Solar-energy conversion by combined photovoltaic converters with CdTe and CuInSe$_2$ base layers

The possibility of the combined use of bifacial thin-film solar cells based on CdTe and frontal solar cells with a CuInSe$_2$ base layer in tandem structures is experimentally confirmed. It is found that, for the use of bifacial solar cells based on cadmium telluride in a tandem structure, the optimal thickness of their base layer should be 1 $\mu$m. The gain in the efficiency of the tandem structure, compared with an individual CuInSe$_2$-based solar cell, is 1.8% in the case of series-connected solar cells and 1.3%, for parallel-connected.