New technology for interconnecting temperature-sensitive solar cells based on TECC-Wire technology

The use of solar energy is a central pillar of the sustainable future energy supply for all mankind. Therefore, the development of more cost-effective and efficient solar cells is progressing steadily. New cell types such as the heterojunction or tandem solar cell are more efficient, but also more temperature-sensitive than conventional cells. The conventional interconnection method, in which the cells are connected to form PV modules using soldered copper wires, is reaching its limits with these new cell generations and requires gentler interconnection methods. In the TECC-Wire technology, silver-plated copper wires replace the conventional solar cell contacting with printed silver conductors and are also used to connect the cells to modules; this leads to silver savings and might result in an increase in efficiency due to resistance and shading minimization.

The wires are coated with a thin-walled, electrically conductive, thermoplastic adhesive layer to be able to produce a permanent electrically conductive connection at low process temperatures (<200°C). For these conductive coated wires to be produced in sufficient quantities for the solar industry, this research project will develop a wire enamel that can be applied in established wire coating equipment, this requires careful adjustment of the properties of the formulation. After drying, a conductive, thermoplastic processable hot melt adhesive layer is formed, which must exhibit permanently high adhesion to solar cells. The conductivity is to be generated by dispersed conductive particles. With the help of the concept of capillary suspensions, this can be achieved at a low filling level. On one hand, this leads to cost savings, and on the other hand, it increases the long-term stability of the compound.

The goal of this project is to develop a new contacting method for solar cells that eliminates soldering, reduces the number of valuable resources such as silver, and thus leads to a faster expansion of solar energy use.