Helpful points, thanks Glenn. -August<br><br><div class="gmail_quote">On Fri, Dec 10, 2010 at 5:23 PM, Glenn Burt <span dir="ltr"><<a href="mailto:glenn.burt@glbcc.com">glenn.burt@glbcc.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div lang="EN-US" link="blue" vlink="purple"><div><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">I just did a review of the TL inverters by SMA for possible use.</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">A few points that are relevant:<br>
They require the use of an external fused combiner (they also sell). It has support for up to 6 strings, with both + and – fuse positions provided.</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">The integrated DC disconnect has no fusing – it will accept only two conductors</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">The manual says these inverters are supposed to be installed in threes</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">They only work on 208VAC</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Obviously they are lighter than their transformer based cousins</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">There is a warning to beware of stray array capacitances in excess of 2 micro Farads or more and 50mA from the cells to ground or the inverter will disconnect</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Obviously an EGC is still necessary from the frame of the array</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Required clearance around the inverter has been increased to 12” (36” below)</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Replaceable varistors are used to protect DC inputs from high voltages (inside DC disconnect)</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Still 600VDC upper limit</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">AC max conductor diameter is 2AWG, min is #6</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">DC conductors - #10 to #6</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">They recommend operating the DC disconnect once a year, 10 times to keep the contacts clean</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">FYI – thought I’d share.</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">-Glenn Burt</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;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">From:</span></b><span style="font-size:10.0pt"> <a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a> [mailto:<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On Behalf Of </b>August Goers<br>
<b>Sent:</b> Friday, December 10, 2010 3:50 PM</span></p><div class="im"><br><b>To:</b> RE-wrenches<br><b>Subject:</b> Re: [RE-wrenches] Tranformless inverter</div><p></p></div></div><div class="im"><p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Hi Bill and Wrenches -</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">For ungrounded arrays what specific fusing and or DC disconnect requirements are needed compared to grounded arrays? </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">I'm trying to sort through the code but nothing is popping out at me besides what was already mentioned about needing to disconnect both the positive and negative lines on the DC side. In SMA's case I'm guessing that their new transformerless inverters with integrated DC disconnects and fuses may already take of all the requirements?</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Best,</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">August</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">August Goers</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Luminalt Energy Corporation</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">1320 Potrero Avenue</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">San Francisco, CA 94110</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">m: 415.559.1525</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">o: 415.641.4000</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><a href="mailto:august@luminalt.com" target="_blank">august@luminalt.com</a></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;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">From:</span></b><span style="font-size:10.0pt"> <a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a> [mailto:<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On Behalf Of </b>Bill Brooks<br>
<b>Sent:</b> Friday, October 01, 2010 8:29 AM<br><b>To:</b> 'RE-wrenches'<br><b>Subject:</b> Re: [RE-wrenches] Tranformless inverter</span></p></div></div><p class="MsoNormal"> </p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">All,</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Transformerless inverters are simply a subset of ungrounded or resistively grounded PV systems covered by the NEC in 690.35 since the 2005 code cycle. Power-One has been marketing their ungrounded inverter in the U.S. for several years now. It was listed by CSA. The requirements for ungrounded systems in 690.35 are as follows:</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p></div><p class="MsoNormal" style="margin-left:.5in"><span>&bull<span style="font:7.0pt "Times New Roman""> </span></span><span style="font-size:11.0pt;color:#1F497D">“Photovoltaic power systems shall be permitted to operate with ungrounded photovoltaic source and output circuits where the system complies with 690.35(A) through 690.35(G).</span></p>
<p class="MsoNormal" style="margin-left:1.0in"><span><span>&minus<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;color:#1F497D">(A) Disconnects. </span></b><span style="font-size:11.0pt;color:#1F497D">All photovoltaic source and output circuit conductors shall have disconnects complying with 690, Part III.</span></p>
<p class="MsoNormal" style="margin-left:1.0in"><span><span>&minus<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;color:#1F497D">(B) Overcurrent Protection. </span></b><span style="font-size:11.0pt;color:#1F497D">All photovoltaic source and output circuit conductors shall have overcurrent protection complying with 690.9.</span></p>
<p class="MsoNormal" style="margin-left:1.0in"><span><span>&minus<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;color:#1F497D">(C) Ground-Fault Protection. </span></b><span style="font-size:11.0pt;color:#1F497D">All photovoltaic source and output circuits shall be provided with a ground-fault protection device or system that complies with (1) through (3):</span></p>
<p class="MsoNormal" style="margin-left:1.5in"><span>&bull<span style="font:7.0pt "Times New Roman""> </span></span><span style="font-size:11.0pt;color:#1F497D">(1) Detects a ground fault.</span></p>
<p class="MsoNormal" style="margin-left:1.5in"><span>&bull<span style="font:7.0pt "Times New Roman""> </span></span><span style="font-size:11.0pt;color:#1F497D">(2) Indicates that a ground fault has occurred</span></p>
<p class="MsoNormal" style="margin-left:1.5in"><span>&bull<span style="font:7.0pt "Times New Roman""> </span></span><span style="font-size:11.0pt;color:#1F497D">(3) Automatically disconnects all conductors or causes the inverter or charge controller connected to the faulted circuit to automatically cease supplying power to output circuits.</span></p>
<p class="MsoNormal" style="margin-left:1.0in"><span><span>&minus<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;color:#1F497D">(D) </span></b><span style="font-size:11.0pt;color:#1F497D">The photovoltaic source and output conductors shall consist of the following:</span></p>
<p class="MsoNormal" style="margin-left:1.0in"><span><span>&minus<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;color:#1F497D">(1) Nonmetallic jacketed multiconductor cables</span></p>
<p class="MsoNormal" style="margin-left:1.0in"><span><span>&minus<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;color:#1F497D">(2) Conductors installed in raceways, or</span></p>
<p class="MsoNormal" style="margin-left:1.0in"><span><span>&minus<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;color:#1F497D">(3) Conductors listed and identified as Photovoltaic (PV) Wire installed as exposed, single conductors.</span></p>
<p class="MsoNormal" style="margin-left:1.0in"><span><span>&minus<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;color:#1F497D">(E) </span></b><span style="font-size:11.0pt;color:#1F497D">The photovoltaic power system direct-current circuits shall be permitted to be used with ungrounded battery systems complying with 690.71(G).</span></p>
<p class="MsoNormal" style="margin-left:1.0in"><span><span>&minus<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;color:#1F497D">(F) </span></b><span style="font-size:11.0pt;color:#1F497D">The photovoltaic power source shall be labeled with the following warning at each junction box, combiner box, disconnect, and device where the ungrounded circuits may be exposed during service:</span></p>
<div class="im"><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">WARNING</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">ELECTRIC SHOCK HAZARD</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">THE DC CIRCUIT CONDUCTORS OF THIS</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">PHOTOVOLTAIC POWER SYSTEM ARE</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">UNGROUNDED AND MAY BE ENERGIZED</span></p><p class="MsoNormal">
<span style="font-size:11.0pt;color:#1F497D">WITH RESPECT TO GROUND DUE TO</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">LEAKAGE PATHS AND/OR GROUND FAULTS.</span></p></div><p class="MsoNormal" style="margin-left:1.0in">
<span><span>&minus<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;color:#1F497D">(G) </span></b><span style="font-size:11.0pt;color:#1F497D">The inverters or charge controllers used in systems with ungrounded photovoltaic source and output circuits shall be listed for the purpose.</span></p>
<div><div></div><div class="h5"><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">We now have several products newly on the market to include on the list such as the SMA and Exeltech products. Ungrounding the array requires additional fusing and disconnects, but the most significant difference is that the module wiring and all external cable must be PV Wire/Cable. Therefore only modules with PV Wire/Cable can be used in these systems. You must confirm from the manufacturer that they have made the switch. Hopefully all manufacturers will be installing PV Wire/Cable soon so that this will not be a problem anymore.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">It is a good call to use up your USE-2 and order PV Wire/Cable from now on.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Bill.</span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p>
<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">From:</span></b><span style="font-size:10.0pt"> <a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a> [mailto:<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On Behalf Of </b>Exeltech<br>
<b>Sent:</b> Friday, October 01, 2010 6:39 AM<br><b>To:</b> RE-wrenches<br><b>Subject:</b> Re: [RE-wrenches] Tranformless inverter</span></p></div><p class="MsoNormal"> </p><table border="0" cellspacing="0" cellpadding="0">
<tbody><tr><td valign="top" style="padding:0in 0in 0in 0in"><p class="MsoNormal">Transformerless grid-tie inverters are permitted under the National Electric Code as of 2008. The Nationally Recognized Testing Laboratories (UL, ETL/Intertek, CSA, etc.) took a while to develop the testing procedures for testing to UL1741, which was the basis for most of the delay.<br>
<br>SMA isn't the only company with transformerless grid-tie inverters. I know of one American manufacturer with transformerless models on the market as well.<br><br>Transformerless inverters are smaller, much lighter, and tend to be more efficient than transformer-based units. No transformer also means lower product cost, and less shipping expense. Win-win-win.<br>
<br><br>Dan<br><br><br>--- On <b>Fri, 10/1/10, Drake <i><<a href="mailto:drake.chamberlin@redwoodalliance.org" target="_blank">drake.chamberlin@redwoodalliance.org</a>></i></b> wrote:</p><p class="MsoNormal" style="margin-bottom:12.0pt">
<br>From: Drake <<a href="mailto:drake.chamberlin@redwoodalliance.org" target="_blank">drake.chamberlin@redwoodalliance.org</a>><br>Subject: Re: [RE-wrenches] Tranformless inverter<br>To: "RE-wrenches" <<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a>><br>
Date: Friday, October 1, 2010, 6:58 AM</p><div><p class="MsoNormal" style="margin-bottom:12.0pt">I also received this advertisement. Previously I had investigated the smaller SMA transformerless inverters, and was told that this type would not be allowed in the US until the 2011 code. Has the ban been lifted?<br>
<br><br><br>At 12:52 AM 9/29/2010, you wrote:</p><p class="MsoNormal">Wrenches:<br><br>I received an advertisement from a distributor that SMA is now shipping 8, 9 and 10 KW transformerless inverters. Don't these require double insulated PV wiring and no connection to ground on the AC side? It's been too long since this subject last crossed my desk and I want to refresh my memory on the specifics.<br>
<br>William Miller<br><br><br><u>Please note new e-mail address and domain:<br><br></u>William Miller <br>Miller Solar<br>Voice :805-438-5600<br>email: <a href="mailto:william@millersolar.com" target="_blank">william@millersolar.com</a><br>
<a href="http://millersolar.com/" target="_blank">http://millersolar.com</a><br>License No. C-10-773985</p></div></td></tr></tbody></table><p class="MsoNormal"><span style="font-size:10.0pt"> </span></p></div></div></div>
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<br></blockquote></div><br><br clear="all"><br>-- <br>August Goers<br><br><br>Luminalt Energy Corporation<br>1320 Potrero Avenue<br>San Francisco, CA 94110<br>O: 415.641.4000<br>M: 415.559.1525<br><a href="mailto:august@luminalt.com" target="_blank">august@luminalt.com</a><br>