In addition to the charging infrastructure for electric cars and a photovoltaic system, a holistic energy concept also includes the appropriate energy storage system. Electricity generated by a photovoltaic system is stored in an energy storage unit so that it can be consumed at a later date. Once the energy storage unit is fully charged and no further electricity is being consumed in the building, the surplus electricity is fed into the grid. 

Having your own energy storage ensures greater self-sufficiency and independence from the grid operator. Self-generated electricity is cheaper than that from the grid operator, as it is not subject to electricity tax, grid charges or levies. In addition, the storage system can reduce peak loads in the electricity supply and thus relieve the grid.