In this work, ZnO, SnO2 and ZnO:Sn films were produced by ultrasonic spray pyrolysis technique. Sn element was incorporated into ZnO precursor at volume percentages of 20, 50 and 80% to produce ZnO-SnO2 systems as an alternative to popular indium tin oxide used in photovoltaic solar cells. Elemental analyzes showed that stoichiometric deviations occurred because of the excess Zn and Sn in addition to the lack of oxygen. From X-ray diffraction patterns, the optimum incorporation rates to produce ZnO-SnO2 systems were determined as 50 and 80%. The transmittance spectra showed that ZnO-SnO2 films have highly transparent in the visible region and transmittances at 600 nm reached 86%. Thicknesses and optical constants were determined by spectroscopic ellipsometer. Photoluminescence spectra showed that natural point defects occur as deep traps. Sn incorporation rate, which creates reduction effect on surface roughness values, was determined as 80% by atomic force microscopy. The electrical resistivities of ZnO-SnO2 films were measured as 1.41 x 10(-2) and 5.15 x 10(-30)Omega cm by four-probe technique. This study shows that ZnO-SnO2 oxide systems produced by incorporating Sn at 50% and especially 80% may be potential candidates to indium tin oxide in solar cell applications due to their high optical transmittances and low electrical resistivities.