Research Project SelemSi

The KOENEN competence team and the research institute for micro sensor and photovoltaic (CiS) have started the development of a selective emitter on a silicon solar cell by using screen printing.

In the last few years the classic solar cell has been continuously developed with the target to scale down the structure of the metallisation lines to increase the effective cell area by minimizing the shadowing areas. Today those kind of solar cells have a market share of around 85 %. Two years ago the cells had an average efficiency of 16 % and up to day they reach 18 % due to the past development. Based on physical limitations the rate of efficiency increase can not be arbitrarily raised with this type of cell as it has been done in the past.

It is more than less important to develop and apply new solar cell technologies which can provide a higher solar cell efficiency than the commonly used ones.

Within this project selective emitter structures have to be realized on a silicon solar cell by using screen printing. Two major aspects have to be considered. On the one hand the precision of a double print is very important (selective emitter and metallization lines). A bad precision would significantly decrease the efficiency of the cell. On the other hand the metallisation structures have to be very thin (< 50 µm) providing a minimum thickness at the same time. The ration between width and height, also called aspect ratio, has to be high (> 0.3) for an undisturbed electricity. This ensures a high solar cell efficiency.

The innovative development of this technology by screen printing constitutes a commercial advantage in comparison to other technologies for the realization of selective emitter structures. The installed solar cell manufacturing lines at customer can be widely used with this technology, so that no further investment is needed.

A rapid market penetration is therefore possible, providing that the development of this technology succeeds.