Solar still is a cheap and convenient device for producing freshwater, but it's not popular due to its low productivity. In this paper, we modified the conventional solar still. The outdoor performance of modified solar stills was studied to assess its potential for real application. The modifications include using flake graphite nanoparticles (FGN), phase change material (PCM), and film cooling. In the presence of the three previous modifications, the productivity was enhanced as high as 73.8% compared with that of the conventional still. The effect of water depth on the enhancement was also investigated. It shoWs that the enhancement of productivity increases by around 13% when the water depth decreases from 2 cm to 0.5 cm. Besides, an indoor experiment was carried out to analyze the enhancement mechanism by FGN. It shows that the increase in both temperature and saturated vapor pressure contributed to the enhancement. (C) 2017 Elsevier Ltd. All rights reserved.