PV converter, NA protection and PV system

The inverters (1a, 1b) have internal dome switches (2a, 2b), and control-inputs (3a, 3b) coupled with a control-output (6) of a dome switch-less external network- and device protection system (5). Error signal-evaluation units (4a, 4b) evaluate a signal (S) applied to the control-inputs for determining error. An error-free condition of the inverter is determined when the signal exhibits a pre-determined time course, and an incorrect condition of the inverter is determined when the signal deviates from the time course. The switch causes network shutdown in incorrect condition of the inverter. An independent claim is also included for a dome switch-less external network- and device protection system.