OK International - Minimizing Micro-cracks in Solar Cell Interconnection

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Solar cell substrates are delicate. The manual soldering process applies stress to the material which can cause micro-cracks to form. This article identifies the requirements and equipment needed to reduce the micro-cracking during solar cell assembly.

Photovoltaic Cell (PV) Module Assembly There are two soldering process steps used to assemble a PV module; the first step is photovoltaic cell interconnection, called stringing or tabbing, and the second step, PV module assembly, is called bussing.

Initially, the cells are electrically connected using tinned copper ribbon which is typically 2mm wide. The solder-coated ribbon is dipped into, or sprayed with, flux. The flux is used to promote wetting and remove oxides from the surface of the ribbon. A point of contact between the collector grid (substrate) and the ribbon is formed by screen printing a metallization paste to the substrate. The tabbing ribbon provides all the solder required to form a bond between the ribbon and the substrate...

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