So-called PERC cells are used in mass production of silicon solar cells, they are considered the workhorses of photovoltaics, dominating the market. Now two teams have shown that such standard silicon cells are also suitable as a basis for tandem cells with perovskite top cells. Currently, the efficiency of the tandem cell is still below that of optimised PERC cells alone, but could be increased to up to 29.5% through targeted optimization. The research was funded by the German Federal Ministry of Economics as part of a joint project.