[RE-wrenches] Tight roof layout questions: edge walkway requirements & "small gap" hardware options
Joel Davidson
joel.davidson at sbcglobal.net
Thu Aug 26 18:16:24 PDT 2010
This May 2010 UL/NFPA report "Fire Fighter Safety and Emergency Response for Solar Power Systems" shows eave-to-ridge solar arrays and has a lot of good information for designers. See http://www.nfpa.org/assets/files/PDF/Research/FFTacticsSolarPower.pdf
----- Original Message -----
From: Mick Abraham
To: RE-wrenches
Sent: Thursday, August 26, 2010 5:53 PM
Subject: Re: [RE-wrenches] Tight roof layout questions: edge walkway requirements & "small gap" hardware options
The Wrench List participants have again responded with aplomb. Thanks to all for the dozen or so replies. My takeaway from this is that I need to send my roof layouts to the nearby fire department...it's another "authority having jurisdiction" situation.
I received the below mail "off list" from a fire captain in San Jose. He cannot post to the List so he asked me to post on his behalf. Moderator Michael approved, so Matt Paiss' remarks are copied below.
Jolliness,
Mick Abraham, Proprietor
www.abrahamsolar.com
Voice: 970-731-4675
Mick,
I wanted to reply to your post. As a firefighter, and an instructor of PV safety for the fire service like Dan Fink, I would like to take a moment to expand on what Dan was eluding to. Firefighters will not always look at an edge-to-edge array and decide to "Let it burn" just based on the array size. We will take into account the size of the fire, the involvement of the actual structural members, and the potential life risk within the structure before any tactical strategy is implemented. I have written off buildings just based on wind, or available water supply.
What a setback (the term being used for walkways) allows is primarily for access to a roof, or rapid egress off a roof when the fire gets out of control, not necessarily for cutting a hole. I teach firefighters to vent on the other side of the ridge from the array. There is no time to remove modules, and while micro-inverters definitely address the safety issues of a 600vdc string, they do not address access or egress. I am not going to recommend that ANY firefighter tear off a module to vent a roof because he "thinks" a micro-inverter is present.
I realize that these new codes are more restrictive, but even wind load zones recommend against edge-to-edge installs. There will be some latitude in the fire codes for setbacks, so I recommend building a good relationship with your local AHJ's. One way of doing this is by demonstrating safe, high quality installs. I have seen too many wire-ties holding up PV wire that will be rubbing against comp shingles for a decade. How confident are you that that will not be a problem?
Regards,
Matt Paiss
Matthew Paiss, Fire Captain
San Jose Fire Department
170 W. San Carlos St.
San Jose, CA 95113
(831) 566-3057 cell
On Thu, Aug 26, 2010 at 12:45 AM, Philip Boutelle <philboutelle at gmail.com> wrote:
Just to clarify what is and isn't law in California:
the final draft guidelines developed and adopted by Cal Fire are guidelines, not law, unless the local fire/AHJ has adopted them or parts of them into local ordinances. I have heard that in Southern Cal, those guidelines have been adopted all over the place already, but not so in the rest of the state.... yet. I think the guideline was officially incorporated into the next NEC/NFPA cycle, so it will be law pretty soon. Bill Brooks could probably confirm here on future adoption.
Not that any of this helps your Atlanta install....
-Phil Boutelle
Real Goods Solar
On Wed, Aug 25, 2010 at 12:38 PM, Max Balchowsky <max at seesolar.com> wrote:
Mick, here in California the fire department in the various agencies has the final say on clearances. There is a very clear cut standard in place for the state, but we have been successful a few times in getting allowances to vary due to various site conditions. A call to the local AHJ is the place to start. In the early days of our installations (mid 1990's) we used power strut and bolted panels directly to the rails. A lot slower but no gaps between panels. We went from there to designing our own "T" clamps. There wasn't as many choices then for mounting hardware.
Max Balchowsky
Design Engineer
SEE Systems
1048 Irvine Ave Suite 217
Newport Beach, Ca. 92660
760-403-6810
--------------------------------------------------------------------------
From: Brian Teitelbaum <bteitelbaum at aeesolar.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Wed, August 25, 2010 11:40:04 AM
Subject: Re: [RE-wrenches] Tight roof layout questions: edge walkway requirements & "small gap" hardware options
Hi Mick,
To answer part of your post, the DPW Power Rail mid-clamps give you a 3/8” gap between modules, and the SnapNrack mids give you a 1/2" gap.
I doubt if that will give you much of a walkway though….
Brian Teitelbaum
AEE Solar
From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Mick Abraham
Sent: Wednesday, August 25, 2010 11:09 AM
To: RE-wrenches
Subject: [RE-wrenches] Tight roof layout questions: edge walkway requirements & "small gap" hardware options
Hello, Team~
I'm laying out some Sanyo modules on paper. Twelve of them fit the roof with almost too much perfection: this would be difficult to install as it would fill the roof "edge to edge" in both directions. Are there consistent guidelines about the amount of roof edge which must remain uncluttered or is this mainly driven by the amount of aggravation that the installer is willing to tolerate? Which organizations would want to influence such decisions in the Atlanta region? Details are: residential, new construction, wooden truss type roof framing, finish roofing yet to be decided.
I've seen fancy photos of rooftops which are covered edge to edge, but I suppose those are "building integrated" PV systems instead of discrete modules mounted above the roofing material. Who decides if those are "OK' for no walkways compared to a roof that is fully loaded with Sanyo type modules? How are such decisions made?
I like the "top clamp" style mounts but UniRac SolarMount rail systems need about a 1" gap from one module to the next. Is there anyone with similar hardware that can get a grip within a smaller gap?
Thanks in advance,
Mick Abraham, Proprietor
www.abrahamsolar.com
Voice: 970-731-4675
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