DE102020112370A1 - Embedding film for solar modules, method for producing a solar module and using an embedding film - Google Patents

Abstract

The invention relates to an embedding film (1) for solar modules with two opposite sides (11, 12) which extend along a direction of film extension (E), a first side (11) of the two opposite sides (11, 12) having a surface profile with elevations (14), formed from a first elevation flank (140) and a second elevation flank (141), and wherein the elevations (14) of an imaginary macroscopically smooth surface (15) of the first side (11) have an elevation height (142) less than one Have millimeters and are arranged repetitively along the film extension direction (E), and wherein the first elevation flank (140) is over 100 times longer than the second elevation flank (141) viewed along the film extension direction (E). The invention further relates to a method for producing a solar module, a method for producing the embedding film and a use of the embedding film for producing a solar module.

Description

The invention relates to an embedding film for solar modules, a method for producing a solar module and a use of an embedding film for producing a solar module.

A solar module regularly has a large number of wafer solar cells, which are electrically connected to one another in series to form so-called solar cell strings. Several solar cell strings, which are connected to one another in parallel or in series, can be arranged in a solar module. The solar cell strings are arranged between a first encapsulation element and a second encapsulation element and are laminated into embedding films. In the laminated solar module, the solar cell strings are permanently protected from the weather.

To manufacture the solar module, a semifinished solar module is subjected to a lamination process. The semifinished solar module has the solar cell strings which are arranged between the embedding films which are arranged between the first and the second encapsulation element. During the lamination process, the embedding films arranged between the solar cell strings and the two encapsulation elements are pressed against the solar cell strings and melted. Particularly when lamination of solar cell strings with wafer solar cells arranged in a spatially overlapping manner, there is a particular mechanical load on the spatially overlapping areas of the wafer solar cells. The areas in which the so-called cell connectors come to rest are particularly problematic. The cell connectors are electrically conductive flat ribbons or round wires that enable the flow of current between neighboring wafer solar cells in the string. Modern wafer solar cells have a thickness that is significantly less than one millimeter, for example 150 micrometers, preferably in the range from 50 to 200 μm. The cell connectors have thicknesses that are regularly less than one millimeter but well over 100 micrometers. During a lamination process, these proportions cause a particular mechanical load on the wafer solar cells, which are mechanically very sensitive to breakage, in the area of the cell connectors. This is often noticeable in these areas through small V-shaped breaks in the wafer solar cells. These lead to an increased drop in performance when the solar module is in operation. Against this background, it is desirable to provide an improved solar module through the use of an improved embedding film.

It is an object of the invention to provide an optimized embedding film for solar modules and an optimized solar module.

This object is achieved by an embedding film having the features of claim 1, a method having the features of claim 10 and a use of the embedding film having the features of claim 11. Advantageous modifications and further developments are given in the subclaims.

The invention relates to an embedding film for solar modules with two opposite sides which extend along a direction of film extension, a first side of the two opposite sides having a surface profile with elevations, formed from a first elevation flank and a second elevation flank, and wherein the elevations are imaginary macroscopically smooth surface of the first side have an elevation height of less than one millimeter and are arranged repetitively along the direction of film extension, and wherein the first elevation flank is over 100 times longer than the second elevation flank when viewed along the direction of film extension.

The present invention is based on the basic idea that a very likely cause of the occurrence of the undesired V-shaped break points in the overlapping areas of the interconnected wafer solar cells is based on a material property of the embedding film, which usually has a relatively low melt index and that the material of the embedding film is due to This material property cavities that are formed between the wafer solar cells or cell connectors and the embedding film fill only very slowly during the lamination process and these V-shaped break points are created by mechanical stress that occurs when the laminate is pressed, especially at the points on the wafer solar cell on which the cell connectors are arranged. The cell connectors exert mechanical pressure on the overlapping wafer solar cell edges. The embedding film now has a profiled first side and thus a thickness variation in order to completely or at least partially fill the cavities created by the overlapping arrangement of the wafer solar cells.

In the context of the present invention, a macroscopically smooth surface is to be understood as meaning a surface whose difference between maxima and minima on the surface is less than 100 micrometers.

The first elevation flank is preferred in comparison to the second elevation flank along the Film extension direction viewed over 150 times, more preferably over 200 times longer. Preferably, a dimension of the first raised edge in the direction of film extension corresponds essentially to a wafer edge length of a wafer solar cell minus the overlap of the wafer solar cells viewed in the direction of film extension. If the second elevation flank drops off very steeply, the length of the first elevation flank essentially also corresponds to the periodicity of the elevation maxima in the direction of the extent of the film. More preferably, the dimension of the first elevation flank in the film extension direction essentially corresponds to a wafer width, for example 8 ", 9", 10 "of the wafer solar cell minus the desired overlap of the wafer solar cells. A dimension of the second elevation flank in the range of a millimeter or less is preferred. In this way, the elevations are designed in such a way that they correspond to the usual dimensions of wafer solar cells.

From an imaginary macroscopically smooth surface of the first side, the elevations preferably have an elevation height of less than 750 μm, more preferably 500 μm. The dimension of the second elevation flank is therefore preferably 750 μm or less, more preferably 500 μm or less.

The elevations are preferably formed periodically along the direction of extent of the film. In a further preferred embodiment, the first elevation flank and / or the second elevation flank is or are formed periodically along the direction of extent of the film. The periodicity preferably corresponds essentially to the intended arrangements of the wafer solar cells and cell connectors in the solar module to be produced with the embedding film, which are usually uniform.

The first elevation flank and / or the second elevation flank preferably has a continuous, that is to say kink-free, profile along the direction of extent of the film.

In a further preferred embodiment, the first elevation flank and the second elevation flank form a sawtooth-shaped contour along the direction of extent of the film. This means that the first elevation flank has a continuously linear profile, as does the second elevation flank. The first elevation flank then merges discontinuously with a kink into the second elevation flank. This contour is preferred if the embedding film is provided for a solar module which has solar cell strings with wafer solar cells arranged in an overlapping manner.

In a preferred embodiment, the other side of the two opposite sides has a macroscopically smooth surface. The second side is thus designed in such a way that it can be laminated to a flat, likewise macroscopically smooth encapsulation element.

The surface profile of the first side is preferably adapted to a surface contour of a wafer solar cell string which is formed from wafer solar cells that are electrically interconnected. In this way, cavities between the embedding film and the solar cell string are avoided or at least reduced during the lamination process in the manufacture of a solar module. The wafer solar cell string preferably has wafer solar cells which are arranged in an overlapping manner and which are interconnected with cell connectors.

The surface profile of the first side is preferably adapted to an edge length and / or a thickness of the wafer solar cells and / or a thickness of the cell connectors. The edge dimensions of the wafer solar cells to be used in the solar module are preferably in the range from 4 to 8 inches. The thickness of the wafer solar cells to be used in the solar module is preferably in the range of significantly less than one millimeter, preferably less than half a millimeter. The elevation height preferably corresponds to a maximum thickness of the respective wafer solar cell plus a maximum thickness of a cell connector arranged thereon.

In a preferred embodiment, an average embedding film thickness is in the range from 400 to 700 μm, more preferably 450 to 600 μm. This dimension is sufficient for laminating wafer solar cell strings in the manufacture of a solar module. The embedding film has an elevation height. The elevation height is a measure of the embedding film which corresponds to a distance between the elevation maximum and the imaginary macroscopically smooth surface of each elevation. The elevation height of the embedding film essentially corresponds to a thickness of the wafer solar cells plus a cell connector arranged thereon.

A material of the embedding film preferably has a melt flow index <5, preferably <3, as measured DIN EN ISO 1133 at a temperature of 190 ° C and a weight of 2.16kg.

Alternatively or additionally, the material of the embedding film preferably has EVA (ethylene-vinyl enactate copolymer) and / or polyolefins or consists of it. EVA and / or polyolefins are very suitable for laminating wafer solar cells in order to protect them against the effects of the weather.

• - Herstellen eines Schichtstapels mit folgenden Schritten
  • - Bereitstellen eines ersten Verkapselungselements,
  • - Anordnen einer Einbettungsfolie nach einer oder mehreren der vorangehend beschriebenen Ausführungsformen auf dem ersten Verkapselungselement, so dass die zweite Seite der Einbettungsfolie auf dem ersten Verkapselungselement aufliegt,
  • - Anordnen von Solarzellenstrings, die aus einer Vielzahl an Wafer-Solarzellen und die Wafer-Solarzellen elektrisch miteinander verschaltenden Zellverbindern gebildet sind und die eine komplementär zum Oberflächenprofil der ersten Seite ausgebildete Unterseitenkontur aufweisen, auf der ersten Seite der Einbettungsfolie, so dass die komplementär ausgebildete Unterseitenkontur der Solarzellenstrings auf dem Oberflächenprofil mit seinen Erhebungen passend zu liegen kommt,
  • - Anordnen einer weiteren Einbettungsfolie nach einer oder mehreren der vorangehend beschriebenen Ausführungsformen mit ihrer ersten Seite, deren Oberflächenprofil komplementär zu einer Oberseitenkontur der Solarzellenstrings ausgebildet ist, auf den Solarzellenstrings, so dass das Oberflächenprofil mit den Erhebungen auf der komplementär ausgebildeten Oberseitenkontur der Solarzellenstrings passend zu liegen kommt,
  • - Anordnen eines weiteren Verkapselungselements auf der weiteren Seite der Einbettungsfolie und
• - Laminieren des Schichtstapels unter Einwirkung von Hitze und/oder mechanischem Druck.

The invention also relates to a method for producing a solar module having

• - Production of a layer stack with the following steps
  • - providing a first encapsulation element,
  • Arranging an embedding film according to one or more of the embodiments described above on the first encapsulation element, so that the second side of the embedding film rests on the first encapsulation element,
  • Arranging solar cell strings, which are formed from a multiplicity of wafer solar cells and cell connectors electrically interconnecting the wafer solar cells and which have an underside contour that is complementary to the surface profile of the first side, on the first side of the embedding film, so that the complementary underside contour the solar cell string comes to rest on the surface profile with its elevations,
  • - Arranging a further embedding film according to one or more of the embodiments described above with its first side, the surface profile of which is designed to be complementary to an upper side contour of the solar cell strings, on the solar cell strings, so that the surface profile with the elevations fits on the complementary upper side contour of the solar cell strings comes,
  • - Arranging a further encapsulation element on the further side of the embedding film and
• - Laminating the stack of layers under the action of heat and / or mechanical pressure.

The first and second encapsulation elements are flat. They are preferably made of glass or plastic. The cell connectors are preferably each designed as a metallic flat conductor. The cell connectors preferably have a thickness in the range from 100 to 300 μm, more preferably 200 to 275 μm. The thickness of the wafer solar cells is preferably in the range from 50 to 200 μm, more preferably 100 to 150 μm. The thickness mentioned is in each case a dimension that is viewed in the direction perpendicular to the flat encapsulation elements in the solar module.

The lamination of the layer stack involves pressing the embedding films against the solar cell strings and melting the embedding films. The lamination is preferably carried out in a laminator.

The invention further relates to a use of an embedding film according to one or more of the embodiments described above for producing a solar module.

• 1 eine schematische und nicht maßstabsgerechte Teil-Querschnittsansicht eines zu laminierenden Solarmodul-Halbzeugs gemäß Stand der Technik;
• 2 eine Draufsicht auf einen Abschnitt eines Solarmoduls gemäß Stand der Technik;
• 3 eine Teil-Querschnittsansicht eines zu laminierenden Solarmodul-Halbzeugs mit zwei erfindungsgemäßen Einbettungsfolien;
• 4 eine Teil-Querschnittsansicht einer der in 3 gezeigten Einbettungsfolien;
• 5 ein Verfahren zur Herstellung der in 4 gezeigten Einbettungsfolie und
• 6 ein Diagramm mit den Verfahrensschritten eines Herstellungsverfahrens für ein Solarmodul unter Einsatz der erfindungsgemäßen Einbettungsfolie.

The invention is explained in more detail below with reference to drawings. It show schematically and not to scale

• 1 a schematic partial cross-sectional view, not to scale, of a semifinished solar module product to be laminated according to the prior art;
• 2 a plan view of a portion of a solar module according to the prior art;
• 3 a partial cross-sectional view of a semifinished solar module product to be laminated with two embedding films according to the invention;
• 4th a partial cross-sectional view of one of the in 3 embedding foils shown;
• 5 a method for producing the in 4th shown embedding film and
• 6th a diagram with the process steps of a manufacturing process for a solar module using the embedding film according to the invention.

1 shows a schematic partial cross-sectional view, not to scale, of a semifinished solar module product to be laminated according to the prior art. The semifinished solar module has several wafer solar cells 2 on that via cell connectors 3 are electrically interconnected to form solar cell strings. The semifinished solar module also has two embedding films 1 on, which are each arranged on one side of the solar cell strings. Any embedding film 1 has two opposite sides 11 , 12th with macroscopically smooth surfaces that extend along the direction of the extent of the film E. extend. The wafer solar cells 2 are along the direction of extent of the film E. arranged overlapping in sections. Between the embedding foils 1 and the solar cell strings result in a plurality of cavities as a result of this arrangement 6th . These cavities 6th cause that during a lamination process in the manufacture of a solar module in areas 4th breaking points can occur due to mechanical loads occurring there. During the lamination process is on the other side 12th the respective embedding film 1 a first and a second encapsulation element (not shown) arranged, for example, in the form of a glass pane. The shown semifinished solar module with these glass panes is subjected to heat and mechanical pressure transversely to the direction of film extension during the lamination process E. exposed.

2 shows a plan view of a section of a solar module according to the prior art. This in 2 The solar module shown is from the in 1 The semi-finished solar module shown has been produced by means of the lamination process described. The wafer solar cells 2 appear in this representation perpendicular to the direction of film extension E. viewed without gaps, butted to each other. Along the direction of extent of the film E. Considered is the section-wise overlap of the wafer solar cells 2 with two areas 4th shown schematically. The cell connectors also run in these areas 3 between the neighboring and interconnected wafer solar cells 2 . The wafer solar cells 2 have V-shaped fractures after the lamination process due to the circumstances mentioned above 5 in the fields of 4th on.

3 shows a partial cross-sectional view of a semifinished solar module product to be laminated with two embedding films according to the invention. This in 3 The semi-finished solar module shown corresponds to that in 1 Semifinished solar module product shown with the difference that a first side 11 a surface profile with elevations 14th has, formed from a first elevation flank 140 and a second elevation flank 141 . The surveys 14th each have an imaginary macroscopically smooth surface 15th the first page 11 an elevation maximum 142 smaller than one millimeter and are along the direction of extent of the film E. arranged repetitively. The first elevation flank 140 is compared to the second elevation flank 141 along the direction of extent of the film E. considered trained over 100 times longer. The surveys 14th are designed and arranged to form the solar cell strings so that they are complementary to one another. This will make the in 1 shown cavities avoided or at least reduced.

4th FIG. 13 shows a partial cross-sectional view of one of the FIGS 3 embedding foils shown. The embedding film 1 has a medium embedding film thickness D1 and an elevation D2 on. The elevation D2 is the measure between the elevation maximum 142 the survey 14th and the imaginary macroscopically smooth surface 15th is equivalent to. The elevation D2 corresponds essentially to the thickness of a wafer solar cell 2 and a cell connector arranged thereon 3 . With the periodicity shown P. the elevation maxima repeat themselves 142 in the direction of film extension E. .

5 shows a schematic representation of a method for producing the in 4th shown embedding film according to the invention. A roller 7th is over one surface of a softened embedding film 1 led along to the first page 11 to be provided with a desired periodic surface profile. The roller 7th has a corresponding roller design along its circumference, so that the elevations 14th into the embedding film 1 on the first page 11 be molded while the other side 12th retains its macroscopically smooth surface.

• - Bereitstellen eines ersten Verkapselungselements,
• - Anordnen einer Einbettungsfolie nach einem der vorangehenden Ansprüche auf dem ersten Verkapselungselement, so dass die zweite Seite der Einbettungsfolie auf dem ersten Verkapselungselement aufliegt,
• - Anordnen von Solarzellenstrings, die aus einer Vielzahl an Wafer-Solarzellen und die Wafer-Solarzellen elektrisch miteinander verschaltenden Zellverbindern gebildet sind und deren Unterseitenkontur komplementär zum Oberflächenprofil der ersten Seite gebildet sind, auf der ersten Seite der Einbettungsfolie, so dass die komplementär ausgebildete Unterseitenkontur des Solarzellenstrings auf dem Oberflächenprofil mit seinen Erhebungen passend zu liegen kommt,
• - Anordnen einer weiteren Einbettungsfolie nach einem der vorangehenden Ansprüche mit der ersten Seite, deren Oberflächenprofil komplementär zu den Solarzellenstrings ausgebildet ist, auf den Solarzellenstrings, so dass das Oberflächenprofil mit den Erhebungen auf einer komplementär ausgebildeten Oberseitenkontur der Solarzellenstrings aufliegt,
• - Anordnen eines weiteren Verkapselungselements auf der weiteren Seite der Einbettungsfolie.

6th shows a diagram with the process steps of a manufacturing process for a solar module using the embedding film according to the invention. In a first method step V1, a semifinished solar module is produced. This consists of a layer stack and is built up in layers with the following steps:

• - providing a first encapsulation element,
• - Arranging an embedding film according to one of the preceding claims on the first encapsulation element, so that the second side of the embedding film rests on the first encapsulation element,
• Arranging solar cell strings, which are formed from a large number of wafer solar cells and cell connectors electrically interconnecting the wafer solar cells and whose underside contour is formed complementary to the surface profile of the first side, on the first side of the embedding film, so that the complementary underside contour of the Solar cell strings come to lie appropriately on the surface profile with its elevations,
• - Arranging a further embedding film according to one of the preceding claims with the first side, the surface profile of which is designed to be complementary to the solar cell strings, on the solar cell strings, so that the surface profile with the elevations rests on a complementarily designed upper side contour of the solar cell strings,
• - Arranging a further encapsulation element on the further side of the embedding film.

Method step V1 is followed by method step V2 for laminating the layer stack under the action of heat and / or mechanical pressure.

List of reference symbols

D1

medium embedding film thickness

D2

Elevation Height

P.

periodicity

E.

Film extension direction of the embedding film

1

Embedding film

11

first page

12th

another page

14th

Elevation

140

first elevation flank

141

second elevation flank

142

Elevation maximum

15th

imagined macroscopically smooth surface

2

Solar cell

3

Cell connector

4th

Area of possible breaks

5

Breaking point

6th

cavity

7th

roller

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Non-patent literature cited

• DIN EN ISO 1133 [0018]

Claims (11)

Embedding film (1) for solar modules with two opposite sides (11, 12) which extend along a direction of film extension (E), a first side (11) of the two opposite sides (11, 12) having a surface profile with elevations (14), formed from a first elevation flank (140) and a second elevation flank (141), and wherein the elevations (14) of an imaginary macroscopically smooth surface (15) of the first side (11) have an elevation height (142) less than one millimeter and along the film extension direction (E) are arranged repetitively, and wherein the first elevation flank (140) compared to the second elevation flank (141), viewed along the film extension direction (E), is over 100 times longer. Embedding film (1) Claim 1 , characterized in that the elevations (14) are formed periodically along the film extension direction (E). Embedding film (1) Claim 1 or 2 , characterized in that the first elevation flank (140) and / or the second elevation flank (141) are formed periodically along the film extension direction (E). Embedding film (1) according to one of the preceding claims, characterized in that the first elevation flank (140) and / or the second elevation flank (141) have a continuous course along the direction of extent of the film (E). Embedding film (1) according to one of the preceding claims, characterized in that the first elevation flank (140) and the second elevation flank (141) form a sawtooth-shaped contour along the direction of extent of the film (E). Embedding film (1) according to one of the preceding claims, characterized in that the further side (12) of the two opposite sides (11, 12) has a macroscopically smooth surface. Embedding film (1) according to one of the preceding claims, characterized in that the surface profile of the first side (11) is adapted to a surface contour of a solar cell string which is formed from electrically interconnected wafer solar cells (2). Embedding film after Claim 7 , characterized in that the surface profile of the first side (11) is adapted to an edge length and / or a thickness of the wafer solar cells (2) and / or a thickness of the cell connector (3) and / or an average embedding film thickness (D) in Range from 400 to 700 µm, more preferably 450 to 600 µm. Embedding film according to one of the preceding claims, characterized in that a material of the embedding film (1) has a melt flow index <5, preferably <3, measured according to DIN EN ISO 1133 at a temperature of 190 ° C and a weight of 2.16kg, and / or the material of the embedding film (1) comprises or consists of EVA (ethylene-vinyl acetate copolymer) and / or polyolefins. A method for producing a solar module, comprising the following process steps: - Production of a layer stack with the following steps - providing a first encapsulation element, - Arranging an embedding film (1) according to one of the preceding claims on the first encapsulation element, so that the second side (12) of the embedding film (1) rests on the first encapsulation element, - Arranging solar cell strings which are formed from a multiplicity of wafer solar cells (2) and cell connectors (3) electrically interconnecting the wafer solar cells (2) and whose underside contour is formed complementary to the surface profile of the first side (11) on the first side (11) of the embedding film (1), so that the complementary underside contour of the solar cell string comes to rest appropriately on the surface profile with its elevations (14), - Arranging a further embedding film (1) according to one of the preceding claims with the first side (11), the surface profile of which is formed complementary to the solar cell strings, on the solar cell strings, so that the surface profile with the elevations (14) on an upper side contour of the complementarily formed Solar cell strings come to lie appropriately, - Arranging a further encapsulation element on the further side (12) of the embedding film (1) and - Laminating the stack of layers under the action of heat and / or mechanical pressure. Use of an embedding film according to one of the Claims 1 until 9 for the production of a solar module.

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