[RE-wrenches] Generators and Grid-tie Systems

Drake Chamberlin drake.chamberlin at redwoodalliance.org
Tue Mar 2 06:18:47 PST 2010


At 06:50 PM 3/1/2010, you wrote:

You Wrote

"This is déjà vu.....
The only other choice would be to use a contactor 
to ensure PV disconnection when the grid is down 
- then you could tap the PV on the load side of the transfer switch."

This is definitely deja vu all over again.  A 
system I designed, that disconnected 3 Sunny Boy 
inverters by having contactors on the load side 
of the transfer switch, had a problem.  When the 
contactors opened on generator exercise 
cycle,  the circuit breakers between the 
inverters and contactors tripped.  They did not 
trip every time, but randomly.  One or two would 
trip and the other would not.

After many hours of investigation and talking 
with SMA, no reason for this was ever found. The 
circuit apparently had no problem with nuisance 
tripping when the Sunny Boys were not 
producing.  We have theories, but tech support 
and other professionals do not think this should happen.

If you try this method, please let me know your results.



Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648  
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