Photovoltaic module with cover glass having a local structure with improved haze and method of making the same

Abstract

The present invention relates to a photovoltaic module comprising at least two solar cells with cell spacing between each other, busbars and / or grid lines above the at least two solar cells, and a front cover glass above the busbars and / or grid lines, characterized in that the front cover glass has a local structure with a haze of at least 50% on the top surface, the local structure being located in the projected area corresponding to part or all of the busbars, grid lines, cell spacing or a combination thereof. The photovoltaic module of the present invention has a higher light transmission of the redirected light, thus can significantly improve the power output of the photovoltaic module. The present invention also discloses a simple and easy method for preparing the photovoltaic module of the present invention.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to photovoltaic modules. In particular, the present invention relates to photovoltaic modules with cover glasses having local structures with improved haze and methods of making the same. BACKGROUND

[0002] Renewable energy will be the major energy source for human beings in the long run. Photovoltaic power generation is one of the rapidly developing renewable energy sources. Photovoltaic power generation converts light energy to electric energy through the photovoltaic effect of solar cells. The voltage generated by a single solar cell is much lower than the voltage required for practical use. Therefore, multiple solar cells are usually connected by wires (e.g., busbars and grid lines) to form a photovoltaic module (also called a solar panel) to provide higher power output.

[0003] A conventional photovoltaic module usually comprises a front side cover, an encapsulant, solar cells, and a back sheet. Sunlight is incident through the front side cover to the solar cells to achieve energy conversion. Therefore, the factors affecting the power output of a photovoltaic module usually include the net amount of sunlight incident to the solar cells and the conversion efficiency of the solar cells themselves. Not all of the incident sunlight can reach the solar cells to be converted to electric energy. On one hand, the incident sunlight has to pass through multiple layers, such as the front side cover and the encapsulant layer, to reach the solar cells. When light passes from one medium to another, reflection and refraction occur, which in turn results in a decrease in the amount of light reaching the solar cells. On the other hand, in a photovoltaic module, parts of the wires (e.g., busbars and grid lines) connecting the solar cells are located between the incident sunlight and the solar cells, which results in some sunlight being blocked and unable to reach the solar cells. Moreover, the solar cells are spaced apart in the photovoltaic module to form cell gaps between them. In these blocked areas and cell gap areas, the photovoltaic module cannot utilize the incident sunlight, thus forming inactive areas. The existence of inactive areas and the reflection and refraction of incident sunlight both result in the net amount of sunlight reaching the solar cells being less than the total amount of incident sunlight. Various methods have been proposed to increase the net amount of sunlight reaching the solar cells to increase the power output of the photovoltaic module.

[0004] Applicant's pending patent application CN103048706A discloses a method of applying an anti-reflective coating on the front side cover to increase the light transmittance of incident sunlight. The entire disclosure of CN103048706A is incorporated herein by reference.

[0005] It has been proposed to use micro busbars and grid lines in photovoltaic modules to reduce the shading effect of the busbars and grid lines. The use of micro busbars and grid lines has the risk of reduced mechanical strength and short circuit.

[0006] It has also been proposed to redirect sunlight incident on inactive areas by reflective and refractive structures to increase the net amount of sunlight reaching the solar cells and thereby improve the power output of the photovoltaic module. For example, WO2013 / 148149 discloses a light redirecting medium in the form of a microstructured film strip carrying a light reflecting layer which directs light that would otherwise be incident on inactive shadowed areas to be incident on the solar cells. The entire content of this patent application is incorporated herein by reference. It has also been proposed to reduce the shadowing effect of busbars and grid lines in photovoltaic modules by laser treatment of the cover glass.

[0007] Sandblasting is a conventional surface treatment process which employs high velocity impinging abrasive to treat surfaces to achieve surface cleaning, surface patterning and to induce stress modification. In the use of sandblasting to treat glass, irregular surface microstructures are imparted to the glass surface due to the impingement and cutting action of the abrasive on the glass surface. These irregular surface microstructures have a redirecting effect on the transmitted light.

[0008] There is still a need to provide photovoltaic modules with light management structures that can significantly improve the power output of the photovoltaic modules.

[0009] Accordingly, the present invention aims to provide a photovoltaic module that meets the above need by modifying the front side cover glass to form local structures with improved haze. The present invention also provides methods of making the front side cover glass and the photovoltaic module. The methods form the local structures with improved haze by sandblasting treatment, which is effective, simple to operate, easy to control and environmentally friendly. SUMMARY

[0010] The present invention relates to the surprising discovery that forming local structures with improved haze on the upper surface of the front side cover glass of a photovoltaic module at locations corresponding to part or all of the projected area of inactive areas (e.g. busbars, grid lines, cell spacing or combinations thereof) can cause the sunlight incident on the inactive areas to be (diffusely) scattered, resulting in part of the sunlight that would otherwise be incident on the inactive shadowed areas to be redirected in a different direction when passing through the front side cover glass, so that a portion of the incident light is incident on the nearby solar cells. As a result, the nearby solar cells can make use of this additional incident light to achieve an increase in power output.

[0011] One embodiment of the present invention is a photovoltaic module comprising:

[0012] at least two solar cells with cell spacing therebetween;

[0013] busbars and / or grid lines above the at least two solar cells; and

[0014] a front side cover glass above the bus bar and / or the grid line,

[0015] characterized in that the upper surface of the front side cover glass is provided with a local structure having improved haze, the local structure being located in the partial or full projected area corresponding to the bus bar, the grid line, the cell gap or a combination thereof.

[0016] Another embodiment of the present application is a method for preparing a front side cover glass for a photovoltaic module, comprising the steps of:

[0017] sandblasting a partial area of the upper surface of the front side cover glass with an abrasive selected from abrasives having a microhardness HV greater than 600 to form a local structure having a haze of at least 50%; and

[0018] applying an anti-reflective coating on the front side cover glass, and

[0019] tempering the front side cover glass coated with the anti-reflective coating.

[0020] Yet another embodiment of the present application is a method for preparing a photovoltaic module, comprising the steps of:

[0021] providing at least two solar cells forming a cell gap therebetween;

[0022] providing a bus bar and / or a grid line above the at least two solar cells;

[0023] providing a front side cover glass above the bus bar and / or the grid line, sandblasting a partial area of the upper surface of the front side cover glass corresponding to the bus bar, the grid line, the cell gap or a combination thereof with an abrasive selected from abrasives having a microhardness HV greater than 600 to form a local structure having a haze of at least 50%; and

[0024] applying an anti-reflective coating on the front side cover glass; and

[0025] tempering the front side cover glass coated with the anti-reflective coating. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings are included to provide a further understanding of the present application and are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and together with the description serve to explain the principles of the present application. In the drawings:

[0027] Figure 1 is a top view of a solar cell for a conventional photovoltaic module;

[0028] Figure 2 is a graph of the relationship between haze and transmittance;

[0029] Figure 3AElectron micrograph of a laser-etched glass surface;

[0030] Figure 3B Electron micrograph of a sandblasted glass surface. DETAILED DESCRIPTION

[0031] The term "front cover glass" as used herein refers to the front cover glass as such or to the front cover glass after processing, having a local structure and / or a coating of an anti-reflective layer.

[0032] The term "projection area" as used herein refers to the area on the front cover glass corresponding to the busbars, the grid lines, the cell spacing in a top view.

[0033] The term "part or all of the projection area" as used herein refers to, for example, 10-100%, 20-100%, 30-100%, 40-100%, 50-100%, 60-100%, 70-100%, 80-100%, 90-100% or 100% of the projection area.

[0034] The term "haze" as used herein characterizes the degree of scattering of light by a transparent or translucent material. It is defined as the percentage of the total luminous flux of the transmitted light which deviates more than 2.5° from the direction of incidence, when a beam of parallel light from a standard light source is directed perpendicularly onto the transparent or translucent material.

[0035] The term "improved haze" as used herein refers to a haze of more than about 50%, preferably more than about 70%, more preferably more than about 80%, even more preferably more than about 90%, most preferably more than about 95%.

[0036] The term "transmission" as used herein is expressed as the percentage of the luminous flux of the transmitted light with respect to the luminous flux of the incident light.

[0037] The term "above" as used herein refers to "directly above" and "indirectly above", i.e. with optional presence of other objects in between.

[0038] According to one aspect of the present application, there is provided a photovoltaic module comprising:

[0039] at least two solar cells, which are separated from each other by a cell spacing;

[0040] a busbar and / or a grid line above the at least two solar cells; and

[0041] a front cover glass above the busbar and / or the grid line,

[0042] The invention is characterized in that a local structure with improved haze is provided on the upper surface of the front cover glass, and the local structure is located in a part or all of the projection area corresponding to the bus bar, grid line, battery spacer or a combination thereof.

[0043] like Figure 1 As shown, a conventional photovoltaic module 100 includes multiple solar cells 101. Any type of solar cell can be used in a photovoltaic module, for example, thin-film solar cells, monocrystalline silicon solar cells, polycrystalline silicon solar cells, and organic solar cells. To collect charge carriers generated in the silicon material, highly conductive metals such as aluminum or silver are deposited on the front and back of the solar cells, forming grid lines 102. To most efficiently collect current, densely packed parallel grid lines are typically metallized and deposited on the front of a single solar cell. The grid lines connect to busbars (not shown), which collect current from the grid lines. To provide sufficient conductivity, the busbars are wider than the grid lines. The grid lines and busbars are opaque, thus blocking incident light from the solar cells. Furthermore, the multiple solar cells are spaced apart in the photovoltaic module, with cell gaps 103 between them. Incident light from the cell gaps is obviously not utilized by the solar cells. Therefore, these areas blocked by the grid lines and busbars and the cell gaps constitute inactive areas of the photovoltaic module, meaning that incident light therein cannot be utilized by the solar cells.

[0044] The photovoltaic module also includes a front cover glass, which is located above the solar cells and their bus bars and / or grid lines. Exemplary materials suitable for the front cover glass include soda-lime-silica-based glass. In some embodiments of the present invention, a local structure with improved haze is provided on the upper surface of the front cover glass corresponding to part or all of the projected area of ​​the inactive area. The local structure is located at part or all of the projected area corresponding to the bus bars, grid lines, cell gaps or a combination thereof. In some embodiments, the haze of the local structure is greater than about 50%, preferably greater than about 70%, more preferably greater than about 80%, even more preferably greater than about 90%, and most preferably greater than about 95%. In some embodiments, the surface roughness Ra of the local structure is about 0.1-10 μm, preferably about 0.5-5 μm. In some embodiments, the transmittance of the redirected light of the local structure is greater than about 2%, preferably greater than about 3.5%, and more preferably greater than about 4%.

[0045] The photovoltaic module also includes a backsheet. In some embodiments, the backsheet comprises an electrically insulating material. Suitable materials include, for example, glass, quartz, polymers, or polymers reinforced with fibers (e.g., glass, ceramic, or polymer fibers). In some embodiments, the backsheet comprises glass or quartz. Exemplary glass materials include soda-lime-silica-based glass. In other embodiments, the backsheet comprises a polymer, preferably a multilayer polymer.

[0046] In some embodiments, located between the front cover plate and the backsheet is an encapsulant that surrounds the solar cells as well as the busbars and the grid lines. The encapsulant is made of a suitable light-transmitting, non-conductive material. Some exemplary encapsulants include thermoset fluoropolymers, acrylics, ethylene-vinyl acetate (EVA), polyvinyl butyral, polyolefins, thermoplastic polyurethanes, transparent polyvinyl chloride, and ionomers.

[0047] In use, the encapsulant is placed in the form of a discrete sheet over and / or under the solar cells, between the front cover plate glass and the backsheet. Subsequently, vacuum heating liquefies the encapsulant to flow around the solar cells and encapsulate the solar cells, while at the same time filling any voids between the front cover plate glass and the backsheet. Upon cooling, the liquefied encapsulant solidifies. In some embodiments, the encapsulant can solidify in situ to form a transparent solid matrix. The encapsulant can also adhere to the front cover plate glass and / or the backsheet.

[0048] According to one aspect of the present invention, there is provided a method of making a front cover plate glass for a photovoltaic module, comprising the steps of:

[0049] sandblasting a portion of the top surface of the front cover plate glass with an abrasive selected from the group consisting of abrasives having a microhardness HV greater than 600 to form a localized structure having a haze of at least 50%;

[0050] applying an anti-reflective coating on the front cover plate glass, and

[0051] tempering the front cover plate glass with the anti-reflective coating.

[0052] According to one aspect of the present invention, there is provided a method of making a photovoltaic module, comprising the steps of:

[0053] providing at least two solar cells that form a cell gap therebetween;

[0054] providing a busbar and / or a grid line over the at least two solar cells;

[0055] providing a front cover plate glass over the busbar and / or the grid line, and sandblasting a portion or all of the top surface of the front cover plate glass corresponding to the projection of the busbar, grid line, cell gap, or a combination thereof with an abrasive selected from the group consisting of abrasives having a microhardness HV greater than 600 to form a localized structure having a haze of at least 50%;

[0056] applying an anti-reflective coating on the front cover plate glass; and

[0057] tempering the front cover plate glass with the anti-reflective coating.

[0058] In some embodiments, the grit blasting process can employ a dry blasting process or a wet blasting process, preferably a dry blasting process using compressed air. Conventional grit blasting process conditions can be employed. For example, the grit blasting pressure is about 0.1-0.5 MPa; the grit blasting angle is about 30-60 degrees, or about 80-90 degrees; the grit blasting height is about 1 cm - 30 cm, preferably 5-15 cm; and the grit blasting coverage is greater than about 100%, preferably greater than about 150%, most preferably greater than about 200%.

[0059] The abrasive has a hardness greater than that of the front cover glass, for example, the microhardness HV of the suitable abrasive is greater than about 600, preferably greater than about 800, most preferably greater than about 1000. The suitable abrasive is selected from the group consisting of quartz sand, corundum sand, silicon carbide sand, zircon corundum sand, zirconia sand, zirconium silicate sand, and combinations thereof. The corundum sand includes, for example, white corundum, brown corundum, single crystal corundum, and the like. The shape of the abrasive is not particularly limited. The preferred abrasive is angular sand and spherical sand. The angular sand can be irregularly shaped angular sand or regularly shaped angular sand. If angular abrasive is selected, the particle size range is preferably F500 - F60 (d50 = 0.01 - 0.3 mm), more preferably the average particle size is about 0.01-0.2 mm, most preferably the average particle size is about 0.01-0.1 mm; if spherical sand is selected, the average particle size is preferably less than about 0.125 mm, more preferably the average particle size is less than about 0.075 mm. In addition, if angular abrasive is selected, a grit blasting angle of about 60 degrees is preferred; if spherical sand is selected, a grit blasting angle of about 80-90 degrees is preferred.

[0060] In some embodiments, after forming the local structure with improved haze on the top surface of the front cover glass, the local structure is subjected to a secondary grit blasting, wherein the average particle size of the abrasive used in the secondary grit blasting is less than the average particle size of the abrasive used in the grit blasting process for forming the local structure with improved haze, to further improve the haze.

[0061] After forming the local structure with improved haze on the top surface of the front cover glass, an antireflective coating is applied to the front cover glass. The antireflective coating includes a porous layer and an optional underlayer between the front cover glass and the porous layer. The underlayer is non-porous. The underlayer has a solid content of about 2-5 wt% and a thickness of about 20-110 nm. The porous layer has a solid content of about 2-10 wt%, a porosity of about 40-70 vol%, and a thickness of about 100-500 nm, preferably about 100-400 nm, more preferably 100-250 nm.

[0062] In some embodiments, the underlayer is deposited as follows: a solution containing a silica gel is provided, the solution is coated on the front side cover glass, and dried. In some embodiments, the porous layer is deposited as follows: a solution containing a silica gel is provided, polymer beads and silica macro-particles having a particle size of about 50-300 nm, preferably about 80-250 nm, more preferably 100-200 nm are added to the solution, and the resulting suspension is deposited on the front side cover glass or, if present, on the underlayer.

[0063] In one variation, the underlayer is formed as follows: tetraethyl orthosilicate (TEOS) and an aqueous hydrochloric acid solution are mixed in a weight ratio of about 1 : 0.1-10, preferably about 1 : 0.5-5, more preferably about 1 : 1-2, for example about 1 : 1.5, to form a solution containing a silica gel, wherein the pH of the hydrochloric acid is 2. The resulting solution is deposited on the front side cover glass. The deposition can be performed by blade coating, curtain coating, spin coating, etc. Preferably, the deposition is performed by spin coating, wherein the spin coating speed is about 500-2000 rpm. Drying is performed at 100°C for 5-10 minutes to form the underlayer.

[0064] In one variation, the porous layer is deposited as follows: TEOS and an aqueous hydrochloric acid solution are mixed in a weight ratio of about 1 : 0.1-10, preferably about 1 : 0.5-5, more preferably 1 : 1-2, for example about 1 : 1.5, to form a solution containing a silica gel, wherein the pH of the hydrochloric acid is 2. About 1-5 wt% of polymer beads, which are polymethyl methacrylate (PMMA) having a particle size of about 20-100 nm, are added to the solution. Silica macro-particles having a particle size of about 50-300 nm, preferably about 80-250 nm, more preferably 100-200 nm are further added to the solution in an amount of about 0.1-5 wt%. The resulting suspension is deposited on the front side cover glass or, if present, on the underlayer. The deposition can be performed by blade coating, curtain coating, spin coating, etc. Preferably, the deposition is performed by spin coating, wherein the spin coating speed is 500-2000 rpm.

[0065] The front side cover glass coated with the anti-reflective coating is subjected to a tempering process. In one embodiment, the tempering process comprises heating the front side cover glass coated with the anti-reflective coating to a temperature of about the softening point of the front side cover glass and holding for a certain period of time, and then rapidly cooling. In one embodiment, the front side cover glass coated with the anti-reflective coating is heated to 600-750°C and held for about 120-180 seconds, and then rapidly cooled to room temperature, thereby performing the tempering process.

[0066] It is believed that the tempering treatment applied to the anti-reflective coating on the front cover glass affects both the anti-reflective coating and the front cover glass. During the heating phase of the tempering treatment, the polymer beads in the porous layer are burned away, leaving gaps that form pores in the porous layer. The presence of the porous structure provides additional scattering. Furthermore, the high-temperature treatment and the application of the anti-reflective coating also affect the microstructure of the localized structures formed on the upper surface of the front cover glass, thereby reducing its haze. The front cover glass obtained by the method of the present invention has a localized structure with improved haze on its upper surface and is coated with an anti-reflective coating. The haze of the localized structure coated with the anti-reflective coating remains greater than approximately 50%, preferably greater than approximately 70%, more preferably greater than approximately 80%, even more preferably greater than approximately 90%, and most preferably greater than approximately 95%, and the transmittance of the redirected light remains greater than approximately 2%, preferably greater than approximately 3.5%, and more preferably greater than approximately 4%. Furthermore, the tempering treatment eliminates internal stresses in the front cover glass, thereby increasing its strength.

[0067] Surprisingly, it was discovered that the presence of a localized structure with improved haze on the upper surface of the front cover glass enables the photovoltaic module according to the present invention to have a higher redirected light transmittance than conventional photovoltaic modules. This increase in optical efficiency significantly increases the power output of the photovoltaic module.

[0068] The haze and redirected light transmittance of different samples were measured as described below, where the control sample was a front cover glass coated only with an anti-reflection coating, and the test sample was a front cover glass with different haze values ​​on its upper surface by sandblasting and coated with an anti-reflection coating. Figure 2 As shown. Figure 2 The light transmittance of the reference sample is not 0, which is attributed to the anti-reflection coating including a porous layer. The porous structure can provide a weak scattering effect. Figure 2 The results show that as the haze increases, from 5% haze in the reference sample to approximately 30-85% haze in the test sample, the redirected light transmittance increases accordingly. Correspondingly, the incremental redirected light transmittance due to the increased haze also increases. This means that some of the sunlight (redirected light) that would otherwise have been incident on the inactive area is now received by the solar cell. The amount of redirected light increases with increasing haze in the local structure. Accordingly, this additional incident light is converted into increased power output by the solar cell.

[0069] Without being bound by any theory, it is believed that the localized structures of the present invention with improved haze are derived from the irregular surface microstructure formed by sandblasting the front cover glass. This irregular surface microstructure imparts improved haze and improved roughness to the localized structures. However, some treatments result in increased surface roughness without a significant increase in haze. Figure 3A and 3BElectron micrograph of a laser etched glass surface and an electron micrograph of a sand blasted glass surface, respectively. Both treatments result in surfaces that can have a similar surface roughness Ra and a completely different haze. Laser etching is achieved by irradiating a laser beam onto the surface of the material to be treated, which absorbs the energy of the laser beam and thereby melts. Due to the directionality of the laser beam, a channelled profile is formed on the treated surface. These channelled profiles increase the roughness of the surface. However, the channelled profile has little scattering effect on light and is more of a refraction effect. Therefore, the laser etched glass surface does not have a significantly increased haze.

[0070] Performance tests

[0071] Haze measurements were performed as follows: The side of the sample with the anti-reflective layer and / or the local structures was used as the side facing the incoming light and the haze was measured on the other side using a BYK-Gardner haze-gard plus AT-4725.

[0072] Surface roughness Ra measurements were performed as follows: The surface roughness Ra value was measured using a contact profilometer, Hommel Tester 1000. The sample surface was cleaned and the measurement probe was placed on the surface to be measured. The Ra value given by the contact profilometer was read and recorded.

[0073] Transmitted light of redirected light measurements were performed as follows: The side of the sample with the anti-reflective coating was covered with black tape, leaving a 2 mm * 24 mm slit in the middle of the black tape, which was used as the side facing the incoming light. On the other side, the area corresponding to the slit was covered with black tape. The side of the sample facing the incoming light was irradiated with sunlight (300-1200 nm) perpendicularly. The transmitted light was measured on the other side using a spectrophotometer Lambda 950. The covering of the sample simulates the situation where light is incident on an inactive area. The transmitted light is the light that would have been incident on the inactive area but is redirected by the sample. Part of the redirected light will be incident on the solar cell. Therefore, the measured transmitted light is referred to as the transmitted light of redirected light. Examples

[0074] The features and advantages of the present application will become apparent from the following examples. The examples are intended to describe rather than limit the application.

[0075] List of reagents:

[0076] White corundum sand: Saint-Gobain Ceramic Materials (Zhengzhou) Co., Ltd., WA F100, angular sand

[0077] Zirconia beads: Saint-Gobain Zirpro Ceramic Materials, Zirpro Microblast B205, spherical sand

[0078] Single crystal corundum sand: Saint-Gobain Ceramic Materials (Zhengzhou) Co., Ltd., MA88 F80, angular sand

[0079] White corundum for secondary blasting: Washington Mills, WA F400, angular sand

[0080] TEOS: tetraethyl orthosilicate, commercial reagent

[0081] Hydrochloric acid: commercial reagent, concentration 36% by weight

[0082] PMMA beads: commercially available polymethyl methacrylate beads, particle size 50 nm

[0083] Large silica particles: commercially available, particle size 100 nm

[0084] Equipment List

[0085] Air Suction Sandblasting Machine: Kaixin TM Air suction sandblasting machine

[0086] Spectrophotometer: Lambda 950

[0087] Spin coater: Commercially available

[0088] Preparation Example 1:

[0089] Sandblasting:

[0090] Cover the upper surface of the front cover glass with a protective film. Remove the protective film from part or all of the projected areas corresponding to the busbars, grid lines, and cell gaps. Sandblast the upper surface of the front cover glass, exposed areas outside the protective film, using an air-suction sandblaster. The sandblasting conditions are: irregular angular white corundum sand with a particle size of F100 (d50 of 150-125 μm); a sandblasting pressure of 0.3 MPa; a sandblasting angle of 60 degrees; a sandblasting distance of 10 cm; and a sandblasting coverage of 200%.

[0091] The parameters of the sandblasted area were measured as described above: its surface roughness Ra was 3.5 μm, its haze was 97%, and its redirected light transmittance was 5.09%.

[0092] Anti-reflective coating

[0093] 500 g of a silica gel solution was prepared by mixing TEOS and a hydrochloric acid solution with a pH of 2 at a weight ratio of 1:1.5. Further hydrochloric acid with a pH of 2 was added to bring the volume up to 2000 g. The resulting solution was deposited onto the sandblasted front cover glass, which had the protective film removed, using a spin coater at 1000 rpm. The coating was dried at 100°C for 10 minutes, forming a lower layer with a thickness of 50 nm.

[0094] A solution 500 g of silica-containing gel was prepared by mixing TEOS and an aqueous hydrochloric acid solution having a pH of 2 in a weight ratio of 1 : 1.5. Further, 1850 g of an aqueous hydrochloric acid having a pH of 2 was added. To the solution, 100 g of PMMA beads having a particle size of 50 nm and 50 g of silica large particles having a particle size of 100 nm were added. The resulting solution was deposited on the lower layer at a speed of 1000 rpm using a spin coater, and the coating thickness was 150 nm.

[0095] Tempering treatment

[0096] The front side cover glass coated with the anti-reflective coating was heated to 700°C and maintained for 120 seconds, and then quenched to room temperature.

[0097] A front side cover glass having a partial structure formed by a sandblasting treatment on its upper surface and coated with an anti-reflective coating was obtained.

[0098] The parameters of the sandblasted area were measured again: the surface roughness Ra was 3.5 μm, the haze was 94.4%, and the light transmission of the cross-polarized light was 5.04%.

[0099] Preparation of Example 2:

[0100] Sandblasting treatment:

[0101] The upper surface of the front side cover glass was covered with a protective film. The protective film was removed on the projection area corresponding to the busbars, the gate lines, and the cell spacing, or on the whole projection area. The area of the upper surface of the front side cover glass exposed to the protective film was treated in an air-suction sandblasting machine, wherein the sandblasting treatment conditions were: spherical Zirpro Microblast B205 zirconium oxide beads (particle size range 0-63 μm); sandblasting pressure was 0.3 MPa; sandblasting angle was 85 degrees; sandblasting distance was 10 cm; and sandblasting coverage was 200%.

[0102] The parameters of the sandblasted area were measured according to the above: the surface roughness Ra was 2.3 μm, the haze was 93.8%, and the light transmission of the cross-polarized light was 4.89%.

[0103] The steps of coating with the anti-reflective coating and tempering treatment in the preparation of Example 1 were repeated to obtain a front side cover glass having a partial structure formed by a sandblasting treatment on its upper surface and coated with an anti-reflective coating. The parameters of the sandblasted area were measured again: the surface roughness Ra was 2.3 μm, the haze was 91.4%, and the light transmission of the cross-polarized light was 4.33%.

[0104] Preparation of Example 3:

[0105] The upper surface of the front cover plate glass was covered with a protective film. The protective film was removed from the areas corresponding to the busbars, the grid lines and the cell intervals on the entire projected area. The areas of the upper surface of the front cover plate glass exposed from the protective film were treated in an air suction type sandblasting machine, wherein the sandblasting treatment conditions were: irregular angular shaped monocrystal corundum sand F80 (d50 of 180-212 μm) was used; the sandblasting pressure was 0.3 MPa; the sandblasting angle was 60 degrees; the sandblasting distance was 10 cm; and the sandblasting coverage was 200%. Then a secondary sandblasting was performed in the same air suction type sandblasting machine, wherein the sandblasting treatment conditions were: white corundum sand F400 (d50 of 20-40 μm) was used; the sandblasting pressure was 0.3 MPa; the sandblasting angle was 60 degrees; the sandblasting distance was 10 cm; and the sandblasting coverage was 200%.

[0106] The parameters of the sandblasted areas were measured according to the above: the surface roughness Ra was 4 μm, the haze was 97.3%, and the light transmission of the light deflected was 6.07%.

[0107] The coating of the antireflection coating and the tempering treatment steps in Example 1 were repeated to obtain a front cover plate glass having an upper surface with a partial structure formed by sandblasting and coated with an antireflection coating. The parameters of the sandblasted areas were measured again: the surface roughness Ra was 4 μm, the haze was 96.3%, and the light transmission of the light deflected was 5.54%.

[0108] It will be appreciated by those skilled in the art that changes can be made to the embodiments described above without departing from the inventive concept thereof. It is therefore intended that the present application not be limited to the particular implementation described herein but cover modifications made by those skilled in the art within the spirit and scope of the present application as defined by the appended claims.

[0109] List of reference signs:

[0110] 100 photovoltaic module

[0111] 101 solar cell

[0112] 102 grid line

[0113] 103 cell interval

Claims

1. A photovoltaic module comprising: at least two solar cells with a cell spacer between them; bus bars and / or grid lines over the at least two solar cells; and The front cover glass above the busbars and / or grid lines, It is characterized by A local structure with a haze of at least 50% is provided on the upper surface of the front cover glass, and the local structure is located in a partial or complete projection area corresponding to the bus bar, grid line, cell gap or a combination thereof.

2. The photovoltaic module according to claim 1, further comprising an anti-reflection coating on the front cover glass.

3. The photovoltaic module according to claim 1, further comprising: a back sheet below the at least two solar cells, and An encapsulant is located between the front cover glass and the backplane. The photovoltaic module according to claim 1 , wherein the surface roughness Ra of the local structure is 0.5-5 μm. The photovoltaic module according to claim 1 , wherein the light transmittance of the local structure is greater than 4%.

6. The photovoltaic module of claim 2, wherein the anti-reflection coating comprises a porous layer and an underlying layer located between the front cover glass and the porous layer. 7 . The photovoltaic module according to claim 6 , wherein the solid content of the lower layer is 2-5% by weight and the thickness is 20-110 nm. 8 . The photovoltaic module according to claim 6 , wherein the porous layer has a solid content of 2-10% by weight, a porosity of 40-70% by volume, and a thickness of 100-500 nm.

9. A method for preparing a front cover glass for a photovoltaic module, the photovoltaic module comprising: at least two solar cells with a cell spacer between them; A bus bar and / or grid line above the at least two solar cells; and a front cover glass above the bus bar and / or grid line; The method comprises the following steps: sandblasting a portion of the upper surface of the front cover glass using an abrasive selected from materials with a microhardness HV greater than 600 to form a local structure with a haze of at least 50%, wherein the local structure is located in a portion or all of a projected area corresponding to the busbar, grid line, cell gap, or a combination thereof; Applying an anti-reflective coating on the front cover glass, and The front cover glass coated with an anti-reflective coating is tempered.

10. A method for preparing a photovoltaic module, comprising the following steps: providing at least two solar cells forming a cell gap between them; Disposing a bus bar and / or a grid line above the at least two solar cells; Disposing a front cover glass above the busbars and / or grid lines, and sandblasting a portion or all of a projected area of ​​the upper surface of the front cover glass corresponding to the busbars, grid lines, cell gaps, or a combination thereof with an abrasive selected from materials with a microhardness HV greater than 600 to form a local structure with a haze of at least 50%; Applying an anti-reflection coating on the front cover glass; and The front cover glass coated with an anti-reflective coating is tempered.

11. The method according to claim 9 or 10, wherein the abrasive is selected from the group consisting of quartz sand, corundum sand, silicon carbide sand, zirconium corundum sand, zirconium oxide sand, zirconium silicate sand, and combinations thereof.

12. The method according to claim 9 or 10, wherein the abrasive is in the shape of angular sand or spherical sand.

13. The method according to claim 9 or 10, wherein the abrasive is an angular abrasive with a particle size range of F500-F60 and d50 = 0.01-0.3 mm.

14. The method according to claim 9 or 10, wherein the abrasive is ball sand with an average particle size of less than 0.125 mm.

15. The method according to claim 9 or 10, wherein the process conditions of the sandblasting treatment are: a sandblasting pressure of 0.1-0.5 MPa; a sandblasting angle of 30-60 degrees or 80-90 degrees; a sandblasting height of 1 cm - 30 cm; and a sandblasting coverage greater than 100%.

16. The method according to claim 9 or 10, further comprising performing secondary sandblasting after the sandblasting, wherein the average particle size of the abrasive used in the secondary sandblasting is smaller than the average particle size of the abrasive used in the sandblasting.

17. The method of claim 9 or 10, wherein applying an anti-reflective coating on the cover glass comprises the steps of optionally applying an underlying layer and applying a porous layer.

18. The method of claim 16, wherein applying to the lower layer comprises the steps of providing a solution containing silica gel, and coating the solution on the front cover glass.

19. A method as claimed in claim 16, wherein applying the porous layer includes the steps of: providing a solution containing silica gel, adding polymer beads and large silica particles with a particle size of 50-300 nm to the solution, and coating the resulting suspension on the front cover glass or on the lower layer if present.

20. The method of claim 16, wherein applying the lower layer comprises the steps of: mixing tetraethyl orthosilicate and aqueous hydrochloric acid solution in a weight ratio of 1:1.5 to form a solution containing silica gel, wherein the pH of the hydrochloric acid is 2; depositing the solution by spin coating at a spin coating speed of 500-2000 rpm; and drying at 100°C for 5-10 minutes.

21. The method of claim 18 , wherein applying the porous layer comprises the steps of: mixing tetraethyl orthosilicate and aqueous hydrochloric acid in a weight ratio of 1:1.5 to form a solution containing silica gel, wherein the hydrochloric acid has a pH of 2; adding 1-5 wt % of polymer beads, which are polymethyl methacrylate with a particle size of 20-100 nm, to the solution; adding large silica particles to the solution, wherein the large silica particles have a particle size of 50-300 nm and are added in an amount of 0.1-5 wt %; and depositing the resulting suspension by spin coating at a spin coating speed of 500-2000 rpm.

22. The method according to claim 9 or 10, wherein the tempering treatment comprises heating the front cover glass coated with the anti-reflection coating to 600-750°C and maintaining it for 120-180 seconds, and then rapidly cooling it to room temperature.

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