Since the energy for discharge is limited in nature, it is important to ensure that the energy can be used during the maximum peak. If the energy is used early, it is possible that the battery is already close to its maximum depth of discharge at the peak period, when it is most needed. To make effective use of the available stored energy in the battery, it will be discharged in an interval of time that includes the maximum evening peak. The amount of energy under the peak portion of the forecasted load curve within an interval {t1, t2}, EPt1t2, is given by,