A photovoltaic system, comprising at least one string of series-connected solar modules (30, 31) and an inverter for converting the direct current generated by the string; wherein in the normal state, the positive end of the string is connected, via a positive pole string line, to the positive pole DC input of the inverter, and the negative end of the string is connected, via a negative pole string line, to the negative pole DC input (91 b) of the inverter; wherein a test circuit is comprised, which is connected in the positive pole string line between the positive end of the string and the positive pole DC input of the inverter, and/or in the negative pole string line between the negative end of the string and the negative pole DC input of the inverter; wherein the test circuit includes at least a first switch for disconnecting the positive pole string line between the positive end of the string and the positive pole DC input of the inverter, or for disconnecting the negative pole string line between the negative end of the string and the negative pole DC input of the inverter; characterised in that the inverter includes a DC-side capacitor; wherein, in an inverter-side testing process, the test circuit opens the first switch so as to disconnect the DC-side capacitor of the inverter from the string and/or from a voltage supply of the test circuit, at least at one side; and wherein the test circuit is responsive to a voltage drop (1, 2) caused by the disconnection of the DC-side capacitor of the inverter to determine whether the inverter is actually connected to the string lines (102a, 102b) at that moment and/or whether the inverter-side section of the string lines (102a, 102b) is closed or not. wherein in the normal state, the positive end of the string is connected, via a positive pole string line, to the positive pole DC input of the inverter, and the negative end of the string is connected, via a negative pole string line, to the negative pole DC input (91 b) of the inverter; wherein a test circuit is comprised, which is connected in the positive pole string line between the positive end of the string and the positive pole DC input of the inverter, and/or in the negative pole string line between the negative end of the string and the negative pole DC input of the inverter; wherein the test circuit includes at least a first switch for disconnecting the positive pole string line between the positive end of the string and the positive pole DC input of the inverter, or for disconnecting the negative pole string line between the negative end of the string and the negative pole DC input of the inverter; the inverter includes a DC-side capacitor; wherein, in an inverter-side testing process, the test circuit opens the first switch so as to disconnect the DC-side capacitor of the inverter from the string and/or from a voltage supply of the test circuit, at least at one side; and wherein the test circuit is responsive to a voltage drop (1, 2) caused by the disconnection of the DC-side capacitor of the inverter to determine whether the inverter is actually connected to the string lines (102a, 102b) at that moment and/or whether the inverter-side section of the string lines (102a, 102b) is closed or not.