hi peter I would put 7 type A in a series and 6 type B with one type A This way the extra performance of the type A would not be lost except for the one module. Darryl.
--- On Mon, 3/30/09, Peter Parrish <peter.parr...@calsolareng.com> wrote: > From: Peter Parrish <peter.parr...@calsolareng.com> > Subject: Re: [RE-wrenches] Mixing and Matching PV modules--Error Corrected > To: "'Peter Parrish'" <peter.parr...@calsolareng.com>, "'RE-wrenches'" > <re-wrenches@lists.re-wrenches.org> > Date: Monday, March 30, 2009, 5:50 PM > I think I understand all the dictums about single-strings of > PV modules: all > the same modules, all the same azimuth and tilt, but I have > a "special > situation". > > We are starting to accumulate a number of "second > hand" PV modules. Some > have frames slightly damaged by the shipper; some have come > from warranty > replacements; and some are odd lots that we haven't > been able to sell. > > What I want to do is to set up a demo system composed of > two different types > of modules. This is my initial design: > > Total of fourteen modules. Two strings of seven modules > each. Each string > consisting of four modules of one type (type A) and three > modules of a > second type (type B). > > Both module types have 50 cells and the type A module has > 155mm-sq cells and > the type B module has 150mm-sq cells. So you would think > that the > performance specs would match pretty well. However, since > the type B modules > are an earlier vintage, they probably don't have the > latest and greatest > surface treatment, etc., so the current specs are lower > than one might > expect. > > Specs on type A: Voc = 30.8V, Vmp = 24.5V, Isc = 8.70A, Imp > = 8.16A. Specs > on type B: Voc = 30.6V, Vmp = 24.6V, Isc = 7.38A, Imp = > 6.93A. > > So here's my question: would putting together the > strings of four type A and > three type B cause any problems? I know the string current > would be limited > by the type B modules, but above and beyond that, what > would be the > operating point of the type A modules and what would be the > stress if any on > the type B modules? I'd like this demo system to last a > while and I > certainly don't want to see scorch marks on the type B > modules after a few > months of use. > > Any thoughts? > > - Peter > > Peter T. Parrish, 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
