Freshwater scarcity remains a critical global challenge, particularly in remote and arid regions where centralized desalination is impractical, creating a strong need for efficient and sustainable decentralized solutions. This study experimentally investigates a novel solar-powered humidification-dehumidification desalination system designed to enhance thermal efficiency while relying on low-cost and sustainable materials. The system combines a dual-fluid solar collector for simultaneous air and water heating with custom-fabricated clay components for the humidifier, dehumidifier, and freshwater storage tank. To improve thermal buffering and operational stability, phase change material balls were integrated within the humidifier, and system performance was evaluated with and without auxiliary electric heating. Experimental results show that incorporating phase change material increased freshwater production by 12.5%, from 2.0 L to 2.25 L over a 5 h operation, and improved the gain output ratio by 4.54% to 0.16 compared with the baseline configuration. Under hybrid operation, the system reached a peak production rate of 0.70 L/h, a maximum humid air temperature of 65 degrees C, and a total yield of 3.5 L. A data-driven economic analysis indicates that, with a capital cost of $1114 and annual operating expenses of $30, the system produces 946 L/year with a positive net present value over a 15-year lifetime at a 5% discount rate. Sensitivity analysis confirms economic robustness, with net present values between approximately $982 and $2321 and a levelized cost of water of $0.12-0.19/L. The study demonstrates, for the first time, the effective integration of clay-based HDH components with phase change material for enhanced thermal management, providing a cost-effective and scalable pathway for sustainable small-scale solar desalination beyond conventional HDH designs.