Abstract：In order to improve the stability and economy of photovoltaic-storage combined power station，a

capacity optimization method of photovoltaic-storage system based on the whole life cycle was proposed. The basic

model of the station was analyzed. The capacity optimization model of energy storage system was established based

on whole life cycle theory. And the revenue and expenditure of the system were considered. The actual case was

simulated and analyzed by the three schemes. It can be obtained that the optimal method of system capacity with

the maximum net present value as the goal has high economy. The net present value is 809 thousand yuan and 738

thousand yuan higher than the method of taking power quality as the goal and not allocating energy storage，

respectively. If the capacity of the energy storage system exceeds 3 MW，it will not give full play to the maximum

benefit，it will lead to the saturation of system power sales revenue and assessment cost，then the battery loss cost is increased. The method of optimizing the system capacity by taking the maximum net present value as the goal can

reduce assessment cost and battery loss cost，it can also increase the system power sales revenue and maximum net present value，and improve power quality.

      Key words：the whole life cycle；photovoltaic-storage power station；energy storage system optimization；

maximum net present value；power quality