Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
  • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
  • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
  • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
  • B32B17/1055—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer
  • B32B17/10788—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer containing ethylene vinylacetate
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F19/00—Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules
  • H10F19/80—Encapsulations or containers for integrated devices, or assemblies of multiple devices, having photovoltaic cells
  • H10F19/85—Protective back sheets
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy

Definitions

• the present invention relates to solar modules which have an extended life due to the particular nature of at least one of their backsheets.
• Solar modules can e.g. have a structure as shown in Figure 1. Accordingly, solar modules can comprise a windshield 2, an intermediate layer 4 and backsheets 3. At least two backsheets can be present as a laminate.
• the intermediate layer 4 is usually composed of (one) embedding material layer (s) 5 and the solar cells 6.
• the embedding material layers 5 may also be laminates, that is, consist of several individual layers.
• the backsheets 3 usually connect to the intermediate layer 4.
• the backsheets, as shown in FIG. 2, are composed, for example, of a weather-resistant film 7, an insulation film 8 and another weather-resistant film 9.
• the solar modules according to the invention basically have a similar structure. They are characterized by a special nature of at least one backsheet, resulting in significantly advantageous properties.
• Solar cells for the direct conversion of solar energy into electrical current should be included for mechanical protection, eg from hail, damage during assembly or maintenance, to protect against corrosive environmental influences and to achieve the required electrical safety.
• the essential components for containment are a transparent windshield, embedding materials in which the solar cells are embedded or embedded, and which are transparent at least between the windshield and the solar cells, and a backsheet on the solar module backside.
• the combination of windshield, embedding materials, solar cells, integrated components and backsheets as well as possibly a frame is called a solar module.
• Transparent in the local context means that a material is permeable to electromagnetic radiation, which radiation has wavelengths that allow the electromagnetic radiation to be converted into electrical energy by means of the solar cells integrated in the solar modules.
• Windscreens are usually made of sodium silicate glass with a thickness of several mm, so that the required load capacity can be achieved and the windscreen is suitable for increasing the mechanical strength.
• Suitable embedding materials are polymeric materials, e.g. EVA (ethylene vinyl acetate), which is relatively inexpensive.
• the embedding materials are usually used in the form of films having thicknesses of, for example, 0.4 to 0.8 mm.
• EVA has several disadvantages as encapsulating material that affect the quality of the modules:
• EVA contains as peroxide initiator a peroxide.
• the peroxide that is not consumed during the lamination process can decompose the EVA and oxidize other components in the solar module.
• thermo-oxidative oxidation by heat
• photo-oxidative oxidation by UV radiation of sunlight
• chemical processes for example due to said peroxide residues. It is assumed that the moisture in the film could also play a role in the chemical and photo-oxidative processes.
• PVB polyvinyl butyral
• the backsheets must fulfill several functions, in particular the electrical insulation of the solar cells against external influences, the protection of the solar cells from environmental influences and the mechanical protection of the solar cell.
• Another requirement for backsheets made of polymer materials is created by the lamination process, since at the high laminating temperatures (with EVA this is usually 140 ° C and more) also soften the backsheets. This creates the risk of puncturing the backsheet (s) with the electrical wiring of the solar cells, resulting in a loss of electrical safety.
• the film materials should therefore soften as little as possible at the temperatures mentioned.
• the known backsheets have the disadvantage of representing high permeation barriers for the decay products present or produced in the solar modules.
• US 5,447,576 describes a structure and method for the encapsulation of solar cells. It should be lowered, the thermally induced discoloration.
• the embedded material such as EVA, is doped with so-called light stabilizers. An analysis of the mechanism of action of stabilizers shows that they act predominantly as selective absorbers and oxidants. The embedding material nevertheless splits off corrosive decomposition products that precipitate on the windscreen.
• DE 698 19 157 T2 discloses an encapsulating material intended for solar modules in the form of an at least three-layer laminate of metallocene polyethylene and polyethylene copolymers, the outer thin layers of the laminate containing UV stabilizers against thermo-oxidative and photochemical decomposition.
• These embedding materials are more expensive than e.g. EVA or PVB.
• UV stabilizers even with such transparent polymer materials, under the influence of UV light, a certain amount of decomposition takes place over a longer period, also due to the presence of corrosive substances.
• US 2008/185033 describes a solar module in which a reflective film is embedded to increase the solar efficiency between the embedding material and the backsheet.
• This film may be permanently bonded to the backsheet in the form of a common laminate.
• This reflecting film is completely impermeable to the fission products produced in the solar module.
• the reflective film is perforated in certain areas. This perforation consists of 10 to 1000 holes per cm 2 with a diameter of 1 to 10 pm and is located only in certain, namely central areas under the solar cells.
• the very small sized holes must be present in a very large number, as I said up to 1000 holes per cm 2 of the film.
• the reflective (metallic) film is in close and extensive contact with the embedding material, for example EVA, which has a non-negligible electrical conductivity. This creates the risk of electrical short circuits or power-reducing Kriechêtn in the module.
• the reflective film can only fulfill its function if it is not perforated in the region of the intermediate spaces. However, this is production-consuming, since the films generally shrink strongly anisotropically during lamination of the modules, and thus it becomes difficult to trim the films appropriately before laminating and to fit them precisely.
• WO 05/035 243 A1 describes reverse side foils for solar modules, which consist of a laminate of a weatherproof PVF or PVDF film (polyvinylidene fluoride) and at least one further film.
• This laminate has the disadvantage that it has a high permeation resistance for corrosive products in the solar modules.
• WO 03/07 438 A1 discloses a rear side film provided for solar modules, which has a significantly higher melting temperature than the encapsulation materials, so that the risk of puncturing the film is reduced.
• the film also consists of ionomer / nylon composites, Zn ionomers or Sorlyn® films.
• the described backsheets like others known from the prior art, have the disadvantage that they have a high permeation resistance for corrosive decomposition products in the solar module.
• the currently available embedding materials therefore lead to the search for methods of removing the corrosive decay products from the solar module.
• the removal of corrosive substances through the front window is not possible.
• the removal of corrosive decay products across the module edges is inefficient for large modules due to the long diffusion paths.
• the removal of corrosive substances on the backsheet is an unsolved task today.
• the present invention relates to a solar module comprising a windshield, an intermediate layer in which solar cells are embedded, and at least one backsheet, wherein at least one backsheet is perforated.
• the holes of the perforation are circular and have a radius of at least 0.2 mm and at most 1 mm.
• the solar module according to the invention has a sufficient carrying capacity, high thermal stability in addition to the reduced concentration of corrosive substances within the module. If a backside film laminate is present in the module, then at least one partial film is perforated.
• the backsheet which has the largest diffusion barrier for corrosive decomposition products of the plastic materials used has holes.
• the person skilled in the art will configure the hole accordingly, which allows a suitable shape deviating from the preferred embodiment.
• the radius of the holes is at least 0.2 mm, so that a sufficiently large area is available for gas exchange.
• the radius of the holes is more than 0.5 mm to prevent clogging, e.g. by dirt particles, to lessen.
• a radius of the holes of 0.7 mm is further preferred according to the invention, whereby the penetration of dirt particles, for example up to the embedding material layers, can be reduced.
• the radius of the holes is at most 1 mm, so that the strength of the film is maintained. Furthermore, this can compensate for unevenness on the back of the module, which are caused by used series connectors.
• Series connectors are electrical connectors between the cells. They are usually made of tinned copper with a rectangular cross section.
• a hole in at least one rear side foil of the solar module has an area of 0.1 mm 2 to 3.3 mm 2 , preferably 0.25 mm 2 to 3 mm 2 . If the hole has an area of 0.7 mm 2 to 1.6 mm 2 , which region is further preferred, on the one hand the corrosive decomposition products can escape from the solar module, on the other hand, clogging of the holes, for example by dirt, can be reduced. Such an embodiment is, as stated, more preferred.
• the density of the holes in at least one rear-side film of the solar module is at least 0.02 cm 2 and at most 0.2 cm 2 .
• the density of the holes is between 0.04 cm “2 and 0.1 cm “ 2 .
• the holes are arranged substantially regularly and may be e.g. in rectangular or hexagonal arrangement.
• the hexagonal arrangement is preferred because this embodiment has a higher tensile strength compared to the rectangular arrangement of the holes.
• Figure 3 shows the principle.
• the entire area of the backsheet which serves for the cover is provided with a corresponding arrangement of the holes, also called perforation.
• the solar module according to the invention preferably has at least one weather-resistant film and an insulating film. Both types of films are backsheets. These backsheets can be arranged differently from each other. For example, two weather-resistant backsheets can each be arranged on one side of the insulating film.
• the structure is "weather-compensated. Resistant film, insulation film, weather-resistant film "symmetrical, ie the weather-resistant films are arranged on one side of the insulating film and have the same thickness, as shown in Figure 2.
• the weather-resistant film or both weather-resistant films according to the invention provided with holes and thus for corrosive substances, especially acetic acid, are permeable.
• the preferred thicknesses of the weather-resistant films are between 10 and 00 ⁇ m, and as a result have a small diffusion barrier for corrosive substances.
• the density of the holes per cm 2 of the film may be in the preferred range according to the invention. The same applies to the area of the holes. The smaller these two values can be maintained, the better the tear strength of the films, which is considered to be advantageous.
• the solar module according to the invention has a perforated insulating film, so that the diffusion barrier for corrosive substances can be further reduced. If, in addition, at least one weather-resistant film is provided with holes, the diffusion barrier can additionally be reduced even further.
• the corrosive acetic acid in particular should escape from the solar module.
• the outermost weather-resistant film is imperforate. So the penetration of dirt particles can be excellent prevented.
• At least one backsheet is perforated. It is further preferred that the front screen of the solar module is not perforated. In one embodiment, the intermediate layer is not perforated. In a particularly preferred embodiment, the backsheet is the only perforated layer in the solar module. Perforated should mean that the respective Layer has a plurality of holes.
• a layer has only a single hole in order to produce electrical contact, for example, this is not regarded as "perforated.”
• Perforated layers ie layers with many small holes, also have individual larger holes, eg for module mounting or contact feedthrough
• the solar cells in the solar module are also preferably not perforated, because this would impair the efficiency of the module are not perforated, does not exclude, as mentioned above, that the solar cells nevertheless have individual holes for electrical feedthroughs, as may be the case in back-contacted solar cells.
• a special embodiment of the present invention is when the insulating film 8 is provided with holes and preferably consists of PET.
• the solar cell 6 is embedded in EVA and the windscreen 2 is made of glass.
• Figure 4 shows the principle.
• the weather-resistant film, which preferably consists of PVF has a thickness of 10 ⁇ m to 100 ⁇ m.
• the insulating film, which preferably consists of PET has a thickness of 50 pm to 1000 pm.
• the PET film is preferably thicker than 300 ⁇ m, with thicknesses in the range from 300 ⁇ m to 350 ⁇ m being suitable. Areas for, for example, suitable thicknesses of the PET films are from 50 ⁇ m to 350 ⁇ m, 100 ⁇ m to 300 ⁇ m, also 50 ⁇ m to 300 ⁇ m or 100 ⁇ m to 350 ⁇ m.
• FIG. 5 shows the principle.
• the backsheets sen circular holes as perforations whose radius a is large enough to allow the corrosive substances such as acetic acid to escape.
• R represents the area of influence of the hole, ie, the corrosive substances surrounding a circular area of radius R diffuse in the direction of the hole.
• Figure 6 illustrates the principle of a further preferred embodiment of a solar module according to the invention, wherein a weather-resistant film 7 and the insulating film 8 are provided with holes on the backsheets.
• the outer weather-resistant film 9 is imperforate.
• the intermediate layer 4 adjoins the backsheet films and the front pane 2 is attached thereto.
• the subsequent intermediate layer consists of conventional embedding materials (ethylene-vinyl acetate, polyvinyl butyral), in which the solar cells are embedded with series connection and string connectors.
• a string connector connects the individual strings within the module and is usually made of tinned copper with a rectangular cross section.
• the total thickness of the embedding material layer (5) is between 500 pm and 2000 pm.
• the backsheets (3) are formed as a laminate and consist of a weather-resistant film (7) of polyvinyl fluoride, an insulating film (8) made of polyethylene terephthalate (PET) and another weather-resistant film (9) made of polyvinyl fluoride (PVF).
• the final film (9) of polyvinyl fluoride has a thickness of 20 to 50 pm.
• the insulating film of polyethylene terephthalate has a thickness in the range between 150 pm and 300 pm.
• the polyethylene terephthalate film is provided with holes which are circular and have a radius of 0.5 mm. The distance between two circular holes is 2 cm. The holes are hexagonal, as exemplified in Figure 3. LIST OF REFERENCE NUMBERS

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• 2009
  • 2009-12-18 DE DE102009059105A patent/DE102009059105A1/de not_active Ceased
• 2010
  • 2010-12-17 EP EP10798309A patent/EP2513976A2/de not_active Withdrawn
  • 2010-12-17 US US13/516,955 patent/US20120325293A1/en not_active Abandoned
  • 2010-12-17 IN IN5094DEN2012 patent/IN2012DN05094A/en unknown
  • 2010-12-17 WO PCT/EP2010/070150 patent/WO2011073423A2/de not_active Ceased
  • 2010-12-17 CN CN2010800576622A patent/CN102668121A/zh active Pending

Non-Patent Citations (1)

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