<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"><meta name="Generator" content="Microsoft Word 14 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p
{mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
p.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-priority:99;
mso-style-link:"Balloon Text Char";
margin:0in;
margin-bottom:.0001pt;
font-size:8.0pt;
font-family:"Tahoma","sans-serif";}
span.BalloonTextChar
{mso-style-name:"Balloon Text Char";
mso-style-priority:99;
mso-style-link:"Balloon Text";
font-family:"Tahoma","sans-serif";}
span.hoenzb
{mso-style-name:hoenzb;}
span.EmailStyle21
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:#1F497D;}
span.EmailStyle22
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:#1F497D;}
span.EmailStyle23
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style></head><body lang="EN-US" link="blue" vlink="purple"><div class="WordSection1"><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Hi All --</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Thanks for the feedback. Yea, we've always used Sunny Islands with batteries for anything that needs to run off grid. This was more of just a theoretical question. From what I heard, it sounds like the excess current from the PV might damage the generator (or I suppose anything running in the house) and this will result in higher voltage. Best case, the inverter will cycle on and off. V = I*R. Worst case something blows up.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Thanks, August</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><div><div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0in 0in 0in"><p class="MsoNormal">
<b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a> [mailto:<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On Behalf Of </b>Greg Seelhorst<br>
<b>Sent:</b> Wednesday, December 12, 2012 8:18 PM<br><b>To:</b> 'RE-wrenches'<br><b>Subject:</b> Re: [RE-wrenches] off grid PV connected to generator</span></p></div></div><p class="MsoNormal"> </p><div><p class="MsoNormal">
<span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1f497d">August –</span></p><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1f497d">I’ve seen this scenario and it is not pretty like William suggests. </span></p><p class="MsoNormal">
<span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1f497d">From what I’ve seen, the problem is not so much the power of the PV being more than the generator, but moreso if the 1) generator is synchronous or non-synchronous with the inverted AC (sine wave) and 2) if the loads are less than the PV. The generator will ‘create’ the voltage and run even if there are zero loads. The inverted AC (from PV) wants to push current onto the ‘local grid’ and if there are no loads (nor heat sink diversion or batteries to charge) then the current will try to backfeed the generator. </span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1f497d">My recommendation is to get a critical loads panel for the generator only back-up, or go grid-tie with back-up using a Sunny Island, or the like, that make the switch seamless during an outage.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p></div><p class="MsoNormal"><b><span style="font-family:"Arial","sans-serif";color:#1f497d">Greg Seelhorst</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"></span></p>
<p class="MsoNormal"><i><span style="font-family:"Arial","sans-serif";color:#1f497d">Designer/Project Manager</span></i><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"></span></p>
<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:#1f497d">NABCEP Certified Solar PV Installer™</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"></span></p>
<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:#1f497d"> </span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"></span></p>
<p class="MsoNormal"><b><span style="font-family:"Arial","sans-serif";color:#1f497d">POSITIVE ENERGY, Inc.</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"></span></p>
<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:#1f497d">510 S. Main Street</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"></span></p>
<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:#1f497d">Las Cruces, New Mexico 88001<b><br></b>Cell: 575-650-1883</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"></span></p>
<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:#1f497d">Office: 575-524-2030</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"></span></p>
<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:#1f497d">FAX:</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><span style="font-family:"Arial","sans-serif";color:#1f497d">575-915-1788</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"></span></p>
<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:#1f497d"> </span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><a href="mailto:gs@PositiveEnergySolar.com" target="_blank"><b><span style="font-size:12.0pt;font-family:"Arial","sans-serif"">gs@PositiveEnergySolar.com</span></b></a></span><span style="font-family:"Arial","sans-serif";color:#1f497d"><br>
</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><a href="/www.positiveenergysolar.com">www.positiveenergysolar.com</a></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><a href="http://www.positiveenergysolar.com/"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d;text-decoration:none"><img border="0" width="263" height="30" id="Picture_x0020_2" src="cid:image001.png@01CDD901.B75F1930" alt="http://www.positiveenergysolar.com/images/stories/PE-logotype.png"></span></b></a><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p></div></body></html>