  Thin-film solar cells that are considered as the second generation of solar
cells are known for their low cost and acceptable efficiency. In this
technology, semiconductor layers with a thickness of micrometer are deposited
on thick enough substrates to maintain physical consistency. The relatively low
processing temperature helps use substrates of different materials. Compared
with crystalline solar cells, which are mainly made up of rigid flat plates, it
is also possible to make thin-film cells on flexible or non-flat substrates. In
this study, a method was first proposed to calculate the efficiency of such
cells without the need for 3D simulation, and then it is investigated using
non-flat conical and paraboloid substrates as a novel method to enhance the
light trapping. As a result, a significant increase in the efficiency of the
studied non-flat cells was observed and reported in comparison with the flat
cells. In addition, the paraboloid shape shows a better performance than that
of the conical, to use as the cell's substrate.
