Welding method for photovoltaic module

Abstract

The invention discloses a welding method for a photovoltaic module, which comprises the following steps of: (1) making marks on a to-be-welded branch bus bar at intervals, putting the branch bus bar into a stamping die, and stamping the marked positions of the branch bus bar by using a stamping process, stamping a marked local position of the branch bus bar into a flat block body, wherein the stamping position corresponds to the position of a battery welding spot; (2) placing the stamped branch bus bar on a battery piece needing to be welded, aligning the position of the flat block body with the position of the battery welding spot, and preheating the battery piece; and (3) connecting the branch bus bar into a power supply, wherein the resistance of the flat block body on the branch bus bar is larger than the resistance of other parts, and more joule heat is generated, so that the coating on the flat block body on the branch bus bar is melted firstly in the process that current flows through the branch bus bar, and welding with the battery piece is realized.

Description

technical field [0001] The invention relates to a welding method for photovoltaic modules. Background technique [0002] At present, photovoltaic module welding is mainly based on high temperature thermal infrared welding. The filament is heated to generate high temperature, and then the sub-confluence strip is heated by heat radiation to melt the coating on the surface and react with the silver electrode of the battery to form an alloy, thereby ensuring welding reliability. [0003] But traditional infrared welding still has some problems. On the one hand, welding needs to be maintained for a long time and at a high temperature to ensure that the coating of the sub-bus strip is fully melted, generally set at 200°C or higher, because the coating of the sub-bus strip that is in contact with the silver battery is blocked by the body of the sub-bus strip , Not all of them receive heat radiation directly, a considerable part comes from the heat conduction from the front and si...

AI Technical Summary

Problems solved by technology

On the one hand, welding needs to be maintained for a long time and at a high temperature to ensure that the coating of the sub-bus strip is fully melted, generally set at 200°C or higher, because the coating of the sub-bus strip that is in contact with the silver battery is blocked by the body of the sub-bus strip , Not all of them receive heat radiation directly, a considerable part comes from the heat conduction from the front and side of the sub-confluence strip, and the overall temperature difference in the welding area is large, so the battery is prone to warping under the action of an uneven thermal field, resulting in poor welding, and With the promotion of photovoltaic grid parity, the thinning of silicon wafers will further aggravate the risk of warpage

On the other hand, for new heterojunction cells, a low-temperature welding process is required to avoid affecting the TCO layer on the surface. Even if low-temperature metals such as Bi and In are added to the coating, the sharp drop in infrared temperature makes it difficult for the coating in contact with the silver electrode to Sufficient melting, resulting in insufficient welding tension

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