[RE-wrenches] PV Recombiner

William Miller william at millersolar.com
Mon Oct 10 22:31:07 PDT 2016


Jay:



I wouldn’t go so far as to say the GSLC is a piece of junk.  It does have
some flaws, however, particularly the breaker wiring.  I informed Outback
of the shortcomings soon after it came out but no improvements have been
made.



We work around the breaker problem with a few procedures:



1.    We remove all AC breakers.  We install off-the-shelf QO panels
immediately adjacent to the GSLC and install all AC breakers in two or
three panels:  Grid fed (if applicable), generator fed and inverter fed.
We handle bypass switching with a custom interlock in the inverter fed
panel.  I just this weekend finished a jig for a router that will make
precise slots in aluminum plate to make sliding interlocks. See photo below
(hope they come through).

2.    The added benefit is if you want to add an AC breaker, you do not
have to provide a jumper for each pole.

3.    We use the minimum quantity of DC Breakers in the GSLC.  If we can
move combiners indoors and near the charge controllers, and have 6 circuits
or less, we label the PV breakers as CC input disconnects.  If we have more
than 6 circuits, we add a 60 or 80 amp breaker to the comb and label it as
a disconnect.  We drill out the screw holes in the covers so they can be
removed without a tool to access the breakers.

4.    We clamp the dead-front in a bench vise with the studs facing up and
prewire the breakers with extra wire.  We can then slip the dead-front in
place without having to work behind it.  See photo below:





And yes, neither QO nor QOU breakers are suitable for 48 volt
applications.  While they are factory rated for 125VDC, they are UL rated
to only 45 BDC, if my memory is correct.



I am starting to believe the MNDC15 might actually be a slick choice.  At
first I thought the form factor was awkward, but in CADing the design, I
see three FM charge controllers will fit right above it.  We always use 6
or 8 inch gutters in our equipment rooms.  We can come out of the gutter
with one or two 3” EMT nipples into the MNDC15, and then out of the top of
the MNDC15 with two 1” EMT nipples into each of three charge controllers.
We can run straight out of the MNDC15 into the battery bus bars.  The MNDC
will hold the PV shunt as well.  I can prewire the breakers with long
pigtails and land them in the CCs above or the busses within.



With external DC and AC panels, the only breakers in the GSLC are the
inverter breakers.  Makes for a much easier to wire installation.  And it
makes better sense to separate the AC and DC breakers.



If I give it a go, I will report back on my results.



Thanks to everyone for the input.



William



PS:  Our last two GSLCs came with some problems:  The shunt supports a
long, heavy bus bar.  One box had been dropped and the shock broke the
plastic base of the shunt.  Both units were missing the A and B bus bars
and one was missing the hardware package.  Outback totally dropped the ball
on replacements.  I did ferret out the manufacturer’s contact information
and they came through with flying colors, sending me replacement parts
immediately.  I was told this is not an uncommon problem of late.  Moral of
the story:  unbox your GSLCs and inventory the parts before you head to the
job.



Wm











[image: Gradient Cap_mini]
Lic 773985
millersolar.com <http://www.millersolar.com/>
805-438-5600



*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *jay
*Sent:* Monday, October 10, 2016 5:21 PM
*To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
*Subject:* Re: [RE-wrenches] PV Recombiner



I”ll chime in here.



Yes the GSLC is a piece of junk.

However it is UL listed for the job. And while you could put together
something that would work with Airpax breakers together, but it wouldn’t be
UL.



What I do is to swap out all the wires to Arctic ultra flex.  This allows
much better movement of the wires with significantly less stress on the
terminals.   And if you want to not attach wires to the back of the
breakers then you can and I’ve seen outback do it, install lay in lugs
facing outwards so you can use a screwdriver or allen key on them.  Allows
for installation and removal of wire without removal of the breaker or the
plate/breakers.  With thimbles of course. And I can’t find them but I know
they make them, shields that fit between each breaker so the lay in lugs
are insulated.



jay

peltz power





On Oct 10, 2016, at 4:40 PM, William Miller <william at millersolar.com> wrote:



Chris:



Thank you for the reply.  I think you misunderstand me.  We always use the
GSLC cabinets.  I just don’t like the design concept that clutters the
cabinet with AC and DC breakers that are difficult to access and block
other components.  See photo below of a prewired GSLC Cabinet we were asked
to work in.  Not a good scenario.



We have created an installation standard using the GSLC that minimizes the
problems inherent with the design.  We run all AC leads to adjacent load
centers and we try to minimize the DC breakers in the cabinet.  It is our
goal to completely eliminate all breakers from the removable dead-front.  I
think it is pretty self-explanatory why one would not prefer to make
connections in a hard to reach location.



Our goal is to constantly improve our installation procedures to create
better, safer and more efficient installations.



Also, I don’t need someone to instruct me on how to make a “finished”
looking install. If you are familiar with my work you know it is as clean
as it gets.  Review my web site.  Below is but one example of one of our
installs.



And lastly, “suck it up” is not a very complimentary phrase.  Please, let’s
keep it professional.



Sincerely,



William Miller



<image007.jpg>

*Figure 1 Factory wired GSLC*



<image008.jpg>

*Figure 2 Miller Solar installed GSLC..*



<image009.jpg>
Lic 773985
millersolar.com <http://www.millersolar.com/>
805-438-5600



*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *Chris Mason
*Sent:* Monday, October 10, 2016 3:40 PM
*To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
*Subject:* Re: [RE-wrenches] PV Recombiner



The GSLC gives the system a nice finished appearance that the customer will
understand. Suck it up and live with the imperfect world we function in.



On Mon, Oct 10, 2016 at 5:55 PM, William Miller <william at millersolar.com>
wrote:

Friends:



I am looking for a PV recombiner.  I need to accept the outputs from 3
remote PV Combiners, send those outputs through GFP circuit breakers, into
charge controllers, back thorough breaker, into a bus bar, through a main
breaker and onto a large battery bank.



I am using 2 Outback Radian inverters, but I refuse to install DC breakers
on their dead-front because wiring to studs facing away from the front is
an inferior design.  Furthermore, I see no need to run PV circuits through
the GSLC cabinets.



I looked at the Midnite MNDC15 but again, these use panel mounted breakers
with studs on the back.



Anyone know of a more thoughtfully designed PV recombiner?



Thanks in advance,



William Miller





<image003.jpg>
Lic 773985
millersolar.com <http://www.millersolar.com/>
805-438-5600




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--

Chris Mason

NABCEP Certified Solar PV Installer™

Solar Design Engineer

Generac Generators Industrial technician



www.cometsolar.com <http://www.cometenergysystems.com/>

264.235.5670

869.662.5670

Skype: netconcepts

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