This senior year project presents a comprehensive numerical investigation of a novel hybrid system for sustainable freshwater production. The proposed design integrates a multi-mode heat pump (HP) with a humidification–dehumidification (HDH) desalination unit and a concentrating photovoltaic-thermal (PVT) collector. The objective is to address the high energy consumption and limited flexibility of traditional desalination systems by utilizing solar energy to generate both electricity and thermal power. A detailed thermodynamic model will be developed and simulated using Engineering Equation Solver (EES) software to evaluate the system’s performance under various operational scenarios. Key performance indicators including the Gain Output Ratio (GOR), Specific Work Consumption (SWC), and freshwater production rate will be systematically analyzed. The study is expected to demonstrate a 15–18% reduction in SWC and a 20–25% enhancement in GOR compared to conventional HP–HDH systems, with an estimated freshwater production cost ranging from 0.024 to 0.027 USD/kg. Through extensive parametric and comparative analyses, this research seeks to identify the optimal operating configuration for maximizing efficiency under varying solar conditions. The outcomes will provide a validated simulation framework and valuable design insights for advancing solar-driven desalination technologies that contribute to energy efficiency, water security, and long term sustainability.