Aiming to enhance the performance of heat pump under adverse working conditions by utilizing solar energy and air source simultaneously, a novel air source hybrid solar assisted heat pump (AS-SAHP) system with finned tube evaporator and collector evaporator connected in series has been proposed. A mathematical model is established to characterize the behavior of the proposed system. Then the influence of key factors such as ambient temperature, solar irradiation, and evaporating area has been analyzed. The results indicate that the AS-SAHP system can operate efficiently under a range of working conditions, with the average COP of 2.71 at the solar irradiation of 100 W/m(2) and ambient temperature of 10 degrees C. Due to the heat transfer characteristics of finned tube evaporator and collector evaporator existing striking difference, the hybrid heat source in AS-SAHP system can play the complementary role at various operating conditions. To assess the irreversibility of the AS-SAHP system, the exergy loss ratio of each component has been analyzed. The results illustrate that most of the irreversibility is yielded in compressor and condenser. At last, the performance of AS-SAHP has been compared with that of conventional ASHP and DX-SAHP, and it is proven that the AS-SAHP system shows the optimal performance. (C) 2019 Elsevier Ltd. All rights reserved.