[RE-wrenches] Interconnection with Generator

Tue Oct 28 17:34:20 PDT 2014

Using PV and battery backup to reduce generator run time is a no-brainer,
and we all are familiar with that sort of stuff. But using PV to augment a
Prime Power generator is not going to work at small generator sizes for a
couple of reasons.
1) Small generators are not built to run continually.
2) Any diesel generator will wet stack and experience problems with
blow-back if ran without load. So you have to load the generator anyway.
I don't think grid tied PV can offer a serious advantage with one generator.

I recently did a design for a 4MW power plant using 5 x 800KW generators
and 400KW of PV, and using ComAp controllers and SMA Fuel Save technology.
This works because there was five generators, so the generators could be
taken offline progressively as the PV came online. Include some grid
storage and it all gets very interesting. You can model all of this in
Sunny Design 3+. Very cool software.

On Tue, Oct 28, 2014 at 7:35 PM, <Jarmo.Venalainen at schneider-electric.com>
wrote:

> Hi:
>
> Xantrex did some early work on generator with inverter compatibility back
> in 2007.  AC coupling PV to generators was very new back then and we wanted
> to find the benefit of using a battery based inverter to reduce the run
> time of generators.  One system was a small 5kW off-grid house and the
> second a 90kW generator running a couple of dozen homes.  For the trial is
> set up with power monitoring for back-feed and much more.
>
> The systems are still running.  Here are a few training slides which
> summarize the results and a link to the archived study from 2007 at the
> Natural Resources Canada.
>
>
>
>
> http://www.nrcan.gc.ca/energy/publications/sciences-technology/renewable/solar-photovoltaic/6215
>
> The bullet form summary is:
>
> - The smaller the generator, the large the savings whether you grid tie to
> the generator or use a battery based inverter to reduce generator run time.
>
> - PV is not needed to get the bulk of the savings in systems using battery
> based inverters to reduce run time of small generators.
>
> JARMO
>
>
> On Oct 28, 2014 4:48 AM, "Corey Shalanski" <*cshalanski at joule-energy.com*
> <cshalanski at joule-energy.com>> wrote:
> Wrenches,
>
> We frequently encounter residences with backup generators. The question
> that arises: how should the PV system be interconnected?
>
> I have searched the archives and found some good information about this
> subject, but nothing definitive. I have fallen into the habit of broadly
> proclaiming that the PV system *must* be interconnected on the "utility"
> side of the transfer switch - in order to prevent backfeeding into the
> generator and thereby eliminate unintentional equipment damage. Is this
> concern justified? If so, should this be an absolute rule or would it
> depend on the generator make/model?
>
> Thanks for any insights.
>
> --
> Corey Shalanski
> Joule Energy
> New Orleans, LA
>
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> _____________________________________________________________________________________
>
> * Jarmo Venalainen*  |  * Schneider Electric **  |  Solar Business*  |
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-- 
Chris Mason
NABCEP Certified Solar PV Installer™
Solar Design Engineer
Generac Generators Industrial technician

www.cometsolar.com <http://www.cometenergysystems.com>
264.235.5670
869.662.5670
Skype: netconcepts
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