PERC-perovskite solar tandem expected to hit 29.5%

The tandem solar cell. Source: Silvia Mariotti / HZB

February 28 (Renewables Now) - A tandem solar cell combining PERC and perovskite technology could reach a power conversion efficiency of 29.5%, according to researchers at Helmholtz Zentrum Berlin (HZB) and the Institute for Solar Energy Research in Hamelin (ISFH).

The two teams have been working on the concept as part of the joint project P3T, funded by the German Federal Ministry of Economics. They have so far managed to achieve an efficiency of 21.3% on an active cell area of about 1 sq cm. This is below the efficiency of optimised PERC cells, but there is room for improvement.

Tandem cells convert the energy spectrum of sunlight into energy more efficiently than the subcells they are made of and many scientists are working on different combinations. HZB and ISFH chose the "workhorse" of photovoltaics – PERC silicon cells on p-type silicon – for their project as it is “particularly interesting” for the commercialisation of a perovskite-silicon tandem technology.

At ISFH they used an industry-compatible PERC process for the backside contact of the bottom cells, while the POLO contact, another “industrialisable technology” was used on the front side of the wafer. It has been adapted for the small-area proof of concept cells. At HZB a tin-doped indium oxide recombination layer has been applied as a contact between the two subcells.

According to Silvia Mariotti from the HZB team, adapting the surface of the silicon wafers as a next step could easily increase the efficiency to about 25%, which would be above that of PERCs alone.

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Browse all articles from Tsvetomira Tsanova

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