The rated cooling capacity of an absorption subsystem in a solar absorption-subcooled compression hybrid cooling system is difficult to design for the entire working period owing to the differences in monthly meteorological data. In addition, the annual performance of the hybrid system deteriorates significantly when the size of the absorption subsystem is designed improperly. Accordingly, the effect of the nominal cooling capacity in the absorption subsystem on the annual performance of an SASCHCS is assessed by means of energy, economic, and environmental analyses. A corresponding model is developed. Additionally, the annual total energy savings, payback period, net present value, and CO2 emissions for different sizes of absorption subsystems are calculated and analysed. It is found that the size of the absorption chiller in the solar absorption-subcooled compression hybrid cooling system should be designed according to the meteorological data for the month of May, when the solar irradiance is at a medium level. The maximum energy saving fractions of a hybrid facility from April to October are 7.67%, 9.42%, 7.62%, 9.16%, 9.29%, 10.2%, and 11.0%, respectively. The minimum values of LCCP and CO2 emissions are 2532.46 t and 113.04 t, respectively. The rated cooling capacity of the absorption subsystem should be designed as 50 kW according to the maximum energy savings and optimal CO2 emissions. It turns to be 47 kW based on the shortest payback period of 17.73 years, as well as the highest net present value. This paper is helpful in improving the performance of solar absorption-subcooled compression hybrid cooling system during the entire operational period.