l'Actualité du Solaire

Researchers at the Fraunhofer ISE want to reduce the losses associated with energy transport in the cells and increase the rate of light absorption. They have achieved a conversion rate

of 25.7% on one cell. They want to get closer to the theoretical conversion rate of 29.4% of solar irradiation. The difference is due to losses related to energy transfer, metallisation and optical losses.

Researchers have found that by improving the material and passivation, metallic contacts limit efficiency. They therefore placed thousands of dot-shaped contacts on the back of the cells, calling them PERC (Passivated Emitter and Rear Local Contacted Cell). Only this solution increases the series resistance because of the load carriers. Fraunhofer ISE has sought to reduce this conflict with selective contact and loss-free transport of the load on the metal contact.

Bine Info December 2017

http://www.bine.info/en/topics/renewable-energy-sources/photovoltaics/publikation/mit-neuem-verfahren-naeher-an-die-ideale-solarzelle/

The difference between the electrical current transport in solar cells with local rear contact (left) and in cells with the new TOPCon rear contact passivated over the entire surface (right) is shown above.

Above: schematic diagram of the TOPCon solar cell (Oxide Passivated Contact Tunnel) with selective contacts over the entire area.