It allows to combine energy production from a photovoltaic power plant and from the grid. If there is sufficient energy production from the sun, this energy is used to run the house and recharge the battery. When the sun is not shining, the energy stored in the battery provides the power to run the house. If the battery is discharged, the house is powered by the grid.
A functional and reliable power grid is not always available. This is even more dificult when there is no grid at all. The only solution to this situation is to install a functional and independent power supply system. In this case, a photovoltaic power system must be designed based on the combined consumption of all electrical appliances in the house.