Thanks, Daryl. That is what I understand, but mine is a superficial understanding right now. For better or worse, I'm one of those guys who want to see the technical details. Does anyone have a reference to the articles Daryl is talking about? - Peter
Peter T. Parrish, Ph.D., President California Solar Engineering, Inc. 820 Cynthia Ave., Los Angeles, CA 90065 Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885 CA Lic. 854779, NABCEP Cert. 031806-26 peter.parr...@calsolareng.com -----Original Message----- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Darryl Thayer Sent: Thursday, December 25, 2008 7:39 AM To: RE-wrenches Subject: Re: [RE-wrenches] Inverter with two strings of different orientation If each string is composed of only one orientation then there would be little loss. There have been a couple of papers on this at different conferences. I also think John Berdner wrote a paper on it for SMA. (I think the annual losses are in the nature of 2 to 5 %) If however a single string has two orientations then much larger losses occur. Daryl --- On Wed, 12/24/08, Peter Parrish <peter.parr...@calsolareng.com> wrote: > From: Peter Parrish <peter.parr...@calsolareng.com> > Subject: [RE-wrenches] Inverter with two strings of different orientation > To: "'RE-wrenches'" <re-wrenches@lists.re-wrenches.org> > Date: Wednesday, December 24, 2008, 1:41 PM > I don't think this topic has been dealt with in this > forum. Ocassionally we > want to use a single inverter with two or more strings, > each string being > loaded by a single sub-array. A sub-array being defined as > having a single > uniform tilt angle and azimuth. All modules are identical. > And each > string/sub-array contains the same number of modules. > > > > The question is: "How different can the orientation be > for the different > sub-arrays? > > > > Let me pose a concrete example: Xantrex GT5.0, two strings > of BP Solar > SX3190s. One string has an orientation of 15 deg tilt and > 188 degrees > azimuth; the other has 23 degrees tilt and 139 degrees > azimuth. For reasons > that are difficult to explain, none of the orientation > angles can be > changed, at least for the purposes of this discussion. To > visualize what I > am talking about: the tilts are fairly close (8 degrees) > and the azimuths > differ by about 45 degrees. > > > > How do I calculate the combined performance? How much power > does one give up > compared to using separate inverters for each > sub-array/string? Are there > rules of thumb as to what works and doesn't? Do > conventional inverters have > algorithms that can navigate the non-ideal I-V > characteristic under load? I > know there was a tech bulletin from Fronius a while ago: I > read it but > didn't come away with any definitive answer. I also had > first hand knowledge > with MPPT algorithm problems with the Fronius inverters > during that time > period, which caused me to discount the tech bulletin. > > > > I am quoting a system as we speak, so my inquiry is not > hypothetical in > nature. Any help would be appreciated. > > > > - Peter > > Peter T. Parrish, Ph.D., President > California Solar Engineering, Inc. > 820 Cynthia Ave., Los Angeles, CA 90065 > Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885 > CA Lic. 854779, NABCEP Cert. 031806-26 > peter.parr...@calsolareng.com > > _______________________________________________ > 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 _______________________________________________ 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 _______________________________________________ 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
