[RE-wrenches] grid-tie inverters & generators

jay peltz jay at asis.com
Wed Nov 19 21:21:49 PST 2008


Hi Kelly

It is an interesting issue and was just dicussing this the other day.

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 Nov 19, 2008, at 5:24 PM, Kelly Keilwitz, Whidbey Sun & Wind wrote:

> Wrenches,
> I'm dredging up this subject again (previous postings 6/08) with a  
> simple question that doesn't seem to have been answered:
>
> Is there any issue connecting a batteryless grid-tie PV system to  
> the load side of a panel that is backed-up by a generator on an  
> automatic transfer switch, when the grid is down and the generator  
> running?
>
> In this case the PV is 5.7kW, the inverter an SMA 6000, the  
> generator unknown size/type, but propane, automatic start, and  
> backing up the entire main panel.
>
> SMA tech support first said it's OK, then that the generator will  
> blow up. I can imagine, if the inverter tries to sync with the  
> inverter, that the voltage could rise, causing the inverter to  
> disconnect, wait 5 minutes, repeat. Is there anything nasty that  
> could happen?
>
> 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
>
>
>
>
>
>
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