[RE-wrenches] Tight roof layout questions: edge walkway requirements & "small gap" hardware options

Wed Aug 25 17:58:11 PDT 2010

Just to throw this into the discussion, maybe there can be exemptions written into ordinances stating that if technical issues (system sizing requirements) provide for less than sufficient setback, or walkway space, then maximum DC system voltage cannot exceed 50VDC. In other words use micro-inverters or similar technology that keeps the DC voltage at a single module's Voc.

Another option would be system that employs devices that are able to disconnect the series connections between modules, again keeping the DC voltages below 50VDC

A fire fighter could put an ax through any module without worry of electrocution if it were under 50VDC. See page 22 in this EPRI paper

http://www.narucmeetings.org/Presentations/Dorr-NARUC%20SV%20Panel%202009.pdf

Brian Teitelbaum
AEE Solar

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Brian Sipp
Sent: Wednesday, August 25, 2010 5:05 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Tight roof layout questions: edge walkway requirements & "small gap" hardware options

Dan, let me start by saying that I am not trying to attack you here and that
I do appreciate the valuable and dangerous job that fire fighters have.
However, this issue is of great concern to me when it comes to the majority
of residential PV systems.    

Since this is a residential, trussed roof, installation; I imagine that the
north slope of this roof will be untouched.  Also, since we are talking
about 12 modules, I would be willing to bet there are also other roof
surfaces that are less ideal for solar and will not be covered with PV
either.  If pathways are included on this roof, it will go from a modest 2kW
system to an unreasonably small 1kW or less.  At that point, the project
will probably not even happen.    

I am very concerned that the AHJ's are going to start killing residential PV
projects with the assumption that any surface that has modules needs 3'
walkways.  Right now most of the AHJ's are telling me that their setbacks
are simply advisory and can be waived.  However, many have also told me that
the those setbacks will soon be mandatory.  If that is the case, I would
have to turn away approx. half of my clients because we are only covering
one ideal section of roof out of many possible access points.      

Would a reasonable fire department really let a house burn because one
section of the roof was covered with PV but the rest was clear?  I
appreciate the difficult job that fire fighters have and I want to make
their jobs as safe as possible.  However, I have heard a lot of alarming
talk lately about "letting it burn" and "too dangerous to fight" when in
fact there are many alternative access and vent points in most pitched roof,
residential installations.  This sort of talk seems to lead the AHJ's to
implement standards without regard to true accessibility. 

Is there some way that we can keep fire fighters safe, while at the same
time recognizing that residential solar is unique from the large flat
commercial roofs for the reasons that I mentioned above?  

Brian M. Sipp
First Source Solar Systems
www.FirstSourceSolar.com 

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Dan Fink
Sent: Wednesday, August 25, 2010 3:35 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Tight roof layout questions: edge walkway
requirements & "small gap" hardware options

Mick;

I train both fire departments and PV installers across the USA on PV systems
and firefighter safety. Covering the roof "edge to edge" as you say is a
very slippery slope for you, as the system designer. It's not legal in many
areas, where setbacks and access pathways for firefighters are required (see
CalFire regulations, or contact me for more information on these).

And even if it *is* legal in your area, an "edge to edge" array cripples
your local fire department as to their options in fighting a fire in or
around that structure--whether it be just an ember from the neighbor's BBQ
lodged in the roof, an oncoming wildfire, or a room on fire inside from a
cigar in a wastebasket.

In any case, as a firefighter since 1998, your question gives me the cold
chills. "Edge to edge" in PV installer jargon can very easily lead to "let
it burn" in firefighter jargon. In PR jargon, you are looking at a possible
newspaper headline that says "Solar panels made house fire too dangerous to
fight, Fire Chief says."

Don't go there. Plan in access pathways. If you don't, an ember from the
neighbors BBQ could bring it all down.

DAN FINK
Buckville Energy Consulting LLC
danfink at buckville.com

>  
>
> 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 <http://www.abrahamsolar.com>
>
>
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