Very important for BESS design: after accommodating aux loss, efficiency loss, you have to consider two more parameters for sizing your BESS that is: 1. Max SOC limit 2. DOD, for example 200 MWH rated, you consider around 235 MWH but 95% max SOC and DOD is also 95%. So more 10% to be added 235+23.5=258.5 MWH----------means 4 more container-----20 cr more capex. Pls ignore if you are maintaining 100% SOC and DOD is also 100%.
For 100% DOD, be ready to pay more and welcome more degradation also.