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--></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 ideas. It definitely sounds like should trying wiring in at least another module in series to see how it acts. </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">Best, August</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><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>Warren Lauzon<br>
<b>Sent:</b> Friday, February 04, 2011 5:55 AM<br><b>To:</b> RE-wrenches<br><b>Subject:</b> Re: [RE-wrenches] Odd Inverter Behavior</span></p></div></div><p class="MsoNormal"> </p><div><div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">That 284 volt number is if the panel is at 25 degrees C. If the panels are in full sun and with little wind, they can be higher temperature than that even in cold weather.</span></p>
</div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"> </span></p></div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">An easy way to get a rough check on that is to disconnect the panels and temporarily haywire an extra panel in series from another string. I suspect the array might have to be rewired for 2 x 12.</span></p>
</div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"> </span></p></div><div><div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black"> </span></p>
</div><div><div><p class="MsoNormal" style="background:whitesmoke"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black"> <a href="mailto:august@luminalt.com" title="august@luminalt.com">August Goers</a> </span></p>
</div><div><p class="MsoNormal" style="background:whitesmoke"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">Sent:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black"> Thursday, February 03, 2011 5:01 PM</span></p>
</div><div><p class="MsoNormal" style="background:whitesmoke"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">To:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black"> <a href="mailto:re-wrenches@lists.re-wrenches.org" title="re-wrenches@lists.re-wrenches.org">RE-wrenches</a> </span></p>
</div><div><p class="MsoNormal" style="background:whitesmoke"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">Subject:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black"> [RE-wrenches] Odd Inverter Behavior</span></p>
</div></div></div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"> </span></p></div></div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">Hi Wrenches - </span></p>
<div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"> </span></p></div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">We were called out today to check out an under performing system installed by another contractor. This is an odd case. </span></p>
</div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"> </span></p></div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">The system has 24 Suntech 180s in three strings of 8 and a SMA Sunnyboy 4000us. Open circuit voltage for each string was about 330 Volts and we verified that everything appeared to be wired in correctly. There is no DC side grounding at all. Just a positive and negative coming down off the roof for each string.</span></p>
</div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"> </span></p></div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">With all modules in direct light the inverter is only pumping out about 250 Watts steady state. We noticed that when we turn it off and on again that the power went up to about 1500 Watts as it started tracking the max power point. Then it slowly veers off course and settles out at about 250 Watts and is running very close to the open circuit voltage of about 330 volts. I would expect the MPP voltage to be closer to ~280 Volts. The inverter MPP tracking range goes down to 250 Volts so I don't think that's the problem.</span></p>
</div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"> </span></p></div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">Anyone ever seen anything like this before? What might be causing the inverter to get confused? The only thing I can think of is that something fishy is going on with the lack of a DC side ground and that certainly needs to be fixed anyway. </span></p>
</div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"> </span></p></div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">All thoughts welcome.</span></p>
</div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"> </span></p></div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">Best,</span></p>
</div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"> </span></p></div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">August</span></p>
</div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"> </span></p></div><div><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"> </span></p>
</div><div class="MsoNormal" align="center" style="text-align:center"><span style="font-family:"Calibri","sans-serif";color:black"><hr size="2" width="100%" align="center"></span></div><p class="MsoNormal" style="margin-bottom:12.0pt">
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