Enhancing solar still performance using nano-coated covers and integrated solar collectors: An experimental study

Freshwater scarcity is a pressing global issue, driving the demand for sustainable desalination technologies. While solar stills offer a simple, eco-friendly solution, their widespread adoption is hindered by low productivity. This study experimentally investigates a novel approach to enhance solar still performance by simultaneously improving condensation with a nano-coated cover and augmenting evaporation with an integrated solar collector. The experiments were conducted using both glass and acrylic covers. Three double-slope solar still configurations were compared: a conventional (SSC), a nano-coated (SSN), and a solar still integrated with a flat-plate solar collector (SSSC). The SSSC configuration demonstrated significantly superior performance. With a glass cover, the SSSC yielded 2810 ml/m² of freshwater, a 73.1 % increase over the SSC (1623 ml/m²) and achieved the lowest production cost of $0.082/L/m². With an acrylic cover, the SSSC's productivity reached 1340 ml/m², marking a 100.2 % improvement over the SSC (669 ml/m²). In contrast, the nano-coated still (SSN) underperformed significantly with a glass cover (774 ml/m²) but showed a marginal 3 % increase in productivity with an acrylic cover. These findings demonstrate that integrating a solar collector is a highly effective and economically viable strategy for significantly enhancing solar still efficiency, whereas the effectiveness of the nano-coating is critically dependent on the cover material.