Effectively using complementary property of various renewable energy sources by an integrated generation system is a concerned study. Considering the uncertainty of PV, spot price and load, the sizing of integrated generation system with combined market operation is a difficult problem. Based on the above uncertain factors, the sizing method of hydro-PV-pumped storage integrated generation system is proposed in this paper. The output characteristic model is established by utilizing the wide range of hydropower output and flexible schedulability of pumped storage. Then, the volatility ratio of the power exchange curve and load tracking coefficient are the evaluation index of the complementary effect, which ensures the stable and smooth output curve. Further, the uncertainty models of PV, spot price and load are established, considering that, the operation of the power generation system is optimized in the day-ahead market, and the predictive deviation of PV and load is balanced in a real-time market. Based on the above factors, the sizing model of the hydro-PV-pumped storage integrated energy system was proposed based on economics and complementary index. Finally, a case study was undertaken, the sensitivity analysis of the economy and complementarity indices was carried out, as the complementarity index is improved, the economy would be down. Further, the optimal sizing of hydro-PV-pumped storage integrated generation system was obtained, hydropower was a total of 165 MW, PV was 100 MW and pumped storage was 50 MW, that could ensure the economy while meeting the complementary index, the effectiveness of the model proposed was verified.Energies 2019, 12, 3001 2 of 23 compensate for PVs better, the pumped storage power station can suppress the fluctuation of output in a shorter time [5], which would improve the grid's ability to PV consumption and the schedulability of the total output of the system. For instance, in China the Longyangxia hydro-PV complementary power station has achieved better coordination operation and complementarity, which has greatly weakened the impact of PV's integration into the power grid [6]. The output model of hydropower is a relatively complex nonlinear function. The upstream and downstream water levels and the net water heads are variables changing over time, the output of hydropower is restricted by the available water resources, has strong seasonal characteristics, therefore, the compensation effect of hydropower on PV is obviously different in different scenarios [7]. Research on the sizing of integrated generation system is particularly important based on multiple typical scenarios.In the electricity market, the uncertain factors would bring more unknown challenges for the sizing of integrated generation system [8], cost from electricity purchase and profit from electricity sales profit are affected by fluctuating spot price, which would bring higher risks for the economy of the system. The higher the transacted electricity of the complementary system in the spot market is, the gr...