<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">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><drake.chamberlin@redwoodalliance.org></i></b> wrote:<br><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left:
5px; padding-left: 5px;"><br>From: Drake <drake.chamberlin@redwoodalliance.org><br>Subject: Re: [RE-wrenches] Tranformless inverter<br>To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org><br>Date: Friday, October 1, 2010, 6:58 AM<br><br><div id="yiv831815003">
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:<br>
<blockquote type="cite" class="yiv831815003cite" cite="">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: william@millersolar.com<br>
<a rel="nofollow" target="_blank" href="http://millersolar.com/">
http://millersolar.com</a><br>
License No. C-10-773985</blockquote></div><br></blockquote></td></tr></table><br>