[RE-wrenches] grid-tie inverters & generators

[Kelly Keilwitz, Whidbey Sun & Wind]

Jay, Drake, Don, Jeff & Wrenches,

The relay seems like a reasonable solution. However, if the main panel is
entirely backed up by the genny, to power the relay from the grid (only)
requires a line-side tap, yes? Is there a simple solution that I¹m missing?

We have another, similar system completed, just waiting for 2009 to
commission. So, I'd like to know if it's really needed, and the best
procedure, before investing the time and cost to go back.

There must be many Wrenches who have encountered such generator backup
systems. Come on, how many of you, besides Don, have connected the inverter
to the gen-tran main panel (with no disconnection relay) without a problem?
Anyone else had a bad experience, like Jeff?


Thanks,
-Kelly

Kelly Keilwitz, P.E.
Whidbey Sun & Wind, LLC
Renewable Energy Systems
NABCEP Certified PV Installer
987 Wanamaker Rd, 
Coupeville, WA 98239
PH & FAX 360-678-7131
sunwind at whidbeysunwind.com


On 11/19/08 9:21 PM, "Jay Peltz" <jay at asis.com> wrote:

> Hi Kelly
> 
> I think what happens if the inverter backfeeds the genny, the generator
> voltage will go up, if it goes up enough, it will go outside the window of the
> inverter and the inverter will drop out, voltage will them return to normal,
> inverter will reconnect and repeat.
> 
> But I sure wouldn't want to fix the generator.  A relay powered from the grid
> will take care of the problem.
> 
> jay
> 
> peltz power
_______________
> 
On 11/19/08 8:52 PM, "Drake Chamberlin"
<drake.chamberlin at redwoodalliance.org>
 wrote:
> It is recommended to use a relay to disconnect the inverter when the
> panel is being fed by the generator.
_______________ 

On 11/19/08 7:28 PM, "I2P at aol.com" <I2P at aol.com> wrote:
>That is the way I see it. I have tested systems with gens and had no
> issues. The Sunny Boy would not boot to a gen source.  However, you can
> understand what the official position must be. There exist gensets with
> accuracy or it might just happen by chance. Low probability, but not zero.
>  
> Don Loweburg
___________________
 
On 11/19/08 9:42 PM, "Jeff Clearwater, Village Power Design"
<jeffc at villagepower.com> wrote:
> 
> We burnt up a gen set's voltage regulator on an off-grid system sunny
> island/sunny boy system when we took the sunny island's off-line but didn't
> shut off the sunny boy.  So the SB backfed the genny and fried the very
> expensive voltage regulator on a 30 KW system. SMA had us install a relay to
> tell the SB to shut down as soon as the AC reference from the SI was gone.
> Same situation as grid-tie really in terms of your question.
> 
> Jeff