US versus DE installation costs [RE-wrenches]

Mon Apr 21 11:09:22 PDT 2003

Bill:

I agree that grounding or ungrounding of the PV array SHOULD be a UL
issue rather than a Code issue.  Ward Bower did get some loophole
language into the code that allows "equivalent grounding methods Listed
and identified for the purpose" or something to that effect.
Unfortunately 690 still says we have to ground one of the current
carrying conductors in a bi polar (two wire)or the neutral conductor of
a bi polar (three wire) array.  I think grounding is the first thing
they teach electrical inspectors and so this is s big taboo that needs
to broken down. 

We are now in the public comments phase for the 2005 code cycle and I am
working on a white paper that describes how to do a floating array.  As
you know, you can't just lift the ground of the array and call it good.
There are other requirements that need to come along with ungrounded
arrays.  UL, W. Bower, J. Wiles, and others are providing pier review to
give the proposal the best chance of not getting shot down at the code
panel.  Hopefully we can build enough support for ungrounded arrays that
we can get it done in 05 and by UL in the interim.  Ungrounded arrays
are safer and allow new inverter topologies that are cheaper and higher
performance as well.  It just makes too much sense not to explore
floating arrays more fully.  

If you have any questions or if I may be of any further assistance,
please do not hesitate to contact me.

Best Regards,

John Berdner

SMA America, Inc.
12438-C Loma Rica Road
Grass Valley, CA  95945
530.273.4595 - Tel
530.274.7271 - Fax

-----Original Message-----
From: Bill Brooks [mailto:billb at endecon.com] 
Sent: Monday, April 21, 2003 10:49 AM
To: RE-wrenches at topica.com
Subject: RE: US versus DE installation costs [RE-wrenches]

John,

Don't you agree that an ungrounded array is essentially a UL issue?
Hopefully we will get the more explicite changes in the 2005 NEC, but it
seems that UL has the ability to list ungrounded equipment right now.
The
key is getting the UL1741 section written to better evaluate them.

The code has allowed ungrounded systems using listed equipment for some
time--the issue is getting it listed as I see it.

Bill.

-----Original Message-----
From: John Berdner [mailto:jberdner at sma-america.com]
Sent: Monday, April 21, 2003 10:30 AM
To: RE-wrenches at topica.com
Subject: RE: US versus DE installation costs [RE-wrenches]

William:

No argument on my side trying to decrease safety.
I think our entire industry needs to do everything possible to make
installations safer and more reliable.  I simply think we need to look
at all the regulatory requirements in total and reduce the ones that add
cost without increasing safety.

After spending tons of time researching WHY certain things are in the
code I have found that some requirements are politically motivated
>gasp< or can not be justified technically. I believe the latter is the
case with grounding of the PV array.  IMHO, there is no technical
justification for grounding the PV array conductors. This requirement
goes back to a time when PV modules had big issues with leakage through
the edge seals and there was no GFDI requirement. I think we should move
to ungrounded PV arrays to increase safety. In an ungrounded system the
first ground fault would simply provide a low impedance ground reference
for the array. This is, in fact, where we start off today in the US. I
think we should move to a situation where it takes two faults to create
a hazardous condition rather than one. I also believe we should move the
GFDI detection level to 30 mA for personnel safety not just fire safety.
This is extremely difficult to do if you start with a grounded PV
negative.

I also feel that the utility requirement for a visible blade lockable
disconnect does not materially increase safety.  It is simply not
plausible that the dc disconnect, two ac breakers, AND the inverter's
anti-islanding circuitry (ours is fully redundant by the way) will all
fail simultaneously and no one will be able to pull the meter.  This
requirement goes back to a Union requirement not the Code.  I was there
when the requirement was first developed at PG&E when we got the first
Trace SW type tested.  This requirement came down to the fact that the
linemen were not allowed to pull the meter because the meter was the
turf of the meter readers.

I do evaluate each section of the Code separately and am not advocating
throwing the baby out with the bath water.  I work closely with many of
the code experts you refer to and I depend on them to vigorously
challenge my proposals to make sure they are technically sound.

Lastly, Joel started discussing installed system costs in Germany versus
the US. Having been there many times I would not say Germany is a third
world country.  Given that they have one third our population and five
times the installed PV that we have I think we should look at what they
do objectively and see what changes we can make that will help us
increase the amount of renewable energy in the US.

If you have any questions or if I may be of any further assistance,
please do not hesitate to contact me.

Best Regards,

John Berdner

SMA America, Inc.
12438-C Loma Rica Road
Grass Valley, CA  95945
530.273.4595 - Tel
530.274.7271 - Fax

-----Original Message-----
From: William Miller [mailto:wrmiller at slonet.org]
Sent: Sunday, April 20, 2003 10:56 PM
To: RE-wrenches at topica.com
Subject: Re: US versus DE installation costs [RE-wrenches]

Colleagues:

I'm not so sure I would want to down grade our standards.  Remember the
SB
50 that went up in flames?  Well there's this little code section that
deals with PV on dwelling roof tops.  You see, it requires that we put
in
ground fault protection.  If that system had been installed with ground
fault protection, we would not have had a fire.

Every year, I suppose hundreds of children die in electrical fires,
world
wide, if not nation wide.  Do we want to increase that number?  I say:
let's evaluate each code section on a case by case basis, but let's not
throw them all out and set ourselves up for disaster.

Sure, I bet it's cheaper to install PV in most third world countries,
but
do you want that type of wiring in your child's bedroom?  I don't!

I am making it a point to comply with the code because every time I
question any one section, I am informed of a reason that section is
there.
I just don't have the resources to second guess the experts, and I'm not
going to do shoddy work!

William Miller

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