Liquid metal battery is a new type of battery. The integrated energy storage system composed of the liquid metal battery energy storage system(BESS)and the hydrogen energy storage system(HESS)can well meet the needs of the microgrid. Firstly

an economical scheduling scheme of the integrated energy storage system is designed

which enables two kinds of energy storage system to stabilize the fluctuation of on-grid photovoltaic power in coordination. Secondly

four indices

which are the cost of the BESS

the annual profit of the microgrid

the expected cycle life of the BESS

and the capacity deficiency days of the BESS

are calculated with the scheduling scheme. An integrated evaluation model for the BESS is established based on these four indices. Finally

a photovoltaic and hydrogen coupled microgrid is used as an example. Evaluation scores of different liquid metal battery capacities are calculated based on the above mentioned model and the optimal capacity of the BESS in this microgrid is obtained.