Abstract: In view of the disadvantages of redundant or insufficient optical storage capacity configuration in a single time scale, a dual-timescale based capacity configuration model was established according to the typical data of photovoltaics and loads. The dynamic operation characteristics and constraints of energy storage as well as the power supply reliability of isolated DC microgrids were taken into consideration. Moreover, a mixed stationary-mobile energy storage model was proposed to deal with power shortage issue caused by network fluctuations. Improved particle swarm optimization was applied in simulation example for solving, and result proved the superiority of the mixed storage model and dual timescale analysis. Moreover, the feasibility of the capacity configuration model was confirmed, which can provide a reference for photovoltaic and energy storage capacity allocation.