Design, Prototyping, Experimental Evaluation, and Thermal Modeling of an Inclined Stepped Solar Distiller with Zigzag Chicanes

• The prototype was tested for 53 days under natural climatic conditions outside Essaouira, Morocco. • IDSSC was developed to facilitate the saline water flow in a zigzag pattern, which maximizes contact time with the heated surface. • The stepped design and fluid circulation minimized salt deposition on evaporation surfaces, eliminating the need for regular maintenance. • Results showed that distilled water had low salinity and pH values within acceptable ranges according to WHO water quality guidelines. • A simple thermal model was sufficient to mimic water heating and cooling trends during the day, which can be used for analysis and improvement of design. Due to the scarcity of water in arid and coastal areas, especially in countries like Morocco where the quantity of available fresh water is limited, the need for desalination has emerged. However, the existing desalination methods, though efficient, require a significant amount of power and maintenance, making them unsuitable for decentralized systems. In this regard, solar distillation has been proposed as a simple and sustainable solution for the production of fresh water. This paper focuses on the design and experimental testing of an inclined distiller with stair step chicanes that has been developed to improve the rate of production, minimize salt deposits, and ensure long-term operation. The proposed IDSSC was tested in the outdoor environment in Morocco, for a period of 53 days. Temperature monitoring were carried out continuously using multiple sensors, and the daily rate of distilled water was measured. The experimental results show stable daily freshwater production. The produced water quality meets WHO water guidelines. A simplified numerical thermal model based on a lumped capacity approach was developed and compared against experimental temperature measurements, showing good agreement in capturing the main heating and cooling phases. The numerical model predicted a cumulative freshwater production of approximately 2.5 L/m²/day, compared to an experimental value of 1.75 L/m²/day, with a deviation of about 0.75 L/m²/day. The temperature validation showed RMSE values ranging from 10.1 to 11.3°C and MAE values between 8.1 and 9.1°C, indicating that the model accurately captures the overall thermal behavior despite simplifications.