Photovoltaic module

Abstract

This application provides a photovoltaic module, comprising a front substrate, a front encapsulating film layer, a cell string layer, a back encapsulating film layer, and a back substrate connected in sequence. The cell string layer includes multiple cells connected in series, each cell having at least one cut edge. A first passivation layer and a second passivation layer are disposed on the cut edge of the cell. The second passivation layer is disposed at the edge of the cell, and the first passivation layer is disposed inside the second passivation layer. The first passivation layer is formed by mixing an organosilicon matrix with a silane compound, and the second passivation layer is formed by doping an organosilicon matrix with nanoparticles. The surface of the second passivation layer is plasma-treated to form a charge density gradient. The photovoltaic module provided by this application achieves a synergistic effect of chemical passivation and field-effect passivation through two passivation layers. Passivation is achieved at low temperatures, avoiding damage to the transparent separator, and improving the minority carrier lifetime and parallel resistance at the cell edge, thereby reducing power loss.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and more particularly to a photovoltaic module. Background Technology

[0002] Back-contact (BC) photovoltaic modules are widely used in distributed photovoltaic power generation due to their unobstructed front surface and aesthetically pleasing all-black appearance. They are suitable for BIPV (Building Integrated Photovoltaics), high-end residential photovoltaic systems, and distributed power station scenarios with high aesthetic requirements. BC photovoltaic modules, with no metal grid lines obstructing the front, achieve a conversion efficiency of up to 24.5% and a power range of 470-500W, making them one of the best products on the market in terms of combining aesthetics and performance.

[0003] In related technologies, the core cell string layer of photovoltaic modules typically involves laser-cutting large-size cells into 1 / 2 or 1 / 3 cells and then encapsulating them in series. To improve the electrical performance of the cell cutting edges, methods such as atomic layer deposition (ALD) are commonly used to form an aluminum oxide passivation layer at the cutting edges to repair surface defects caused by laser cutting and reduce minority carrier recombination.

[0004] However, existing passivation techniques can cause the insulating adhesive used in BC photovoltaic module encapsulation to soften, deform, or even decompose during high-temperature annealing. Summary of the Invention

[0005] This application provides a photovoltaic module to solve the technical problem that existing passivation technologies cause the release liner to soften, deform, or even decompose during high-temperature annealing.

[0006] This application provides a photovoltaic module, including a front substrate, a front encapsulating film layer, a cell string layer, a back encapsulating film layer, and a back substrate connected in sequence. The cell string layer includes multiple cells connected in series, each cell having at least one cut edge. A passivation layer is disposed on the cut edge of the cell, the passivation layer including a first passivation layer and a second passivation layer. The second passivation layer is disposed on the edge of the cell, and the first passivation layer is disposed inside the second passivation layer. The first passivation layer is formed by mixing an organosilicon matrix with a silane compound, and the second passivation layer is formed by doping an organosilicon matrix with nanoparticles. The surface of the second passivation layer is plasma-treated to form a charge density gradient.

[0007] The photovoltaic module provided in this application repairs the cut edges using two passivation layers. The first passivation layer is formed by mixing an organosilicon matrix with silane compounds, using chemical bonding to repair dangling bonds and lattice distortions caused by laser cutting. The second passivation layer is composed of an organosilicon matrix doped with nanoparticles, and its surface is treated with plasma to introduce a charge density gradient, resulting in a smooth transition from "chemical passivation-dominated" to "field-effect passivation-dominated" from the inner to the outer layers. The two passivation layers adhere tightly to the cut edges of the solar cell, and through the synergistic effect of chemical and field-effect passivation, the edge recombination rate is reduced and minority carrier loss is suppressed. This process does not require high-temperature operation and provides good passivation performance.

[0008] As an alternative implementation, the first passivation layer is formed by the hydrolytic condensation of methyltriethoxysilane and vinyltriethoxysilane, wherein the mass ratio of methyltriethoxysilane to vinyltriethoxysilane is 3:1.

[0009] As an optional implementation, the second passivation layer is formed by doping an organosilicon substrate with nano-alumina particles, wherein the weight percentage of the nano-alumina particles is 1.0-1.5 wt%.

[0010] As an optional implementation, the nano-alumina particles have a particle size of 8-12 nm, and the surface of the nano-alumina particles is modified with 3-aminopropyltriethoxysilane.

[0011] As an alternative implementation, the surface of the second passivation layer is treated with an argon-hydrogen mixed plasma.

[0012] As an optional implementation, there is a gap between adjacent solar cells, and the gap is filled with a spectrally selective black adhesive film. The spectrally selective black adhesive film includes a visible light absorption layer, a near-infrared high reflectance and ion blocking layer and an all-angle diffuse reflection adhesive layer arranged sequentially.

[0013] The second passivation layer abuts against the spectrally selective black adhesive film.

[0014] As an optional implementation, the visible light absorption layer is composed of an EVA matrix with 0.5-0.8 wt% phthalocyanine black organic dye.

[0015] As an optional implementation, the near-infrared high reflectivity and ion blocking layer is composed of a POE matrix with 12-15 wt% core-shell structured infrared reflective particles and 2-3 wt% zeolite ion scavenger, and the near-infrared high reflectivity and ion blocking layer is configured to reflect infrared light.

[0016] As an optional implementation, the full-angle diffuse reflective adhesive layer consists of a POE matrix with 3-5 wt% silica diffuse reflective particles, and the full-angle diffuse reflective adhesive layer is configured to reflect infrared light back to the surface of the cell in a manner that scatters infrared light at all angles.

[0017] As an optional implementation, the battery cell is printed with a high-resistance conductive strip, which is made of silver paste and carbon paste in a mass ratio of 1:4. The width of the high-resistance conductive strip varies in a gradient so that the sheet resistance of the high-resistance conductive strip decreases linearly from the side near the cut edge of the battery cell to the side away from the cut edge.

[0018] This application provides a photovoltaic module, comprising a front substrate, a front encapsulating film layer, a cell string layer, a back encapsulating film layer, and a back substrate connected in sequence. The cell string layer includes multiple cells connected in series, each cell having at least one cut edge. A passivation layer is disposed on the cut edge of the cell, comprising a first passivation layer and a second passivation layer. The second passivation layer is disposed at the edge of the cell, and the first passivation layer is disposed inside the second passivation layer. The first passivation layer is formed by mixing an organosilicon matrix with a silane compound, and the second passivation layer is formed by doping an organosilicon matrix with nanoparticles. The surface of the second passivation layer is plasma-treated to form a charge density gradient. The photovoltaic module provided by this application achieves a synergistic effect of chemical passivation and field-effect passivation through two passivation layers. Passivation is achieved at low temperatures, avoiding damage to the transparent separator, and improving the minority carrier lifetime and parallel resistance at the cell edge, thereby reducing power loss.

[0019] In addition to the technical problems solved by the embodiments of this application, the technical features constituting the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions described above, other technical problems that the photovoltaic modules provided by this application can solve, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further explained in detail in the specific embodiments. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of a photovoltaic module provided in an embodiment of this application;

[0022] Figure 2 A schematic diagram of the passivation layer provided in the embodiments of this application;

[0023] Figure 3 This is a schematic diagram of the structure of the spectrally selective black film provided in the embodiments of this application;

[0024] Figure 4 This is a schematic diagram of the installation of the high-resistance conductive strip provided in an embodiment of this application.

[0025] Explanation of reference numerals in the attached figures:

[0026] 10- Photovoltaic modules;

[0027] 100-front substrate;

[0028] 200 - Front sealing film layer;

[0029] 300 - Battery string layer; 310 - Battery cell; 320 - Passivation layer; 321 - First passivation layer; 322 - Second passivation layer; 330 - Spectral selective black adhesive film; 331 - Visible light absorption layer; 332 - Near-infrared high reflectance and ion blocking layer; 333 - All-angle diffuse reflection adhesive layer; 340 - High resistance conductive strip;

[0030] 400 - Backside encapsulation film layer;

[0031] 500-Back substrate. Detailed Implementation

[0032] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0033] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application 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 application.

[0034] The terms "first," "second," and "third" (if any) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein.

[0035] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such as a process, method, system, product, or maintenance tool that includes a series of steps or units, not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or maintenance tool.

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] BC (back-contact) photovoltaic modules are widely used in distributed photovoltaic power generation due to their unobstructed front surface and aesthetically pleasing all-black appearance. They are suitable for BIPV (Building Integrated Photovoltaics), high-end residential photovoltaic systems, and distributed power station scenarios with high aesthetic requirements. With no metal grid lines obstructing the front, BC photovoltaic modules achieve a conversion efficiency of up to 24.5% and a power range of 470-500W, making them one of the best products on the market in terms of combining aesthetics and performance.

[0038] In related technologies, the core cell string layer of photovoltaic modules typically involves laser-cutting large-size cells into 1 / 2 or 1 / 3 cells and then encapsulating them in series. To improve the electrical performance of the cell cutting edges, methods such as atomic layer deposition (ALD) are commonly used to form an aluminum oxide passivation layer at the cutting edges to repair surface defects caused by laser cutting and reduce minority carrier recombination.

[0039] However, existing atomic layer deposition (ALD) passivation technology, which uses ALD-Al2O3 for passivation, requires high-temperature annealing above 400°C. The transparent sealant used in BC module encapsulation (used to isolate the positive and negative electrode solder strips) has a long-term temperature tolerance of only 150-200°C. High-temperature annealing can cause the sealant to soften, deform, yellow, or even decompose, leading to module short circuits and reliability failures. Other passivation technologies, such as plasma passivation and wet chemical passivation, have poor passivation effects and poor passivation layer stability.

[0040] To address the aforementioned technical issues, this application provides a photovoltaic module that repairs the cut edges of the solar cell using two passivation layers. The first passivation layer is formed by mixing an organosilicon matrix with a silane compound, using chemical bonding to repair dangling bonds and lattice distortions caused by laser cutting. The second passivation layer is composed of an organosilicon matrix doped with nanoparticles, and its surface is treated with plasma to introduce a charge density gradient, resulting in a smooth transition from "primarily chemical passivation" to "primarily field-effect passivation" from the inner to the outer layers. The two passivation layers adhere tightly to the cut edges of the solar cell. Through the synergistic effect of chemical and field-effect passivation, the edge recombination rate is reduced and minority carrier loss is suppressed. This eliminates the need for high-temperature operation, preventing damage to the separator adhesive caused by softening, and provides good passivation effect and layer stability.

[0041] Figure 1 This is a schematic diagram of the structure of a photovoltaic module provided in an embodiment of this application; Figure 2 A schematic diagram of the passivation layer provided in the embodiments of this application; Figure 3 This is a schematic diagram of the structure of the spectrally selective black film provided in the embodiments of this application; Figure 4 This is a schematic diagram of the installation of the high-resistance conductive strip provided in an embodiment of this application.

[0042] Reference Figure 1 and Figure 2 As shown, this application provides a photovoltaic module 10, including a front substrate 100, a front encapsulating film layer 200, a cell string layer 300, a back encapsulating film layer 400, and a back substrate 500 connected in sequence. The front substrate 100 is the outermost structure of the photovoltaic module 10, and is usually made of glass or other transparent materials to protect the internal structure and allow light to pass through. It can be low-iron tempered glass, ultra-clear glass, etc. The front encapsulating film layer 200 is disposed between the front substrate 100 and the cell string layer 300, and the back encapsulating film layer 400 is disposed between the cell string layer 300 and the back substrate 500. The front encapsulating film layer 200 and the back encapsulating film layer 400 are used to fix the cell string layer 300 and transmit mechanical stress. They can be POE (polyolefin elastomer) or EVA (ethylene-vinyl acetate copolymer) materials. The back substrate 500 is the innermost structure and can be black glass.

[0043] The battery string layer 300 is the main power generation structure. Sunlight enters from the front substrate 100 and shines on the battery string layer 300, which converts light energy into electrical energy to generate electricity. The battery string layer 300 includes multiple battery cells 310 connected in series. The battery cells 310 are typically formed by laser cutting of a large battery cell 310, and their size is 1 / 2 or 1 / 3 of the size of the large battery cell 310. Each battery cell 310 has at least one cut edge. A passivation layer 320 is provided on the cut edge of the battery cell 310. The passivation layer 320 includes a first passivation layer 321 and a second passivation layer 322. The second passivation layer 322 is disposed on the edge of the battery cell 310, and the first passivation layer 321 is wrapped by the second passivation layer 322 and located inside the second passivation layer 322. The first passivation layer 321 is formed by mixing an organosilicon substrate with a silane compound, and the second passivation layer 322 is formed by doping an organosilicon substrate with nanoparticles. The surface of the second passivation layer 322 is treated with plasma to form a charge density gradient.

[0044] It should be noted that the localized high temperatures exceeding 1000℃ generated during the laser cutting of the solar cell 310 will form a thermal damage layer with a thickness of approximately 1-2 μm at the cutting edge. This region contains high-density dangling bonds, microcracks, and lattice distortion, causing the minority carrier lifetime to plummet from >100 μs in the bulk phase to <5 μs, resulting in a 1.5%-2.0% power loss in the module. The first passivation layer 321 at the cutting edge of the solar cell 310 mainly repairs the dangling bonds and lattice distortions generated by laser cutting through chemical bonding. The second passivation layer 322 is composed of an organosilicon substrate doped with nanoparticles, and its surface is treated with plasma to introduce a charge density gradient, so that the passivation layer 320 exhibits a smooth transition from "chemical passivation as the main method" to "field effect passivation as the main method" from the inner layer to the outer layer. Field effect passivation is a mechanism that suppresses carrier recombination on the semiconductor surface through a built-in electric field, and physically repels carriers away from defect areas, thereby significantly improving the performance of devices such as solar cells. The two passivation layers 320 are closely attached to the cut edge of the cell 310. Through the synergistic effect of chemical passivation and field-effect passivation, the edge recombination rate is reduced and minority carrier loss is suppressed. No high-temperature operation is required. The passivation effect is close to more than 90% of the ALD-Al2O3 passivation effect, and the passivation cost is lower.

[0045] In some embodiments, the first passivation layer 321 is formed by the hydrolytic condensation of methyltriethoxysilane and vinyltriethoxysilane, wherein the mass ratio of methyltriethoxysilane to vinyltriethoxysilane is 3:1.

[0046] Understandably, the methyl groups provide Si-H bonds to bond with the dangling bonds on the surface of the battery cell 310, while the vinyl groups enhance the structural stability of the inner layer through cross-linking reactions. When mixed in a specific ratio, the inner passivation layer 320 effectively passivates the dangling bonds at the battery edge through chemical bonding. Through the synergistic effect of methyltriethoxysilane and vinyltriethoxysilane, the chemical bonding ability of the first passivation layer 321 is significantly enhanced, effectively repairing dangling bond defects at the battery edge, reducing the edge recombination rate, and maintaining a low recombination rate and high parallel resistance during long-term use. When methyltriethoxysilane and vinyltriethoxysilane are mixed in a 3:1 mass ratio, the high reactivity of the methyl groups preferentially bonds with the dangling bonds on the battery surface, while the vinyl groups form a stable three-dimensional network structure through cross-linking reactions. This ratio ensures that the first passivation layer 321 achieves an optimal balance between chemical bonding and mechanical stability.

[0047] In some embodiments, the second passivation layer 322 is formed by doping an organosilicon substrate with nano-alumina particles, wherein the weight percentage of the nano-alumina particles is 1.0-1.5 wt%.

[0048] Understandably, after alumina particles are doped into the outer organosilicon substrate, a negative charge layer is formed through surface charge accumulation. This negative charge layer suppresses electron-hole recombination at the battery surface through a field-effect passivation mechanism, while simultaneously forming a gradient charge distribution with the inner chemical passivation layer 320, improving the uniformity of the passivation effect. Through the doping of alumina particles, the field-effect passivation capability of the outer passivation layer 320 is significantly enhanced, further reducing the recombination rate at the battery edges. At the same time, the gradient charge distribution optimizes the overall performance of the passivation layer 320, improving the long-term reliability of the module.

[0049] The nano-alumina particles have a particle size of 8-12 nm, and the surface of the nano-alumina particles is modified with 3-aminopropyltriethoxysilane to improve the dispersibility of the nano-alumina particles in the organosilicon matrix.

[0050] It should be noted that the chemical composition between the first passivation layer 321 and the second passivation layer 322 is a smooth transition. A transition layer is formed between the first passivation layer 321 and the second passivation layer 322 during their formation, achieving a smooth functional transition from "inner layer chemical passivation dominance - intermediate layer transition - outer layer field effect passivation dominance". The chemical gradient change is shown in Table 1.

[0051] Table 1 Gradient changes in chemical composition

[0052]

[0053] In this embodiment, the surface of the second passivation layer 322 is treated with argon-hydrogen mixed plasma. The argon-hydrogen mixed plasma treatment introduces a high-density negative charge onto the surface of the second passivation layer 322 through the reduction effect of hydrogen, while the inert protective effect of argon prevents material oxidation. This treatment further increases the charge density of the second passivation layer 322, forming a more pronounced gradient charge distribution with the first passivation layer 321, further suppressing the recombination rate at the edge of the solar cell 310, and enhancing the long-term stability of both passivation layers 320.

[0054] It should be noted that the H2 content in the argon-hydrogen mixed plasma is 5%-10%. After the first passivation layer 321 and the second passivation layer 322 are formed, the surface of the passivation layer 320 is treated with argon-hydrogen mixed plasma for 60 seconds, introducing a high-density negative charge onto the surface of the second passivation layer 322, with a surface charge density ≥1×10⁻⁶. 12 cm -2 This achieves a synergistic effect between chemical passivation and field-effect passivation.

[0055] The preparation temperature of the first passivation layer 321 and the second passivation layer 322 is ≤100℃, which is far below the upper temperature limit of the separator adhesive and is fully compatible with the entire encapsulation process of the photovoltaic module 10. After passivation, the minority carrier lifetime at the edge of the cell 310 is increased from <5μs to >20μs, the parallel resistance is increased by more than 50%, and the module power is increased by 1.0%-1.3%.

[0056] The specific process steps for the first passivation layer 321 and the second passivation layer 322 are as follows.

[0057] Step 1: Deposition of the first passivation layer 321 on the substrate.

[0058] The laser-cut BC solar cell 310 was immersed in the inner passivation solution (MTES:VTES:ethanol:deionized water = 3:1:15:6, containing 0.05wt% photoinitiator 1173) for 20 seconds.

[0059] After removal, dry in 70℃ hot air for 3 minutes. At this time, the passivation solution forms a semi-cured silicone film with a thickness of about 30nm on the silicon surface.

[0060] Key control: The drying temperature is strictly controlled below 70℃ to ensure that the organosilicon undergoes only partial cross-linking and retains its molecular diffusion ability.

[0061] Step 2: Gradient penetration of the second passivation layer 322.

[0062] Immediately immerse the semi-cured battery cell 310 in the outer passivation solution (MTES: ethanol: deionized water = 1:6:2, containing 1.2wt% surface-modified nano alumina + 0.08wt% photoinitiator 1173) for 25 seconds.

[0063] Since the inner film is still in a semi-cured state, the nano-alumina particles in the outer passivation solution will penetrate into the inner layer through capillary action, while the organosilicon molecules in the inner layer will diffuse outward.

[0064] The penetration time is precisely controlled at 25 seconds, so that the penetration depth of the alumina particles reaches exactly 30nm, forming a continuous concentration gradient.

[0065] Step 3: Gradient curing locks in component distribution.

[0066] After removing the 310 solar cell, dry it at 80°C for 4 minutes to further crosslink the organosilicon molecules.

[0067] Irradiate with 365nm ultraviolet light in two stages: first at 50mW / cm 2 Irradiate with high intensity for 2 minutes to fully cure the inner layer; then apply 100mW / cm² of light. 2 Irradiate with high intensity for 3 minutes to fully cure the outer layer.

[0068] During the curing process, the component gradient is permanently locked, and no subsequent component migration will occur.

[0069] X-ray photoelectron spectroscopy (XPS) depth profiling confirmed the continuous gradient distribution of elements in passivation layer 320: silicon (Si): the content gradually decreases from 99% to 25% from the silicon substrate to the surface of passivation layer 320; oxygen (O): the content gradually increases from 1% to 45%; aluminum (Al): the content gradually increases from 0% on the surface of the silicon substrate to 30% on the surface of passivation layer 320; carbon (C): the content gradually increases from 0% on the surface of the silicon substrate to 15% in the intermediate layer, and then gradually decreases to 5% on the surface.

[0070] The changes in charge gradient are shown in Table 2.

[0071] Table 2. Changes in charge density gradient

[0072]

[0073] The steps of the argon-hydrogen mixed plasma gradient injection process are as follows.

[0074] A radio frequency inductively coupled plasma (ICP) source was used, with an argon-hydrogen mixture (8% H2 content) introduced at a working pressure of 0.5 Pa. The plasma power was 200 W, the processing time was 60 seconds, and the sample stage temperature was maintained below 60 °C. A pulsed plasma injection technique was employed, with a pulse frequency of 10 kHz and a duty cycle of 50%. When the pulse was on, high-energy hydrogen and argon ions bombarded the surface of the passivation layer 320, generating numerous dangling bonds and defect states. When the pulse was off, electrons were trapped in the defect energy levels of the alumina particles, forming stable negative charges. Due to the limited penetration depth of the plasma (approximately 50 nm) and the exponential decay of ion energy with increasing depth, the negative charge density naturally formed a gradient distribution that gradually decreased from the surface to the interior.

[0075] The gradient distribution of negative charges in passivation layer 320 was confirmed by capacitance-voltage (CV) testing and Kelvin probe force microscopy (KPFM) testing.

[0076] The surface contact potential difference of the passivation layer 320 is -0.8V, corresponding to a negative charge surface density of approximately 1.2 × 10⁻⁶. 12 cm -2 .

[0077] The contact potential difference at a depth of 30 nm is -0.4 V, corresponding to a surface negative charge density of approximately 6 × 10⁻⁶. 11 cm -2 .

[0078] At a depth of 100 nm (at the interface with silicon), the contact potential difference is -0.1 V, corresponding to a surface negative charge density of approximately 8 × 10⁻⁶. 10 cm -2 .

[0079] Understandably, the outer high-concentration alumina layer forms a dense ion-barrier layer, effectively preventing ions in the film from migrating to the silicon surface; the inner organosilicon layer forms a strong chemical bond with the silicon surface, which is not easily broken; the built-in electric field formed by the charge density gradient further inhibits ion migration; experimental data show that after DH1000h testing, the edge minority carrier lifetime of the gradient passivation layer 320 remains above 18.5μs, with a decay rate of only 17%, while the decay rate of the pure organosilicon passivation layer 320 is 62%. The comparative experimental data of the gradient structure and the non-gradient structure are shown in Table 3.

[0080] Table 3 Comparison of gradient structures and non-gradient structures

[0081]

[0082] Reference Figure 3 , combined Figure 1To prevent short circuits caused by contact between adjacent solar cells 310, and to prevent compression caused by volume changes in the solar cells 310 due to temperature variations, gaps are provided between adjacent solar cells 310. These gaps are filled with a spectrally selective black adhesive film 330. The spectrally selective black adhesive film 330 includes a visible light absorption layer 331, a near-infrared high reflectance and ion blocking layer 332, and an all-angle diffuse reflection adhesive layer 333, arranged sequentially. The visible light absorption layer 331 is located on the outermost layer, the near-infrared high reflectance and ion blocking layer 332 is located in the middle layer, and the all-angle diffuse reflection adhesive layer 333 is located on the innermost layer. The spectrally selective black adhesive film 330 absorbs sunlight and is black, matching the color of the solar cells 310, giving the photovoltaic module a pure black appearance.

[0083] Because the spectrally selective black adhesive film 330 is disposed between the battery cells 310 and abuts against the edge of the battery cells 310, the second passivation layer 322 of the cut edge of the battery cells 310 is in contact with the spectrally selective black adhesive film 330. The spectrally selective black adhesive film 330 provided in this embodiment absorbs visible light while reflecting infrared and near-infrared light. The ratio of visible light absorptivity to near-infrared reflectivity of the spectrally selective black adhesive film 330 is ≥1.12, which can reduce temperature rise during long-term use and help extend the service life of the first passivation layer 321 and the second passivation layer 322.

[0084] In some embodiments, the visible light absorption layer 331 is composed of an EVA matrix with 0.5-0.8 wt% phthalocyanine black organic dye. The thickness of the visible light absorption layer 331 is 60-80 μm, and the absorption rate in the 400-700 nm visible light band is ≥98%, ensuring that it presents a pure black appearance from any angle, without any reflection or color difference.

[0085] In some embodiments, the near-infrared high reflectivity and ion blocking layer 332 is composed of a POE matrix with 12-15 wt% core-shell structured infrared reflective particles and 2-3 wt% zeolite ion scavenger. The core-shell structured infrared reflective particles have silver nanoparticles as the core and titanium dioxide as the shell. The silver nanoparticles have a particle size of 50-80 nm, and the titanium dioxide shell has a thickness of 10-15 nm. The near-infrared high reflectivity and ion blocking layer 332 has a thickness of 120-150 μm and a reflectivity of ≥88% in the 700-1200 nm near-infrared band, while effectively blocking the migration of free ions in the film to the battery surface.

[0086] In some embodiments, the all-angle diffuse reflection adhesive layer 333 is composed of a POE matrix with 3-5 wt% silica diffuse reflection particles, the particle size of which is 2-4 μm. The thickness of the all-angle diffuse reflection adhesive layer 333 is 60-80 μm, which can reflect the near-infrared light reflected from the middle layer back to the surface of the solar cell 310 in an all-angle scattering manner, thereby maximizing the photon recovery efficiency and improving the power generation efficiency of the photovoltaic module 10.

[0087] It should be noted that an optimized addition of 3-5 wt% silica diffuse reflective particles yields the highest diffuse reflectance efficiency without significantly increasing the haze of the encapsulant film. If the addition is less than 3 wt%, the particle concentration is too low, resulting in insufficient scattering centers and low diffuse reflectance efficiency. If the addition is greater than 5 wt%, the particle concentration is too high, leading to multiple scattering, causing some light to be scattered back to the middle layer and absorbed by the silver nanoparticles. The POE matrix has a transmittance of ≥92% in the 700-1200nm near-infrared band, far exceeding that of the EVA matrix. POE has low water vapor transmittance, effectively blocking external water vapor from entering the module. Simultaneously, the high adhesion strength between POE and the glass and 310 solar cells ensures the long-term reliability of the module.

[0088] Table 4 shows the experimental data comparing the performance of different film structures.

[0089] Table 4. Performance Comparison of Different Film Structures

[0090]

[0091] This application achieves a CTM value >100% for the first time: through efficient photon recovery effect, additional photocurrent is contributed, enabling the module's CTM value to break through the theoretical upper limit of 100%; a pure black appearance with zero reflection is achieved: visible light absorption rate ≥98.5%, ΔE<0.8; the module's operating temperature is significantly reduced, and near-infrared light is reflected and utilized, reducing the module's operating temperature by 3-4℃ and improving the overall power generation efficiency by 0.7%-1.0%; at the same time, all three layers of the structure use materials with excellent weather resistance, and zeolite ion scavengers can effectively block free ions, ensuring that the film will not yellow or degrade in performance within its 25-year service life.

[0092] When sunlight strikes the black film region between solar cells 310, the following continuous optical process occurs, ultimately converting the previously wasted near-infrared light into electrical energy: The incident light first reaches the upper visible light absorption layer 331, where the 400-700nm visible light is completely absorbed by the phthalocyanine black dye (absorption rate ≥98%), producing no reflected light; the 700-1200nm near-infrared light (accounting for approximately 43% of the total solar energy) is hardly absorbed by the phthalocyanine black dye and passes through the upper layer with a transmittance of over 95%, reaching the middle layer; the near-infrared light reaching the middle layer encounters the core-shell structured silver nanoparticles, and due to the plasmon resonance effect of silver, over 88% of the near-infrared light is specularly reflected, while the remaining near-infrared light... Light is reflected to the lower layer. Near-infrared light, mirror-reflected, reaches the glass-air interface at an angle greater than the critical angle for total internal reflection, preventing it from escaping the front substrate 100. It is then totally internally reflected back into the module and ultimately reflected to the lower diffuse reflection adhesive layer 333. Near-infrared light reflected downwards from the middle layer reaches the lower diffuse reflection adhesive layer 333, where it is scattered by the silica diffuse reflection particles, transforming into Lambertian-type diffuse light with a scattering angle covering 0-180°. Approximately 40%-50% of the scattered light directly illuminates the back of the adjacent solar cell 310, is absorbed by the N-type silicon substrate, and generates photogenerated carriers. The remaining 50%-60% of the scattered light passes upwards through the middle and upper layers, reaching the inner surface of the front glass. When the angle of incidence is greater than the critical angle for total internal reflection at the glass-air interface (approximately 42°), total internal reflection occurs, confining the light within the glass substrate and ultimately being absorbed by the front of the solar cell 310.

[0093] Reference Figure 4 , combined Figure 1 Each cell 310 has a high-resistance conductive strip 340 printed on its back. The high-resistance conductive strip 340 is made of silver paste and carbon paste in a mass ratio of 1:4. The width of the high-resistance conductive strip 340 varies in a gradient so that the sheet resistance of the high-resistance conductive strip 340 decreases linearly from the side near the cut edge of the cell 310 to the side away from the cut edge.

[0094] For example, each high-resistance conductive strip 340 is perpendicular to the cut edge of the battery cell 310, and its width varies in a gradient of 0.6-0.8 mm. Correspondingly, the sheet resistance of the high-resistance conductive strip 340 decreases linearly from 500Ω to 100Ω from the side near the cut edge to the side away from the cut edge, forming a resistance gradient.

[0095] It is understandable that the photovoltaic module 10 is a back-contact photovoltaic module 10, with all electrodes concentrated on the back side. The reverse current generated by partial shading will preferentially concentrate at the cell cutting edge, forming an "edge hot spot". This causes the temperature of the cell cutting edge to rise. A high-resistance region can be formed by the high-resistance conductive strip 340. When the cell edge is partially shaded, the high-resistance region near the edge will limit the magnitude of the reverse current, while the low-resistance region far from the edge will quickly conduct away the remaining current, thereby limiting the hot spot temperature to below 85°C without any additional active devices.

[0096] The high-resistance conductive strip 340 can reduce the maximum temperature of local hot spots on the cut edge of the solar cell 310 from over 105°C to ≤85°C, which is far below the safety limit of 110°C specified by the IEC standard, significantly improving the reliability and service life of the module.

[0097] The two passivation layers 320 and the spectrally selective black film 330 have a synergistic effect: the spectrally selective black film reduces the operating temperature of the photovoltaic module 10, thereby slowing down the thermal aging rate of the two passivation layers 320 at low temperatures, and keeping the passivation effect stable within a 25-year service life; at the same time, the two passivation layers 320 improve the corrosion resistance of the edge of the cell 310, and can effectively resist the erosion of trace ions that may exist in the black film.

[0098] The two passivation layers 320 work synergistically with the hot spot suppression structure: the two passivation layers 320 reduce the leakage current at the edge of the cell 310, thereby reducing the reverse current when partially blocked, and further enhancing the hot spot suppression effect of the high-resistivity conductive strip 340; at the same time, the high-resistivity conductive strip 340 can quickly conduct away the heat generated at the edge, avoiding damage to the two passivation layers 320 by local high temperature.

[0099] Synergy between spectrally selective black film 330 and hot spot suppression structure: The spectrally selective black film 330 reduces the overall operating temperature of the module, providing a better foundation for hot spot suppression; at the same time, the hot spot suppression structure avoids local aging and discoloration of the black film caused by local high temperature, maintaining the consistency of the module's all-black appearance.

[0100] By combining two passivation layers 320, a spectrally selective black encapsulant film 330, and a high-resistivity conductive strip 340, the overall conversion efficiency of the photovoltaic module 10 is increased by 1.8%-2.4%, and the power is increased from 490W to 510-512W while maintaining an all-black appearance.

[0101] The following describes the preparation method of photovoltaic module 10.

[0102] S100 uses N-type back contact solar cells 310. The size of solar cell 310 is 182mm×182mm, the conversion efficiency is 25.3%, the open circuit voltage is 725mV, and the short circuit current is 11.2A.

[0103] S200, Laser scribing: The picosecond laser scribing machine is used to cut the 310 battery cell into 1 / 2 size sub-cells. The laser power is 12W, the scribing speed is 300mm / s, and the cutting depth is 1 / 2 the thickness of the 310 battery cell.

[0104] S300, gradient low-temperature in-situ edge passivation.

[0105] Preparation of inner passivation solution: Mix methyltriethoxysilane, vinyltriethoxysilane, ethanol and deionized water in a mass ratio of 3:1:15:6, add 0.05wt% photoinitiator 1173, and stir until homogeneous.

[0106] Preparation of outer passivation solution: Mix methyltriethoxysilane, ethanol, and deionized water in a mass ratio of 1:6:2, add 1.2 wt% of surface-modified nano-alumina particles (particle size 10 nm) and 0.08 wt% of photoinitiator 1173, and stir until homogeneous.

[0107] The cut battery cell 310 was immersed in the inner passivation solution for 20 seconds, and then dried at 70°C for 3 minutes.

[0108] Irradiate with ultraviolet light at a wavelength of 365nm for 2 minutes to solidify the inner passivation solution.

[0109] Immerse the 310 battery cell in the outer passivation solution for 25 seconds, then remove it and dry it at 80°C for 4 minutes.

[0110] Irradiate with ultraviolet light at a wavelength of 365nm for 3 minutes to solidify the outer passivation solution.

[0111] The passivation layer 320 surface was treated with argon-hydrogen mixed plasma (H2 content 8%) for 60 seconds at a power of 200W.

[0112] S400, High Resistance Conductive Strip 340 Printing: On the back of the battery cell 310, at a distance of 0.3mm from the cutting edge, a gradient high resistance conductive strip 340 with a width of 0.7mm is printed, with the sheet resistance linearly reduced from 500Ω to 100Ω, and dried at 150℃ for 10 minutes.

[0113] S500, Battery String Fabrication: Utilizing OBB (Operational Busbar-less) technology, passivated sub-cells are connected in series to form a battery string using 0.25mm × 0.1mm flat solder strips. The spacing between the 310 cells is 0.5mm. A transparent separator is applied between the 310 cells, and the separator cures at 100℃.

[0114] S600, layered paving.

[0115] The back black glass substrate, the back POE film, and the battery string layer 300 are laid out sequentially from bottom to top.

[0116] A photon-recovery spectrally selective black adhesive film 330 is precisely filled in the gap area of ​​the solar cell 310, and the width of the adhesive film is consistent with the gap of the solar cell 310.

[0117] Lay out the front POE film and the front low-iron tempered glass substrate.

[0118] S700, Lamination and Curing: Lamination is carried out at 140℃ and 1 atm pressure for 15 minutes to cure and bond each layer of adhesive film.

[0119] S800, Subsequent Processes: Perform conventional component manufacturing processes such as trimming, framing, and installing junction boxes.

[0120] The following is a comparative experiment of photovoltaic module 10.

[0121] I. Standardize experimental conditions

[0122] All experimental groups used the exact same basic process and raw materials, only changing the technical features involved in this invention, to ensure the uniqueness and comparability of the experimental results.

[0123] Cell 310: Same batch of Gaojing GBC-3.0N type back contact battery, 182mm×182mm, single cell efficiency 25.2%±0.1%, open circuit voltage 724mV±2mV.

[0124] Module specifications: 54-cell 1 / 2-cut double-glass module, 0.5mm gap between cells, low-iron tempered glass on the front and black glass on the back.

[0125] Slicing process: The same picosecond laser scribing machine, with a power of 12W, a scribing speed of 300mm / s, and a cutting depth of 1 / 2 of the battery thickness.

[0126] Encapsulation process: POE film is used on both the front and back sides, with lamination conditions of 140℃ / 15min / 1atm.

[0127] Testing standards: All tests were conducted in accordance with IEC61215-2021 standards, using a Class A photovoltaic simulator under STC conditions (1000W / ㎡, 25℃, AM1.5).

[0128] Aging conditions: Damp heat aging DH1000h (85℃ / 85%RH), thermal cycling TC200 times (-40℃~85℃).

[0129] II. Experimental Group Design

[0130] Table 5 Experimental Group Design

[0131]

[0132] III. Core Performance Comparison Data

[0133] Table 6 Comparison of Electrical Performance and Core Indicators

[0134]

[0135] Table 7. Specific Comparison of Edge Passivation Performance

[0136]

[0137] Table 8 Comparison of Optical and Thermal Properties

[0138]

[0139] Table 9 Comparison of Reliability and Aging Performance

[0140]

[0141] Table 10 Experiment on Optimization of Total Thickness of Gradient Passivation Layer

[0142]

[0143] Conclusion: When the total thickness of the passivation layer 320 is 80-120nm, the passivation effect and stability are optimal. This invention selects 100nm as the optimal thickness.

[0144] The three technical features of this invention are not simply superimposed, but rather generate a synergistic gain of 1+1+1>3.

[0145] Table 11 Quantitative Analysis of Synergistic Effect

[0146]

[0147] Explanation of the mechanism of synergistic effect.

[0148] 1. The spectrally selective black sealant reduced the overall operating temperature of the module by 3.9℃, slowed down the thermal aging rate of the low-temperature passivation layer 320, kept the passivation effect stable over a 25-year service life, and contributed an additional power gain of approximately 0.15%.

[0149] 2. The low-temperature passivation layer 320 reduces the leakage current at the battery edge, reduces the reverse current when partially blocked, enhances the hot spot suppression effect of the high-resistivity conductive strip 340, reduces the power attenuation caused by hot spots, and contributes an additional power gain of about 0.13%.

[0150] Standard textual description of experimental results:

[0151] (1) As shown in Table 6, compared with the existing mass-produced GK-3-54HGDb modules, the complete solution of the present invention increases the maximum power of the module from 490W to 502.7W, the conversion efficiency from 24.50% to 25.14%, the overall power is increased by 2.59%, and the CTM value breaks through 100% for the first time, reaching 100.35%.

[0152] (2) After using gradient low-temperature in-situ edge passivation technology alone, the minority carrier lifetime at the edge of the battery increased from 4.7μs to 21.8μs, the parallel resistance increased by more than 50%, and the edge leakage current decreased by 82%, proving that the passivation structure of the present invention can effectively repair edge damage caused by laser cutting and solve the problem of edge recombination loss of BC battery.

[0153] (3) When photon-recovery spectrally selective black glue is used alone, the near-infrared reflectance increases from 67.8% to 87.5% while maintaining the all-black appearance. The steady-state operating temperature of the module decreases by 2.8℃ and the CTM value increases by 0.88 percentage points, proving that the black glue of the present invention can effectively recover near-infrared light from the gaps and reduce the heat loss of the module.

[0154] (4) After using the edge gradient high resistance conductive strip 340 alone, the highest temperature of the hot spot under local 3% shading decreased from 106.5℃ to 86.9℃, and the power attenuation rate after the hot spot decreased from 2.1% to 0.7%, proving that the passive hot spot suppression structure of the present invention can effectively solve the edge local hot spot problem unique to BC components.

[0155] (5) The combination of the three produced a significant synergistic effect. The actual power increase (2.59%) was greater than the effect of the single technology superposition (2.31%), and an additional synergistic gain of 0.28% was obtained, which fully proves that the technical solution of the present invention has outstanding substantive features and significant progress.

[0156] This application provides a photovoltaic module 10, including a front substrate 100, a front encapsulating film layer 200, a cell string layer 300, a back encapsulating film layer 400, and a back substrate 500 connected in sequence. The cell string layer 300 includes a plurality of cells 310 connected in series. Each cell 310 has at least one cut edge. A passivation layer 320 is provided on the cut edge of the cell 310. The passivation layer 320 includes a first passivation layer 321 and a second passivation layer 322. The second passivation layer 322 is disposed on the edge of the cell 310, and the first passivation layer 321 is disposed inside the second passivation layer 322. The first passivation layer 321 is formed by mixing an organosilicon matrix with a silane compound, and the second passivation layer 322 is formed by doping an organosilicon matrix with nanoparticles. The surface of the second passivation layer 322 is plasma-treated to form a charge density gradient. The photovoltaic module 10 provided in this application achieves the synergistic effect of chemical passivation and field-effect passivation through two passivation layers 320. Passivation is achieved at low temperature, avoiding damage to the transparent separator, and improving the minority carrier lifetime and parallel resistance at the edge of the cell, thereby reducing power loss.

[0157] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A photovoltaic module, characterized in that, The device includes a front substrate (100), a front encapsulation film layer (200), a battery string layer (300), a back encapsulation film layer (400), and a back substrate (500) connected in sequence. The battery string layer (300) includes a plurality of battery cells (310) connected in series. Each battery cell (310) has at least one cut edge. The cut edge of the battery cell (310) is provided with a passivation layer (320). The passivation layer (320) includes a first passivation layer (321) and a second passivation layer (322). The second passivation layer (322) is disposed at the edge of the battery cell (310), and the first passivation layer (321) is disposed inside the second passivation layer (322). The first passivation layer (321) is formed by mixing an organosilicon matrix with a silane compound. The second passivation layer (322) is formed by doping the organosilicon matrix with nanoparticles. The surface of the second passivation layer (322) is treated with plasma to form a charge density gradient.

2. The photovoltaic module according to claim 1, characterized in that, The first passivation layer (321) is formed by the hydrolytic condensation of methyltriethoxysilane and vinyltriethoxysilane, wherein the mass ratio of methyltriethoxysilane to vinyltriethoxysilane is 3:

1.

3. The photovoltaic module according to claim 1, characterized in that, The second passivation layer (322) is formed by doping an organosilicon substrate with nano-alumina particles, wherein the weight percentage of the nano-alumina particles is 1.0-1.5 wt%.

4. The photovoltaic module according to claim 3, characterized in that, The alumina nanoparticles have a particle size of 8-12 nm, and the surface of the alumina nanoparticles is modified with 3-aminopropyltriethoxysilane.

5. The photovoltaic module according to claim 1, characterized in that, The surface of the second passivation layer (322) is treated with argon-hydrogen mixed plasma.

6. The photovoltaic module according to claim 1, characterized in that, There is a gap between adjacent battery cells (310), and the gap is filled with a spectrally selective black adhesive film (330). The spectrally selective black adhesive film (330) includes a visible light absorption layer (331), a near-infrared high reflectance and ion blocking layer (332), and an all-angle diffuse reflection adhesive layer (333) arranged sequentially. The second passivation layer (322) abuts against the spectrally selective black adhesive film (330).

7. The photovoltaic module according to claim 6, characterized in that, The visible light absorption layer (331) is composed of an EVA matrix with 0.5-0.8 wt% phthalocyanine black organic dye.

8. The photovoltaic module according to claim 6, characterized in that, The near-infrared high reflectivity and ion blocking layer (332) is composed of a POE matrix with 12-15 wt% core-shell structured infrared reflective particles and 2-3 wt% zeolite ion scavenger added. The near-infrared high reflectivity and ion blocking layer (332) is configured to reflect infrared light.

9. The photovoltaic module according to claim 6, characterized in that, The full-angle diffuse reflection adhesive layer (333) is composed of POE matrix with 3-5 wt% silica diffuse reflection particles, and the full-angle diffuse reflection adhesive layer (333) is configured to reflect infrared light back to the surface of the solar cell (310) in a full-angle scattering manner.

10. The photovoltaic module according to claim 1, characterized in that, The battery cell (310) is printed with a high-resistance conductive strip (340), which is made of silver paste and carbon paste in a mass ratio of 1:

4. The width of the high-resistance conductive strip (340) varies in a gradient so that the sheet resistance of the high-resistance conductive strip (340) decreases linearly from the side near the cut edge of the battery cell (310) to the side away from the cut edge.

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