The more electricity from the photovoltaic (PV) system that is available for users' own needs, the more profitable the system is for them. The PV system produces electricity even when the flats are unoccupied during the day and energy requirements are low, resulting in a power surplus. Without a ZEV, this power is then fed into the power grid and remunerated at only a low price. If the parties merge as a self-consumption initiative (ZEV), they can jointly produce and consume power. For example, the neighbour who works in home office, who is charging his e-car and has the tumble drier running, could use the energy surplus from the PV system and thereby obtain inexpensive eco-electricity.