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.
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. 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. Dan --- On Fri, 10/1/10, Drake <drake.chamber...@redwoodalliance.org> wrote: From: Drake <drake.chamber...@redwoodalliance.org> Subject: Re: [RE-wrenches] Tranformless inverter To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org> Date: Friday, October 1, 2010, 6:58 AM 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? At 12:52 AM 9/29/2010, you wrote: Wrenches: 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. William Miller Please note new e-mail address and domain: William Miller Miller Solar Voice :805-438-5600 email: will...@millersolar.com http://millersolar.com License No. C-10-773985
_______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
