In solar still, transparent cover plays a decisive role in the process of evaporation and condensation of water. Also receiving the solar radiation strongly depends on the geometry and orientation of the glass. In order to determine the impact of changing glass cover geometry on conventional solar still heat balance, we elaborate a theoretical model for a spherical solar still. The obtained equations are solved by using 4th order Runge–Kutta method. The numerical results allowed us to evaluate the water temperatures and the yield of still. Theoretical results are validated by the experimental tests in different climatic conditions. We observed that the spherical geometry of the transparent cover has the advantage of a large surface of condensation and does not have a preferred direction to capture maximum of solar energy.