Reference is now also made to FIG. 7A which illustrates in more detail converter 705. Converter 705 is equipped with a current sensing mechanism 707 which upon sensing a variation in current through serial string 723 signals controller 306 to shut down and stop converting power. Typically, current sensing mechanism 707 includes an analog/digital converter which continuously feeds data to controller 306. Controller 306 detects a shutdown in current and decides to shut down the converters 705 accordingly.