One solution is to restring up to the max of the outback, say double what you got now, easy to do on the combined. This will not change the fact of cause that the modules are molding some of the power but will get the input voltage up where it needs to be Jerry On May 31, 2015 4:03 PM, "Randy Brooks" <ra...@brookssolar.com> wrote:
> I second Jay. If one string is significantly lower, I’d check each module > in the string. Could be a bad module. > > Randy > > On May 31, 2015, at 1:23 PM, jay peltz <jay.pe...@gmail.com> wrote: > > HI Luke, > > To add here. I'm unclear if you have measured each string or the whole > array at 71v. > I would check each string for voc/isc. > > And then if they are consistent, I agree that putting 2 strings in series > with a new controller might help out. > You can try it with the MX-60 as you are at only 142v. If it works better > then a new higher voltage CC would be required for winter higher voc. > > Let us know what you find out. > > jay > > > On 5/31/2015 11:55 AM, Luke Christy wrote: > >> Hello Off-Grid Wrenches, >> >> I recently made a periodic maintenance visit to a residential off-grid >> system I take care of here in Southern CO, and discovered an interesting >> problem. >> >> This system has an array of 48x Uni-Solar PVL-68 laminate modules applied >> directly to standing-seam metal roofing. >> >> The data logging on the controller (Outback MX-60) indicated that the system >> was having trouble completing a charge cycle and going to float. Initially I >> assumed was due to heavy electrical use by the occupants (renters). After a >> little checking, I noticed that the module string voltage was only about >> 0.5V above the battery voltage! >> This was a cool late morning, with full sun, and the array was charging >> almost 2kW at 54.5V. The module strings were running at 55V. I've noticed >> the module voltage being lower than I'd like before, but it has never been >> this low. I suspect this is the real reason the system hasn't been able to >> complete a charge cycle. >> >> By removing the loads I was able to get an open-circuit voltage of 71V, but >> that still seems pretty low. >> >> Has anyone else experienced a voltage degradation issue with the Uni-Solar >> laminate? What was the expected annual voltage degradation for this >> technology? >> >> These modules do have some age on them. The system was installed about 15 >> years ago (by a competent installer who is now retired). The system was >> installed before MPPT controllers were common, so I assume the modules are >> wired in strings of 4 for 48V nominal. >> >> Any experiences or opinions are appreciated. >> Thanks in advance. >> >> -Luke >> >> >> Luke Christy >> >> >> >> Jay Peltz > Peltz Power > jay.pe...@gmail.com > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > >
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