I'm with you guys and we actually had a bad transformer bushing at this
site initially which was causing exactly that issue. The site still runs
high (498-508Vac nominal) but is well below the 528V default upper limit of
the TLs, and the shut-offs are not correlated with higher AC voltages.
Also
It sure looks like it could be an AC voltage issue. Around here the utility
voltage is often high in the morning and then gets dragged down when loads
in the neighborhood spike from air conditioning (yes, even in winter here
in Florida). We see drop-outs (with other brand inverters) in the
Andrew, I've seen this in multiple inverter systems when the AC voltage
gets pushed outside the upper limit by the inverter output currents. One
or two inverters will cycle on-off, those with the lowest setting or
tolerance. Cause can be (1) high AC voltage from the utility to start
with, and/or
Andrew
What is the AC Voltage when this occurs, to much VAC will shut down the
inverter. It also looks like you are clipping all the inverters during the
mid day, is due to low temps or does this always happen. What is the DC
MPPT voltage, is it at the upper limit.
Jerry
NABCEP PV inspector
On
Wrenches,
I have a couple of Solectria 36TLs at a small community solar site in CO
that shut themselves down occasionally for what appears to be no reason.
[image: image.png]
Voltages and frequency are normal, firmware is updated, IR scan shows
nothing irregular, and the other 2 inverters at
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