Flexible photovoltaic module with frame for balcony and laminated structure thereof

Abstract

The invention discloses a flexible photovoltaic module with a frame for a balcony and a laminated structure of the flexible photovoltaic module, and belongs to the technical field of photovoltaic modules, the module comprises a flexible laminated piece and an aluminum frame with a mounting hole, and the flexible laminated piece and the aluminum frame are bonded through a sealant; a transparent front plate containing a base material layer and a waterproof layer, a first layer of POE adhesive film, a front plate prepreg, a second layer of POE adhesive film, a battery string group formed by TOPCon batteries, a third layer of POE adhesive film and a reinforced rear plate containing a polymer base layer and a metal foil barrier layer are sequentially laminated on the laminated piece from a light receiving surface to a back surface. The problem that a flexible laminated piece is torn due to wind vibration is fundamentally avoided, the frame enhances the stiffness of the edge of the assembly and reduces slapping subfissure with a handrail, the TOPCon battery and the multi-layer high-water-resistance packaging material are combined, the conversion efficiency of the assembly and the long-term reliability in a humid and hot environment are remarkably improved, and the overall structure is light and convenient to install on a balcony.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic module technology, specifically relating to a framed flexible photovoltaic module and its laminated structure suitable for building balcony scenarios. Background Technology

[0002] With the deepening of the national energy structure transformation and the accelerated implementation of the "dual carbon" target, distributed photovoltaic systems, as an important part of energy consumption, are ushering in unprecedented development opportunities.

[0003] In the urban residential sector, balcony photovoltaics, as an innovative form of micro-energy center for home applications, has moved from conceptual exploration to practical application, demonstrating enormous market potential.

[0004] Currently, balcony photovoltaic systems mainly use flexible photovoltaic module technology. Its core advantages lie in its lightweight, portability, and good installation adaptability, which can effectively alleviate the problem of limited rooftop resources in urban high-rise residential buildings.

[0005] However, existing technologies still face many problems in practical application. Most mainstream flexible photovoltaic modules for balconies on the market adopt a frameless design, relying solely on mounting holes on the edge of the module and securing it to the balcony railing with straps. This design has revealed the following significant problems in long-term operation:

[0006] 1. Under wind-induced vibration, the mounting hole area at the edge of the component is subjected to concentrated stress, which can easily cause material stretching or even tearing, leading to component structural failure;

[0007] 2. Frameless flexible components are subject to repeated collisions and impacts with railings under wind vibration, which can easily cause internal microcracks in the battery cells and seriously affect the service life of the components.

[0008] 3. Most existing flexible modules use PERC cell technology, and their conversion efficiency is generally maintained at around 18.5%, which is difficult to meet users' increasing demand for high-efficiency power generation;

[0009] 4. In addition, the existing encapsulation material system of flexible modules (such as the use of EVA film) has insufficient water vapor barrier performance and lacks effective sealing at the edge of the module, making it difficult to match with water vapor-sensitive high-efficiency cells (such as TOPCon cells), resulting in severe power degradation of the module in humid and hot environments;

[0010] 5. Existing systems generally lack enhanced protection mechanisms for component edges, making them unable to withstand mechanical damage caused by wind vibration. They also have significant shortcomings in terms of ease of installation and long-term operational reliability.

[0011] In summary, the aforementioned problems severely restrict the large-scale promotion and user acceptance of balcony photovoltaic systems, hindering the transformation and upgrading of household energy consumption patterns.

[0012] Therefore, developing a flexible photovoltaic module specifically designed for balconies that combines high conversion efficiency, high structural reliability, and excellent environmental adaptability has become a key issue in driving the market toward maturity and large-scale development. Summary of the Invention

[0013] This invention aims to solve three major defects of existing flexible photovoltaic modules for balconies: first, the mechanical reliability problem caused by the frameless design; second, the conversion efficiency bottleneck caused by the use of PERC cells; and third, the power attenuation in humid and hot environments caused by the poor water resistance of the encapsulation material and the lack of edge protection.

[0014] To address the above problems, the present invention provides the following technical solution:

[0015] In a first aspect, the present invention provides a framed flexible photovoltaic module for balconies.

[0016] The component includes a flexible laminate and an aluminum frame surrounding it. The flexible laminate consists of, from the light-receiving side to the back side, the following layers stacked sequentially: a transparent front panel, a first layer of POE film, a front panel prepreg, a second layer of POE film, a battery string, a third layer of POE film, and a reinforced back panel. The battery string is composed of TOPCon batteries.

[0017] The aluminum frame is bonded to the edge of the flexible laminate with sealant, and the aluminum frame has mounting holes. The sealant is silicone.

[0018] Preferably, the aluminum frame is composed of two long sides and two short sides connected by corner brackets; and the component also includes a busbar and a junction box, wherein the battery string is connected in series through the busbar and electrically connected to the junction box.

[0019] Secondly, the present invention provides a flexible laminated structure for balcony photovoltaic modules.

[0020] The structure, from the light-receiving surface to the back, includes, in sequence: a transparent front panel, a first layer of POE film, a front panel prepreg, a second layer of POE film, a battery string consisting of TOPCon cells, a third layer of POE film, and a reinforced back panel.

[0021] Preferably, the transparent front panel includes a substrate layer and a water-blocking layer disposed on at least one side of the substrate layer; the reinforced back panel includes a polymer base layer and a metal foil barrier layer laminated thereon; the first POE film and the second POE film are of high light transmittance type, and the third POE film is of high cutoff type; the front panel prepreg is composed of fiber-reinforced material and resin composite.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. Significantly improved mechanical reliability and extended service life: By placing the mounting holes on the aluminum frame instead of the flexible laminate, and by using the aluminum frame to enhance the rigidity of the component edges, the problem of tearing of the mounting holes caused by wind vibration is effectively avoided. At the same time, the direct impact between the component and the balcony railing is reduced, thereby greatly reducing the risk of internal hidden cracks.

[0024] 2. Significantly improved photoelectric conversion efficiency: By replacing traditional PERC cells with TOPCon cells, the module conversion efficiency is increased to about 20%, meeting users' demand for high power generation efficiency.

[0025] 3. Enhanced environmental weather resistance: By combining a highly water-resistant transparent front panel, a reinforced back panel with a metal foil barrier layer, and a high-transmittance and high-cutoff POE film, a comprehensive water-resistant protection system is constructed, which effectively solves the problem of cell grid line corrosion in humid and hot environments and ensures the long-term power stability of the module in harsh environments.

[0026] 4. Combining ease of installation with structural reliability: The aluminum frame is made of lightweight aluminum alloy through heat treatment, making it thinner than traditional aluminum frames. This reduces the overall weight of the component, making it easier for a single person to move and install, while maintaining the structural reliability required for a balcony setting. Attached Figure Description

[0027] Figure 1 This is a material stacking sequence diagram of the Topcon flexible component for balconies according to the present invention;

[0028] Figure 2 This is a front structural diagram of the Topcon flexible component for balconies according to the present invention;

[0029] Figure 3 This is a schematic diagram of the rear structure of the Topcon flexible component for balconies according to the present invention;

[0030] Figure 4 This is a cross-sectional diagram of the long and short sides of the aluminum frame;

[0031] Figure 5 This is a schematic diagram of the structure of the aluminum frame's D-side;

[0032] In the diagram: 1. Transparent front panel; 2. First layer of POE film; 3. Front panel prepreg; 4. Second layer of POE film; 5. Battery string; 6. Third layer of POE film; 7. Reinforced back panel; 8. Busbar; 9. Aluminum frame; 10. Junction box; 11. Flexible laminate; 12. Through hole; A. View from side A; B. View from side B; C. View from side C; D. View from side D. Detailed Implementation

[0033] To enhance understanding of the present invention, the invention will be further described in detail below with reference to embodiments and accompanying drawings. These embodiments are only for explaining the invention and do not constitute a limitation on the scope of protection of the invention.

[0034] like Figures 1 to 5 As shown, a preferred embodiment of the present invention provides a flexible photovoltaic module with a frame for balconies. The core of the module consists of two main parts: a flexible laminate 11 that undertakes photoelectric conversion and encapsulation protection functions, and an aluminum frame 9 that provides mechanical support and installation interface for it.

[0035] The flexible laminate 11 is integrally formed by a lamination process, and its stacking sequence is as follows: Figure 1 As shown, from the sun-facing side (front) to the back, the structure consists of: transparent front panel 1, first POE film 2, front panel prepreg 3, second POE film 4, battery string 5, third POE film 6, and reinforced back panel 7. This specific structural design is the foundation for achieving high reliability, high efficiency, and high weather resistance in this solution.

[0036] The transparent front panel 1 is the first barrier for the component to resist environmental erosion. In this embodiment, it adopts a high water-resistant composite structure. Specifically, a PET (polyethylene terephthalate) film with a thickness of 320~350μm is used as the substrate layer. On the back side of the PET substrate (the side facing the battery), a water-resistant layer formed by silicon oxide (SiOx) deposition is laminated by adhesive. Subsequently, a fluorinated resin coating is coated on both sides of the PET substrate to give it excellent UV resistance, weather resistance and self-cleaning properties.

[0037] With this design, the water vapor transmission rate (WVTR) of the transparent front panel 1 can be controlled below 0.5 g / m²·d, while the light transmittance is as high as 85% or more, which is far superior to the single PET or ETFE front panel used in conventional flexible modules.

[0038] Both the first layer POE film 2 and the second layer POE film 4 are made of high-transmittance polyolefin elastomer (POE) film with a basis weight of not less than 480g / ㎡ and a water vapor transmission rate of ≤4g / ㎡·d. Their main function is to bond and encapsulate the front panel prepreg 3 and the battery string 5 with high light transmittance and low water permeability.

[0039] The front panel prepreg 3 is made of glass fiber cloth with a light transmittance of ≥87% impregnated with transparent resin, and its thickness is between 100 and 160 μm.

[0040] It is sandwiched between two layers of high-transmittance POE film. Its main function is to enhance the lateral mechanical strength of the front of the module and prevent excessive deformation when bent or under wind pressure. At the same time, its porous structure helps to release air during lamination and maintains extremely high light transmittance. This is fundamentally different from traditional double-glass modules that use a whole piece of glass as support, achieving a unity of lightweight and flexibility.

[0041] Battery string group 5 is the core power generation unit of this invention, which is formed by connecting TOPCon (tunneling oxide passivated contact) crystalline silicon half-cells in series via interconnecting ribbons, as shown below. Figure 2 As shown, in this embodiment, 11 half-cell batteries are connected in series to form a string, and a total of 6 such battery strings are then connected in series through a busbar 8 to form a complete battery string group.

[0042] Compared to the PERC cells commonly used in flexible balcony modules, TOPCon cells have a higher theoretical conversion efficiency limit. In this embodiment, the use of this cell technology can improve the overall conversion efficiency of the module to about 20%, which is significantly higher than the average level of about 18.5% for similar products on the market. However, the silver-aluminum paste used in the front sub-grid lines of TOPCon cells is extremely sensitive to moisture, which places unprecedentedly stringent requirements on the water resistance of its encapsulation environment.

[0043] The third layer of POE film 6 uses a high-cutoff POE film with a basis weight of ≥480g / ㎡ and a water vapor transmission rate of ≤4g / ㎡·d. The so-called high cutoff means that the film formula contains functional fillers that can effectively block ultraviolet rays and enhance reflection. While encapsulating the battery string 5, it can reflect or absorb specific wavelengths of light (especially ultraviolet rays) that are not absorbed by the battery. On the one hand, it reduces the degradation of the back material, and on the other hand, it can reflect some light back to the battery for secondary absorption, thereby slightly increasing the module short-circuit current.

[0044] The reinforced back panel 7 is the core protective and functional layer on the back of the component. In this embodiment, it is a lightweight laminated composite board with a total thickness between 830 and 900 μm. Its core structure includes: a polymer base layer made of PET or PA (polyamide) and a metal foil barrier layer laminated on the base layer. The metal foil is preferably an aluminum foil with a thickness of 130 to 150 μm.

[0045] Aluminum foil forms a near-absolute water vapor barrier with a water vapor transmittance of ≤0.1g / ㎡·d. At the same time, the surface of the aluminum foil is treated to have a light reflectance of no less than 70%, which can efficiently reflect the light passing through the gaps in the battery back, further improving the module's efficiency in utilizing light energy.

[0046] The outer surfaces of the reinforced back panel 7, busbar 8, and aluminum frame 9 are all treated black to meet the market demand for aesthetically pleasing (all-black) components in balcony applications.

[0047] The above-mentioned materials are arranged according to Figure 1 After being stacked in sequence, the layers are placed in a laminator and laminated under certain temperature, vacuum and pressure conditions, so that each layer of POE film melts, flows and cross-links and cures, ultimately forming a tightly bonded, bubble-free flexible laminate 11.

[0048] After the flexible laminate 11 is formed, as Figure 2 and Figure 3 As shown, its outgoing electrodes are connected to a junction box 10 by soldering, followed by the critical frame assembly step.

[0049] The aluminum frame 9 is made of 6005 aluminum alloy, treated with T6 heat treatment to achieve a Webster hardness of over 15HW, thus possessing sufficient mechanical strength. Its design thickness is 16mm, which is thinner and lighter than the 35-50mm thick aluminum frames commonly used in traditional ground-mounted photovoltaic modules. The frame consists of two long sides and two short sides, connected by inserting corner brackets into the frame cavity and securing them with screws, forming a stable rectangular frame. Figure 4 As shown.

[0050] During assembly, first work on the C side of aluminum frame 9 (see...). Figure 4 A continuous layer of silicone sealant (the sealant mentioned above) is injected into the inner surface of the groove that contacts the laminate. Then, the edge of the flexible laminate 11 is precisely embedded into the slot of the frame. A slight pressure is applied by the clamp to form a uniform and dense adhesive and sealing layer between the edge of the laminate and the frame. This process completely changes the traditional state where the edges of flexible components are directly exposed to the environment. The silicone not only provides a strong mechanical bond, but its excellent elasticity and permanent weather resistance can also compensate for the difference in thermal expansion and contraction between materials and effectively block the path of moisture intrusion from the edge for a long time.

[0051] Crucially, such as Figure 4 and Figure 5 As shown, multiple through holes 12 are pre-processed on the B side (outer long side) and D side (bottom side) of the aluminum frame 9. In this embodiment, four elliptical through holes 12 with a size of 3mm×10mm are evenly distributed on each frame. A component has a total of 16 mounting holes. When installing on the balcony, the user can directly use nylon straps or metal buckles to pass through these through holes 12 and firmly bind the component to the balcony railing. This is completely different from the practice of drilling mounting holes on the flexible laminate body in the prior art. It fundamentally eliminates the risk of stress concentration at the installation point causing the laminate to tear. In addition, the sturdy frame acts as a buffer skeleton between the component and the railing, eliminating direct impact caused by wind vibration.

[0052] At this point, a complete high-performance flexible photovoltaic module suitable for balcony applications has been assembled.

[0053] To enable those skilled in the art to better understand the present invention, a specific implementation example is provided below, with the aim of preparing a flexible photovoltaic module for balconies with a rated power of approximately 550W.

[0054] Material preparation: The transparent front panel uses a 340μm thick PET substrate composite SiOx water-blocking film, with a double-sided fluorine coating. The measured water vapor transmission rate is 0.4g / ㎡·d, and the light transmittance is 86.5%. The first and second layers of POE film use a high-transmittance model from a certain brand, with a basis weight of 500g / ㎡. The front panel prepreg uses a 125μm thick transparent glass fiber resin board. The battery string is composed of 66 TOPCon half-cell batteries (6 strings × 11 cells) connected in series (size 182mm*91mm). The third layer of POE film uses a high-cutoff model from the same brand. The reinforced back panel uses a PET / aluminum foil / PET composite board with a total thickness of 870μm, of which the aluminum foil is 140μm thick and the back is black.

[0055] Lamination and Assembly: By Figure 1 After sequential stacking, the laminator is fed into a laminator, where it is vacuumed and pressurized at 148°C for 18 minutes to form a flexible laminate. The laminate is then welded to a junction box with an IP68 protection rating.

[0056] Subsequently, four 6005 aluminum alloy frames (approximately 1750mm long, 1100mm short, and 16mm thick) that have undergone T6 heat treatment were taken, and four 3*10mm oval through holes 12 were machined on both the B and D sides. Dow Corning DC795 silicone was injected into the frame slots, the laminate was embedded and fixed, and left to cure for 24 hours.

[0057] Performance testing: The fabricated modules were tested, and the results showed that the module conversion efficiency reached 20.2%, which is significantly higher than the control group flexible modules (efficiency 18.7%) using PERC cells of the same size.

[0058] After mechanical load testing (5400Pa on the front), no microcracks or power attenuation were observed, and there was no damage at the mounting hole location. In contrast, the frameless flexible component in the control group, after being fixed with a simulated strap, showed obvious wrinkles and delamination of the adhesive film around the mounting hole during the same test.

[0059] After undergoing a 1000-hour damp heat aging test at 85°C / 85% relative humidity, the power degradation rate of the module of the present invention is <2%, while the degradation rate of the control group PERC flexible module encapsulated with EVA film is >5%.

[0060] The stable degradation curve unique to TOPCon batteries proves that the high water resistance encapsulation system of this invention effectively suppresses water vapor corrosion.

[0061] The component weighs approximately 18kg and can be carried by a single person. It can be quickly installed on various balcony railings using straps.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A flexible photovoltaic module with a frame for balconies, comprising a flexible laminate and an aluminum frame surrounding it, characterized in that, The flexible laminate, from the light-receiving surface to the back side, includes a transparent front panel, a first layer of POE film, a front panel prepreg, a second layer of POE film, a battery string, a third layer of POE film, and a reinforced back panel. The battery string is composed of TOPCon batteries; The aluminum frame is bonded to the edge of the flexible laminate with sealant, and the aluminum frame is provided with mounting holes.

2. The flexible photovoltaic module according to claim 1, characterized in that, The sealant is silicone.

3. The flexible photovoltaic module according to claim 1, characterized in that, The transparent front panel includes a substrate layer and a water-blocking layer disposed on at least one side of the substrate layer.

4. The flexible photovoltaic module according to claim 1, characterized in that, The reinforced back plate includes a polymer base layer and a metal foil barrier layer laminated thereon.

5. The flexible photovoltaic module according to claim 1, characterized in that, The first and second POE films are of the high light transmittance type, and the third POE film is of the high cutoff type.

6. The flexible photovoltaic module according to claim 1, characterized in that, The front panel prepreg is composed of fiber-reinforced material and resin.

7. The flexible photovoltaic module according to claim 1, characterized in that, The aluminum frame is composed of two long sides and two short sides connected by corner brackets.

8. The flexible photovoltaic module according to claim 1, characterized in that, It also includes a busbar and a junction box, with the battery string group connected in series through the busbar and electrically connected to the junction box.

9. A flexible laminated structure for balcony photovoltaic modules, characterized in that, From the light-receiving side to the back side, the following are included in sequence: A transparent front panel includes a substrate layer and a water-blocking layer disposed on at least one side of the substrate layer; First layer of POE film; Front panel prepreg; Second layer of POE film; Battery string arrays composed of TOPCon batteries; The third layer of POE film; The reinforced back panel includes a polymer base layer and a metal foil barrier layer laminated thereon.

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