Luke, I have never worked with Uni-Solar laminates, although I expect to for the first time this summer, at 12,800' in the White-Inyo mountains, but that's another story. I installed one small cabin system with US64s in 1999 (the rancher wanted modules that would keep performing with a few vandals' bullet holes, which never happened) and they continue to perform as new.
So take my two comments with that disclaimer in mind. First, you measured only 63% of rated output. That's pretty low at the controller, even if the roof is hot. Could there be something else to search for as a cause? Assuming it's indeed simply weak voltage, consider a Midnite Classic 200 or 250, to give the voltage window to allow repairing to a higher nominal input, maybe 72 or 96 volts, so that the charge voltage will always be higher than battery voltage. Allan > On May 31, 2015, at 11:55 AM, Luke Christy <sgsrenewab...@gmail.com> 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 > > NABCEP Certified PV Installation Professional™: Certification #031409-25 > NABCEP Certified Solar Heating Installer™: Certification #ST032611-03 > CoSEIA Certified PV Installer > > Solar Gain Services, LLC > PO Box 531 > Monte Vista, CO. 81144 > sgsrenewab...@gmail.com > 719.588.3044 > www.sgsrenewables.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
