The Mastervolt Smart Grid Box is a device which is able to control the maximum output power and frequency window of all connected Mastervolt PV inverters. The output power and frequency window can be controlled by the local net operator in different ways.
According to the Italian CEI 0-21 directive, the Smart Grid Box is obligatory in certain installations. More information can be found here.
In Germany this device can be used as Ripple Control Receiver.