[RE-wrenches] SB Power during countdown

[Drake]

Hello Wrenches,

I'm troubleshooting an SWR 2100U.  During the countdown, the inverter 
begins producing power.  There is a utility style kWh meter (Hialeah 
meter) next to the inverter.  During the countdown the wheel on the 
meter spins fast for several seconds, then stops.  The inverter 
continues to count down and the green light continues to flash in the 
waiting mode.  The display on the inverter never says it is producing power.

The inverter blew its ground fault fuse.  There is no indication of a 
fault.  I haven't Megger tested yet, but array produces around 500 
Voc.  With wires off the terminals, in free air, there are readings 
of between 0.0 and 0.1 V to ground on both the positive and negative 
wires.  SMA tech support agrees that this is a very clean reading.

This inverter shows all the signs of being a glitchy unit, for 
sure.  The problem is that this is a replacement for the original 
inverter that had very similar issues.

What would make an inverter produce power during the countdown?  Is 
this part of a larger pattern?  Is there a problem with the system, 
or did I get a second, problematic inverter?

Thanks,

Drake