improves the safety and maintenance convenience of the encapsulant film 100, and plays an early warning role in the transportation, encapsulation, and protection of the encapsulant film 100 during actual use.

[0033] Therefore, by placing the stress chromogenic body 20 on the encapsulant film body 10, the stress chromogenic body 20 reacts with the encapsulant film body 10 after the stress exceeds the limit value. This allows relevant personnel to quickly identify the fracture state of the encapsulant film 100 without the need for professional testing equipment, thereby facilitating the monitoring and hazard investigation of photovoltaic modules and improving the safety and maintenance convenience of the encapsulant film 100.

[0034] Among them, such as Figure 1 As shown, the stress-sensitive color-changing body 20 includes: a release film and a photochromic compound. The release film is disposed on the film body 10 and forms an inner cavity. The photochromic compound is disposed in the inner cavity. The release film breaks after the stress exceeds the limit value, thereby allowing the photochromic compound to come into contact with the film body 10 and undergo a color reaction.

[0035] In other words, the isolation film and the photochromic compound constitute the stress chromatic body 20. The isolation film is disposed on the encapsulating film body 10, which allows the isolation film to not occupy additional space in the encapsulating film 100, thus optimizing the layout space of the encapsulating film 100. A certain space is formed inside the isolation film, which is the inner cavity of the isolation film. The inner cavity can provide an installation or storage location for the photochromic compound, keeping the photochromic compound in a closed and stable environment, preventing the photochromic compound from reacting with other external substances, and avoiding its misuse or accidental damage during transportation. This design prevents the photochromic compound from reacting with other substances or the film body 10 when the stress level is below the limit, thus ensuring the stability and reliability of the encapsulation film 100 when it does not reach the warning state. Furthermore, the photochromic compound is encapsulated in the isolation film, which allows for the partitioned arrangement of the photochromic compound and the film body 10. This not only ensures the adhesion and protection of the film body 10 itself, but also allows the photochromic compound to adhere to the stress-bearing area of ​​the film body 10, thereby improving the targeting and warning capability of the stress-bearing area of ​​the encapsulation film 100.

[0036] When the stress on the isolation membrane exceeds a preset critical value, the isolation membrane ruptures, releasing the photochromic compound inside. The photochromic compound comes into contact with the encapsulant film 10, and a color reaction occurs between them. This method not only allows for direct and rapid triggering, but also eliminates the need for additional components. The color reaction between the photochromic compound and the encapsulant film 10 is visually apparent, facilitating quick on-site identification of the approximate location of any damage to the encapsulant film 100 without compromising its integrity. This allows for compatibility with various types of encapsulant films 100 and different usage environments, while also ensuring the reliability and timely warning of the encapsulant film 100.

[0037] Specifically, the photochromic compound has stable color-changing properties. When it is not triggered or in contact with the film body 10, it can remain colorless or light-colored for a long time without affecting the appearance and light transmittance of the film body 10. This ensures the normal performance of the encapsulation film 100. Moreover, the photochromic compound has a sensitive color reaction and high recognition, which can form a clear and conspicuous warning state, making it easy for relevant personnel to quickly identify stress overload areas with the naked eye. At the same time, the photochromic compound has mild chemical properties and good compatibility with the film body 10. It will not corrode or damage the structure of the film body 10.

[0038] Optionally, the photochromic compound is one of a spiropyran compound and a spiroxazine compound, and the film body 10 is one of a vinyl acetate copolymer film and a polyolefin elastomer film.

[0039] Understandably, spiropyran and spiroxazine compounds possess excellent photochromic properties. When not triggered or in contact with the film substrate 10, their color is light or even colorless, not affecting the appearance and light transmittance of the film substrate 10, thus ensuring the normal performance of the encapsulating film 100. Furthermore, pyran and spiroxazine compounds exhibit rapid color-changing response, significant color difference, and good fatigue stability. Upon contact with the film substrate 10, they quickly form a clear and conspicuous warning state. Simultaneously, their chemical properties are stable and not easily affected by environmental temperature and humidity, allowing for long-term use. For example, the photochromic compound may be trimethylindoline spiropyran or a spiroxazine derivative.

[0040] The vinyl acetate copolymer film exhibits excellent adhesion, moderate flexibility, and excellent compatibility with photochromic compounds, ensuring a full color development reaction without compromising the performance of the film body 10. The polyolefin elastomer film possesses good toughness, durability, and resistance to stress deformation, making it adaptable to diverse environments. It also provides a stable substrate for the isolation membrane and photochromic compounds. Furthermore, both the vinyl acetate copolymer film and the polyolefin elastomer film are easy to process and have moderate costs. They are highly compatible with spiropyran or spiroxazine compounds, ensuring not only the adhesion, sealing, and cushioning properties of the film body 10 but also facilitating the color development reaction between the film body 10 and the photochromic compounds. This ensures the reliability and timely warning of the encapsulation film 100.

[0041] Optionally, the separator is either a polyurea film or a gelatin-gum arabic composite film. The polyurea film has good strength and toughness, and can precisely set the stress threshold value. It remains intact within the normal stress range and can effectively protect photochromic compounds. When the stress exceeds the limit value, the polyurea film becomes brittle and easily releases photochromic compounds. Moreover, the polyurea film has good chemical stability and is not prone to reacting with the film body 10, which can ensure the long-term storage and use of the separator. The gelatin-gum arabic composite film has good film-forming properties and excellent sealing performance. It can form a stable inner cavity, has mild performance and controllable breakage, and can accurately respond to stress overload signals. It has good compatibility with spiropyran or spiroxazine compounds and is not prone to material failure. Both the polyurea film and the gelatin-gum arabic composite film can achieve the sealing protection of photochromic compounds. They are also compatible with vinyl acetate copolymer films or polyolefin elastomer films, which can ensure the stability and reliability of the encapsulation film 100 and facilitate the color reaction after the stress exceeds the limit value.

[0042] Optionally, the isolation membrane is capsule-shaped, and the particle size of the isolation membrane is L, where L satisfies the relationship: 5μm≤L≤20μm.

[0043] In other words, the capsule shape ensures the regularity and airtightness of the isolation membrane, preventing leakage, volatilization, or premature contact with the encapsulated film 100 during preparation and transportation. It also ensures that the photochromic compound remains dormant until the stress reaches its limit, thereby improving the stability of the encapsulated film 100. Furthermore, the rounded shape of the capsule ensures uniform stress distribution on the isolation membrane, allowing for precise setting of the stress limit. In addition, the small size of the capsule facilitates its distribution within the encapsulated film 10 without compromising its adhesion and flexibility, thus ensuring the early warning effect of the encapsulated film 100.

[0044] The particle size of the isolation membrane must be within a reasonable range. If the particle size is less than 5μm, the membrane will be too small, which is not only detrimental to manufacturing but also results in a weak stress-bearing capacity, making it impossible to accurately control the stress limit. If the particle size is greater than 20μm, the membrane will be too large, which is not only detrimental to transportation and assembly but also prevents the photochromic compound in the inner cavity from contacting the film body 10 in time when the stress exceeds the limit, leading to a sluggish color development reaction or an increase in the cost of the photochromic compound. If the particle size is within a reasonable range, it facilitates manufacturing, transportation, and assembly, allows for precise control of the stress limit, optimizes the material cost of the photochromic compound, and makes the color development reaction between the photochromic compound and the film body 10 more sensitive.

[0045] In addition, such as Figure 2 As shown, the encapsulant film body 10 includes a color-changing area 11 and a non-color-changing area 12. The stress-sensitive color-changing element 20 is only disposed in the color-changing area 11. This arrangement allows the encapsulant film body 10 to achieve precise color differentiation, ensuring stress warning in the color-changing area 11 and maintaining the basic performance of the non-color-changing area 12. This avoids material waste and increased costs caused by the entire encapsulant film body 10 exhibiting a color reaction. The placement of the stress-sensitive color-changing element 20 in the color-changing area 11 enables targeted color development, providing warnings at critical stress points and easily damaged areas, thereby achieving the desired effect. Stress monitoring at high-risk locations does not affect the adhesion, sealing, and light transmittance of the film itself, thus ensuring the reliability of the encapsulation film 100. It also reduces the amount of stress-sensitive color-changing agent 20 used, thereby reducing the material cost of the encapsulation film 100. In addition, compared with the non-color-changing area 12, the color-changing area 11 is easier for relevant personnel to quickly identify, making the warning of the encapsulation film 100 clearer and more identifiable. This further improves the efficiency and accuracy of fault diagnosis and balances the functionality and practicality of the encapsulation film 100.

[0046] Among them, such as Figure 2 As shown, the color-changing area 11 includes a battery gap color-changing area 111 and a frame color-changing area 112. The battery gap color-changing area 111 extends along one of the length direction and the width direction of the adhesive film body 10 and is adapted to correspond to the battery gap. The frame color-changing area 112 extends along the other of the length direction and the width direction of the adhesive film body 10, and the frame color-changing area 112 is connected to the end of the battery gap color-changing area 111 and is adapted to correspond to the frame.

[0047] Specifically, the battery gap color-changing area 111 is located between two adjacent battery cells 400, and the frame color-changing area 112 is located between the battery cell 400 and the frame. The battery gap color-changing area 111 and the frame color-changing area 112 can provide zoned warnings for key areas of the encapsulating film 100, thereby ensuring the targeted nature of the battery gap color-changing area 111 and the frame color-changing area 112. The battery gap color-changing area 111 extends along the width direction of the encapsulating film body 10, and the frame color-changing area 112 extends along the length direction of the encapsulating film body 10, or the battery gap color-changing area 111 extends along the length direction of the encapsulating film body 10, and the frame color-changing area 112 extends along the width direction of the encapsulating film body 10. This ensures that the color-changing area 11 covers areas with obvious stress, thereby facilitating the identification and color-changing warning.

[0048] Taking the battery gap color-changing area 111 extending along the width direction of the film body 10 and the frame color-changing area 112 extending along the length direction of the film body 10 as an example, this allows the battery gap color-changing area 111 to correspond to the battery cells 400 arranged along the width direction of the film body 10, and the frame color-changing area 112 to correspond to the frame extending along the length direction of the film body 10. The battery gap color-changing area 111 can focus on monitoring the lamination force or the force generated by thermal expansion and contraction at the gap between the battery cells 400, and can promptly reflect the stress overload at the gap between the battery cells 400, thereby preventing the damage between the battery cells 400 from continuing to expand and affecting the power generation efficiency. The frame color-changing area 112 can focus on monitoring the pressing force or the installation force at the gap between the frame and the battery cells 400, and can promptly reflect the stress overload between the frame and the battery cells 400, thereby preventing the film body 10 at the frame from aging, cracking and breaking.

[0049] The edges of the frame color-changing area 112 are connected to the ends of the battery gap color-changing area 111. This allows the frame color-changing area 112 and the battery gap color-changing area 111 to form a continuous and complete early warning area. This can prevent the generation of monitoring blind spots and clearly reflect the stress state of each component. As a result, relevant personnel can quickly identify the damaged location without interfering with the light transmission and power generation performance of the photovoltaic module. This can improve the comprehensiveness of the monitoring of the encapsulation film 100 and ensure the stability and reliability of the encapsulation film 100.

[0050] In particular, such as Figure 2 As shown, there are multiple battery gap color-changing areas 111, which are distributed at intervals along the length and width directions of the adhesive film body 10. There are two border color-changing areas 112, which are respectively connected to the two ends of the battery gap color-changing areas 111. The width of the battery gap color-changing areas 111 is smaller than the width of the border color-changing areas 112.

[0051] Understandably, multiple battery gap color-changing areas 111 extend along the width direction of the encapsulant film body 10 and are spaced apart along the length direction of the encapsulant film body 10. This allows the gaps between the battery cells 400 to correspond one-to-one with the battery gap color-changing areas 111, thereby enabling dense and blind-spot-free stress monitoring between the battery cells 400. This allows for precise detection of stress concentration or deformation risks in each gap of the battery cells 400. Moreover, the spacing of the battery gap color-changing areas 111 does not affect the light transmittance and encapsulation of the encapsulant film body 10, thus ensuring the basic performance of the encapsulant film 100.

[0052] Two border color-changing areas 112 are respectively connected to the two ends of the cell gap color-changing area 111 along the width direction of the film body 10. This allows the border color-changing area 112 and the cell gap color-changing area 111 to form a continuous and complete warning area, which can prevent the generation of monitoring blind spots and facilitate the monitoring of locations where stress exceeds the limit value. Moreover, the width of the cell gap color-changing area 111 is smaller than the width of the border color-changing area 112, which allows the cell gap color-changing area 111 to adapt to the gap between the cells 400. It can also monitor and warn without obstructing the cells 400. The wider border color-changing area 112 adapts to the larger stress area and stronger stress impact of the border part, thereby ensuring the warning sensitivity and color recognition of the photovoltaic module edge position. It can better adapt to the actual structure and stress law of the photovoltaic module, thus making stress monitoring more accurate and efficient.

[0053] Optionally, the limit value of the stress chromatic body 20 is P, which satisfies the relationship: 60 MPa ≤ P ≤ 62 MPa.

[0054] In other words, the stress-sensitive chromatic anode 20 must be within a reasonable range. If the stress-sensitive chromatic anode 20's limit is less than 60 MPa, it will easily break, causing frequent color reactions between the photochromic compound and the encapsulant film 10. Furthermore, the load-bearing capacity of the separator film will be incompatible with the load-bearing capacity of the gaps or frames between the solar cells 400, thus affecting the monitoring effect of the encapsulant film 100. Conversely, if the stress-sensitive chromatic anode 20's limit is greater than 62 MPa, it will be less prone to breakage, and the load-bearing capacity of the gaps or frames between the solar cells 400 will exceed the limit. Subsequently, the photochromic compound and the encapsulant film 10 fail to react in time, causing further damage and affecting the normal performance of the photovoltaic module. If the limit value of the stress chromic agent 20 is within a reasonable range, it can not only match the limit value of the stress chromic agent 20 with the load-bearing capacity of the gap or frame between the solar cells 400, but also allow the photochromic compound and the encapsulant film 10 to react in time. This allows relevant personnel to quickly identify the damaged location, thereby improving the comprehensiveness of monitoring of the encapsulant film 100 and ensuring the stability and reliability of the encapsulant film 100. For example, the limit value of the stress chromic agent 20 can be matched with the tolerance limit of the solar cells. The limit value of the stress chromic agent 20 is 60 MPa, 61 MPa, or 62 MPa, with the specific value limited according to the actual situation. This way, when two adjacent solar cells are subjected to a force exceeding the limit value, the stress chromic agent 20 will also break and react in time, thereby improving the color sensitivity of the encapsulant film 100.

[0055] Figure 3 This is a flowchart of a method for preparing an encapsulating film 100 according to an embodiment of the present invention. Figure 4 This is a flowchart of a method for casting a film by mixing the stress chromophore 20 and the substrate of the adhesive film body 10. (Example) Figure 3 and Figure 4 As shown, the method for preparing the encapsulating film 100 according to an embodiment of the present invention includes: S1. Prepare stress chromosome 20; Step S1, the step of preparing the stress chromatic body 20, includes: encapsulating the photochromic compound in an isolation membrane to form the stress chromatic body 20.

[0056] Specifically, trimethylindoline spiropyran or a spiroxazine derivative is a photochromic compound, and a polyurea membrane is used as the isolation membrane. Stress chromosome 20 is prepared via in-situ polymerization, resulting in capsule-shaped stress chromosome 20 with a particle size of 8μm-12μm. This ensures uniform stress distribution within the isolation membrane, allowing for precise setting of stress limits. The small capsule size facilitates distribution within the membrane body 10 without compromising its adhesion and flexibility, thus guaranteeing the warning effect of the encapsulated membrane 100. For example, trimethylindoline spiropyran or a spiroxazine derivative can be encapsulated within the isolation membrane via in-situ polymerization, followed by drying and sieving to obtain the stress chromosome 20 with the target particle size.

[0057] S2. The stress chromophore 20 and the substrate of the adhesive film body 10 are mixed and then cast into a film.

[0058] Specifically, firstly, a stress chromatic atom 20 is prepared, then the prepared stress chromatic atom 20 is mixed with the adhesive film body 10, and finally, a film is cast. This not only simplifies the process, but also enables the stress chromatic atom 20 to be uniformly dispersed in the adhesive film body 10, thereby ensuring the monitoring sensitivity of the color-changing area 11. The method of casting the film is to mix, melt, and plasticize the stress chromatic atom 20 and the adhesive film body 10, and then cast the film through a mold at a certain temperature.

[0059] Step S2, which involves mixing the stress chromophore 20 and the substrate of the adhesive film body 10 and then casting them into a film, includes: S21. Lay a portion of the substrate of the adhesive film body 10 to form a base film layer; S22. After mixing the stress-sensitive chromogenic agent 20 with another portion of the substrate of the adhesive film body 10, it is then cast into a film with a base film layer. For example, after mixing trimethylindoline spiropyran with the adhesive film body 10, it is melted and stirred at 100℃-120℃ for 30 minutes, and then cast into a film with a thickness of 0.2mm in the color-changing zone 11. The base film layer has a thickness of 0.3mm. Finally, the two film layers are stacked, so that the thickness of the adhesive film body 10 in the color-changing zone 11 can reach 0.5mm. Alternatively, after mixing the spiroxazine derivative with the adhesive film body 10, the thickness of the adhesive film body 10 in the color-changing zone 11 can reach 0.4mm. The color-changing response time is less than 5 seconds. This not only ensures stress monitoring at high-risk locations of the encapsulation adhesive film 100, but also does not affect the adhesion, sealing, and light transmittance of the adhesive film body 10 itself, thereby ensuring the reliability of the encapsulation adhesive film 100. For example, after trimethylindoline spiropyran and the film body 10 are mixed, they are melted and stirred at 110°C for 30 minutes. This facilitates the full melting of trimethylindoline spiropyran and the film body 10 without affecting the performance of the film body 10.

[0060] The adhesive film body 10 includes a color-changing area 11 and a non-color-changing area 12. Step S22, mixing the stress color-changing body 20 and another part of the substrate of the adhesive film body 10 and then casting it with the base film, includes: mixing the stress color-changing body 20 and another part of the substrate of the adhesive film body 10 and then casting it with the base film in the color-changing area 11.

[0061] Specifically, a layer of adhesive film body 10 is first laid inside the frame. This adhesive film body 10 is the base film layer. Then, the stress color-changing body 20 and other unlaid adhesive film bodies 10 are cast into a film and laid on the color-changing area 11 corresponding to the base film layer. This ensures that the encapsulation film 100 can perform early warning monitoring in areas of stress concentration without affecting the light transmittance and encapsulation properties of the encapsulation film 100.

[0062] Optionally, the mass percentage of the stress chromophore 20 and another portion of the substrate of the film body 10 located in the color-changing area 11 is a, where a satisfies the relationship: 0.3%≤a≤0.8%.

[0063] In other words, the mass percentage of the stress chromogen 20 and the other part of the substrate of the encapsulating film 10 located in the color-changing region 11 must be within a reasonable range. If the mass percentage of the stress chromogen 20 and the other part of the substrate of the encapsulating film 10 located in the color-changing region 11 is less than 0.3%, the amount of stress chromogen 20 will be too small. When the color-changing region 11 in the encapsulating film 100 reaches its limit, the color reaction of the photochromic compound in the stress chromogen 20 and the other part of the substrate of the encapsulating film 10 will not be obvious, making rapid separation impossible and thus affecting the stress monitoring of the encapsulating film 100. If the mass percentage of the stress chromogen 20 and the other part of the substrate of the encapsulating film 10 located in the color-changing region 11 is less than 0.3%, the stress chromogen 20 will be too small. If the mass percentage of the color-changing region 11 is greater than 0.8%, it will result in an excessive amount of stress chromogen 20. Even if the color-changing region 11 in the encapsulating film 100 does not reach the limit value, a color reaction will occur between the photochromic compound and another part of the substrate of the encapsulating film body 10, which will affect the stress monitoring of the encapsulating film 100 and increase the material cost of the encapsulating film 100. If the mass percentage of the stress chromogen 20 and another part of the substrate of the encapsulating film body 10 in the color-changing region 11 is within a reasonable range, it can not only ensure the sensitivity of the color reaction of the photochromic compound and the other part of the substrate of the encapsulating film body 10, but also will not increase the material cost of the encapsulating film 100.

[0064] like Figure 1As shown, a photovoltaic module according to an embodiment of the present invention includes: a cover plate 200, a back sheet 300, a plurality of solar cells 400, a first encapsulating film and a second encapsulating film. The plurality of solar cells 400 are disposed between the cover plate 200 and the back sheet 300, the first encapsulating film is disposed between the cover plate 200 and the plurality of solar cells 400, and the second encapsulating film is disposed between the back sheet 300 and the plurality of solar cells 400; wherein, at least one of the first encapsulating film and the second encapsulating film is the encapsulating film 100 of the above embodiment.

[0065] It is understandable that a photovoltaic module is formed by sequentially laminating a cover plate 200, a first encapsulating film, multiple solar cells 400, a backsheet 300, and a second encapsulating film. The multiple solar cells 400 are located between the cover plate 200 and the backsheet 300, providing stable support and protection for the solar cells 400. This allows the solar cells 400 to perform photoelectric conversion by utilizing the proximity between the cover plate 200 and the backsheet 300. The first encapsulating film is located between the cover plate 200 and the solar cells 400, and the second encapsulating film is located between the backsheet 300 and the solar cells 400. This allows the first and second encapsulating films to bidirectionally encapsulate the solar cells 400, preventing moisture and dust from penetrating them and buffering external stresses. This reduces damage to the solar cells 400 during lamination and transportation, thereby improving the sealing performance of the photovoltaic module and extending its lifespan.

[0066] The first encapsulation film is a color-reactive encapsulating film 100, or the second encapsulating film is a color-reactive encapsulating film 100, or both the first and second encapsulating films are color-reactive encapsulating films 100. This allows for monitoring of stress concentration locations within the photovoltaic module without altering its original performance. For example, when the photovoltaic module is under installation, transportation, or other hazardous conditions, it may experience overload. The color change of the encapsulating film 100 will trigger a color reaction, enabling personnel to quickly identify damaged locations with the naked eye without the need for specialized equipment. This allows for early detection of potential hazards, reducing the spread of damage, and improving the reliability, safety, and lifespan of the photovoltaic module.

[0067] Among them, such as Figure 2 As shown, the encapsulating film 100 includes a color-changing area 11, which includes a battery gap color-changing area 111. The gap between the battery gap color-changing area 111 and the gap between two adjacent battery cells 400 is arranged opposite to each other in the thickness direction of the cover plate 200.

[0068] In other words, the encapsulating film 100 is provided with a color-changing area 11. This does not affect the adhesion and light transmittance of the encapsulating film 100. It allows the film body 10 to achieve precise color differentiation, ensures stress warning in the color-changing area 11, and also ensures the basic performance of the non-color-changing area 12. This avoids material waste and increased costs caused by the entire film body 10 having a color reaction. The stress-sensitive color-changing body 20 in the color-changing area 11 can achieve a fixed-point layout of color development, and provide targeted warnings in key stress-bearing parts and easily damaged areas. This ensures stress monitoring in high-risk locations of the encapsulating film 100, thereby ensuring the reliability of the encapsulating film 100. It also reduces the amount of stress-sensitive color-changing body 20 used, thus reducing the material cost of the encapsulating film 100.

[0069] The gap between the cell gap color-changing area 111 and the gap between the two adjacent cell sheets 400 is set opposite to each other in the thickness direction of the cover plate 200. This avoids the main body area of ​​the cell sheet 400, does not block light, and can ensure the photoelectric conversion efficiency of the cell sheet 400. It also places the cell gap color-changing area 111 in a stress concentration area, so that the phenomenon of local stress concentration during the lamination of the cover plate 200 and the encapsulating film 100 can be monitored. This facilitates real-time maintenance of the damaged location and prevents further expansion.

[0070] In addition, such as Figure 2 As shown, the photovoltaic module also includes a frame, a cover plate 200 and a back plate 300 disposed within the frame, and a color-changing area 11 including a frame color-changing area 112, which is disposed opposite to the frame in the thickness direction of the cover plate 200.

[0071] Specifically, the frame provides installation positions and structural support for the cover plate 200, back plate 300, and solar cells 400, and can withstand the compression during transportation and installation, thereby ensuring the structural strength and deformation resistance of the photovoltaic module and extending its service life. The color-changing area 112 of the frame is set opposite to the frame in the thickness direction of the cover plate 200. This allows the color-changing area 112 to be located in a place where stress concentration is likely to occur at the frame, without occupying the light-transmitting area of ​​the solar cells 400, and without interfering with the normal operation of the photovoltaic module. This allows for monitoring of key parts of the photovoltaic module, thereby identifying potential problems and preventing the spread of damage.

[0072] In particular, such as Figure 2As shown, the width of the color-changing area 111 between the battery gaps is greater than the width of the gap between two adjacent battery cells 400. This arrangement allows the color-changing area 111 between the battery gaps to adapt to the gaps between the battery cells 400, and enables monitoring and early warning without obstruction or minimal obstruction, without affecting the performance of the battery cells 400 themselves. This ensures the early warning sensitivity and color recognition between two adjacent battery cells 400, thereby making stress monitoring more accurate and efficient.

[0073] In addition, the thickness of the color-changing area 11 is d1, and the thickness of the non-color-changing area 12 is d2. d1 and d2 satisfy the relationship: 0.6d1≤d2≤0.75d1.

[0074] Specifically, the ratio between the thickness of the color-changing area 11 and the thickness of the non-color-changing area 12 should be within a reasonable range. If the thickness of the non-color-changing area 12 is less than 60% of the thickness of the color-changing area 11, this will result in the non-color-changing area 12 being too thin and the color-changing area 11 being too thick. This will not only affect the light transmittance and adhesion of the encapsulating film 100, but also lead to material waste of the encapsulating film 100. If the thickness of the non-color-changing area 12 is greater than 75% of the thickness of the color-changing area 11, this will result in the non-color-changing area 12 being too thick and the color-changing area 11 being too thin. The large difference in thickness between the two will not only affect the assembly of the solder ribbon or other components, but also affect the light transmittance of the encapsulating film 100. If the ratio between the thickness of the color-changing area 11 and the thickness of the non-color-changing area 12 is within a reasonable range, it will not only facilitate the assembly of other components in the photovoltaic module with the encapsulating film 100, but also ensure the light transmittance and adhesion of the encapsulating film 100, thereby ensuring the performance of the photovoltaic module. For example, the thickness of the non-discoloration area 12 is 0.3mm, and the thickness of the discoloration area 11 is 0.4mm-0.5mm. The specific values ​​are selected according to the actual situation. This ensures the light transmittance of the encapsulation film 100 while facilitating the assembly of the solder ribbon or other components with the encapsulation film 100.

[0075] 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.

[0076] In the description of this invention, "first feature" and "second feature" may include one or more of the features. In the description of this invention, "a plurality of" means two or more. In the description of this invention, "above" or "below" the second feature may include direct contact between the first and second features, or it may include contact between the first and second features not being in direct contact but through another feature between them. In the description of this invention, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0077] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0078] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An encapsulating film, characterized in that, include: Film body (10); A stress chromophore (20) is disposed on the adhesive film body (10). When the stress applied to the stress exceeds the limit value, the stress chromophore (20) reacts with the adhesive film body (10) to produce a color.

2. The encapsulating film according to claim 1, characterized in that, The stress chromatic body (20) includes: An isolation membrane is disposed on the adhesive film body (10) and forms an inner cavity; A photochromic compound is disposed in the inner cavity. The isolation membrane breaks after the stress exceeds the limit value, so that the photochromic compound comes into contact with the adhesive film body (10) and a color reaction occurs.

3. The encapsulating film according to claim 2, characterized in that, The photochromic compound is one of spiropyran compounds and spiroxazine compounds; and / or The film body (10) is one of vinyl acetate copolymer film and polyolefin elastomer film.

4. The encapsulating film according to claim 2, characterized in that, The isolation membrane is one of a polyurea membrane and a gelatin-gum arabic composite membrane.

5. The encapsulating film according to claim 2, characterized in that, The isolation membrane is capsule-shaped with a particle size of L, where L satisfies the relationship: 5μm≤L≤20μm.

6. The encapsulating film according to claim 1, characterized in that, The film body (10) includes a color-changing area (11) and a non-color-changing area (12), and the stress color-changing body (20) is only disposed in the color-changing area (11).

7. The encapsulating film according to claim 6, characterized in that, The color-changing area (11) includes: A battery gap color-changing area (111) extends along one of the length and width directions of the adhesive film body (10), and the battery gap color-changing area (111) is adapted to correspond to the battery gap; A border color-changing area (112) extends along the other of the length and width directions of the adhesive film body (10) and is connected to the end of the battery gap color-changing area (111). The border color-changing area (112) is adapted to correspond to the border.

8. The encapsulating film according to claim 7, characterized in that, The battery gap color-changing area (111) is multiple, and the multiple battery gap color-changing areas (111) are distributed at intervals along the length direction and width direction of the adhesive film body (10); and / or There are two border color-changing areas (112), and the two border color-changing areas (112) are respectively connected to the two ends of the battery gap color-changing area (111); and / or The width of the battery gap color-changing area (111) is smaller than the width of the border color-changing area (112).

9. The encapsulating film according to claim 1, characterized in that, The limit value of the stress chromatic body (20) is P, which satisfies the relationship: 60 MPa ≤ P ≤ 62 MPa.

10. A method for preparing an encapsulating film according to any one of claims 1-9, characterized in that, include: Prepare the stress chromosome (20); The stress chromophore (20) and the substrate of the film body (10) are mixed and then cast into a film.

11. The method for preparing the encapsulating film according to claim 10, characterized in that, The step of preparing the stress chromatic body (20) includes: The photochromic compound is encapsulated within an insulating membrane to form the stress chromatic body (20).

12. The method for preparing the encapsulating film according to claim 10, characterized in that, The step of casting a film by mixing the stress chromogenic material (20) and the substrate of the film body (10) includes: A portion of the substrate of the adhesive film body (10) is laid to form a base film layer; After mixing the stress chromophore (20) and another part of the substrate of the adhesive film body (10), the mixture is then cast with the base film to form a film.

13. The method for preparing the encapsulating film according to claim 12, characterized in that, The adhesive film body (10) includes a color-changing region (11) and a non-color-changing region (12). The step of mixing the stress-sensitive color-changing body (20) and another part of the substrate of the adhesive film body (10) and then casting it with the base film includes: After mixing the stress chromogenic body (20) and another part of the substrate of the adhesive film body (10), the mixture is then cast with the base film in the color-changing area (11) to form a film.

14. The method for preparing the encapsulating film according to claim 13, characterized in that, The mass percentage of the stress chromatic body (20) and another portion of the substrate of the adhesive film body (10) located in the chromatic area (11) is a, and a satisfies the relationship: 0.3%≤a≤0.8%.

15. A photovoltaic module, characterized in that, include: Cover plate (200); Back panel (300); Multiple battery cells (400) are disposed between the cover plate (200) and the back plate (300); A first encapsulating film is disposed between the cover plate (200) and the plurality of battery cells (400); A second encapsulating film is disposed between the backplate (300) and the plurality of battery cells (400); Wherein, at least one of the first encapsulating film and the second encapsulating film is the encapsulating film (100) according to any one of claims 1-10.

16. The photovoltaic module according to claim 15, characterized in that, The encapsulating film (100) includes a color-changing area (11), the color-changing area (11) includes a battery gap color-changing area (111), and the gap between the battery gap color-changing area (111) and two adjacent battery cells (400) is disposed opposite to each other in the thickness direction of the cover plate (200); and / or The photovoltaic module also includes a frame, the cover plate (200) and the back plate (300) are disposed within the frame, and the color-changing area (11) includes a frame color-changing area (112), which is disposed opposite to the frame in the thickness direction of the cover plate (200).

17. The photovoltaic module according to claim 16, characterized in that, The width of the color-changing area (111) between the battery gaps is greater than the width of the gap between two adjacent battery cells (400); and / or The thickness of the color-changing area (11) is d1, and the thickness of the non-color-changing area (12) is d2. d1 and d2 satisfy the relationship: 0.6d1≤d2≤0.75d1.

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