For example, when there is a storm that suddenly results in an abundance of windgenerated electricity the balance between supply and demand is lost. This causes an overload on the public power grid. A virtual storage consisting of thousands of sonnenBatteries can store huge amounts of excess energy for later use within a matter of seconds. This takes the strain of the public power grid and keeps its operation stable.
Members of the sonnenCommunity can now use their sonnenBatterie to become part of such a battery pool by providing a small share of their individual storage for the public power grid. As a financial compensation, they can get the sonnenFlat for 0 € energy cost (within the limits of the sonnenFlat-rate*).