Batteries: thermoelectric and photoelectric – Photoelectric – Panel or array
Reexamination Certificate
2002-03-11
2003-03-04
Diamond, Alan (Department: 1753)
Batteries: thermoelectric and photoelectric
Photoelectric
Panel or array
C136S261000, C136S244000, C438S063000, C438S064000, C257S461000, C257S465000, C257S466000
Reexamination Certificate
active
06528717
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photovoltaic panel including a plurality of photovoltaic elements and a method of producing a photovoltaic cell.
2. Discussion of Related Art
Japanese Patent Document No. 6(1994)-13633 discloses a method of producing a photovoltaic panel. This method includes (a) the step of forming a number of holes in an aluminum foil as an electrically conductive member; (b) the step of fitting, in each of the thus formed holes, a photovoltaic element having P-N junction between a core portion and a shell portion; (c) the first connecting step of pressing, by impact pressing, the photovoltaic elements which have been heated up to 500° C. to 577° C., into the holes and then cooling those elements down to the room temperature, so that the conductive member is electrically connected to the shell portion of each photovoltaic element; (d) the step of removing one of respective half portions of the shell that correspond to the opposite major surfaces of the conductive member, so that the respective cores of the photovoltaic elements are partly exposed; (e) the step of forming an electrically insulating layer on the exposed portions of the cores of the photovoltaic elements and the corresponding one major surface of the conductive member; (f) the step of polishing portions of the insulating layer covering the cores of the photovoltaic elements, so that the cores are partly exposed and (g) the second connecting step of electrically connecting a second electrically conductive plate-like member to the thus exposed portions of the cores of the photovoltaic elements.
SUMMARY OF THE INVENTION
The present invention provides a photovoltaic-panel producing method and a photovoltaic panel which have one or more of the following technical features that are described below in respective paragraphs given parenthesized sequential numbers (1) to (20). Any technical feature that includes another technical feature shall do so by referring, at the beginning, to the parenthesized sequential number given to the latter feature. However, the following technical features and the appropriate combinations thereof are just examples to which the present invention is by no means limited. In addition, in the case where one technical feature recites a plurality of items, it is not essentially required that all of those items be simultaneously employed. That is, it is possible to select and employ only a portion (one, two, . . . , but not all) of those items.
(1) According to a first feature of the present invention, there is provided a method of producing a photovoltaic panel, comprising the steps of forming a plurality of holes in a first electrode plate, fitting, in the plurality of holes, a plurality of photovoltaic elements, respectively, each of which has a P-N junction between a core portion thereof and a shell portion thereof, electrically connecting a first portion of the shell portion of the each photovoltaic element to the first electrode plate, removing one of opposite second portions of the shell portion of the each photovoltaic element that are located on both sides of the first portion of the shell portion, so that a third portion of the core portion of the each photovoltaic element that corresponds to the one second portion of the shell portion is exposed, and electrically connecting the third portion of the core portion of the each photovoltaic element to a second electrode plate, wherein at least one of the step of electrically connecting the first portion and the step of electrically connecting the third portion comprises soldering, with a solder, a corresponding one of the first portion and the third portion to a corresponding one of the first electrode plate and the second electrode plate.
In the present photovoltaic-panel producing method, the electrical connection between each of the photovoltaic elements and at least one of the first and second electrode plates is done by soldering. In contrast, in the first connecting step of the conventional producing method, each photovoltaic element and an electrically conductive member are connected by diffused junction in which two elements are bonded to each other by utilizing the diffusion of atoms occurring at the interface of the two elements. A device for carrying out the diffused junction is expensive, and needs to be used at a high temperature not lower than 500° C. Moreover, the diffused junction needs a long time. The soldering, utilized in the present method, does not need an expensive device. In addition, the solder can be molten at a temperature (from 150° C. to 300° C. depending on sorts) which is considerably lower than a temperature at which the diffused junction is done. Since the solder is easily molten, the electrical connection can be done, by the soldering, in a shorter time. The core portion and shell portion of each photovoltaic element may be connected, either directly or indirectly, to the first and second electrode plates, respectively.
(2) According to a second feature of the present invention that includes the first feature (1), the photovoltaic-panel producing method further comprises forming the each photovoltaic element from a silicon-based material, so that the each element has the P-N junction between the core portion and the shell portion, and forming a to-be-soldered layer from a material having a good capability to be connected to both the solder and the silicon-based material, so that the to-be-soldered layer covers at least the first portion of the shell portion of the each photovoltaic element.
Thus, the to-be-soldered layer is formed from the material having the good capability to be connected to both the solder and the photovoltaic element. This capability can be called as a capability to be connected to metals, or an affinity to metals. The to-be-soldered layer may cover the entire outer surface of each photovoltaic element or a portion of the outer surface of the same. The to-be-soldered layer may be formed by plating. The plating may be either electrolytic plating or chemical (i.e., electroless) plating. Since the chemical plating can be carried out by a cheaper device, it contributes to reducing the production cost of the photovoltaic panel. The material from which the to-be-soldered layer is formed may comprise at least one of nickel, titanium, cobalt, palladium, gold, and silver. A material comprising nickel or titanium is preferable.
(3) According to a third feature of the present invention that includes the second feature (2), the step of electrically connecting the first portion comprises soldering the to-be-soldered layer covering the first portion of the shell portion, to the first electrode plate.
Since the shell portion of each photovoltaic element is soldered to the first electrode plate via the to-be-soldered layer, the shell portion is more easily connected to the electrode plate than the case where the former is directly connected to the latter.
(4) According to a fourth feature of the present invention that includes the second or third feature (2) or (3), the to-be-soldered layer additionally covers the one second portion of the shell portion, and wherein the step of removing the one second portion comprises removing both the to-be-soldered layer covering the one second portion, and the one second portion.
The to-be-soldered layer can be removed by using a plating releasing or removing agent, and the shell portion can be removed by using an etching agent or liquid. The remaining portion of the to-be-soldered layer that is other than the portion thereof to be connected by the soldering, may be removed when the one second portion of the shell portion is removed. It is preferred that the plating removing agent be selected from one of those which are not influential to the solder. For example, a strong acid removing agent is preferable. The etching agent may be selected from strong acids such as sulfuric acid, nitric acid, hydrochloric acid, or hydrogen fluoride. For example, a mixture of nitric acid and hydrogen fluoride i
Asai Koichi
Muto Yasuo
Suzuki Kazuya
Diamond Alan
Fuji Machine Mfg. Co. Ltd.
Oliff & Berridg,e PLC
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