This article presented the feasibility study of a solar photovoltaic/loop-heat-pipe (PV/LHP) heat-pump water heating system. The overall investigation was undertaken through annual performance prediction, economic analysis and environmental sustainability assessment of the proposed system in regions of London, Shanghai and Hong Kong. The results interpret this system was operated best in the warm climate, such as Hong Kong area, when the total energy amount or heat output is most desired. Hong Kong was found with the electrical, thermal and overall energy output respectively at about 435MJ/m²-yr, 2670MJ/m²-yr and 3104MJ/m²-yr, which could allow the tank-water temperature increasing over the criteria of 45°C throughout the year. In comparison with a conventional electric water heater, the system’s payback periods were estimated at nearly 6, 23, 12 years in above individual climate region owing to different electricity charging tariffs, and the life-cycle cost saving would be around £638, £30 and £303 accordingly during its life span of 25 years. The life-cycle CO2 emission reduction could achieved at about 3.05t, 7.83t and 6.13t respectively. This technology would assist to develop new solar driven heating system and may enable a significant reduction or even elimination of building's carbon footprint in the future.