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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:#1F497D'>The wire would be a one-time-cost. Even “ultra-efficient” transformers cheat you out of energy for the long-haul, and are an added potential point of failure.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>We are running into customers that have 480V service with 480->120/208 transformers and they want Enphase microinverters. I cringe a little, but go with it if the sustained loads on the secondary side of the transformer are likely to consume all of the PV production. On a larger system (relative to consumption) I would insist on a 480V inverter.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><div><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>Jason Szumlanski<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Fafco Solar</span><span style='font-size:4.0pt;color:#1F497D'> <o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p></div><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></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"'> re-wrenches-bounces@lists.re-wrenches.org [mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>Mark Frye<br><b>Sent:</b> Monday, July 25, 2011 11:11 AM<br><b>To:</b> 'RE-wrenches'<br><b>Subject:</b> Re: [RE-wrenches] Efficient step up, down transformers<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>Lars,</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>Scary stuff. I worked with a system similar to this and went with big wire.</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>The problem with xfrms is that you can either have low standby losses and good efficency at load or vis-a-versa, but you can't really have both. </span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>Were the xfrms specifically wound for 120x480 conversion? If not, it is possible that the coil taps are connected in a manner that is not efficient.</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>That being said, 15.6 A @ 120V sound like an awefully large number. Perhaps you have a bad connection at one of your pull boxes.</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>I would be happy to stop by and take a look at the xfrm spec etc. with you.</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><br></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Mark Frye</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <br></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Berkeley Solar Electric Systems</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <br></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>303 Redbud Way</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <br></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Nevada City, CA 95959</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <br></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>(530) 401-8024</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <br><a href="http://www.berkeleysolar.com/"><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>www.berkeleysolar.com</span></a></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p></div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p> </o:p></span></p><div class=MsoNormal align=center style='text-align:center'><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><hr size=2 width="100%" align=center></span></div><p class=MsoNormal style='margin-bottom:12.0pt'><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"'> re-wrenches-bounces@lists.re-wrenches.org [mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>lars Ortegren<br><b>Sent:</b> Monday, July 25, 2011 7:43 AM<br><b>To:</b> re-wrenches@lists.re-wrenches.org<br><b>Subject:</b> [RE-wrenches] Efficient step up, down transformers</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p><p class=MsoNormal>Wrenches,<o:p></o:p></p><p class=MsoNormal> I recently installed three “ultra -efficient” step up-down transformers on an off grid micro grid project with a 1500’ wire run. The grid is powered by a an old SW4024(120v) output, stepped up to 480v, and stepped down to 240v at two locations. I was told by the manufacturer that they were “99% efficient under a full load”, but upon firing up the system, I found a NO LOAD AMPEREAGE OF 15.6 amps!!! Needless to say, a completely unworkable situation for an off grid scenario, as the 840ah battery would be drained in a couple of hours before anything was turned on. I’m wondering if anyone out there has either found off grid friendly step up-down transformers, or if I’m just screwed and need to pull parallel 4/0 runs (probably the price of a new car) to fix the problem. HELP!<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><b><i>Lars Ortegren<o:p></o:p></i></b></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-family:"Bodoni MT","serif"'>Director of Operations<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Berlin Sans FB","sans-serif";color:#002060'>California Solar Electric Company<o:p></o:p></span></p><p class=MsoNormal>10141 Evening Star Drive, Suite 6<o:p></o:p></p><p class=MsoNormal>Grass Valley, CA 95945<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Phone : (530)274-3671<o:p></o:p></p><p class=MsoNormal>Fax: (530)274-7518<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>