Q: With a DC coupled system using the Schneider Electric XW MPPT80-600 charge controller & Tigo optimizers, what else is needed to comply with 2017 rapid shutdown requirements? Can an exterior mounted switch signal the charge controller to shut down from a distance?
A: It would be nice if this worked but there are some potential problems. One is that I’ve heard that the Tigo TS4 may not work with some charge controllers, specifically the XW MPPT80-600. It also does not work with most of the arc fault devices used for this application. The other problem is that there is no way to remotely shut off the XW MPPT80-600 charge control. Even if you do shut it off it will still have voltage on the array side for longer than the time allowed. This means that the Rapid Shutdown (RSD) system must disconnect the charge controller input from the array output circuit. Using an array disconnect near the charge control to trigger RSD might be acceptable to some inspectors in some cases. For use with the XW MPPT80-600 I use two of the MidNite MNSOB, one for each end of the PV circuits. At this time the only charge control I know of that has a built in RSD command and shutdown is the OutBack FM100. The TS4 is currently being tested with that charge control, and the Tigo does work with the FM60 and FM80 charge controls (but not the ICS+).