The technology elaborated by the authors [1] demonstrates the possibility of the formation of photovoltaic SIS structures by spray deposition of a thin layer of a mixture of indium tin oxide (ITO) on the surface of a standard silicon wafer, which is the basic absorbent material of solar cells. The spray method replaces the traditional process of diffusion necessary for the formation of a p-n junction and is characterized by a low temperature of receiving (450oC instead of 1200oC in the case of p-n junction formation); as a result, a significant reduction in energy consumption and the cost of producing solar cells is obtained. The subject of this report are studies leading to the further optimization of the photovoltaic parameters of the ITO-SiO2-nSi structures fabricated by spray pyrolysis, and getting mono-and bifacial low-cost and efficient solar cells based on them. With that end in view, a method was developed of texturing the surface of silicon wafers oriented in the (100) plane and Si wafers were obtained with regular and irregular surface reliefs. For plates with an irregular relief, the depths of etch pits were 2-3μm. A regular micro-structured surface has a hexagonal pattern of the inverse 4-sided pyramid with a side of the base of~ 4μm and a depth of ~23μm, located at the distance of ~ 4μm from each other. The structure and composition of ITO layers were studied with the help of a scanning electron microscope. Such layers, obtained by spray pyrolysis on textured (100) surfaces of single crystal silicon wafers, copy the wafer surface relief, are continuous and consist of crystallites with sizes of about 30nm. The thickness of an ITO layer at the base of the pyramids on the silicon surface is ~0.5μm, while at the vertices it is about 100nm. The composition of the films corresponds to the stoichiometry. Solar cells based on n+ITO-SiO2-n-n+Si structures with one-and two-sided sensitivity and improved photovoltaic parameters have been fabricated by the authors of the present communication [2]. The peculiarity of those solar cells is that they consist of only isotype n-n transitions. The efficiency of solar cells with a one-sided sensitivity and irregular surface relief of a silicon wafer is 11.88%, which is by 2% higher than of similar solar cells with non-optimized parameters. With solar cells with a one-sided sensitivity and surface relief of silicon wafer in the form of inverse pyramids, the efficiency increases up to 15.79%, which is more than 5% of the value of solar cells with an unstructured surface of silicon. The resultant efficiency of solar cells with bilateral sensitivity increases from 12.6% to 15.73% in the case of an irregular relief of silicon surface and up to 20.89% in the case of a regular relief. The efficiency of not optimized structures, illuminated from the back side, is 0.4 of the value in the case of frontal illumination. For bifacial solar cells fabricated on the base of textured silicon wafers surface, this ratio reaches 0.75. The investigations of the effective quantum yield spectral distribution show that the region of the sensitivity of the elaborated structures is situated in the interval of wavelengths 350-1200nm and does not depend on the illumination direction. The increase of the effective quantum yields for both frontal and rear illumination has been also observed. The maximum value of the quantum yield for bifacial structures with nontexturated silicon wafers surface is about 0.84 in the case of frontal illumination and 0.33 for rear one. For bifacial structures with a regular relief surface in the form of inverse pyramids these values are ~ 0.93 and ~ 0.60, respectively. [1] Simashkevich, A.; Serban, D.; Bruc, L.; Coval, A.; Fedorov, V.; Bobeico, E. & Usatii. Iu. (2005). Proc. of the 20th European Photovoltaic Solar Energy Conference, ISBN 3-936338-19-1, Barcelona, Spain, 2005, pp.980-982. [2] A.V.Simashkevich, D.A. Sherban, L.I.Bruc, E.E. Kharya, Yu. V. Usaty. Surface Engineering and Applied Electrochemistry, Vol. 47, No. 3, 2011, pp. 266–271.