The invention relates to the production of solar panels which comprise an array of jointly connected solar cells. Such solar cells or photovoltaic cells are optoelectronic devices by means of which radiation can be converted into electrical current. The cells generally consist of crystalline silicon and are jointly connected by an electrical circuit. That electrical circuit is connected to the contacts of each solar cell. An embodiment is known wherein those contacts are arranged on the front side of the solar cell. In such an embodiment, the electrical circuit, for example in the form of electrically conductive strips of material, is arranged on the front side of the solar panel. A drawback of that embodiment is that a portion of the surface of the panel is occupied by the electrical circuit and therefore cannot be used for the photovoltaic conversion.
Further to this, solar cells are known wherein the contacts are arranged on the back side. The electrical circuit is therefore also arranged on the back side, so that a larger portion of the available surface of the solar panel remains available for the photovoltaic conversion.
Solar panels of these types can be produced in various ways. It is known from U.S. Pat. No. 5,972,732 that a solar panel can be formed consecutively from a layer of foil, an electrically conductive layer, an array of solar cells, followed again by a layer of foil and finally a sturdy light translucent panel, such as a glass panel. Such a package is heated in a kiln, thereby curing the layer of foil, which usually consists of ethylene vinyl acetate.
Before the solar panel is ready after heating and curing the foil layers, however, the various components thereof are arranged in a package in a relatively loosely stacked position with respect to one another. In this state, the package needs to be treated very carefully since relative displacement of the components may otherwise occur. If the various components are dislocated, however, the end-product will be faulty, thus resulting in the malfunction of the electrical contacts. It is also inevitable that the package is subjected to certain displacements during transport, as it is transferred from the assembly station to a kiln for the final production of the solar panel.
The object of the invention is therefore to provide a method for the production of solar panels as referred to in the foregoing, wherein the risk of dislocation of the different components in a package is prevented. This object is achieved by a method for the production of a solar panel with a plurality of solar cells, comprising the steps of:
In the method according to the invention, the various components from the package that must be formed to compose the solar panel are fixated at an early stage with respect to one another by heating at a moderately high temperature. This fixation process may take place, for example, on the workbench where the package is assembled. The package thus fixated can then be finished, without the risk of displacement of the various components with respect to one another, in a kiln or laminator, whereupon the finished solar panel is obtained. The temperature at which the package is fixated is for example approx. 120° C., whereas the temperature at which the package is formed to produce a finished solar panel is, for example, approx. 150° C. In particular, the fixation of the package in the auxiliary heating station can be performed under atmospheric pressure or ambient pressure.
The method according to the invention can be applied to the production of different types of solar panels. Specifically, but not exclusively, the method can be applied to the production of a solar panel wherein the contacts of the individual solar cells are arranged on the back side thereof, so that a relatively large photovoltaic surface is obtained. In that case the method according to the invention comprises the steps of:
The electrical connection between the contacts of the individual solar cells and the electrically conductive foil is now established by the electrically conductive adhesive layer in the holes of the EVA layer. However, alternatively, the method may also be applied for the production of solar panels constructed in the traditional manner, whereby the contacts of the solar cells are attached to electrically conductive strips by soldering means. These strips may be applied either on the back side or the front side of the solar cells.
The invention further relates to a semi-product for use in the method as described in the foregoing, respectively comprising a backing foil with a pattern of electrically conductive wires and which is provided with a thermally activated adhesive, a fusible foil, such as ethylene vinyl acetate (EVA), provided on the side of the layer of foil to which the adhesive layer is applied, an array of solar cells, a layer of fusible foil, such as EVA, and a translucent panel, wherein the semi-product has been subjected to an increased temperature at atmospheric pressure.
According to a first embodiment, the thermally activated adhesive layer can be electrically conductive. The EVA layer bordering on said adhesive layer has holes, while the electrical contacts formed on the solar cells are connected via the holes with the electrically conductive adhesive layer and the foil. Alternatively, the contacts of the solar cells can be soldered to the electrically conductive strips. According to a first optional embodiment, in this case the contacts of the solar cells and the electrically conductive strips may be arranged on the front side of the solar cells. According to a second optional embodiment, the contacts of the solar cells and the electrically conductive strips may be arranged on the back side of the solar cells.
The invention will now be described in more detail with reference to the exemplary embodiment shown in the figures.
The arrangement depicted in
As shown in
An array of solar cells 8 with electrical contacts 9 (see also
In the arrangement shown in the
Upon cooling, the package 1 is fixated in such a manner that a semi-product 13 is formed and this can then be transported without the risk of relative dislocation of the various components occurring. The semi-product 13 can be transferred to a kiln, for example, in order to cure the layers of ethylene vinyl acetate 6, 10 and to produce a finished solar panel 15. This curing process may take place in the usual manner under overpressure.
A semi-product 13 is then heated further in the kiln 14 to a temperature of 150° C., for example, and then subjected to an overpressure. After some time, whilst maintaining heating and overpressure, for example between 5-7 minutes, the adhesion between the different parts is formed, after which the finished solar panel 15 is obtained.