ZEN Renewables Photovoltaïc systems are installed grid connected. A private installation will convert the AC power to DC power, wich can be consumed directly. The public power network is a backup supplier when the solar energy is not efficiently present (at night, shorter winter days, heavenly clouded weather). Secondly, the generated power can be "given" to the public network at times of non-consumation.

Therefore the yearly production is to be related to the yearly need of the private household.