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-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@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-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@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 danf...@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> > > _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@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 _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@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 _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@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
