Checking arrangement for individually built-up network of photovoltaic device

A monitoring device for an ungrounded electric network of a photovoltaic system. The monitoring device includes a short circuit measuring circuit having a first electric measuring circuit conductor connecting a first electric pole of the photovoltaic system with a reference point by means of at least one protective component, and second electric measuring circuit conductor for connecting a second electric pole of the photovoltaic system with ground be means of at least one protective component. A first component is connected between one of the measuring circuit conductors and ground, and a measuring device for measuring an electric parameter of the first component, wherein a non-zero value of the parameter and/or a change of the value of the parameter indicate an electric fault between the photovoltaic system and ground.