[RE-wrenches] Ground Mount Screening

[Bill Brooks]

Mark,

Although these are tough issues, I don't see that the sky is falling or that
systems are too dangerous to install in residential applications.

That being said, I think we are still a ways off from safe PV systems. My
opinion is that some type of "smart PV modules" that can do ground-fault and
arc-fault detection will become the practical solution to safety issues
related to buildings and people. The critical things with module level
control is reliability, efficiency, and cost. It is too soon to broadly
require these technologies, but safety concerns will push the development.
It is not unlikely that the 2014 NEC will have requirements that the PV
industry has not widely adopted on its own.

The 2011 NEC already requires series arc fault detection, which is not
currently available nor are there published standards to evaluate them. It
is an interesting time with lots of changes currently underway.

Bill.


-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Mark Frye
Sent: Friday, October 22, 2010 9:24 AM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Ground Mount Screening

Thanks for the response Bill.

It's a tough nut to crack and we are all doing our best to move the industry
forward.

It is interesting that you bring up the issue of vermin. Unfortunately, I
had to address squirrel damage on one of my own residential roof top
installations. Not pretty. But the one thing I can say is that a squirrel
can eat right through both wood or plastic lattice in a heart beat. For that
matter, a squirrel can move right through a standard steel chain link fence.

So where does that really leave residential level PV installations in the
US. It appears that everywhere we turn we see more and more issue being
brought up, with ad hoc solutions that make installation more and more
difficult. Are we really moving in a direction that PV is so complicated and
dangerous that I can only be installed in commercial and industrial venues
where these concerns can be managed in the context of "access by qualified
personnel only"?
 
Mark Frye
Berkeley Solar Electric Systems
303 Redbud Way
Nevada City,  CA 95959
(530) 401-8024
www.berkeleysolar.com 

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Bill Brooks
Sent: Friday, October 22, 2010 8:27 AM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Ground Mount Screening

Mark,

I certainly was not implying that you were in any way unintelligent. I was
merely suggesting that fences or only one means of compliance. You have a
different opinion, and you are entitled to it. However, if all jurisdictions
viewed prevention of ready access to mean fences, that would not be good for
the PV industry as a whole. 

Both crawl spaces and unfinished basements can have numerous hazards so
these locations are generally not seen as habitable and should not be
readily accessible locations. However, a garage does require that NM be
above 8' or protected--usually by sheetrock--below 8 feet. Under a PV array
that is lower than 8' would be like a crawl space only if access to the
underside were protected as crawl spaces should be. We tried to get specific
language in the NEC on types of guards that were permitted, but the Code
Making Panel rejected the proposal stating that it was well-understood in
the electrical industry how to prevent ready access--maybe not so much.

The much bigger problem is that installers put not protection around their
wiring systems so that children can use the "black vines" to play Tarzan on
them. I think you would agree that is not good--but we see it all the time
in rural areas. 

Animals are another big problem in certain places. While this thread is
about ground mount systems, roof mounting in wooded areas populated by
squirrels is a serious problem--as discussed many times in this forum. The
code currently does not address this problem, but perimeter screening may be
a requirement in the future to prevent both squirrels and debris from
creating a fire hazard under a PV array. Just yesterday I was talking to a
contractor that had just come back from an installation with a fully eaten
6-foot section of USE-2 where they had to remove the array to repair the
wiring. Fortunately, the ground fault protection activated and prevented a
fire.

Bill.

_______________________________________________
List sponsored by Home Power magazine

List Address: RE-wrenches at lists.re-wrenches.org

Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive:
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out participant bios:
www.members.re-wrenches.org