The scarcity of freshwater drives the development of efficient, cost-effective small-scale desalination devices that are suitable for off-grid power solutions. This research formulates and evaluates an integrated humidification-dehumidification (HDH) desalination system powered by photovoltaic energy and supplemented by a heat pump cycle. This study experimentally demonstrates the hybrid architecture in outdoor conditions, measuring the influence of airflow and spray rate on water yield, thermodynamic performance, and cost, surpassing previous laboratory-only or single-subsystem investigations. We constructed a full-scale prototype and conducted operations in Ismailia, Egypt (July 2022, 07:00-22:00), adjusting the air mass flow from 252 to 504 kg center dot h- 1 and the humidifier spray rate from 1 to 2 L center dot min- 1. We documented environmental and process variables and calculated distilled-water productivity, gained-output ratio (GOR), and levelized water cost. The system attained a maximum productivity of 17.64 L center dot h- 1 at an air flow of 504 kg center dot h- 1, with a peak gas-to-oil ratio (GOR) of 2.98 and a daily distillate of 141.1 L. Within the identical operational parameters, the projected water cost was $0.034 per liter. The productivity of distilled water rose approximately linearly with air flow within the examined range. The results indicate that a photovoltaic-powered, heat-pump-assisted humidificationdehumidification system can yield significant freshwater production at a low unit cost in arid regions, offering a viable solution for decentralized, sustainable water supply. The originality of this work is the outdoor experimental demonstration and parametric evaluation of an integrated PV-heat-pump-assisted HDH desalination system, including a transparent cost assessment under real weather.