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Mark,<br>
<br>
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.<br>
<br>
Kent Osterberg<br>
Blue Mountain Solar<br>
<br>
<br>
<br>
Mark Frye wrote:
<blockquote cite="mid:FC8461684BD94CE881BA47DD47D7B70F@marksdell"
type="cite">
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<div dir="ltr" align="left"><span class="671071521-26032011"><font
color="#0000ff" face="Arial" size="2">Eric,</font></span></div>
<div dir="ltr" align="left"><span class="671071521-26032011"></span> </div>
<div dir="ltr" align="left"><span class="671071521-26032011"><font
color="#0000ff" face="Arial" size="2">I do not have direct experience
with this but have been exploring the issue for a project I am
currently doing.</font></span></div>
<div dir="ltr" align="left"><span class="671071521-26032011"></span> </div>
<div dir="ltr" align="left"><span class="671071521-26032011"><font
color="#0000ff" face="Arial" size="2">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.</font></span></div>
<div dir="ltr" align="left"><span class="671071521-26032011"></span> </div>
<div dir="ltr" align="left"><span class="671071521-26032011"><font
color="#0000ff" face="Arial" size="2">Here are the reasons why:</font></span></div>
<div dir="ltr" align="left"><span class="671071521-26032011"></span> </div>
<div dir="ltr" align="left"><span class="671071521-26032011"><font
color="#0000ff" face="Arial" size="2">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.</font></span></div>
<div dir="ltr" align="left"><span class="671071521-26032011"></span> </div>
<div dir="ltr" align="left"><span class="671071521-26032011"><font
color="#0000ff" face="Arial" size="2">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.</font></span></div>
<div dir="ltr" align="left"><span class="671071521-26032011"></span> </div>
<div dir="ltr" align="left"><span class="671071521-26032011"><font
color="#0000ff" face="Arial" size="2">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.</font></span></div>
<div dir="ltr" align="left"> <br>
<span lang="en-us"><font face="Arial" size="2">Mark Frye</font></span>
<br>
<span lang="en-us"><font face="Arial" size="2">Berkeley Solar
Electric Systems</font></span> <br>
<span lang="en-us"><font face="Arial" size="2">303 Redbud Way</font></span>
<br>
<span lang="en-us"><font face="Arial" size="2">Nevada City, CA 95959</font></span>
<br>
<span lang="en-us"><font face="Arial" size="2">(530) 401-8024</font></span>
<br>
<span lang="en-us"></span><a moz-do-not-send="true"
href="http://www.berkeleysolar.com/"><span lang="en-us"><u><font
color="#0000ff" face="Arial" size="2">www.berkeleysolar.com</font></u></span></a><span
lang="en-us"><font face="Arial" size="2"> </font></span> </div>
<div> </div>
<br>
<div dir="ltr" class="OutlookMessageHeader" align="left" lang="en-us">
<hr tabindex="-1"><font face="Tahoma" size="2"><b>From:</b>
<a class="moz-txt-link-abbreviated" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>
[<a class="moz-txt-link-freetext" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">mailto:re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On Behalf Of </b>Eric
Thomas<br>
<b>Sent:</b> Saturday, March 26, 2011 2:09 PM<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a><br>
<b>Subject:</b> [RE-wrenches] Generator and Enphase<br>
</font><br>
</div>
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.<br>
<br>
Take Care,<br>
<br>
<br>
Eric Thomas<br>
Solar Epiphany LLC<br>
(206) 919-3014<br>
<a moz-do-not-send="true" href="http://www.solarepiphany.com"
target="_blank">www.solarepiphany.com</a><br>
<br>
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