HOMER calculates a suggested value of lifetime throughput for a storage based on the information entered in the lifetime curve. The suggested value is equal to the average value of the lifetime throughput values that fall within the allowable range of depth of discharge. (This allowable range is determined by the minimum state of charge -- if the minimum state of charge is 40%, then the storage will only experience depths of discharge between 0% and 60%.) You can accept the suggested value or modify it according to your judgment.
See also