Reference is now also made to FIG. 8A which illustrates converter 805 in more detail. The keep-alive signal is constantly monitored and detected by a line communications receiver 807. Only while receiver 807 senses the keep-alive signal does receiver 807 provide an enable signal to controller 306. When controller 306 doesn't receive an enabling signal from receiver 807, controller 306 shuts down power conversion of converter 805.

Alternatively, instead of a “keep-alive” signal, a stop signal 814 which is first generated by monitoring and detection mechanism 701 when an islanding condition is detected, is transmitted to receiver 807. The stop signal is transmitted over line communications by superimposing a varying (e.g. 10 Khz to 100 Mhz) signal over the power lines of serial string 823. Receiver 807 receives the stop signal and relays the stop signal to controller 306 using, e.g., a single disable bit. Controller 306 on receiving a disable signal, stops converting power to the output of converter 805. Typically, when converters 805 are disabled they go into a bypass mode which allows current from other converters 805 to pass through. Hence, the stop signal may be continued until all power stops being supplied on string 823 by all of converters 805.