Bifacial solar module

Abstract

The invention relates to a bifacial solar module having a front side and a back side, with a front-side encapsulation element (1) forming the front side of the solar module, a plurality of solar cells (2) electrically connected to one another, a back-side encapsulation element (3) forming the back side of the solar module having a back-side plane, and at least one junction box (4) and a housing (41) arranged at least partially on the back side, characterized in that the housing (41) consists of a material which is optically transparent in the wavelength range from 380 nm to 1100 nm.

Description

Technical Field

[0001] This invention relates to a bifacial solar module. In particular, this invention relates to a bifacial solar module having a front and a back side, comprising a front encapsulation element forming the front side of the solar module, a plurality of solar cells electrically connected to each other, a back encapsulation element forming the back side of the solar module having a back plane, and at least one junction box and housing at least partially disposed on the back side. Background Technology

[0002] Bifacial solar modules have the characteristic of generating electricity using light incident on both the front and back sides. In bifacial solar modules, a film or corresponding glass transparent to visible light is used as the back-side encapsulation element. Therefore, unabsorbed light passing through the solar module and reflected light from around the module incident on the back of the solar cells can also be utilized. Single-sided solar modules, on the other hand, can only generate electricity using light incident on the front side. Unlike current bifacial solar modules, single-sided solar modules use opaque or highly light-absorbing back-side encapsulation elements.

[0003] Therefore, bifacial solar modules are solar modules that can utilize sunlight from both sides. They can use not only light directly incident from the front but also light indirectly incident from the back, thus achieving higher efficiency compared to single-sided solar modules. For example, light reflected from a bright house wall can be used from the back of a bifacial solar module. However, further optimization of the efficiency of bifacial solar modules is still needed. Summary of the Invention

[0004] Therefore, the object of the present invention is to provide a bifacial solar module with further improved efficiency.

[0005] The solution of the present invention to achieve the above-mentioned objective lies in a bifacial solar module having the features of claim 1. Advantageous further embodiments and variations are described in the dependent claims.

[0006] According to the present invention, the housing of the junction box is made of an optically transparent material in the wavelength range of 380nm to 1100nm.

[0007] Junction boxes, also known as junction boxes, are typically made of black plastic. However, the shading on the back of these boxes, related to the material, reduces optimal (light) output, thus decreasing the efficiency of the solar module. Using transparent junction boxes reduces this shading, thereby improving the efficiency of the solar module.

[0008] Within the scope of this invention, the term "transparent" specifically refers to allowing visible light to pass through. A transparent material is one that allows electromagnetic waves within a defined wavelength range to pass through. These electromagnetic waves include light, i.e., electromagnetic waves within the human visible spectrum. Visible radiation, relative to the brightness sensitivity of the human eye, refers to wavelengths between 380 nm and 780 nm. Only about half of solar radiation energy is visible sunlight. Sunlight includes the ultraviolet spectrum, the visible spectrum, and the near-infrared and mid-infrared. Optically transparent materials may, but are not required to, be colorless. They are preferably colorless.

[0009] The junction box preferably has at least one first contact electrically connected to the solar cell and at least one second contact suitable for contact with a complementary structure. Alternatively or supplementary, the junction box preferably has at least one electrical connector, at least one diode, and / or at least one bypass diode.

[0010] In a preferred embodiment, the material of the housing, measured according to DIN EN 1013:2015-03, has an average light transmittance of more than 80%, preferably more than 70%, and more preferably more than 60% within a defined wavelength range.

[0011] Light transmittance, or light transmittance, refers to the proportion of visible radiation that passes through a material under perpendicular illumination. Besides the choice of material, light transmittance is also affected by material thickness, reflection, and coatings.

[0012] The shell is preferably made of glass and / or plastic. More preferably, the shell is made of an amorphous polymer.

[0013] In a preferred embodiment, the housing is made of glass. The glass is, for example, silicate glass. Silicate glass, in particular, has a transparency between 170 nm and 5000 nm, encompassing the entire visible light range and portions of the ultraviolet and infrared ranges.

[0014] As an alternative or supplementary option, the shell material is preferably plastic. Compared to glass, plastic has the advantage of being more shatterproof. The plastic is more preferably an amorphous polymer. In the case of an amorphous polymer, the polymer chains are not uniformly distributed in space. Therefore, plastics made of amorphous polymers are suitable as transparent materials. As an alternative, semi-crystalline polymers are also preferably suitable as shell materials, especially when a nucleating agent is added to this material. The addition of a nucleating agent, known as a clarifying agent, is a brightening agent that ensures the polymer's transparency. Examples of brightening agents are (activated) azodicarboxylic acid diamide, p-toluenesulfonyl hydrazine, 2,4,6-trihydrazino-1,3,5-triazine, p-toluenesulfonylaminourea, or 5-phenyltetrazole. Examples of semi-crystalline polymers that can be made transparent are polyethylene, polypropylene, polyvinylidene fluoride, or polyethersulfone.

[0015] In a preferred embodiment, the housing material is selected from the group consisting of glass, polystyrene, polymethyl methacrylate, polycarbonate, polyvinyl chloride, ethylene glycol-modified polyethylene terephthalate, polyphenylene ether, polyethylene, polypropylene, polyvinylidene fluoride, amorphous polyethylene terephthalate, thermoplastic polyester, polyetherimide, and / or polysulfone. All materials have a transparency suitable for bifacial solar modules.

[0016] The shell is preferably made of polystyrene. Styrene-acrylonitrile is preferred as the polystyrene. Solid amorphous polystyrene is relatively hard but sensitive to impact. Solid amorphous polystyrene is not very heat-resistant, aging accelerates from 55°C, therefore it can only be used at 70°C. Although polystyrene has high resistance to the effects of water, it decomposes upon exposure to ultraviolet radiation. Therefore, polystyrene can be used outdoors, especially when it also has UV protection.

[0017] The housing is preferably made of polymethyl methacrylate (PMMA), also known as acrylic glass. PMMA has UV resistance due to its chemical composition, making it suitable for outdoor use. In the transparent embodiment, the PMMA is suitable for a temperature range of -40°C to +90°C. PMMA has very high light transmittance, even exceeding that of inorganic glass. PMMA has a hard, highly scratch-resistant surface, but due to the brittleness of the plastic, it is relatively sensitive to fracture.

[0018] The shell is preferably made of polycarbonate. The main characteristics of polycarbonate are its very high impact resistance and excellent fracture performance. However, polycarbonate is not scratch-resistant and is unstable under ultraviolet light. Therefore, polycarbonate can be used outdoors, especially when it also provides UV protection. However, one advantage of polycarbonate is its applicable temperature range of -100°C to +120°C. Furthermore, polycarbonate is non-flammable.

[0019] The housing is preferably made of polyvinyl chloride (PVC), particularly rigid PVC. PVC is relatively impact-resistant and has sufficient fracture resistance and scratch resistance. Rigid PVC is not freeze-resistant, has a narrow applicable temperature range of 0°C to +60°C, and is not UV-resistant; therefore, PVC should be equipped with UV protection for outdoor use. Transparent PVC has the advantages of very good chemical resistance and low flammability.

[0020] The shell is preferably made of ethylene glycol-modified polyethylene terephthalate (PEG). PEG is not UV-resistant and lacks weather resistance, but it is transparent, impact-resistant, not easily broken, and fire-retardant. Furthermore, it has very high chemical resistance and is insensitive to low temperatures. PEG is suitable for use in temperatures ranging from -40°C to +65°C. If intended for outdoor use, it should have UV protection.

[0021] The shell is preferably made of polyphenylene ether (also known as polyphenylene oxide). Polyphenylene ether is characterized by its resistance to hot water, high impact resistance, and high fire resistance. Furthermore, polyphenylene ether can also be used in combination with polystyrene.

[0022] The housing is preferably made of polyethylene. Depending on the type, the maximum continuous operating temperature is approximately 60°C to 85°C. Polyethylene has good electrical insulation properties and good chemical resistance. However, polyethylene is not resistant to ultraviolet radiation and must be equipped with UV protection for outdoor use.

[0023] The housing is preferably made of polypropylene. Polypropylene is harder, stronger, and more heat-resistant than polyethylene. The maximum continuous operating temperature is approximately 100°C. However, polypropylene is not UV resistant and must be equipped with UV protection for outdoor use.

[0024] The shell is preferably made of polyvinylidene fluoride (PVDF). PVDF has good heat resistance and UV resistance.

[0025] The shell is preferably made of amorphous polyethylene terephthalate (PET). Amorphous PET has good impact resistance and dimensional stability. Its application limits are between -40°C and +60°C.

[0026] The shell is preferably made of thermoplastic polyester. Thermoplastic polyester is preferably polyethylene terephthalate (PET). Semi-crystalline and unreinforced PET has high mechanical strength and hardness, and exhibits good dimensional stability due to its low coefficient of thermal expansion and low hygroscopicity.

[0027] The shell is preferably made of polyetherimide. Polyetherimide is amber or gold in color. Polyetherimide has inherent flame retardancy, produces less smoke, and has relatively high strength. In addition, polyetherimide is waterproof and UV resistant.

[0028] The housing is preferably made of polysulfone. Polysulfone is amber or yellow. Polysulfone has relatively good mechanical strength and rigidity and can be used in a temperature range of -50°C to +180°C. Polysulfone has excellent dimensional stability, very good hydrolysis resistance, and radiation resistance. Polysulfone is degraded by ultraviolet light below 320 nm, therefore, UV protection should be provided for outdoor applications.

[0029] As mentioned above, the casing material must be UV-resistant for outdoor use. If the material itself is not UV-resistant, UV protection must be provided. One way to achieve UV protection is to add UV stabilizers to the casing material. Another way is to further coat the casing material with a coating containing UV stabilizers. UV stabilizers, such as antioxidants, anti-ozone agents, and anti-light agents, are used to protect plastics, especially casing materials, from undesirable aging effects. These UV stabilizers can also act as free radical scavengers. UV stabilizers can be UV absorbers or UV inhibitors.

[0030] Ultraviolet (UV) absorbers operate based on the principle of light absorption and Beer-Lambert law. In this case, the amount of UV radiation absorbed is a function of the thickness of the object through which it passes and the concentration of the stabilizer. The absorbed UV radiation is then released again as heat. When a UV absorber is used as an inhibitor, it does not absorb UV radiation but instead acts as a hydrogen donor at the site of material degradation caused by UV radiation. Specifically, it provides hydrogen atoms to peroxide free radicals. In this case, stable free radicals are formed; therefore, the inhibitor acts as a free radical scavenger.

[0031] The shell material preferably contains a UV stabilizer. A UV stabilizer is a compound added as an additive to a polymer suitable as a shell material and used as protection against aging caused by UV radiation. Examples of UV stabilizers include benzotriazoles such as 2,4-di-tert-butyl-6-(5-chlorobenzotriazol-2-yl)phenol, benzophenone, cyanoacrylates, triazines such as phenyltriazine, and HALS (hindered amine light stabilizers). Hindered amines (HALS) are based on 2,2,6,6-tetramethylpiperidine.

[0032] In a preferred embodiment, the housing material is coated with an optically transparent ultraviolet-absorbing coating in the wavelength range of 380 nm to 1100 nm. This prevents the housing from aging during outdoor use. The coating is preferably provided on the outer side of the housing. The optically transparent ultraviolet-absorbing coating in the wavelength range of 380 nm to 1100 nm can be applied to the housing in the form of a paint or adhesive, preferably in the form of a paint. This paint is preferably a varnish containing at least one colorless ultraviolet stabilizer that does not cause color change. Nano-titanium dioxide can be used as an inorganic ultraviolet stabilizer in the paint. Very fine titanium dioxide is transparent compared to coarser titanium dioxide used as a pigment. This titanium dioxide does not cause the paint to become cloudy. Furthermore, this coating can contain the aforementioned ultraviolet stabilizer.

[0033] Furthermore, the junction box preferably also has an optically transparent filler material in the wavelength range of 380 nm to 1100 nm, which is disposed within the housing. This ensures additional protection, thus preventing moisture from penetrating to the electrical contacts located in the junction box, or at least significantly reducing the amount of moisture that can penetrate to the electrical contacts. This prevents or at least delays corrosion of these electrical contacts. The transparency of the filler material also prevents efficiency reduction due to opacity. The optically transparent filler material is preferably a transparent silicone resin that is optically transparent within the range defined above.

[0034] In a preferred embodiment, the bifacial solar module further includes a sealing member arranged in a manner between the front and rear encapsulation elements, such that it surrounds the housing and / or is positioned between the housing and the front encapsulation element. This prevents or at least reduces the ingress of moisture into the electrical contacts located in the junction box. This sealing member is preferably made of an optically transparent sealing member material (e.g., in the form of transparent silicone resin) in the wavelength range of 380 nm to 1100 nm.

[0035] This double-sided module can be used in junction boxes and / or as a sealing component with an optically transparent filling material in the wavelength range of 380nm to 1100nm. Attached Figure Description

[0036] The invention will now be described in detail with reference to the accompanying drawings, which are shown schematically and not to scale:

[0037] Figure 1 A cross-sectional view of a bifacial solar module section according to the first embodiment;

[0038] Figure 2 A cross-sectional view of a bifacial solar module section according to the second embodiment; and

[0039] Figure 3 This is a cross-sectional view of a bifacial solar module section according to the third embodiment. Detailed Implementation

[0040] Figure 1 A cross-sectional view of a bifacial solar module segment according to a first embodiment is shown. This bifacial solar module has a front encapsulation element 1, which includes a glass plate 11 and an embedded polymer layer 12, for example, of ethylene vinyl acetate. Solar cells 2 are arranged on the embedded polymer layer 12, and these solar cells are connected to other solar cells (not shown) via a cell connector (not shown due to the segment illustration) to form a cell string (not shown). Furthermore, this bifacial solar module also has a back encapsulation element 3, which has an embedded polymer 32 (e.g., ethylene vinyl acetate) and a back encapsulation structure 31. Additionally, this bifacial solar module has a junction box 4, the housing 41 of which is made of a material that is optically transparent in the wavelength range of 380 nm to 1100 nm. In this embodiment, the junction box 4 is constructed as a flat plug that does not protrude or only slightly protrudes from the back encapsulation element 3 and is partially embedded (e.g., laminated to) the back encapsulation element 3. The junction box 4 has a socket 42 for accommodating complementary contact structures (not shown). Optionally, a layer 7 is arranged below the junction box 4, which is made of, for example, an embedded polymer (such as ethylene vinyl acetate). The junction box 4 is arranged on the optional layer 7 or directly on the solar cell 2.

[0041] Figure 2 A cross-sectional view of a bifacial solar module section according to the second embodiment is shown. Figure 2 The bifacial solar module shown corresponds to Figure 1 The bifacial solar module shown differs in that the junction box 4 is not laminated into the back-side encapsulation element 3 and has a different shape and design, causing it to protrude from the back-side encapsulation element 3 and have a filler material 43 arranged within the housing 41. The filler material 43 is specifically chosen to be optically transparent in the wavelength range of 380nm to 1100nm. For clarity, Figure 2 The glass plate 11, the embedded polymer layer 12, the solar cell 2, the embedded polymer 32, and the back encapsulation structure 31 are not shown.

[0042] Figure 3 A cross-sectional view of a bifacial solar module section according to a third embodiment is shown. Figure 3 The bifacial solar module shown corresponds to Figure 2The bifacial solar module shown differs in that it also has a sealing member 6, which is arranged in a manner between the front encapsulation element 1 and the back encapsulation element 3, such that the sealing member surrounds the housing 41, and the housing 41 optionally has a filler material 43. In an alternative variant not shown, the sealing member 6 is also alternatively or supplementarily arranged between the edges of the front encapsulation element 1 and the circumference of the housing 41.

[0043] Appendix Label Table

[0044] 1. Front-facing packaged components

[0045] 11 Glass Plate

[0046] 12 Embedded Polymers

[0047] 2 Solar cells

[0048] 3. Backside packaged components

[0049] 31 Backside Packaging Structure

[0050] 32 Embedded Polymer

[0051] 4 Junction Box

[0052] 41. Shell

[0053] 42 sockets

[0054] 43 Filler material

[0055] 6 Sealing components

[0056] 7th floor

Claims

1. A bifacial solar module having a front and a back side, which has The front-side encapsulation element (1) forms the front side of the solar module. Multiple solar cells (2) that are electrically connected to each other, A back-side encapsulation element (3) is formed on the back side of the solar module having a back-side plane, and At least one junction box (4) and housing (41) at least partially arranged on the rear side, characterized in that, The housing (41) is made of an optically transparent material in the wavelength range of 380 nm to 1100 nm.

2. The solar module according to claim 1, characterized in that, According to DIN EN 1013:2015-03 (published by the German Institute for Standardization in March 2015, "Transparent single-layer shaped plastic panels for interior and exterior roofs, walls and ceilings - requirements and test methods"), the material of the housing (41) has an average transmittance of more than 60% in the defined wavelength range.

3. The solar module according to claim 1, characterized in that, According to DIN EN 1013:2015-03 (published by the German Institute for Standardization in March 2015, "Transparent single-layer shaped plastic panels for interior and exterior roofs, walls and ceilings - requirements and test methods"), the material of the housing (41) has an average transmittance of more than 70% in the defined wavelength range.

4. The solar module according to claim 1, characterized in that, According to DIN EN 1013:2015-03 (published by the German Institute for Standardization in March 2015, "Transparent single-layer shaped plastic panels for interior and exterior roofs, walls and ceilings - requirements and test methods"), the material of the housing (41) has an average transmittance of more than 80% in the defined wavelength range.

5. The solar module according to any one of claims 1 to 4, characterized in that, The shell (41) is made of glass and / or plastic.

6. The solar module according to any one of claims 1 to 4, characterized in that, The shell (41) is made of an amorphous polymer.

7. The solar module according to claim 1, characterized in that, The material of the housing (41) is selected from the group consisting of glass, polystyrene, polymethyl methacrylate, polycarbonate, polyvinyl chloride, ethylene glycol-modified polyethylene terephthalate, polyphenylene ether, polyethylene, polypropylene, polyvinylidene fluoride, amorphous polyethylene terephthalate, thermoplastic polyester, polyetherimide and polysulfone.

8. The solar module according to claim 7, characterized in that, Styrene-acrylonitrile was chosen as the polystyrene.

9. The solar module according to claim 1, characterized in that, The material of the housing (41) contains an ultraviolet stabilizer.

10. The solar module according to claim 1, characterized in that, The material of the housing (41) is coated with an optically transparent ultraviolet-absorbing coating in the wavelength range of 380 nm to 1100 nm.

11. The solar module according to claim 1, characterized in that, The junction box (4) also has an optically transparent filling material (43) in the wavelength range of 380nm to 1100nm, which is arranged in the housing (41).

12. The solar module according to claim 11, characterized in that, The optically transparent filler material (43) is silicone resin.

13. The solar module according to claim 1, characterized in that, A sealing member (6) is arranged in a certain way between the front encapsulation element (1) and the back encapsulation element (3) such that the sealing member surrounds the housing (41) and / or is arranged between the housing (41) and the front encapsulation element (1).

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