Hi Chris,
Thanks for a glimpse of how our German brethren handle PV design &
installation. After all, who has more experience with design, execution,
and funding than the Germans? There remains an arrogance that the US has
a lock on how best to do any number of things. Hopefully, this
antiquated attitude will change, soon; hopefully, before we are all
reduced to asking the equivalent of, "Would you like to Supersize that
meal?"
Best wishes on your install. Please keep us informed of how others
around the world better handle these items.
Bill Loesch
Solar 1 - Saint Louis Solar
On 28-Mar-13 1:03 PM, Chris Mason wrote:
I am working on a large installation in a country that uses 230/400V
60Hz for the grid, so we had to look to Europe for the inverters and
work 1000V.
I spent some time on the phone with SMA Germany to discuss the
reqiurements in Germany and to understand the design methodology the
inverters were designed for.
First of all, the inverters are gorgeous. The first one we installed
is a 3Ph 17KW with 6 sets string inputs, 2 x MPPT. They connect the
strings directly to the inverters, no disconnects. The inverters have
a Electronic Solar Switch on the bottom, pull it down and the strings
are disconnected.
We are using 26 module strings or that install, which massively
reduces cabling and components.
I showed the engineer a photo of our larger installs, he laughed at
the use of "pipes" for the cables.
We install massive AC disconnects, they use a little isolator about
the size of a Coke can.
Everything is a multi-core cable.
I also read a guide to the British Standards on PV installation, and
their approach to grounding is absolutely different.
Since PV conductors are all isolated now, they don't even want you to
ground the array structures, in fact they describe grounding as a
shock hazard. Very different mentality.
I might think that the US way is likely safer if we were comparing
with China or the third world, but this is Germany. I think they know
electricity.
Chris
On Wed, Mar 27, 2013 at 12:16 PM, John Berdner
<john.berd...@solaredge.com <mailto:john.berd...@solaredge.com>> wrote:
Exposed single conductor sunlight resistant cable in cable trays
are widely used in PV systems outside the US.
There is a very large installed base of systems with good long
term performance data using this type of construction.
We should not discount the advantages of wire cable trays just
because we are unfamiliar with it.
Look at data cabling – Characterized by many, relatively small,
cables over long distances with periodic drops.
Sounds a lot like PV source circuits (other than voltage and
current in the wires of course).
There are lots of videos out there showing how to pull 10’s of
pairs of wires simultaneously in cable trays.
IMHO, we need to look at ideas like this to reduce installation
cost and time.
Installation costs are becoming the tall pole in the tent and new
thinking is needed.
As systems are falling to sub $3.00 /Watt all-in, running wire in
conduit will simply not be cost effective.
Running wire in conduit is one of the reasons PV installation
costs in the US are double (or more) of those in Europe.
As one of my former German colleagues noted:
“It is only in the US where you need first to be a plumber before
you can be an electrician”
Best Regards,
John Berdner
General Manager, North America
SolarEdge Technologies, Inc.
3347 Gateway Boulevard, Fremont CA 94538 USA */(*Please note of
our new address.)/*
T: 510.498.3200, X 747 <tel:510.498.3200%2C%20X%20747>
M: 530.277.4894 <tel:530.277.4894>
*From:*re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>
[mailto:re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>] *On Behalf Of
*Allan Sindelar
*Sent:* Wednesday, March 27, 2013 8:51 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Cable tray
Andrew,
We have used #10 USE-2 for about 16 years, and our high-elevation
New Mexico sun is quite intense. I have yet to see any degradation
exceeding fading discoloration on any conductors from that far
back, even when directly exposed to sunlight. No cracking,
peeling, delaminating, or hardening.
Allan
*Allan Sindelar*
al...@positiveenergysolar.com <mailto:al...@positiveenergysolar.com>
NABCEP Certified Photovoltaic Installer
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder and Chief Technology Officer
*Positive Energy, Inc.*
3209 Richards Lane (note new address)
Santa Fe, New Mexico 87507
*505 424-1112 <tel:505%20424-1112>*
www.positiveenergysolar.com <http://www.positiveenergysolar.com/>
On 3/27/2013 8:41 AM, Andrew Truitt wrote:
Bill - What is your take in conductor insulation degradation
over time when exposed to UV? Regardless of the "sunlight
resistant" labeling, USE-2 (and I assume PV wire though I
haven't seen it yet) does show wear after years of exposure to
direct sunlight. Maybe best practice would be to use cable
trays where conductors are shaded and [properly installed]
conduit when exposed to direct UV?
- Andrew Truitt
Sent from my iPad
On Mar 26, 2013, at 11:55 PM, "Bill Brooks"
<billbroo...@yahoo.com <mailto:billbroo...@yahoo.com>> wrote:
William,
I have all the respect in the world for you, but I’m not
referring to “basket tray”, which is only appropriate for
small conductors. I’m talking about legitimate cable tray
that can be up to 12” wide and that has a top and rungs
every 12”. The main facilities that use it in the United
States are large industrial facilities. Most electricians
don’t get to work with it. It is clearly superior to EMT
and is at least as good as IMC without all the hassle of
threaded fittings and setting up expansion joints and
worrying about 20 years of conductors thermal cycling.
Even the best electricians have problems with this stuff.
I am talking about projects with 800 foot long feeder
runs. We can bring them in the building and build a rack
for the conduit or run covered tray outside. As the 2014
NEC will require, you will have to use contactor combiners
or some other means to shut down the conductors inside a
building. It’s all doable. My recommendation after seeing
the aftermath of rooftop conduit by good electricians is
to put cable tray on roofs and use conduit if you bring
the feeders indoors. It will become common practice soon.
Hopefully sooner than later.
Bill.
*From:*re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On
Behalf Of *William Miller
*Sent:* Tuesday, March 26, 2013 9:49 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Cable tray
Bill:
I have to disagree with you on this one. We can not
abandoned a tried and true practice just because some
practitioners don't do it right. I don't know how one can
justify saying that encapsulating high voltage conductors
in a conduit is less safe than exposed in a flimsy
basket. Consider snow and ice and falling objects.
Too many installers entered the PV field without first
acquiring the necessary skills as journeymen or women
electricians. I don't see the benefit of rewriting the
code to accommodate a lack of skills in the industry.
Respectfully,
William Miller
PS: The temperature adders always encourage us to enter
the building envelope at the first appropriate location to
avoid adding them. Thoughtful installers will do the same.
Wm
At 10:15 PM 3/25/2013, you wrote:
Content-Type: multipart/alternative;
boundary="----=_NextPart_000_00E3_01CE29A6.37CC5110"
Content-Language: en-us
William,
I would strongly disagree that conduit is tried and true
on rooftops. I have rarely seen good conduit runs on
rooftops. Most electricians have no clue how to work with
expansion joints. Conduit on rooftops is a bad idea in
general. Most conduit runs in big buildings are all done
indoors for good reason. We are the crazy people doing
things on the roof.
The sooner we get away from conduitparticularly for long
feeder runsthe better.
In Europe they don’t have problems with their rooftop
wiring systems because everything is in tray.
For those that don’t allow cable tray for anything less
than 1/0, just remember that if it isn’t called cable
tray, then 392 doesn’t apply. The NEC would allow us to
use treated lumber in place of cable tray. This makes no
sense.
We did some research on the origin of the 1/0 requirement,
and it is ancient and no longer relevant. Just because it
is in the code, does not mean it is correct. That’s why we
try to fix it every three years.
Bill.
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