Photovoltaic module and method for producing same

Abstract

A photovoltaic module comprises a glass pane (110) on a light incidence side; a further glass pane (120) on a side facing away from the light; a multiplicity of solar cells (131, 132) which are arranged between the glass pane (110) and the further glass pane (120); an electrical contact structure (140) which form a multiplicity of cell connectors, wherein each cell connector electrically connects opposite sides of in each case two adjacent solar cells (131, 132) to one another; and a spacer (150) between the in each case two adjacent solar cells (131, 132), wherein the spacer (150) has through openings (155) or depressions through which the respective cell connector (140) is guided.

Description

[0001] PHOTOVOLTAIC MODULE AND A METHOD FOR ITS MANUFACTURING

[0002] The present invention relates to a photovoltaic module and a method for its manufacture, and in particular to the use of spacers in encapsulation-free glass-glass photovoltaic modules.

[0003] BACKGROUND

[0004] Conventional photovoltaic modules can be designed as double-glass modules (so-called GIS modules) with encapsulated solar cells. The encapsulation material completely surrounds the solar cells and protects them—especially from mechanical stress. This encapsulation material consists, for example, of an EVA film (EVA = ethylene vinyl acetate) and decouples the solar cells from the glass, so that they form a shear bond for the module. However, film-based photovoltaic modules are more complex to manufacture, have a higher CO2 footprint, require lamination, and are more difficult to recycle. Furthermore, omitting the encapsulation material often results in limited light yield, and high-efficiency solar cells are currently unsuitable for this application.

[0005] To ensure long-term stability, lead is also used, and the plastic material in the module interacts with the solar cells, altering their properties. Furthermore, in conventional photovoltaic modules, the solar cells are electrically interconnected via soldered cell connectors. These connectors are typically electrically conductive wires or ribbons, or busbars. Soldered connections represent a weak point, as thermal and mechanical stresses can compromise the long-term stability of the electrical connections and thus the functionality of the entire module. Therefore, conventional photovoltaic modules frequently experience problems with mechanical stability, as cell delamination can occur during or after the lamination process.

[0006] Photovoltaic modules that do not require an encapsulating material and therefore do not have the problems mentioned above are already in use. In glass-glass modules, the glass panes exert varying degrees of pressure directly on the cells. The sometimes considerable temperature fluctuations in the field repeatedly lead to mechanical stresses due to differing pressure conditions within the modules, which then repeatedly result in cell breakage.

[0007] Therefore, there is a need for alternative photovoltaic modules that, on the one hand, can do without an embedding material if possible, but at the same time can ensure long-term stability with regard to thermal stresses.

[0008] Brief description of the invention

[0009] At least some of the aforementioned problems are solved by a photovoltaic module according to claim 1 and a method for manufacturing the photovoltaic module according to claim n. The dependent claims relate to further advantageous embodiments of the subject matter of the independent claims.

[0010] The present invention relates to a photovoltaic module comprising a glass pane on a light-incident side, another glass pane on a light-shielded side, and a plurality of solar cells arranged between the glass pane and the other glass pane. The photovoltaic module also includes an electrical contact structure forming a plurality of cell connectors and (at least) one spacer. Each cell connector electrically connects opposite or identical sides of two adjacent solar cells. The spacer is arranged between each pair of adjacent solar cells and comprises openings or recesses through which the respective cell connector passes. The spacer(s) with the recesses, notches, or holes for the cell connectors (e.g., wires) can, for example, form a frame around each solar cell.This allows for all-around protection of the solar cells. For example, the wires of the cell connectors can be completely embedded in the spacers so that they do not contact the (other) glass pane. The electrical contact structure serves to connect the solar cells electrically, e.g., as a series connection in the form of so-called strings or as a parallel connection.

[0011] Optionally, the spacer has a minimum thickness so that at least one solar cell is flush with the spacer, or the spacer is slightly thicker than the solar cell. In particular, the spacer can be selected so that the glass panes have no or only minimal direct contact with the solar cells (especially at the edges) to prevent breakage. The minimum thickness can be, for example, 0.2 mm, 0.3 mm, or 1 mm, and the minimum width is chosen so that the solar cells cannot touch each other directly and sufficient support force is ensured (e.g., >50 nm, >1 pm, >1 mm).

[0012] Optionally, the spacer can be made of a material that, under a pressure load of 1 bar along the spacing direction, has a minimum thickness of 1.1 times the thickness of the cell connectors and an interposed solar cell. This ensures that the resulting pressure (e.g., due to temperature differences) is absorbed solely or primarily by the spacers.

[0013] Optionally, the spacer can contain a UV-resistant additive to prevent aging. For example, the spacer could be made of UV-stabilized PET (polyethylene terephthalate).

[0014] Optionally, the spacer is fixed to the glass pane and / or the other glass pane using a UV-resistant adhesive layer. Preferably, UV-stabilized acrylic adhesive can be used, which forms a stable bond to both glass and PET and is characterized by its mechanical flexibility. Optionally, an adhesive layer can also be formed between the solar cells and the glass panes, in which the contact structure can be partially embedded.

[0015] Optionally, the multitude of solar cells is embedded or arranged in a gas-filled cavity between the first and second glass panes. The photovoltaic module can then include a seal to create a gas-tight closure within this cavity. A vacuum can be formed within the gas-filled cavity to establish a press-fit connection between the multitude of solar cells and the contact structure.

[0016] The "embedding" of the solar cells in the gas-filled space should be understood as meaning that the solar cells can be surrounded by a gas within the gas-filled space (e.g., a protective gas such as nitrogen or argon), and can still be in direct contact with the gas, but this is not mandatory, as the contact structure is positioned between them. The photovoltaic module does not need to include a polymer encapsulation of the solar cells (for example, the EVA film mentioned above). According to the exemplary embodiments, the solar cells are arranged without encapsulation between the two glass panes (in the gas-filled space).

[0017] According to the exemplary embodiments, the photovoltaic module does not have any soldered connections for electrically contacting the solar cells. The solar cells can be electrically interconnected via press contacts, thus creating a solderless connection. The press or pressure contact can be created by a vacuum that forces the two glass panes together, thereby establishing electrical contact with the solar cells via the electrical contact structure.

[0018] This embodiment also does not include an electrically conductive coating. Therefore, a so-called ECA material (Electric Conductive Coating) is also unnecessary. The photovoltaic module can thus be ECA-free.

[0019] This design of the photovoltaic modules offers the advantage that no mechanical stresses can occur due to temperature fluctuations, as the solar cells can move relative to the two glass panes without causing any stress. The electrical press contacts are kept permanently intact by the existing negative pressure.

[0020] The seal optionally includes butyl. This ensures that the pressure differential is maintained and that the pressure or crimp contact permanently provides a reliable electrical connection.

[0021] Optionally, the multitude of solar cells includes at least one of the following cell types: thin-film cells, tandem cells, perovskite silicon cells, heterojunction solar cells, or a combination thereof.

[0022] Back-contact solar cells, also known as BC cells, are electrically contacted only from the back. In these cells, both the (highly doped) p-regions and the (highly doped) n-regions can be electrically contacted from the back. This offers the technical advantage that no busbars, cell connectors, or wires / strips need to be formed between the solar cells on the front side. Electrical contacting of the solar cells can be achieved simply by correctly placing the solar cells onto the glass plate with its integrated electrical contact structure and then applying pressure. In embodiments of back-contact solar cells, the electrical contact structure only needs to be formed on one glass plate.

[0023] Heterojunction solar cells, such as HJT solar cells (HJT; English: hetero junction cells), represent a combination of crystalline silicon and thin-film cells, where, for example, amorphous silicon is deposited onto the monocrystalline silicon. Thin-film cells are semiconductor layers that are often only a few micrometers thick and are produced by a CVD (chemical vapor deposition) process or sputtering.

[0024] Perovskite solar cells are simple and inexpensive to manufacture because the mineral perovskite allows for easy coating of substrates. Through photon recycling, they possess a significantly higher efficiency than other cell types. Disadvantages of perovskite-silicon solar cells, such as their sensitivity to mechanical stress, are overcome in certain applications because the electrical connections are established solely through pressure contact resulting from the pressure difference between the ambient air and the lower pressure within the module. Therefore, no EVA encapsulation or solder contacts are required, which are often the source of voltage issues in conventional modules. A tandem cell consists of at least two sub-cells, which, for example, exhibit different absorption wavelength ranges.Exemplary embodiments relate in particular to perovskite-silicon tandem glass-glass modules, which are sealed between the glasses at low pressure, with the electrical connection also being made via press contacts.

[0025] Optionally, an anti-reflective coating is formed in the gas-filled space on at least one of the following components: on a surface of the glass layer, on a surface of the further glass layer, on a surface of the multitude of solar cells.

[0026] Optionally, a protective gas such as nitrogen or argon is present in the gas-filled space. The protective gas can be in direct contact with the solar cells.

[0027] Exemplary embodiments also relate to a method for manufacturing a photovoltaic module. The method comprises: - providing a glass sheet with an electrical contact structure comprising a plurality of cell connectors,

[0028] - Arranging a large number of solar cells on their respective cell connectors;

[0029] - Arranging a spacer between adjacent solar cells, wherein the spacer has through-holes or recesses,

[0030] - Passing the respective cell connectors through the openings or recesses of the spacer and connecting the respective cell connector to one side (opposite or same) of an adjacent solar cell to establish an electrical contact between the adjacent solar cells; and

[0031] - Arranging another glass pane on top of the multitude of solar cells, so that the multitude of solar cells are fixed between the glass pane and the other glass pane.

[0032] Exemplary embodiments overcome the aforementioned problems by having the photovoltaic module consist of a cell matrix with at least two solar cells enclosed between two glass panes—one on the light-incident side and another on the light-difference side—and electrically connected to each other. According to these embodiments, this space contains no (polymeric) embedding material, which is used in conventional photovoltaic modules between the front glass and the solar cells or between the back glass and the solar cells.

[0033] In tests, exemplary embodiments demonstrated the following advantages. Even after lamination and extended storage, no cell breakage occurred. The mechanical stresses inherent in conventional photovoltaic modules were avoided in these embodiments by spacers, which can extend, in particular, as a frame around the cells. Even after the glass panes were compressed, no mechanical stresses on the cells were observed. Another important advantage of these embodiments is the elimination of encapsulation material. Therefore, the photovoltaic modules can be classified as non-combustible. Nevertheless, cohesion is ensured by a vacuum between the two glass panes, which, due to the sealing, could be maintained even over long periods.

[0034] BRIEF DESCRIPTION OF THE FIGURES

[0035] The embodiments of the present invention are better understood from the following detailed description and the accompanying drawings, which, however, should not be understood as limiting the disclosure to the specific embodiments, but merely serve for explanation and understanding.

[0036] Fig. i shows a photovoltaic module according to an embodiment of the present invention.

[0037] Figs. 2A and 2B show further views of the spacers according to exemplary embodiments.

[0038] Fig. 3 shows a schematic flowchart for a process for manufacturing a photovoltaic module according to exemplary embodiments.

[0039] DETAILED DESCRIPTION

[0040] Fig. i shows a photovoltaic module according to an embodiment of the present invention. The photovoltaic module comprises a glass pane 110 on a light-incident side, a further glass pane 120 on a light-shielded side, and a plurality of solar cells 131, 132 arranged between the glass pane 110 and the further glass pane 120. The photovoltaic module also includes an electrical contact structure 140, which forms a plurality of cell connectors. Each cell connector 140 electrically connects opposite sides of two adjacent solar cells 131, 132 to achieve, by way of example, a series connection of the solar cells. According to embodiments, spacers 150 are formed between each pair of adjacent solar cells 131, 132. The spacers 150 have through-openings or recesses 155 through which the respective cell connector 140 is guided.

[0041] According to the illustrated embodiment, the spacer 150 is connected to the glass pane 110 via an adhesive layer 160 and to the second glass pane 120 via another adhesive layer 160. The adhesive layers 160 serve to fix the spacers 150 in order to suppress lateral displacement as much as possible. The solar cells 131, 132 can also be arranged flush with the spacer 150 without any gap. If the spacer 150 is designed, for example, as a frame, the solar cells 131, 132 are also fixed via the fixed spacers 150. The frame-like spacers 150 have the advantage that they provide complete protection for the edges of the solar cells 131, 132.

[0042] The multiple solar cells 131, 132 are arranged, according to exemplary embodiments, in a gas-filled, non-embedding space 170 between the glass pane 110 and the second glass pane 120. A vacuum can be created in the gas-filled space, pressing the two glass panes 110, 120 together and thus holding the solar cell assembly in place. Lateral seals 180 are provided to seal the gas-filled space 170 airtight. After the sealing material 180 has cured, the solar cells 131, 132 remain firmly in position within the gas-filled space 170 due to the vacuum present there. Additionally, the spacers 150—if they form a frame—can prevent lateral displacement of the solar cells (for example, due to thermal stresses).

[0043] The spacers 150 are designed, according to exemplary embodiments, to reduce the pressure on the solar cells 131, 132. For example, the spacers can be made of a material that exhibits only minimal deformation when a vacuum is created between the glass panes 110, 120 and the glass panes 110, 120 are pressed vertically onto the assembly of solar cells 131, 132 and the contact structure 140. In particular, when thermal stresses occur due to more or less significant temperature changes, the spacers 150 prevent excessive pressure on the solar cells by the glass panes 131, 132. According to exemplary embodiments, the cell connectors 140 (the conductive wires or the busbars) are guided in recesses or through-openings of the spacers 150 to prevent displacement of the cell matrix.

[0044] An adhesive layer or an antireflective coating (not shown) can be formed between the solar cells 131, 132 and the glass panes 110, 120 to further fix the solar cells 131, 132 within the module. The glass panes 110, 120 can also be in direct press contact with the contact structure 140, ensuring a reliable electrical connection. Additional contact structures may also be present, which have been omitted from the figure.

[0045] Fig. 2A shows a top view (e.g., from a light-incidence side) of a cell assembly with two solar cells, as also shown in Fig. 1. The two solar cells comprise a first solar cell 131 and a second, adjacent solar cell 132. A spacer 150 is formed between the first solar cell 131 and the second solar cell 132. The cell connectors 140 extend through the spacer 150, with a first cell connector 141 extending from a top surface of the first solar cell 131 through the spacer 150 and subsequently making electrical contact with a bottom surface of the second solar cell 132. A further cell connector 142 accordingly makes contact with a top surface of the second solar cell 132 and leads, for example, to a bottom surface of another solar cell, which is not shown in Fig. 2A.

[0046] Fig. 2A shows only three cell connectors 140. However, more or fewer cell connectors can be formed, depending on the size of the solar cells 131, 132 and the expected current density. In principle, it is also possible for the cell connectors 140 to be formed on only one side (e.g., only on the back or only on the front). Fig. 2B shows a cross-sectional view through the spacer 150 (along a vertical line in Fig. 2A), showing that the spacer 150 has exemplary recesses 155 in which the three exemplary cell connectors 140 are embedded. The recesses 155 can be designed such that the cell connectors 140 do not protrude in a vertical direction (upwards in Fig. 2B) and thus do not come into contact with the glass pane.

[0047] In contrast to conventional glass-glass modules, the solar cells 131, 132 are not embedded in an encapsulating material (EVA film), as already explained. The EVA film actually serves to mechanically decouple the solar cells 131, 132 from the front and back glass panels 110, 120. However, an EVA film would have the disadvantage that temperature changes would lead to shear forces within the module. Exemplary embodiments aim to overcome this disadvantage.

[0048] Omitting the EVA film can lead to significantly higher pressure on the cell matrix at low temperatures, which in turn could cause cell breakage. For example, photovoltaic modules can reach internal temperatures of 90 °C, which can generate a pressure of 900 mbar. To prevent overpressure within the module even at these temperatures, the internal pressure is set at only 60 mbar for an external temperature of -40 °C. This is a significant pressure difference compared to the atmospheric pressure outside the module, resulting in the aforementioned forces that the solar cell matrix must withstand. However, exemplary embodiments overcome these stresses by using spacers 150, which absorb the aforementioned pressure forces. In particular, by forming frames as spacers 150 that extend to the solar cells 131, 132, tilting of the edge areas is prevented.No cell breaks were detected in the experiments.

[0049] Fig. 3 shows a schematic flowchart for a method for manufacturing a photovoltaic module according to exemplary embodiments. The method comprises: - Providing a glass sheet 110 with an electrical contact structure 140 comprising a plurality of cell connectors,

[0050] - Arrange S120 a plurality of solar cells 131, 132 on respective cell connectors 140;

[0051] - Arranging S130 a spacer 150 between adjacent solar cells 131, 132, wherein the spacer 150 has through-holes 155 or recesses,

[0052] - Passing S140 of the respective cell connectors 140 through the through-openings 155 or recesses of the spacer 150 and connecting the respective cell connector 140 to an opposite or same side of an adjacent solar cell 131 to establish an electrical contact between the adjacent solar cells 132; and

[0053] - Arrange S150 of another glass pane 120 onto the plurality of solar cells 131, 132, such that the plurality of solar cells 131, 132 are fixed between the glass pane 110 and the further glass pane 120.

[0054] It goes without saying that the individual steps in the production of the photovoltaic module can also be carried out in a different order.

[0055] To better protect the solar cells 131, 132 from environmental influences (such as moisture or dust), a sealing material 180, such as butyl, can be used as a sealant in an edge area of ​​the photovoltaic module. This ensures an airtight seal, which also maintains the negative pressure in the gas-filled space.

[0056] According to exemplary embodiments, the spacers 150 are made of a material that can withstand pressure loads of 1 bar and has a minimum thickness of 1.1 times the sum of the thicknesses of the cell connectors 140 and the solar cells 131, 132. The material of the spacers 150 can be designed to reliably withstand environmental factors (such as UV radiation). This can be achieved, for example, through the use of additional additives or by selecting a suitable material. Although significant temperature fluctuations (day-night effects) can occur in the operating environment, exemplary embodiments can withstand the resulting pressure differences within the photovoltaic module and the resulting deformations of the front and back glass, since the spacers 150 prevent uneven or inhomogeneous pressure loads, ensuring that the glass panes 110, 120 exert full contact with the cell array.Even at the edges of the solar cells 131, 132, no higher pressures occur, as is the case with conventional cell arrays, because the spacers are arranged as flush as possible at these points and absorb the pressure acting there. According to exemplary embodiments, the spacers 150 have a minimum thickness of approximately 0.3 mm, or the thickness of the solar cells, so that a flat surface results and there is no step at the edge of the solar cells 131, 132. The spacers 150 are advantageously designed as a frame around the solar cells 131, 132 with the smallest possible distance to the solar cells 131, 132. For example, the solar cells 131, 132 can be arranged flush with each other. However, the spacers 150 are designed to be at least large enough so that the solar cells 131, 132 themselves are not in direct mechanical contact with each other, but are held at a minimum distance by the spacer.

[0057] An adhesive layer 160 can optionally be arranged between the spacers 150 and the front glass 110 or rear glass 120. This adhesive layer holds the spacers 150 in a desired position on the glass pane 110 or the other glass panes 120, so that the solar cells 131, 132 are also held in their desired positions by the spacers 150 and cannot shift relative to each other due to thermal fluctuations. The optional adhesive layer 160 is protected against environmental influences such as UV light.

[0058] According to exemplary embodiments, the spacers 150 comprise, at those positions where the cell connectors 140 or the electrical wires or the busbars pass through them, corresponding recesses or through-openings 155 (feedthroughs), the shape of which can be round or N-shaped and have a depth that ensures that the corresponding electrical contact structure is completely embedded in the spacers 150 and does not protrude upwards towards the glass panes 110.

[0059] The features of the invention disclosed in the description, claims and figures may be essential for the realization of the invention, either individually or in any combination.

[0060] REFERENCE MARK LIST no. 120 glass panes (e.g. front and back)

[0061] 131,132 large number of solar cells

[0062] 140 electrical contact structure

[0063] 141,142 Cell connectors (part of the electrical contact structure)

[0064] 150 spacers

[0065] 155 through openings (e.g. recesses, holes, notches)

[0066] 160 adhesive layers

[0067] 170 gas-filled space

[0068] 180 Sealing

Claims

REQUIREMENTS 1. Photovoltaic module comprising: a glass pane (110) on a light-incident side; another glass pane (120) on a light-away side; a plurality of solar cells (131, 132) arranged between the glass pane (110) and the other glass pane (120); an electrical contact structure (140) forming a plurality of cell connectors, each cell connector electrically connecting opposite or identical sides of each pair of adjacent solar cells (131, 132); and a spacer (150) between each pair of adjacent solar cells (131, 132), the spacer (150) having through-openings (155) or recesses through which the respective cell connector (140) passes.

2. Photovoltaic module according to claim 1, wherein the spacer (150) at least partially forms a frame around at least one solar cell (131, 132) and has a minimum thickness such that the at least one solar cell is flush with the spacer (150) or the spacer (150) is thicker than the at least one solar cell (131, 132).

3. Photovoltaic module according to claim 1 or claim 2, wherein the spacer (150) comprises a material which, under pressure load along the spacing direction of 1 bar, has a minimum thickness of 1.1 times the thickness of cell connectors (140) and a solar cell (131, 132) arranged between them. 4- Photovoltaic module according to one of the preceding claims, wherein the spacers (150) have a UV-resistant additive to prevent aging.

5. Photovoltaic module according to one of the preceding claims, wherein the spacer (150) is fixed to the glass pane (110) and / or the further glass pane (120) via a UV-resistant adhesive layer (160).

6. Photovoltaic module according to one of the preceding claims, wherein the plurality of solar cells (131, 132) are arranged between the glass pane (110) and the further glass pane (120) in a gas-filled space (170) and the photovoltaic module further comprises: a seal (180) to close the gas-filled space (170) in a gas-tight manner, wherein a vacuum is formed in the gas-filled space (170) to create a press contact between the plurality of solar cells (131, 132) and the contact structure (140).

7. Photovoltaic module according to claim 6, wherein the seal (180) comprises a butyl.

8. Photovoltaic module according to one of the preceding claims, wherein at least one of the following cell types is used for the plurality of solar cells (131, 132): thin-film cells, tandem cells, perovskite silicon cells, heterojunction solar cells or a combination thereof.

9. Photovoltaic module according to one of the preceding claims, wherein an antireflection coating is formed in the gas-filled space (170) on at least one of the following components: on a surface of the glass layer, on a surface of the further glass layer, on a surface of numerous solar cells.

10. Photovoltaic module according to one of the preceding claims, wherein the gas-filled space (170) comprises a protective gas such as nitrogen or argon, wherein the protective gas is in direct contact with the solar cells.

11. Method for manufacturing a photovoltaic module, the method comprises: Providing (S110) a glass disc (110) with an electrical contact structure (140) comprising a variety of cell connectors, Arranging (S120) a plurality of solar cells (131, 132) on respective cell connectors (140); Arranging (S130) a spacer (150) between adjacent solar cells (131, 132), wherein the spacer (150) has through-openings (155) or recesses, Passing (S140) the respective cell connectors (140) through the through-holes (155) or recesses of the spacer (150) and connecting the respective cell connector (140) to a opposite side of an adjacent solar cell (131) to establish an electrical contact between the adjacent solar cells (132); and Arrange (S150) another glass pane (120) onto the plurality of solar cells (131, 132) such that the plurality of solar cells (131, 132) are fixed between the glass pane (110) and the further glass pane (120).

12. The method of claim 11, wherein establishing an electrical contact between the adjacent solar cells (131, 132) comprises: Forming a negative pressure in a gas-filled space (170) between the glass pane (110) and the other glass panes (120); and Sealing the gas-filled space (170) to maintain the negative pressure.

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