[RE-wrenches] Generators and Grid-tie Systems

[Jason Szumlanski]

This is déjà vu.

I would say that the only safe and "correct" way is to connect the PV inverter output on the line side of the transfer switch. If you are on the generator side of the xfer switch, you are asking for trouble. 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. 

And to answer Eric's #1 question in the original post, you may not need to resize/replace the panel if you follow this approach. We go with a line side tap in this scenario unless there is a compelling reason to do otherwise.

Jason Szumlanski
Fafco Solar
http://fafcosolar.com

>>> Hi Eric:
    Did you notice my e-mail on this subject last week?  I was hoping that someone would have some new, more concrete information on this subject, but I guess the old story still applies.  Here is the basic run down.
    The inverters will likely see the generator as utility power, especially if it is a decent quality generator, with a clean wave form.  The inverters will connect to the generator and back-feed the power into the generator's alternator, causing heat and generator failure.  The solar will burn up the alternator.  I have heard that this has occurred before.
    The only way to prevent this is to connect the solar directly to the utility power (not through the >generator's backed-up emergency load center.)  
>    If you must connect the solar through the generator's emergency load center, then the generator must >not be placed into "Auto," but must instead be in "manual."  The customer must be clear that the solar >breakers must be turned off before the generator is turned on.  This probably should include signage >which makes this clear to the customer.