Solar water heating systems have been proven to be reliable and economical for producing hot water. In Taiwan, the cumulative area of solar collectors installed by the end of 2014 was approximately 2.39 million m2, in which approximately 98% of the systems were installed in the domestic sector. Further, preheating water for livestock processing plants, where hogs are killed and processed for consumption, is potential of cost-effective application. Heated water can be used in the plants for evisceration, sanitation during processing, and the daily cleanup of the plant. In Taiwan, the number of pig farming was 8,457, and the supply for slaughtering was approximately 7.47 million heads in 2013. A livestock processing plant using combined solar thermal and heat pumps systems was chosen as the case study by the field measurements. The results showed that the hot water consumption, mass flow rate, operation of circulation pumps and heat pumps would affect the thermal efficiency, economic viability and attractiveness of a system. This study would provide useful information for all parties related to this market, manufacturers, potential users and policymakers in Taiwan and other countries.