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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='font-family:"Arial","sans-serif";color:#1F497D'>Russell:<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>I am curious, how do you perform anti-islanding tests?<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>The SW4024 should work great with a 3.3 kW array. Due to battery and inverter inefficiencies you would never see the full 3.3 sell back any way, which is less than the rating of the inverter.<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>The SW4024 was UL listed at one time but the listing was removed due to failure to apply the testing regimen properly, if I remember correctly. We were not required to retrofit existing installations by adding the GTI, only to add them to pending installations. Our utility lost a lot of applications during that era and years later, when forced to reapply, they accepted the SWs without GTIs. If you really want one, I have one in the shop I would sell cheap, but I don’t have much faith in the design.<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>Lastly, I can’t comment on the efficiency of the SW versus a modern GTBB inverter. That question would justify some research. If the SW is significantly less efficient than, say, a Sunny Island, the impetus may be there to upgrade.<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>William Miller<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><img width=64 height=28 id="Picture_x0020_1" src="cid:image004.jpg@01CFCC0D.965619E0" alt="Gradient Cap_mini"><br>Lic 773985<br><a href="http://www.millersolar.com/"><span style='color:blue'>millersolar.com</span></a><br>805-438-5600<o:p></o:p></span></p></div><p class=MsoNormal><span style='font-family:"Arial","sans-serif";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 [mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>Russell Mueller<br><b>Sent:</b> Tuesday, September 09, 2014 7:43 AM<br><b>To:</b> RE-wrenches@lists.re-wrenches.org<br><b>Subject:</b> [RE-wrenches] Grid-tied Trace SW<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Hello Esteemed Wrenches,<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I have a prospective client who has an old GTBB system using a Trace SW -- it was permitted and signed off by the utility way back when and has been operational ever since. It's a Trace SW 4024 that's feeding the grid through a Trace T-240 transformer -- I didn't see a GTI. All he wants me to do is replace his failing array (which would increase his array size from 1152W to 3300W) -- not pull a permit, not change the BOS other than to add a 2nd charge controller.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>The original question that lead me to write this post is whether the SW4024 can handle the full 4kW sell-back onto the grid -- I couldn't find any specs on that on the web. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>But the question I have now is whether the Trace SW is UL1741 compliant. I didn't think to do an anti-islanding test before I left the site. If it's not, then I'm thinking maybe I should insist that he change out his inverter for a modern one, or I'll pass on the job. If it fails an anti-islanding test (which I'll do next time I'm in his neighborhood), then the dangers are obvious, and I don't want the liability.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>What would you all do in this situation? Do any of you have experience with grid-tied SWs -- any advice?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Thanks,<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Russ<o:p></o:p></p></div><div><div><p class=MsoNormal><b><span style='color:black'><br>--</span></b><span style='color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal><b><span style='color:black'>Russell Mueller</span></b><span style='color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal><i><span style='color:black'>NM EE98 Electrical Contractor, license #382671</span></i><span style='color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal><i><span style='color:black'>NM ER1J Journeyman Electrician</span></i><span style='color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal><i><span style='color:black'>Photovoltaic Designer / Installer</span></i><span style='color:black'><o:p></o:p></span></p></div><p class=MsoNormal><span style='color:black'><br><img border=0 width=150 height=130 id="_x0036_47AC074-E454-4A32-8364-F3822320EFA0" src="cid:image003.jpg@01CFCC0D.96481020"><o:p></o:p></span></p><div><p class=MsoNormal><b><span style='color:black'><br><br>BUFFALO SOLAR LLC</span></b><span style='color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:black'>Taos, New Mexico<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:black'>575-770-4877<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:black'><a href="mailto:russ@buffalosolartaos.com">russ@buffalosolartaos.com</a><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p></div><p class=MsoNormal><span style='color:black'><br><br style='orphans: auto;text-align:start;widows: auto;-webkit-text-stroke-width: 0px;word-spacing:0px'><br></span><o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p></div></body></html>