Energy, economic, and environmental performance analysis of hybrid water source heat pumps with directly connected solar collectors

• A hybrid water source heat pump with a direct configuration (DHWSHP) is analyzed. • 3E performances of DHWSHP are compared to conventional heat pumps. • The DHWSHP shows a 53.9 % higher annual COP than conventional heat pumps. • The DHWSHP exhibits a 20 % lower lifecycle cost and 47.0 % lower CO 2 -eq emissions. • DHWSHPs are efficient, cost-effective, and ideal for areas with high solar energy. Heat pumps offer significant environmental benefits by harnessing renewable energy sources. However, those relying on a single heat source often suffer from performance degradation and imbalances between energy demand and supply. Hybrid heat pumps, which combine multiple heat sources, have been developed to address these issues, but most studies have predominantly focused on ground and air sources with limited focus on water sources and plant-level comprehensive evaluations. This study investigates a direct hybrid water source heat pump (DHWSHP) integrating solar energy to evaluate energy, economic, and environmental performance. A validated plant-level model is used for the DHWSHP, and the key design parameters, which are solar collector (SC) area, thermal energy storage (TES) volume, and pump flow rate, are analyzed to optimize performance. The optimized DHWSHP not only maximizes energy performance but also minimizes environmental impacts. Compared with conventional WSHP and indirect HWSHP (IDHWSHP) baselines, the DHWSHP achieves 53.9 % and 22.4 % higher annual system coefficients of performance (COPs), respectively. Furthermore, based on economic and environmental analyses, the life cycle cost and CO 2 -eq emissions of the DHWSHP are 20 % and 47 % lower than those of the WSHP, respectively. These results underscore the DHWSHP as an efficient, economical, and environmentally sustainable solution for building heating and cooling.