I agree, scratch my previous suggestion of 8 in series on the Outback
controller. I got so used to Midnites that I forgot how unforgiving
the Outback controllers are with high Voc. Run the Unisolar modules
through the Midnite sizer. http://www.midnitesolar.com/sizingTool/index.php
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 5/31/2015 10:59 PM, Allan Sindelar wrote:
Jay,
Whoa, I'd be careful there. Unless there's been a change while I was
away on my bicycle, Outbacks are still 140V rated maximum voltage and
150V hard maximum. 142Voc in May suggests that doubling strings in
series will easily exceed max Voc in winter. That's why I previously
suggested Classic 200 or 250. Am I missing something?
Allan
*Allan Sindelar*
al...@sindelarsolar.com <mailto:al...@sindelarsolar.com>
NABCEP Certified PV Installation Professional
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder (Retired), Positive Energy, Inc.
*505 780-2738 cell*
**
On 5/31/2015 2:23 PM, jay peltz 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 <mailto:jay.pe...@gmail.com>
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