German startup Solyco has presented a new low-temperature solar panel interconnection technique that does not require the use silver, lead, or bismuth.
Called Thermoplastic and Electrically Conductive Coating (TECC-Connect), the proposed technology consists of a round copper core with a diameter of 210 μm that is covered by a very thin layer of silver for corrosion protection and then surrounded by a 20 μm coating of an electrically conductive thermoplastic.
It is implemented through a process that is similar to multibusbar technology, in which cables are coated with an electrically conductive thermoplastic instead of a solder alloy. With this approach, however, the cables can be processed with a slightly modified commercial stringer, with the melting point of the coating being engineered in a range between 130 C and 180 C.
With different chemistries of the coating, a wide variation in process temperature can be achieved, and the material can be engineered for the respective type of solar cell. The melting temperature of the coating can be adjusted, by using different thermoplastics for the wire coating.
According to Solyco, there is no limitation to the number of wires used per solar cell. Furthermore, no solderable electrical contact
surface, busbars and flux are required in the manufacturing step.
“With TECC, we achieve material independence from silver and enable full Restriction of Hazardous Substances (RoHS) compliance,” Lars Podlowski, Managing Director and CTO of Solyco, said.
According to Solyco, the elimination of silver reduces material costs in module production by up to 10%. “TECC-Connect is ideal for high-efficiency solar cells such as heterojunction (HJT) and tandem perovskite solar cells,” Podlowski said.
The first industrially manufactured TECC Connect solar modules will be presented at Intersolar, Munich, Germany, in May. The HJT modules are composed of cells that are connected with copper plating instead of silver fingers, according to Podlowski.
The technology has passed all standard quality and durability tests, according to Solyco. The company is currently working with several unspecified industry partners to scale up industrial mass production and launch the first products in 2026.
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