"Storage" refers to technologies that capture electricity, store it as another form of energy (chemical, thermal, mechanical), and then release it for use when needed. Lithium-ion batteries are one such technology. While using energy storage is never 100% efficient - some energy is always lost during energy conversion and recovery - storage allows for flexible use of energy at different times when it is produced. Therefore, storage can improve system efficiency and resiliency, and can improve power quality by matching supply and demand.   Energy storage facilities distinguish between energy capacity, the total amount of energy that can be stored (usually measured in kilowatt-hours or megawatt-hours), and power capacity, the total amount of energy that can be released at a given time. Usually measured in kilowatts or megawatts). Different energy and power capacities stored can be used to manage different tasks. Short-term storage, lasting only a few minutes, will ensure that solar power plants operate smoothly during output fluctuations caused by cloud transmission, while long-term storage can help provide days or weeks of supply during periods of low solar production or major weather events.