The yield of solar still can be depend on the tilt angle of the solar glass.
This angle in turn depends on inclination and the direction the cover is facing, and also its latitude. It is expected that covers that has an inclination that is aligned with the angle of the latitude will be the recipient of a normal solar radiation annually. This is deemed as important due to the fact that evaporation is reliant on intensity of solar radiation. This leads to the adjustment of the angle of inclination with respect to the solar azimuth angle and solar intensity. Singh and Tiwari (2004) conducted a numerical analysis for latitudes of (13–28ºN), taking into account the effect of solar radiation, wind speeds, water depths, and cover tilt angle on productivity. They observed that the optimum glass tilt angle for maximum annual output should be the latitude of the location.
A similar study was conducted in India (latitude 28.36ºN) by (Kumar, Tiwari & Singh, 2000), and based on their numerical analysis, a glass tilt angle of 15º resulted in the best performance. Akash et al. (2000) discovered that a 35º glass inclination angle results in the maximum yield in the month of May. The experiments conducted at (latitude 31.
57ºN) in Jordan by Khalifa and Hamood (2009) investigated the effect tilting a cover on the performance of basin solar stills. It was surmised that output could change by almost 63% via tilting the covers alone.