Output parameters and diode characteristics under illumination of flexible thin-film solar cells ITO/CdS/CdTe/Cu/Au formed on polyimide films by vacuum methods are studied. Using mathematical modeling of the effect of diode characteristics under illumination on the efficiency, the physicothechnical parameters of such structures are optimized. This made it possible to obtain laboratory samples of flexible solar cells based on cadmium sulfide and telluride with an efficiency of 11.4%. Solar modules with an efficiency of 4.5% based on the developed flexible solar cells are formed for the first time.