Optical efficiency differences between the evacuated tube receiver and a triangular cavity receiver are theoretically analyzed. Furthermore, the calculation expressions of the critical installation position for the optimal effective absorptivity of the cavity receiver are given, which is validated through TracePro software simulation. Simulation results show that the optical efficiency of cavity receiver can reach 89.1%, while the evacuated tube′ s efficiency is 77.1%. Meanwhile, the installation position deviations in the vertical or parallel direction have similar impacts on efficiencies of both receivers, but the cavity′s efficiency curve is slightly asymmetrical, which indicates that the best vertical installation position is 5~20 mm below focal length. It is also observed that mirror deflection error has greater influence on receiver efficiency, and the deflection angle should be controlled within 0.4°. Beyond this range, the descend degree of cavity receiver efficiency is less than the evacuated tube, which is confirmed by experimental test results. In addition, the thermal efficiencies of both receivers would meet at equilibrium point of 55.0%, in the case of ideal installation condition and heat collecting temperature of 168.6 ℃. Below this critical temperature, cavity receiver has a higher efficiency.