DE202008006549U1 - solar module - Google Patents

Abstract

solar module with an electrically interconnected, areal trained Solar cell arrangement, at the back of which a rear construction and provided at the front of a radiation-transparent front are, as well as with a solar cell array between the back construction and the windscreen surrounding embedding material, characterized that the back construction as a separate module in Shape of a rigid, thin metallic, ceramic or organic sheet as a module carrier is that the Front screen with its surface facing the module carrier over the entire surface by means of a solidifying and mechanical loads transferable, radiation transparent Potting compound is connected to the module carrier, which is the Solar cell arrangement between the windscreen and the module carrier encloses.

Description

Technical area

The The invention relates to a solar module with an electrically interconnected, flat solar cell arrangement, at the back of a Back construction and at the front of a radiation transparent Front are provided, and with a solar cell arrangement between surrounding the back construction and the windscreen Embedding material.

State of the art

solar Panels are photovoltaic devices for direct generation of electricity from sunlight. Key factors for a cost-efficient Generation of solar power are the manufacturing costs and the durability the solar modules.

Solar modules usually consist of a composite of a windshield, the interconnected solar cells, which are enclosed by an embedding material, and a rear side construction. A common variant of solar modules is still provided for handling and later mounting with aluminum profiles, which are circumferentially mounted as a frame and sometimes supportive as bracing. The individual elements of a solar module have to fulfill the following functions:
The windscreen, usually made of glass, about 3-4 mm thick, serves to protect against mechanical and weathering and provides part of the mechanical stability of the module. It must be highly transparent, preferably made of white glass with 90-92% transmittance in the upper spectral range, to minimize absorption losses in the optical spectral range of about 300 nm to 1500 nm and thus to maximize the efficiency of the silicon solar cells commonly used.

The Embedding material, often for this ethylene-vinyl acetate films or short EVA films used, is used for embedding the interconnected Cells and the bonding of the entire module network. such Embeddings, however, are not capable of mechanical stress to transfer, an aspect, which will be discussed later becomes.

On the back of the module is used to protect the solar cells and of the embedding material from moisture and oxygen, as mechanical Protection and as electrical insulation a composite foil, mostly existing made of polyvinyl fluoride (PVF) and polyethylene terephthalate (PET) or made of PVF and aluminum. In some cases also on the back as on the front a glass pane used.

A Common embedment technology is vacuum lamination because of the vacuum during lamination, the formation of air bubbles is largely avoided. EVA melts during lamination at about 150 ° C, flows around the interconnected solar cells and is thermally crosslinked.

The The encapsulation or embedding materials used should be included have good barrier properties against water vapor and oxygen, especially due to water vapor or oxygen damage caused by corrosion occur on metal contacts and it comes to the degradation of the EVA material. Thus, the front and back of the solar module should be have high weathering stability and the embedded Solar cells by barrier effect z. B. against water vapor and oxygen protect against corrosion.

in principle need solar modules for their use, eg. B. on Rooftops, high mechanical stability, in particular a high flexural strength and bending strength, harmless by the wind and snow loads that are possible during operation to be able to bear. The mechanical stability known solar modules can by its back, its Front and / or other additional supports, z. B. in the form of aluminum frame, aluminum struts, a stable support structure, which allows bending of the module under Load prevented, guaranteed.

About that In addition, solar modules should reach very long operating times, to ensure profitability. Today usual Requirements for the lifetime of the solar modules are at least 25 Years, rising. In operation, the solar modules are subject high mechanical loads, eg. Due to wind and snow loads, as well as by cyclically occurring temperature fluctuations, that of 80 ° C in full sunlight until below freezing can lie.

Height Material and production costs, for example due to special front glass, special composite film for the back, vacuum lamination, Aluminum frames etc., the necessary manual work, eg. Soldering the electrical cables, mounting and contacting the junction boxes, and the relatively long process times, eg. B. for the lamination and crosslinking of the EVA to a comparatively high proportion of the cost of the Modular construction of the total costs in the double-digit percentage range.

By The relatively thick front glass pane has conventional solar modules In addition, a high weight, which in turn stable and expensive mounting structures required.

One Another important point is the heat dissipation. At full Solar irradiation heat the modules up to 80 ° C on what a reduction in the efficiency of solar cells for Episode has.

Although there are various proposals to reduce the manufacturing cost of solar modules by lower-cost components and Herstellungsm but also these proposals are not really effective. Significant for the invention are next to possible others the patent EP000000325369A2 (Abbr. EP) and the published patent application DE 10101 770 A1 Bayer AG (abbreviation DE).

In EP 325369 A2 describes a photovoltaic module based on embedding a "photovoltaic panel" in a reactive elastomer.The photovoltaic panel consists of a combination of a layer of transparent material, an array of interconnected photovoltaic cells, and a backside layer, but none provides mechanical stability.

In DE 10 101 770 A1 describes a solar module in which the solar cells are completely encapsulated by a polyurethane material, either of the same or of two different polyurethane materials. The transparent polyurethane is elastomeric which, so that its flexural rigidity is negligible. This has the consequence that in the polyurethane molded variant, the flexural rigidity of the entire solar module can be very low.

A Another variant of a solar module described is the, in the the solar cells on a module rear side serving Formed are fixed on the then a transparent polyurethane is sprayed on. In this variant, although a higher Bending stiffness of the solar module by using a rigid Shaped as module back, for example. With glass fibers reinforced polycarbonate can be achieved. To the for a solar module with high mechanical stability at the beginning To achieve defined requirements, the backside needs to be of the solar module are made relatively thick, what with a poor heat dissipation as well as a higher one Weight of the solar module goes along.

Presentation of the invention

task The invention is the development of solar modules with high mechanical Stability, in particular high flexural rigidity and flexural strength, based on photoactive elements. The solar module should in particular inexpensive, robust against external influences, be of long life and high efficiency even at ensure high solar radiation temperatures.

The The object underlying the invention is defined by the claim 1 solved. The concept of the invention advantageously further Features are the subject of the dependent claims and the other Description with reference to the embodiments refer to.

One Solvent-based solar module with an electric interconnected, flat solar cell arrangement, at the back of a back construction and at the front of a radiation-transparent front are provided, and with a solar cell arrangement between surrounding the back construction and the windscreen Embedding material, characterized by the fact that the back construction as a separate module a rigid, thin metallic, ceramic or organic sheet as a module carrier is that the windscreen with its the module carrier facing Surface over the entire surface by means of a solidifying and mechanical loads transferable, radiation transparent Potting compound is connected to the module carrier, which is the Solar cell arrangement between the windscreen and the module carrier encloses.

In a preferred embodiment consists of the module carrier from a metallic sheet. The sheet can punch out any Geometries included. The sheet can completely with another Material, eg. As a plastic, an enamel, a ceramic or a glass, be coated. But the coating material can Cover only parts of the sheet, both on both sides as well as only on one side of the sheet.

Of the The edge of the sheet can be used for mounting the solar module become. For this purpose, z. B. holes located in the sheet metal, to which the solar module attached during assembly becomes.

The Sheet metal typically has thicknesses in the range between 0.2 mm and 4 mm up. If the windscreen a significant part of the load can wear or the solar panel later flat can be placed on a supporting structure, a thinner sheet metal used with a thickness in the range between 0.01 mm and 0.2 mm become. With such thin sheet thicknesses can also from a Sheet metal foil to be spoken.

Next The use of metallic sheet materials are also organic or ceramic materials, in particular for the Formation of the above thin films.

The solar module consists in a preferred embodiment of a module carrier made of a metallic sheet, with or without coating material, on the back, a transparent Windscreen, z. Example of glass, glass ceramic or a transparent plastic, for. B. on the basis of PMMA, on the front, the interconnected and contacted solar cells in the space between the front glass and module carrier and a module carrier and the front glass bonding, the gap between the module carrier and windscreen bubble free filling adhesive layer, which at the same time the solar cells and the contact system encapsulated ,

Of the Module carrier provides a significant portion of the mechanical Stability of the solar module. The windscreen consists of a material that is the same thickness z. B. in the case of PMMA almost the same density by about a factor of 10 higher bending stiffness owns as transparent polyurethane. By the bonding of Windscreen and module carrier through the adhesive layer carries also the windscreen with the mechanical stability of the Solar module at. If one considers the solar module as a plate, then takes the bending stiffness with the cube of the plate thickness. The thickness of the solar module is calculated from the thickness of the module carrier, the Thickness of the windscreen and the thickness of the adhesive layer between windscreen and module carrier. Because the windscreen is carrying through the load Bonding contributes to the flexural rigidity of the module carrier the back are made thinner, which has significant advantages in heat dissipation and in weight - the Density of polyurethane and PMMA are about equal - to Episode has.

One Another advantage of the direct bonding of windscreen and module carrier is that by gluing the solar cells containing Adhesive layer between windscreen and module carrier closer to the neutral bending line or neutral fiber, resulting in lower mechanical stresses in the adhesive layer and thus also in the solar cells leads and due to the lower Load levels can expect a much longer life.

When Another advantage may be mentioned that due to the lower mechanical Tensions in the neutral bending line not only elastic bonds, but also structural bonds with harder adhesives can be used, which in turn leads to significantly higher Bending stiffness and bending strength leads.

On the front side facing the module carrier can additional layers are applied, for. B. an IR-reflective Plastic layer for better use of the incident light for increasing the efficiency or as barrier layers. The layers may be on the support either after shaping or in the process of molding in the tool with in the plastic processing known technologies are applied z. As the in-mold coating or a spray application or flooding with a reactive polymer in the tool or by inserting and injecting of foils in the mold before injecting the plastic for the carrier.

To The production of the module carrier will be the solar cells placed on the carrier and their connections connected by cables to the junction box. The solar cells can be unbonded before application to the carrier or already partially interconnected, z. For example, in wafer-based cells in the form of strings, or fully interconnected, e.g. B. as a connected thin-film module or wafer-based Cells as prefabricated foil with the applied, contacted solar cells, which are the interconnects for interconnection contains the individual cells with each other.

In an advantageous embodiment of the module carrier contains a border at the places where the cells are placed for each cell that allows for fixation of the cells. This can either be a depression in which the Cells are inserted, or a small increase in the Edges of each cell. Besides, the surface is of the wearer in the places, where the cells on the Carrier rest, so structured that the cells are not lie flat against the carrier so as to later Placing the adhesive in the space between the disc and Carrier for their bonding the whole Flow around the cells to ensure.

The Connection of the electrical connections of the solar cell array with the contacts on the module carrier and the supply lines to the junction box for the external connections is carried out by joining techniques known to the person skilled in the art, such as soldering, Wire bonding or other common technologies.

On the front of the solar module is the windscreen. The Thickness of the windscreen is in the range between a few tenths Millimeters and a few millimeters. The windscreen is preferably from a transparent plastic, z. B. based on PMMA.

at Thin-film cells, usually already on a disk, z. Example of glass, plastic, glass ceramic or ceramic, deposited This disc is the windscreen of the module.

In an advantageous embodiment, in order to reduce the reflected portion of the incident light, antireflection layers or texturing known to the person skilled in the art can be applied to the surface of the sheet facing the incident light be applied.

In an advantageous embodiment, the windscreen for Increasing the photon yield even with fillers be provided that the wavelength of the radiating Convert light and in this way the quantum efficiency in the Increase wavelength range in which the photoactive cells have their greatest efficiency.

Of the The space between the disc and the carrier becomes bubble-free filled with an elastic polymer, which on the one hand glued the windscreen with the carrier and the other the photoactive in the space between the carrier and the windscreen Protects cells and the contact and interconnect system from media influence. In the case of wafer-based cells, it is preferably a high transparent polymer. The thickness of the gap is in the range a few tenths of a millimeter to a few millimeters.

For the long-term stability of the invention Solar modules are due to changing temperatures and different Expansion coefficients of the materials used thermal Tensions of particular importance. These voltages can to defects in the solar cells or on the contact and track system, Delamination between module carrier and adhesive layer or adhesive layer and windscreen and destroying the Lead module composite. By using an elastic Polymers of the adhesive layer become temperature-induced mechanical Tensions in the area between windscreen and carrier largely reduced.

By the use of one with low viscosities, e.g. B. at room temperature in the range of less than 1000 mPas and below, processable plastic encapsulation, z. B. as a reactive system or as a dispersion, thinnest Column be filled by a few microns pore-free.

The elastic polymer of the plastic encapsulation can either first on the support with the electrically contacted solar cells applied and then put on the windscreen. For the order of the polymer of the plastic encapsulation on the carrier is suitable for. B. a non-pressurized casting process. The corresponding Technologies are known to the person skilled in the art.

through Fixation aids, z. B. a tool, but can also first the windscreen in its final position above the carrier fixed and then the polymer of the plastic encapsulation in the gap be introduced between the windscreen and the carrier. Therefor can handle both high pressure and low pressure processes be used. The corresponding technologies are the specialist known.

When elastic polymers of the plastic encapsulation are transparent Polyurethane systems, for example of aliphatic polyisocyanates, native polyuronic systems, casting silicones, native epoxides, Plastisols.

Brief description of the invention

The Invention will hereinafter be understood without limitation of the general Erfindungsgedankenens with reference to embodiments below Reference to the drawings described by way of example. Show it:

1a -F sequence image representation for the production of a solar module

Ways of carrying out the invention, commercial usability

In the 1a to manufacturing steps for cost-effective production of a solar module are shown.

In 1a is the module carrier 1 shown. At the module carrier 1 is at the same time an electrical connection structure 2 provided for the subsequent electrical contacting of the solar cell array. The electrical connection structure 2 has the back to the module carrier 1 a central junction box 2 via which the completed solar module can be connected to an external control and supply unit.

In the production step according to 1b be in a frame 4 arranged solar cells 3 on the front of the module carrier 1 placed in position and in the process step according to 1c by means of electrical connection lines 5 with the electric, in the module carrier 1 integrated connection structure 2 connected. Not shown in detail on the front of the module carrier 1 formed, plastic receiving structures, in which the over the frame 4 connected solar cells 3 can be fitted so that the solar cells 3 in a predefined position relative to the module carrier 1 can be brought to the plant.

In the production step according to 1e becomes a radiation transparent, preferably made of PMMA material windscreen 6 on the solar cell array 3 . 4 applied, leaving the windscreen 6 a gap with the module carrier 1 included in the in 1f illustrated manufacturing step with a potting compound 7 is completed completely. The potting compound 7 encloses the internal solar cell arrangement 3 + 4 Hermetically complete, ie, the side edges of the solar cell array are with the potting compound 7 enclosed.

In addition, the potting compound serves 7 in the manner of an adhesive layer, through which the windscreen 6 with the module carrier 7 intimately connected so that the potting compound 7 is able to transmit mechanical loads accordingly.

The solar module designed in accordance with the solution thus has the following advantages:
By using injection-moldable thermoplastics for the production of the module carrier this can be formed with a high rigidity and strength.

The Windscreen is made of a radiation-transparent material, preferably made of plastic based on PMMA, the proven way has a high long-term UV stability.

The Windscreen and the module carrier with the intermediate Solar cell assembly is by way of a low-stress casting process glued together, giving a high long-term stability even under changing operating conditions with regard to temperature fluctuations and mechanical loads is guaranteed.

The Production time of the production of the solution according to Solar module can by appropriate decoupling of the production considerably shortened from front and module carrier side become.

1

module carrier

1'

rib lines

2

electrical terminal structure

2 '

junction box

3

solar cells

4

frame elements

5

electrical connecting structure

6

windscreen

7

potting compound

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 000000325369 A2 [0013]
• - DE 10101770 A1 [0013, 0015]
• - EP 325369 A2 [0014]

Claims (8)

Solar module with an electrically interconnected, flat solar cell arrangement, at the back of a rear side construction and at the front of a radiation transparent front side are provided, and with a solar cell assembly between the rear side structure and the windscreen surrounding embedding material, characterized in that the back construction as a separate module in shape a rigid, thin metallic, ceramic or organic sheet as a module carrier is that the front panel with its module carrier surface facing the whole surface by means of a solidifying and mechanical loads transferable, radiation transparent potting compound is connected to the module carrier, which encloses the solar cell assembly between the windscreen and the module carrier , Solar module according to claim 1, characterized that the front glass is made of glass, glass ceramic, or of a transparent Plastic, preferably a PMMA-based plastic exists. Solar module according to claim 1 or 2, characterized that the solar cell assembly between the windscreen and the Module carrier along or near the area of itself arranged at bending of the solar module adjusting neutral fiber crops is. Solar module according to one of claims 1 to 3, characterized in that the solidified potting compound both the solar cell array as well as a required in this regard Pouring contact system. Solar module according to one of claims 1 to 4, characterized in that the front pane has a pane thickness between a few tenths of a millimeter and a few millimeters. Solar module according to one of claims 1 to 5, characterized in that facing away from the solar module Surface of the windshield an antireflection coating is applied. Solar module according to one of claims 1 to 6, characterized in that the windscreen the wavelength the incident on the windscreen radiation converting substances contains such that the converted in wavelength Radiation achieved a higher efficiency in the solar cell array as the unconverted radiation. Solar module according to one of claims 1 to 7, characterized in that the solar cell assembly is a thin film solar cell with a radiative transparent topcoat, and that the topcoat the solar cell assembly serves as a windscreen, at least in Near-surface surface area of the radiation-transparent Encapsulant is enclosed and a load transferring Establishes connection with the module carrier.