This doesn't solve the reliability concern of a contactor but on a webinar I heard a rep from Schneider say the XW (with GEN and GRID AC IN's) will not backfeed a generator and will do it without a contactor. Is that true?
Larry Liesner Wirewiz Westport, CT Phone: 203-644-2404 Fax: 203-557-0556 [email protected] www.wire-wiz.com On Mar 27, 2011, at 3:50 PM, Kent Osterberg wrote: > Larry, > > Yes, the PV system was straight grid-tie. The back-upped loads were only > covered by the generator (no battery-based inverter was involved). The ATS > also does the generator startup, so an inverter on the backed-upped loads > would require some thinking I haven't done. If the generator startup were > changed, my first thought would be to put the battery-based inverter on the > generator side of the ATS. > > Kent Osterberg > Blue Mountain Solar > > > > [email protected] wrote: >> >> Kent, >> >> Situations vary but this one line helps a lot, thanks. >> >> So, "To PV System" would go to the output of a grid tie inverter and "To >> Backed Up Loads" would go to the AC IN (transfer switch) of a battery >> inverter. >> >> I have been going to homes with existing 100A gen/utility ATS and wondering >> if I could keep it as is and be able to add a grid tie battery backup to it >> (using same backup loads). This schematic would work in that situation as >> well but wouldn't have the "To Non-Backed UP Loads" tap. >> >> >> Larry Liesner >> Wirewiz >> Westport, CT >> Phone: 203-644-2404 >> Fax: 203-557-0556 >> [email protected] >> www.wire-wiz.com >> >> >> >> On Mar 27, 2011, at 2:36 PM, Kent Osterberg wrote: >> >>> Larry, >>> >>> Situations vary so much that this might not be very useful. But here you >>> go. The attached sketch shows how we recently connected a customer that had >>> a backup generator and transfer switch that wasn't service rated. There >>> were nice gutters existing from the original install so accessing points to >>> tap conductors wasn't difficult. We could have connected the inverters to >>> the non-backed upped loads panel instead, but the utility requires an >>> accessible disconnect by the meter so it was more convenient to just get >>> into the gutter. >>> >>> Kent Osterberg >>> Blue Mountain Solar >>> >>> >>> >>> [email protected] wrote: >>>> >>>> Kent, Jason, or anyone else >>>> >>>> Would you a have a simple one-line you could share for wiring the inverter >>>> on the utility side of the transfer switch? >>>> >>>> Thank you. >>>> >>>> Larry Liesner >>>> Wirewiz >>>> Westport, CT >>>> Phone: 203-644-2404 >>>> Fax: 203-557-0556 >>>> [email protected] >>>> www.wire-wiz.com >>>> >>>> >>>> >>>> On Mar 26, 2011, at 6:04 PM, Jason Szumlanski wrote: >>>> >>>>> We’ve explored this strategy many times due to all of the whole house and >>>>> critical load generators in Florida. We’ve stayed away from the contactor >>>>> solution because of the potential for the NC contactor failing to open, >>>>> keeping the inverters “online” when transferred to generator power. While >>>>> unlikely, this is a possibility that must be considered. >>>>> >>>>> The other issue presented here is that the inverters will shut down every >>>>> time the generator exercises. >>>>> >>>>> The only sure-fire way seems to be wiring the inverter on the utility >>>>> side of the transfer switch, as Kent said. >>>>> >>>>> Jason Szumlanski >>>>> Fafco Solar >>>>> >>>>> >>>>> From: [email protected] >>>>> [mailto:[email protected]] On Behalf Of Kent >>>>> Osterberg >>>>> Sent: Saturday, March 26, 2011 5:56 PM >>>>> To: RE-wrenches >>>>> Subject: Re: [RE-wrenches] Generator and Enphase >>>>> >>>>> Mark, >>>>> >>>>> I agree it is best to wire the inverters on the utility side of the >>>>> transfer switch. When that isn't easy, a normally closed contactor that >>>>> is opened by generator voltage, will isolate the inverters from the >>>>> generator and allow automatic return to utility operation when the >>>>> generator is off. >>>>> >>>>> Kent Osterberg >>>>> Blue Mountain Solar >>>>> >>>>> >>>>> >>>>> Mark Frye wrote: >>>>> Eric, >>>>> >>>>> I do not have direct experience with this but have been exploring the >>>>> issue for a project I am currently doing. >>>>> >>>>> My response will be to take the trouble to interconnect the Enphase >>>>> inverters on the line side of the tranfer switch so that the inverters >>>>> can never be connected to the generator. >>>>> >>>>> Here are the reasons why: >>>>> >>>>> 1 - Enphase states that any such application is considered an "off-grid" >>>>> application which voids their warrenty. As I am installing under the >>>>> California CSI program, I am required to provide a 10 year manufacture >>>>> equipment warranty so I cannot afford to install the inverters in a >>>>> dis-allowed manner. >>>>> >>>>> 2 - Enphase states that the waveform of the generator may be "clean" >>>>> enough such that the inverter may attempt to syncornize and connect to it >>>>> as if it were the utility. If this were to happen Enphase believes the >>>>> inverters will ruin the generator regulator before the generator ruin the >>>>> inverter. I don't want to be the one to run the experiment to find out >>>>> which would be which. >>>>> >>>>> 3 - I considered a contactor on the output of the inverters, such that >>>>> the inverters would isolated by a loss of line voltage, requiring some >>>>> form of reset. Ulitmately my customer agreed with me that this was an >>>>> undesirable constraint on the operation of an otherwise reliable >>>>> grid-tied system and it was not clear that this would satify the warranty >>>>> issue. >>>>> >>>>> Mark Frye >>>>> Berkeley Solar Electric Systems >>>>> 303 Redbud Way >>>>> Nevada City, CA 95959 >>>>> (530) 401-8024 >>>>> www.berkeleysolar.com >>>>> >>>>> >>>>> From: [email protected] >>>>> [mailto:[email protected]] On Behalf Of Eric >>>>> Thomas >>>>> Sent: Saturday, March 26, 2011 2:09 PM >>>>> To: [email protected] >>>>> Subject: [RE-wrenches] Generator and Enphase >>>>> >>>>> I have a customer with a "30A Mechanically Interlocked Breaker" for their >>>>> generator feed at the main panel. My question is: If the home power is >>>>> transferred from utility to generator power, will the backfed PV see the >>>>> generator as grid power and sync up and produce? This is a nice Honda >>>>> Generator so the power should be fairly clean. Any experiences are >>>>> appreciated. >>>>> >>>>> Take Care, >>>>> >>>>> >>>>> Eric Thomas >>>>> Solar Epiphany LLC >>>>> (206) 919-3014 >>>>> www.solarepiphany.com >>>>> >>>>> >>>>> _______________________________________________ >>>>> List sponsored by Home Power magazine >>>>> >>>>> List Address: [email protected] >>>>> >>>>> Options & settings: >>>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>>>> >>>>> List-Archive: >>>>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>>>> >>>>> List rules & etiquette: >>>>> www.re-wrenches.org/etiquette.htm >>>>> >>>>> Check out participant bios: >>>>> www.members.re-wrenches.org >>>>> >>>> >>>> >>>> _______________________________________________ >>>> List sponsored by Home Power magazine >>>> >>>> List Address: [email protected] >>>> >>>> Options & settings: >>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>>> >>>> List-Archive: >>>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>>> >>>> List rules & etiquette: >>>> www.re-wrenches.org/etiquette.htm >>>> >>>> Check out participant bios: >>>> www.members.re-wrenches.org >>>> >>>> >>> <OneLine.JPG>_______________________________________________ >>> List sponsored by Home Power magazine >>> >>> List Address: [email protected] >>> >>> Options & settings: >>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> >>> List-Archive: >>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>> >>> List rules & etiquette: >>> www.re-wrenches.org/etiquette.htm >>> >>> Check out participant bios: >>> www.members.re-wrenches.org >>> >> >> >> _______________________________________________ >> List sponsored by Home Power magazine >> >> List Address: [email protected] >> >> Options & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out participant bios: >> www.members.re-wrenches.org >> >> > _______________________________________________ > List sponsored by Home Power magazine > > List Address: [email protected] > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org >
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