Why store energy? How energy can be stored? Solar energy is not always generated when energy is most needed. Electricity demand peaks often occur in the afternoon and evening of summer, when solar generation is declining. At these times, temperatures may be highest, people who have been working during the day come home and begin using electricity to cool their homes, cook, and run appliances.
Even when the sun is not shining, storage can help solar contribute to electricity supply. It can also help to smooth out the way solar flows onto the grid. These fluctuations are due to changes in the amount of sunlight falling on photovoltaic (PV) panels or concentrating solar power (CSP) systems. Solar production can be affected by obstacles such as seasonality, time of day, clouds, dust, haze or shadow, rain, snow, and dirt. Sometimes storage is co-located or adjacent to the solar system and sometimes it is independent, but in either configuration, it can help integrate solar more effectively into the energy landscape. So what is energy storage? How energy can be stored?
How energy can be stored? "Storage" refers to the technology that captures electricity and stores it as another form of energy (chemical, thermal, mechanical) that can then be released for use when needed. Lithium-ion batteries are one such technology. Although energy storage will never reach 100% efficiency - some energy is always lost in the process of conversion and recovery - storage allows energy to be used flexibly at different times of energy generation. Therefore, storage can improve system efficiency and resilience and can improve power quality by matching supply and demand.
How energy can be stored? Storage facilities differ in energy capacity, the total amount of energy that can be stored, 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 of storage can be used for different tasks. Short-term storage lasting only a few minutes will ensure that solar power plants operate smoothly during periods of output fluctuations caused by the passage of clouds, while long-term storage will help provide days or weeks of supply during periods of low solar output or major weather events.