Last but not least, the figure for ‘Capacity [kWh]’ must be interpreted as the practically usable capacity, which is not necessarily the same as the purchased capacity.
Traditional storage technologies do generally not allow full charge/discharge between 0% and 100% without compromising the system’s lifetime. In other words, if a traditional battery would be used between 0% and 100%, then its lifetime will be dramatically shortened.
In battery specifications, this phenomenon is referred to as ‘Depth of Discharge’ or DoD [%], describing the maximum allowed charge and discharge level. Following graph shows the relation between DoD and Lifetime of traditional storage systems.
Source: Levelised cost of storage: A better way to compare battery value by JOHN RODRIGUEZ on MAY 23, 2017, in USEFUL SOLAR TOOLS AND RESOURCES, BATTERIES & ENERGY STORAGE