<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Kirk</div><div>The 43volt 5.5 amp panel will operate at 3.6 amps, so it's voltage will move up toward open circuit voltage, raising the mppt voltage of that string. I would bet that the voltage of that entire string will rise to match the higher voltage string by moving toward open circuit voltage. It should work fine.</div><div>David Katz<br><br>Sent from my iPhone</div><div><br>On Apr 28, 2013, at 9:01 AM, "Kirk Herander" <<a href="mailto:kirk@vtsolar.com">kirk@vtsolar.com</a>> wrote:<br><br></div><blockquote type="cite"><div>
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</o:shapelayout></xml><![endif]--><div class="WordSection1"><p class="MsoNormal"><span style="font-size:14.0pt">Hello everyone,<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">I am at present adding to a -20- panel array of old Sanyo HIT “lipped” 200 watt panels. They are configured in -4- series strings of -5- panels, with a string MPP voltage of 279 vdc (55.8 v, 3.6 a each). The customer wants to add another nominal 2 kw using the (now) Panasonic 235 watt HIT’s which have an MPP of 43.0 vdc, 5.5 a. I am locked in to an existing SMA 6000US inverter. Obviously I cannot get all the strings to the same voltage. But I can get relatively close by rewiring:<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">String 1: -7- 200 watt @ 55.8 ea. = 390.6 v MPP<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">String 2: same as string 1<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">String 3: -6- 200 watt @ 55.8 plus -1- 235 watt @ 43.0 = 377.8 v MPP<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">String 4: -9- 235 watt @ 43.0 = 387 v MPP<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">Under this scenario there is a delta of about 12 vdc between high and low MPP. I assume the entire array will operate at the 377.8 V MPP. I know that the 235 watt panel will be current limited also in string 3. Am I missing anything obvious in doing it like this? How will the inverter arrive at an operational MPP voltage?<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">PS. In a pinch I could install a leftover 200 watt HIT I have in the shop. That way I could have -3- strings of -7- 200’s @ 390.6 v MPP, and one string of 235’s @ 387v MPP. But I would prefer not to use this panel since the frame is damaged.<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">Kirk Herander<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">VT Solar, LLC<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">dba Vermont Solar Engineering<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">NABCEP<sup>TM </sup>Certified Inaugural Certificant<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">NYSERDA-eligible Installer<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">VT RE Incentive Program Partner<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:14.0pt">802.863.1202<o:p></o:p></span></p><p class="MsoNormal"><o:p> </o:p></p></div></div></blockquote><blockquote type="cite"><div><span>_______________________________________________</span><br><span>List sponsored by Home Power magazine</span><br><span></span><br><span>List Address: <a href="mailto:RE-wrenches@lists.re-wrenches.org">RE-wrenches@lists.re-wrenches.org</a></span><br><span></span><br><span>Change email address & settings:</span><br><span><a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a></span><br><span></span><br><span>List-Archive: <a href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org">http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a></span><br><span></span><br><span>List rules & etiquette:</span><br><span><a href="http://www.re-wrenches.org/etiquette.htm">www.re-wrenches.org/etiquette.htm</a></span><br><span></span><br><span>Check out participant bios:</span><br><span><a href="http://www.members.re-wrenches.org">www.members.re-wrenches.org</a></span><br><span></span><br></div></blockquote></body></html>