• Rated power capacity, is the total possible instantaneous discharge capability (in kilowatts [kW] or megawatts [MW]) of the ESS, or the maximum rate of discharge that the ESS can achieve, starting from a fully charged state.
• Energy capacity, is the maximum amount of stored energy (in kilowatt-hours [kWh] or megawatt-hours [MWh]).Such as 51.2V100Ah power wall battery is 5.12KWh.
• Storage duration is the amount of time storage can discharge at its power capacity before depleting its energy capacity. For example, a battery with 1 MW of power capacity and 4 MWh of usable energy capacity will have a storage duration of four hours.
• Cycle life/lifetime is the amount of time or cycles a battery storage system can provide regular charging and discharging before failure or significant degradation. Using capacity reaches 80% of initial capacity will count one cycle. LiFePO4 battery can reach 8000 cycles for home use.
• Self-discharge occurs when the stored charge (or energy) of the battery is reduced through internal chemical reactions, or without being discharged to perform work for the grid or a customer. Self-discharge, expressed as a percentage of charge lost over a certain period, reduces the amount of energy available for discharge and is an important parameter to consider in batteries intended for longer-duration applications. Good quality battery have low self-discharge.
