Method for producing a photovoltaic module, and photovoltaic module

Abstract

The invention relates to a method for producing a photovoltaic module, having the steps of: providing (S110) a first glass pane (110); forming (S120) an electrical contact structure (120) on the first glass pane (110); applying (S130) a plurality of solar cells (130) onto the electrical contact structure (120); applying (S140) the second glass pane (140) onto the plurality of solar cells (130), the plurality of solar cells (130) being embedded in a gas-filled intermediate space (150) between the first glass pane (110) and the second glass pane (140); forming (S150) a negative pressure in the gas-filled intermediate space (150), an electrical contact being established between the plurality of solar cells (130) and the contact structure (120) as a press contact; and sealing (S160) the gas-filled intermediate space (150).

Description

[0001] METHOD FOR MANUFACTURING A PHOTOVOLTAIC MODULE AND A PHOTOVOLTAIC MODULE

[0002] The present invention relates to a method for manufacturing a photovoltaic module and to a photovoltaic module.

[0003] BACKGROUND

[0004] In conventional photovoltaic modules, the solar cells are electrically interconnected via soldered cell connectors and embedded in an encapsulation material, which completely surrounds and protects the solar cells. The cell connectors are typically electrically conductive wires or ribbons, or busbars, soldered to current collectors. The encapsulation material protects against mechanical stresses because the cells are decoupled from the glass. The encapsulation material consists, for example, of an EVA (ethylene vinyl acetate) film and serves as a shear reinforcement for a finished laminated module. Nevertheless, mechanical stresses occur at the solder joints of the cell connectors because the different materials expand and contract differently.

[0005] This manufacturing process for conventional photovoltaic modules has further disadvantages. For example, production results in a higher CO2 footprint, recycling is more complex, and lamination and soldering require additional effort. Furthermore, lead is necessary to ensure long-term stability, and the plastic material in the module interacts with the solar cells, altering their properties.

[0006] Therefore, there is a need for alternative photovoltaic modules that do not require encapsulation but can simultaneously ensure long-term stability with regard to thermal stresses. Brief description of the invention

[0007] At least some of the aforementioned problems are solved by a method for manufacturing a photovoltaic module according to claim 1 and a photovoltaic module according to claim 9. The dependent claims relate to further advantageous embodiments of the manufacturing method.

[0008] The present invention relates to a method for manufacturing a photovoltaic module. The method comprises:

[0009] - Providing a first pane of glass;

[0010] - Forming an electrical contact structure on the first glass pane;

[0011] - Applying a large number of solar cells to the electrical contact structure;

[0012] - Applying a second glass pane to the plurality of solar cells, wherein the plurality of solar cells are embedded in a gas-filled space between the first glass pane and the second glass pane;

[0013] - Creating a vacuum in the gas-filled space, whereby an electrical contact is established between the multitude of solar cells and the contact structure as a press contact (pressure contact); and

[0014] - Sealing the gas-filled space.

[0015] The term "embedding" means that the solar cells are surrounded by a gas, typically on all sides – at least until a vacuum is created that forces the two glass panes together, thus creating direct contact between, for example, the front glass (second glass pane) and the solar cells. However, the solar cells remain in direct contact with the gas in the gas-filled space at all lateral edges and on the underside.

[0016] The manufactured photovoltaic module is a glass-glass module, where glass panes are formed on both sides, i.e., on the light-incidence side (front) and on the back (back glass). The first glass pane can be the back glass pane, which is opposite the light-incidence side. The process notably does not involve encapsulating the solar cells in a polymer material (for example, EVA films). Thus, the solar cells are arranged without encapsulation between the two glass panes (in the gas-filled space). Likewise, the photovoltaic module does not contain any soldered connections for electrical contacting the cells. The solar cells are electrically interconnected via press-fit connections, resulting in a solderless connection. No electrically conductive coating is required. Therefore, an ECA (Electrical Conductive Coating) material is also unnecessary.The photovoltaic module is therefore ECA-free.

[0017] This 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 thus kept permanently intact.

[0018] Optionally, the formation of the electrical contact structure on the first glass pane includes at least one of the following:

[0019] Performing screen printing, vapor deposition of a metallization, sputtering, application of an adhesive film, application of a decal, direct placement of a metal conductor.

[0020] The technical benefit of this is that the electrical contact structure can be formed as a very thin metallization. This avoids local pressure on the solar cells, allowing them to be arranged largely without pressure. In particular, cell connectors (as electrical conductor strips) are not required. The formation of the electrical contact structure can be automated, which is not possible, or only partially possible, with conventional photovoltaic modules that use the usual soldering of cell connectors.

[0021] Optionally, forming the electrical contact structure on the first glass pane includes applying a pre-fabricated conductor track or a pre-fabricated connector matrix.

[0022] Optionally, forming the electrical contact structure on the first glass pane includes applying a metallization and subsequently structuring the applied metallization. The structuring can include at least one of the following: laser cutting, etching, sandblasting, waterjet cutting, machining, or grinding.

[0023] For example, the electrical contact structure can be applied to the back glass (first glass pane) as a full-surface layer, as pre-fabricated conductor tracks, or as a connector matrix (e.g., as a film). If the electrically conductive material is applied across the entire surface, the structuring, including optional edge insulation, can then be carried out using the same process. In some embodiments, the back glass pane (first glass pane) can also be supplemented with an additional functional coating that serves to connect the back-contact solar cells. The first glass pane thus serves as a substrate for the electrically conductive material of the electrical contact structure.

[0024] Optionally, at least one of the following cell types is used for the multitude of solar cells: back-contact solar cells, thin-film cells, tandem cells, perovskite silicon cells, heterojunction solar cells or a combination thereof such as a perovskite silicon tandem cell.

[0025] The use of back-contact solar cells, so-called BC cells (back-contact cells), is particularly advantageous, as they are electrically contacted only from one side. 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 or strips need to be formed between the solar cells. The electrical contact of the solar cells can be achieved simply by (correctly) placing the solar cells onto the first glass plate and then applying pressure.

[0026] Heterojunction solar cells, such as HJT solar cells, represent a combination of, for example, crystalline silicon and thin-film cells, where, for instance, amorphous silicon is deposited onto the monocrystalline silicon. Thin-film cells are semiconductor layers, often only a few micrometers thick, and are produced using a CVD (chemical vapor deposition) process or sputtering.

[0027] 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 often cause voltage spikes 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.

[0028] Optionally, an anti-reflective coating is formed in the gas-filled intermediate layer on at least one of the following components: on a surface of the first glass layer, on a surface of the second glass layer, on a surface of the multitude of solar cells.

[0029] High module performance can be ensured by simply coating the inside of the glass with an anti-reflective layer. In particular, perovskite tandem cells (but also other cell types) can be provided with an anti-reflective layer optimized for air, which further increases the light yield.

[0030] Optionally, a protective gas such as nitrogen or argon is introduced into the gas-filled cavity. This protective gas can be in direct contact with the solar cells, preventing any contact between humidity or oxygen and the solar cells. Glass-glass modules without encapsulation material offer the advantage of having no or only a very low (butyl) fire load, allowing the module to be classified as non-combustible (N2, Ar).

[0031] Optionally, a butyl sealant is used during the sealing step. This ensures that the pressure differential is maintained, thus guaranteeing a permanent electrical connection via the pressure or crimp contact.

[0032] It is understood that, insofar as technically possible, the order of all the aforementioned steps can be arbitrary.

[0033] Further examples of implementation refer to a photovoltaic module with:

[0034] - a first pane of glass and a second pane of glass;

[0035] - an electrical contact structure on the first glass pane;

[0036] - a multitude of solar cells arranged on the electrical contact structure between the first glass pane and a second glass pane in a gas-filled space; - a seal to close the gas-filled space gas-tight.

[0037] A vacuum is formed in the gas-filled space to create a pressure contact between the multitude of solar cells and the contact structure.

[0038] Exemplary implementations solve the aforementioned problems of conventional photovoltaic modules by completely eliminating the need for an encapsulating film. Furthermore, so-called glass-glass photovoltaic modules are used, where the cells are arranged between two glass layers and permanently pressed together by a vacuum. Finally, electrical contacts are applied to the back glass, so that the solar cells are automatically electrically connected due to the vacuum.

[0039] Advantages of this approach include the elimination of adhesives or adhesive layers (e.g., on the back glass), as the solar cells are pressed directly onto the front glass. Since there are no soldered connections, and electrical contact is achieved solely through press contacts, thermal stresses due to differing coefficients of thermal expansion cannot damage the solar cells. Instead, they can move relative to each other within a certain range and are not fixed to the cell connectors by rigid soldered (or welded) contacts. Because the contact is made solely from the back, active interconnection of the solar cells is unnecessary. The interconnection occurs automatically through the back-side contacting via the press contacts.

[0040] BRIEF DESCRIPTION OF THE FIGURES

[0041] 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.

[0042] Fig. 1 shows a schematic flowchart for a process for manufacturing photovoltaic modules according to exemplary embodiments.

[0043] Fig. 2 shows a cross-sectional view through a photovoltaic module which was manufactured using the method according to the invention.

[0044] Fig. 3 shows an embodiment of a contact structure on a back glass of a photovoltaic module.

[0045] DETAILED DESCRIPTION

[0046] Fig. 1 shows an exemplary embodiment of a schematic flowchart for a process for manufacturing photovoltaic modules according to exemplary embodiments. The process comprises the following steps:

[0047] Providing S110 of a first glass pane 110;

[0048] Forming S120 of an electrical contact structure 120 on the first glass pane 110;

[0049] Applying a large number of solar cells 130 to the electrical contact structure 120;

[0050] Applying S140 of the second glass pane 140 to the plurality of solar cells 130, wherein the plurality of solar cells 130 are embedded in a gas-filled space 150 between the first glass pane 110 and the second glass pane 140;

[0051] Forming a vacuum S150 in the gas-filled space 150, whereby an electrical contact is established between the plurality of solar cells 130 and the contact structure 120 as a press contact; and

[0052] Sealing S160 of the gas-filled space 140.

[0053] Fig. 2 shows a cross-sectional view through a photovoltaic module produced by the method. The photovoltaic module comprises a first glass pane 110 and a second glass pane 140, between which solar cells 130 are arranged. An electrical contact structure 120 is formed between the first glass pane 110 and the solar cells 130. The solar cells 130 are located between the electrical contact structure 120 and the first glass pane 110 in a gas-filled space 150. Finally, the photovoltaic module includes a seal 160, which is designed to permanently seal the gas-filled space 150 in a gas-tight manner. A negative pressure is created in the gas-filled space 150 compared to the surrounding atmospheric pressure in order to establish a press-fit or pressure contact between the solar cells 130 and the electrical contact structure 120.

[0054] As shown in Fig. 2, exemplary embodiments dispense with polymer encapsulation material (e.g., an EVA film) and do not use permanent electrical connections (such as soldering or gluing) between the solar cells 130, but instead use pressure or press contacts. This type of contact allows for relative displacement, thus dissipating thermal stresses. The press contact is maintained permanently by the pressure difference between the ambient air and the pressure in the gas-filled space 150. To protect the solar cells in the gas-filled space 150 (e.g., from condensation or oxygen), a protective gas such as nitrogen or argon can be introduced.

[0055] Although the embodiments are not necessarily limited to this, the solar cells 130 are advantageously back-contact solar cells (so-called BC solar cells), which are electrically contacted only from one back side (i.e., the side facing away from the light). In these solar cells 130, the p- and n-regions are electrically contactable as a pattern on the back side, and the electrical contact structure 120 is designed such that these regions are electrically contacted and thus the solar cells 130 are electrically interconnected.

[0056] Fig. 3 shows an embodiment of a contact structure 120 on the first glass pane 110 (back glass) of a photovoltaic module. The placement of the solar cells 130 is indicated by dashed lines. The electrical contact structure 120 contacts the exemplary solar cells 130 at various points. The electrical contact structure 120 can have any shape. The interlocking finger structure shown as an example in Fig. 3 is just one possibility. Much more complex structures can also be formed to electrically contact the individual electrical contacts of the solar cells 130 and thus connect the solar cells 130 to each other. The solar cells 130 are spaced apart from each other for clarity only. Generally, the solar cells 130 will be positioned as close together as possible to maximize the utilization of incident light.

[0057] The electrical contact structure 120 shown can be produced, in particular, by structuring a fully formed contact coating. In this way, it can be manufactured very thin (but wide enough) to optimize the press contacting used. This structuring and edge insulation can be achieved by laser, etching, sandblasting, waterjet cutting, or mechanical machining / grinding.

[0058] The electrical contact structure 120 shown is applied directly to the first glass pane 110, so that the first glass pane 110 serves as a carrier substrate for the electrical contact structure 120. Therefore, in exemplary embodiments, no connecting means are provided between the applied solar cells 130 and the electrical contact structure 120. The solar cells 130 are simply placed onto the first glass pane 110 with the electrical contact structure 120 and finally pressed onto the first glass pane 110 by creating a vacuum. The solar cells 130 therefore do not need to be embedded in a polymer encapsulation or a film, but are located in the gas-filled space 150 between the first glass pane 110 and the second glass pane 140.

[0059] These embodiments are therefore particularly suitable for the use of so-called perovskite-silicon solar cells or perovskite tandem cells, since these are sensitive to humidity, temperature, and mechanical stresses and therefore cannot be used in conventional silicon module technology with soldered, encapsulated solar cells. These solar cells have a higher efficiency, which can be utilized according to the embodiments.

[0060] Potential reflections at the interface between the glass and the gas-filled space 150 can be avoided in exemplary embodiments by applying an anti-reflective coating. This can be applied, for example, to an inner surface of the first glass pane 110 or to a surface of the solar cells 130. This ensures a high light yield for the incident light on the first glass pane 110. Reflections at this point can be largely avoided. An anti-reflective coating with a refractive index close to 1 with respect to air can be used. This can further optimize, for example, the use of perovskite tandem cells for the solar cells 130. The light yield is thus optimized and is not negatively affected by the glass-gas interface.

[0061] In exemplary embodiments, the sealant 160, for example, contains butyl. This sealant 160 offers the technical advantage that the pressure differential can be maintained for a long time.

[0062] Compared to conventional photovoltaic technologies, these implementation examples offer the following advantages:

[0063] Thermal stresses are avoided by avoiding soldered joints or lamination.

[0064] - Moisture stresses on glass-glass modules are avoided (e.g. by the protective gas) and the exemplary butyl sealant effectively prevents diffusion of moisture to the solar cells.

[0065] - Mechanical stresses are avoided because the pressure contact does not represent a fixed electrical connection; the corresponding electrically conductive structures 120 can move relative to the solar cells 130.

[0066] - There is no loss of performance in the solar cells as a result of the anti-reflection coating, which effectively ensures that the incident light can be used to its maximum extent, especially in tandem solar cells.

[0067] - The manufacturing process is cost-effective because no encapsulation or electrically conductive adhesive is required. This allows for high production throughput.

[0068] - These examples are very well suited for thin-film solar cells.

[0069] - The architecture of the solar cells 130 can be chosen arbitrarily, as long as they can be connected to each other via rear contacts.

[0070] - The electrical contacting of the solar cells 130 from the back can be implemented simply and cost-effectively via an electrically conductive coating of the back glass, since the coating can be vapor-deposited or applied as a layer and then structured.

[0071] - By structuring, any conductor paths or a texture for the interconnection of the solar cells 130 can be produced from the back glass 110.

[0072] - Since only contact from the rear is provided, exemplary embodiments are particularly advantageous for tandem solar cells, which are otherwise very sensitive to pressure from cell connectors that run from the front to a rear side of the solar cells (as with conventional photovoltaic modules).

[0073] Since the modules do not have solder strips, the associated Hertzian pressure of the otherwise present solder strips is avoided. The features of the invention disclosed in the description, the claims, and the figures can be essential for the realization of the invention, both individually and in any combination.

[0074] REFERENCE MARK LIST

[0075] 110 first pane of glass

[0076] 120 electrical contact structure

[0077] 130 variety of solar cells

[0078] 140 second pane of glass

[0079] 150 gas-filled spaces

[0080] 160 Sealing

Claims

REQUIREMENTS 1. Method for manufacturing a photovoltaic module, the method comprises: Providing (Sno) a first pane of glass (no); Forming (S120) an electrical contact structure (120) on the first glass pane (110); Applying (S130) a plurality of solar cells (130) onto the electrical contact structure (120); Applying (S140) the second glass pane (140) to the plurality of solar cells (130), wherein the plurality of solar cells (130) are embedded in a gas-filled space (150) between the first glass pane (110) and the second glass pane (140); Forming (S150) a vacuum in the gas-filled space (150) (140), wherein an electrical contact is established between the plurality of solar cells (130) and the contact structure (120) as a press contact; and Sealing (S160) the gas-filled space (150).

2. The method of claim 1, wherein forming the electrical contact structure (115) on the first glass pane (110) comprises performing at least one of the following steps: Performing screen printing, vapor deposition of a metallization, sputtering, Applying an adhesive film, Applying a decal, direct connection of a metal conductor.

3. Method according to claim 1 or claim 2, wherein forming the electrical contact structure (120) on the first glass plate (110) comprises applying a prefabricated conductor track or a prefabricated connector matrix.

4. Method according to claim 1 or claim 2, wherein forming the electrical contact structure (120) on the first glass plate (110) comprises applying a metallization and subsequently structuring the applied metallization, wherein the structuring comprises at least one of the following: laser treatment, etching, sandblasting, use of a water jet process, mechanical processing, grinding.

5. Method according to any of the preceding claims, wherein at least one of the following cell types is used for the plurality of solar cells: back-contact solar cells, thin-film cells, tandem cells, perovskite silicon cells, heterojunction solar cells or a combination thereof.

6. Method according to one of the preceding claims, wherein an antireflection coating is formed in the gas-filled intermediate on at least one of the following components: on a surface of the first glass layer, on a surface of the second glass layer, on a surface of the plurality of solar cells.

7. Method according to one of the preceding claims, wherein a protective gas such as nitrogen or argon is introduced into the gas-filled space and the protective gas is in direct contact with the solar cells.

8. Method according to any one of the preceding claims, wherein in the step (Si6o) a butyl or other non-flammable sealant is used for sealing.

9. Photovoltaic module comprising: a first glass pane (110) and a second glass pane (140); an electrical contact structure (120) on the first glass pane (110); a plurality of solar cells (130) arranged on the electrical contact structure (120) between the first glass pane (110) and the second glass pane (140) in a gas-filled space (150); and a seal (160) to close the gas-filled space (150) gas-tight, wherein a vacuum is formed in the gas-filled space (150) to create a press contact between the plurality of solar cells (130) and the contact structure (120).

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