The Fraunhofer ISE has developed a new laser process for connecting solar cells without busbars. Improve design and reduce production costs.
A new breakthrough for flexible and efficient solar modules.
Flexible or thin-film photovoltaics today represent the greatest promise of energy integration.
But flexibility and efficiency do not always coincide. And if the goal is to achieve high performance, conventional rigid crystalline silicon panels are still the best option.
Now, a new project from the Fraunhofer Institute for ISE Solar Energy Systems is changing that. A team of scientists created and recorded the technology FoilMet® which transforms rigid photovoltaic cells into flexible solar modules.
It is a laser micro-welding process capable of connecting PERC and TOPCon solar cells together without busbars, using a simple sheet of aluminum. A) Yes, no traditional solder wires or conductive adhesives.
The result is a mechanically flexible connection which allows both a tile-like layout of cells and a “single-row” layout. This saves several materials, starting with the silver that covers the traditional conductor bars.
This new technology allows a thin strip of aluminum to be directly connected to the conductive elementsbonding it to the silicon nitride surface in the area between the metal fingers.
The first advantage is the speed. As the German researchers explain, the whole process takes less than a tenth of a second per slice. In addition, it guarantees a very low contact resistance between the sheet and the electrodes, which allows maximum efficiency of the module. And, by abandoning busbar traditions, you can save up to 30% money.
If many small cells are connected instead of a few but large ones, the current loss and resistance generated in them decreases and the voltage increases.
Despite these advantageous properties, a solar module composed of many small cells is more complex and expensive to connect; that’s exactly what FoilMet® technology is trying to solve.
The team plans to create a pilot plant to produce larger quantities of flexible solar modules in a reproducible way. At the same time, the technology will undergo a lifetime analysis.
More information: FoilMet®: Ressourcenschonende, flexible Solarzellen-Verschaltung durch Laser-Mikrofügen – Fraunhofer ISE