Energy production from renewable energy sources depends on solar irradiation and wind strength and is therefore subject to extremely strong fluctuations. If too much energy is produced by the renewable energy from photovoltaic systems, biogas and wind power plants, it must be stored in quarter storage or other energy storage systems. When there is no wind and little solar radiation, the energy is fed back into
the grid. In this case, the missing energy is retrieved from the battery storage units and fed back into the power grid.The storage and release of energy that is subject to strong fluctuations is part of the concept of smart charging. Storage batteries, home storage or battery banks are best suited for energy storage and short-term energy recovery. In addition to the batteries mentioned above, storage concepts also include electric vehicle batteries. This concept is called Vehicle to Grid (V2G) and stores excess energy, feeding it back into the smart grid as needed: grid to vehicle (G2V). The smart grid controls battery charging and power draw during peak loads. In the V2G concept, the battery management system
controls the feedingback into and the energy withdrawal from the smart grid via
. TheV2G concept can only work if a sufficient number of electric cars make their batteries
available forenergy buffering. In addition, the charging stations must be able to control the energy bidirectionally between the power grid and the battery. The Chademo charging system
supports the bidirectional flow of energy. If the energy stored in the car batteries is used for the smart home, then this is referred to as Grid to Building (G2B).