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<font size=3>Geoff:<br><br>
We installed a large-ish system for the state of California
(<a href="http://mpandc.com/Portfolio/Commercial/Cal_Trans/cal_trans_gorda.html" eudora="autourl">http://mpandc.com/Portfolio/Commercial/Cal_Trans/cal_trans_gorda.html</a>)
This is a location with homes, an office and workshops that has had a
generator or two running 24/7 for decades.<br><br>
The premise was that a large generator system could handle the peak loads
and the battery based PV system would handle the off peak loads.
There was no load segregation, but instead the design relied on a
"quick response," multi sync-able generator system. The
three generators were to start, sync and assume any loads in excess of
those that the inverters were capable of handling.<br><br>
The premise was fatally flawed. There is no generator system that
can respond to loads quickly enough.<br><br>
There is a design philosophy that was violated on this project: Any
power system needs to be sized large enough to handle the maximum load
that is possible to apply to the system.<br><br>
We are now contracted to double the inverter capacity. The load
studies were re-run but are still inconclusive. We agreed to the
capacity of our installation, but we made no commitment as to the ability
of our equipment to handle unknown loads.<br><br>
Load studies are critical to every design and each power source needs to
adhere to the results of those studies.<br><br>
Good luck.<br><br>
William Miller<br><br>
<br><br>
<br><br>
At 06:48 PM 3/12/2009, you wrote:<br><br>
<blockquote type=cite class=cite cite>Thanks Drake and
others...<br><br>
<br><br>
I will ping SMA on this... and perhaps with utility "special
case" approval a non-typical window could be allowed (with
additional anti island logic switchgear)...<br><br>
<br><br>
keep on slingin panels everyone!<br><br>
For a brighter energy future,<br><br>
Geoff Greenfield<br>
President<br>
Third Sun Solar & Wind Power Ltd.<br>
340 West State Street, Unit 25<br>
Athens, OH 45701<br><br>
740.597.3111 Fax 740.597.1548<br>
<a href="http://www.third-sun.com/" eudora="autourl">www.Third-Sun.com</a><br><br>
Clean Energy - Expertly Installed<br><br>
<br><br>
<br><br>
<br>
----- "Drake Chamberlin"
<drake.chamberlin@redwoodalliance.org> wrote: <br>
> This should be possible. I have discussed what it might take
to set <br>
> up a system like that in the Gambia, with wind generators. It
would <br>
> take a control system with differential current sensors and other
<br>
> features. The UL 1741 specifications would probably need to be
<br>
> opened up on multiple direct grid tie inverters. There would be a
<br>
> practical limit on the percentage of feed to the generator mini
grid.<br>
> This being said, I've not received much encouragement with this
<br>
> idea. There are a lot of factors to consider.<br>
> At 09:35 AM 3/11/2009, you wrote:<br>
> >Undoubtably many of us are getting interesting project requests
as <br>
> >folks want to sprinkle magic stimulus dust on things to make
solar <br>
> >panels grow...<br>
> ><br>
> ><br>
> ><br>
> >We have a project with a huge electrical load, pumping water for
a <br>
> >medium sized city. They want solar... great.
Easy.<br>
> ><br>
> ><br>
> ><br>
> >They had a power outage and kept running with 2.6 MW of diesel
<br>
> >generators. They are interested in solar's ability to do
<br>
> >"backup". I don't think that many batteries will
fit in my pickup <br>
> >truck, and I hate working with 300/0 wire.<br>
> ><br>
> ><br>
> ><br>
> >QUESTION: (and maybe its an easy one and the SMA guys will
say, <br>
> >sure, we did that in Greece). Is it viable to set up a
micro-grid <br>
> >in this scenario and run an island-mode, with available solar
<br>
> >reducing the genny plant demand? Should I just say
"forget it" or, <br>
> >at this MW scale, would the switchgear and effort be
practical?<br>
> ><br>
> ></font></blockquote></body>
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