Innovative industrial strategy based on Electrically Conductive Adhesive for HJT solar cells
Résumé
Heterojunction technology (HJT) became a key technology for cell and module manufacturers especially in Europe. However the high sensitivity of the HJT cells to temperature [1-2], revealed the interconnection system as a challenging step in order to achieve competitive performance, reliability and low processes cost. The most mature and advanced interconnection technology adopted to that system foresee the use of an Electrically Conductive Adhesive (ECA) suitable for the connection of ribbons onto the cells [3]. This method, though, may require a significant consumption of silver, required for cells metallization process, ECA interconnection and, additionally, for the ribbons coating [4].
Indeed, the photovoltaic industry is one of the main worldwide silver consumers representing about 10% of the global demand. Anticipating the continuous solar industry expansion, a technological breakthrough is necessary to reduce the silver consumption and avoid silver shortage issues [5-6].
A first optimization has to be implemented at cell design level. Increasing the number of ribbons or wires on the cell layout allows to decrease the silver quantity employed in the cell metallization. However, when using ECA interconnection technology, this solution may imply an increased amount of ECA itself and ribbons hence an optimal trade-off has to be found.
The second optimization would be to reduce the silver consumption during interconnection process at the module level. Indeed, several paths could be considered: (i) reduce the silver content in ECA, (ii) reduce ECA consumption and (iii) implementation of ribbons/wires without silver coating. All these solutions shall be implemented while maintaining the same module performances and reliability.