[RE-wrenches] Voltage Degradation with Uni-Solar laminate

Roy Rakobitsch windsine at gmail.com
Sun May 31 12:53:32 PDT 2015


Ive installed a few systems with these laminates years ago, but havent kept
up with performance much unfortunately.  I have heard of the diodes going
bad (which are glued into the laminate along the sides). Maybe thats your
issue? Just speculating...

Roy Rakobitsch
NABCEP Certified Small Wind Installer®
NABCEP Certified Solar PV Installer®
Certified Advanced Tower Climbing, Safety & Rescue
Wind/PV Design Engineer
Windsine LLC
631-514-4166
www.windsine.org
On May 31, 2015 2:49 PM, "Allan Sindelar" <allan at sindelarsolar.com> wrote:

> 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 <sgsrenewables at 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
> > SGSRenewables at Gmail.com
> > 719.588.3044
> > www.sgsrenewables.com
> >
> >
> >
> >
> >
> >
> >
> >
> >
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