Re: [RE-wrenches] PV and Roof Flammability
One thing to consider is that PV is installed on a lot of buildings here, and many more in Europe. There is ample data available to determine if PV is a fire hazard. We should not create codes based on speculation. Early on the what if factor seemed to play heavily into the equation. At this point safety evaluations can be based on field experience. At 10:12 PM 9/22/2010, you wrote: Wrenches, See http://www.solarabcs.org/flammability/ and the report at http://www.solarabcs.org/flammability/Flammability_Interimreport.pdf Is there any flammability difference between PV equipment on a roof and HVAC or air handling equipment on a roof? My concern is whether PV is being singled out as a flammability concern while other more established industries with more powerful lobbyists are not. Joel Davidson ___ 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
Re: [RE-wrenches] PV and Roof Flammability
Wrenches, Building fires are serious stuff. The Northbrook UL labs fire tests are awesome. Imagine a gale-force wind driving a wide, roaring natural gas flame at the roof eave to see how far the fire will spread as it consumes the roofing material and anything else combustible. Tremco has a photo of the spread-of-flame test at http://www.tremcoroofing.com/qa/fire_test.asp Some roofing material is self-extinguishing. Some roofing material burns to ashes. PV module glass does not feed the fire from the top but module backsheets combust. Non-glass modules combust readily but can be rated Class A in low-pitch applications. For a photo of the burning brand test see http://www.extension.org/pages/Fire_Ratings_for_Roofing_Material Glass solar modules on stand-off mounts have saved homes from flying burning brands. I think that most wrenches warn their customers about fire hazards. Stay safe. Joel Davidson - Original Message - From: Matt Lafferty gilliga...@gmail.com To: 'RE-wrenches' re-wrenches@lists.re-wrenches.org Sent: Thursday, September 23, 2010 6:22 PM Subject: Re: [RE-wrenches] PV and Roof Flammability Wrenches, I'm coming from a perspective of comparing beneath array areas to not beneath array areas of the same roof. Regarding flammability, I don't really care what the source of ignition is in this conversation. I prefer to think that the PV isn't the cause, frankly. Would rather think in terms of flying embers from a fire in the area (wild fire, neighbor's house on fire, chimney, etc.), but I don't think we can discount any cause out of hand. I think it is very important to understand that the UL tests are designed to emulate pre and early-stage combustion, as opposed to emulating a fully-involved fire situation. This is important because it marks the difference between fire resistant and fire proof materials. Only fire proof materials would survive to pass a full-on fire test. These tests essentially test the fire resistance of roofing materials. Another element to understand is that these tests only test from the top. They don't emulate an attic-fire burning thru the sheathing and engulfing the roofing materials from the back. Based on observation and farm boy commons, it seems to me that the biggest problem area is low-profile, flush mounted arrays over petroleum-based roofing materials. These are parallel to and close to the roof surface. Most commonly with horizontal rails below the surface of the modules, thereby reducing the effective clearance to the roof by the height of the rail. Which dramatically reduces convection. This mounting configuration concentrates heat onto the roof surface and traps roof gasses beneath the array from otherwise normal ventilation. Gassing is normal and occurs throughout the life of most roofing materials. Petroleum based roofing products tend to gas at a declining rate throughout their life cycle. This gassing is not generally combustible in these concentrations. Combustible gasses are created when a roofing material begins to burn. Early-stage combustion. If these combustible gasses are not allowed to evacuate quickly, the fire is exacerbated Gaining heat and intensity quickly. Flame spread. Once the roofing material is fully involved, meaning self-sustained burning, it's probably not gonna matter much whether there is an array above it or not unless someone is there to fight the fire. The chimney effect behind a tilted array would have three primary effects on this cycle. The first effect is that normal gassing would occur similarly to adjacent roof sections not covered by the array. The second is that, during pre and early-stage combustion, the combustible gasses will not concentrate between the module and the roof, effectively reducing the fuel and heat concentration by some amount. Possibly to a level that is equal to adjacent roof sections not covered by the array. Possibly even extinguishing an ember or small flame in a manner similar to blowing on a lit match. The third effect would occur once the roofing material is fully involved. In this part of the cycle, the chimney effect could certainly draw more air into the fire, possibly increasing its intensity, much like blowing into the base of a campfire. From a pure flammability perspective, I like the tilted array better than the flush array. My reasoning is primarily that normal aging will be more likely and, if an ember were to reach the roof beneath the module, it is more likely to self-extinguish or at least act like the adjacent roof. These characteristics reduce the overall liklihood of actually catching fire in the first place. Which I like. In the event that the roof beneath a tilted array were to become involved and induce an adverse chimney effect, the fire would be WAY more accessible to a water hose than with a flush mounted array. Another negative that a flush mounted array has in the fully involved scenario, is that it's
Re: [RE-wrenches] PV and Roof Flammability
On the plus side, roofs under PV arrays receive less ultraviolet radiation. On the negative side, some roofing shaded by PV arrays experience mold growth. - Original Message - From: Darryl Thayer daryl_so...@yahoo.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Thursday, September 23, 2010 6:39 PM Subject: Re: [RE-wrenches] PV and Roof Flammability Hi all Of course there were some fires with thermal collectors where the wood and shingles cought fire with inadaquite venting. No venting was the case. But I have measured the temperature under PV when it was vented and the roof was cooler under the array than elsewhere. ___ 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
Re: [RE-wrenches] PV and Roof Flammability
Joel, The problem is not with the rating of the modules. It is with the way we install them. The air gap is a problem. If HVAC systems were installed like PV modules, they would have the same problem. There will be changes of some sort coming in the next year or so. The IBC in 2012 will require PV systems to have a fire rating. Module fire rating may become irrelevant. Time will tell. This is in a very preliminary stage. All we know is that changes are likely with this new IBC language. There is a group working on this issue that includes several representatives from the PV manufacturing and PV installing industries. If this is something you want to put a lot of personal effort into, there are ways to accommodate good input. The SolarABCs will be helping coordinate ongoing efforts. Bill. -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Joel Davidson Sent: Wednesday, September 22, 2010 7:12 PM To: RE-wrenches Subject: [RE-wrenches] PV and Roof Flammability Wrenches, See http://www.solarabcs.org/flammability/ and the report at http://www.solarabcs.org/flammability/Flammability_Interimreport.pdf Is there any flammability difference between PV equipment on a roof and HVAC or air handling equipment on a roof? My concern is whether PV is being singled out as a flammability concern while other more established industries with more powerful lobbyists are not. Joel Davidson ___ 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
Re: [RE-wrenches] PV and Roof Flammability
Hi Joel, Trying to compare HVAC equipment to PV in a roof covering flammability discussion is about the same as the proverbial apples to oranges. They are profoundly different. I will even go out on a limb and say the the PV industry lobbyists are probably foaming at the mouth more than HVAC lobbyists. Go to SPI and then go to the next national SMACNA or ASHRAE convention to see the difference. Deciding to study the effects of putting PV over roof coverings, and not do the same for HVAC equipment, didn't have squat to do with lobbyists. Let's start with the differences: First and foremost, the amount of roof covering that is covered by PV is far greater than HVAC equipment. Think in terms of 25-100X, or infinity. In flush-mounted systems, the PV is mounted close to the surface of the roof covering. HVAC equipment is enclosed in a steel cabinet and generally does NOT sit over the roof-covering due to curb-mounting. I see these differences as the primary ones. We should all want to know how spreading PV across many contiguous square feet of roof affects the flammability of the roof covering. Good or bad, we should want to know. If putting PV over the top of a roof covering decreases the effective fire resistance of that roof covering by an unacceptable amount, maybe we shouldn't just throw it up there willy nilly. If we find that some application is bad for protecting the structure and people in it, we need to address that. If we find that it doesn't cause any negative effects, we want to know that. If we don't address it, sooner or later installations are simply gonna stop on a Public Saftey issue. If we don't address it, when (not if) there is a fire with human casualties, and the roof beneath the PV is involved, the lawyers are gonna insist the PV is at least partly to blame. If you don't have a valid study, you don't have a defense. I say be proactive. The question has been around since before I got into PV. I know that some comp shingles get brittle because they are under an array and some don't. I've seen many aging low-profile flush-mounted rooftop PV systems at this point, and there is a distinct difference in the weathering of some materials. Because the PV is over them. Specifically because the PV is over them. Although I haven't tracked hard data on this, my unscientific observation is that arrays mounted farther away from the roof have less adverse effects on the roof covering. I haven't bought the standard solar industry line that your roof will last longer because the solar shades it. I believe it's true in some cases and patently false in others. But I don't know how to identify which brands and models of shingles have which characteristics. Particularly if the material is 5 or 10 years old already. And, if I don't know, then I sure ain't gonna expect the salesperson to know, much less care. It's always been in the back of my mind whether or not the PV affects the ACTUAL flammability of the roof covering. And not just when they are both new. What happens over time? Does the flammability change with age? My instinct is that it likely does in some and does not in others. But which ones? Are they the same ones that get brittle? From a big-picture view, I'm glad somebody is at least studying this and reporting on it. I'm glad that it's not just the roofing industry, or worse, UL on their own. I'm glad that folks from the Solar ABC's are involved. I haven't read this whole interim report yet, but I will. The Exec Summary was encouraging and disappointing at the same time. Nevertheless, these findings will affect the way we build stuff going forward. And they should! Some module or rack manufacturer is gonna have to come up with a convection enhancement that minimizes gassing and gas stagnation beneath the modules, for instance. Or maybe we find that simply installing at least X number of inches off the roof surface has no negative affect on the roof covering. Or maybe we find that PV simply should not be installed above certain roof covering products at all. And learn how to identify them, inform building owners of the situation, recommend a solution, and move on. For all kinds of reasons, PV isn't right for every roof. Shade, orientation, structural deficiencies, roof type or condition, owner-is-a-jerk... All kinds of reasons. I'm not afraid to find out the truth in this matter. I want to know. I hope that the rabid solar lobbyists don't somehow block or marginalize responsible efforts to study and understand the issue. $0.02001 Solar Janitor -Original Message- From: Joel Davidson Sent: Wednesday, September 22, 2010 7:12 PM To: RE-wrenches Subject: [RE-wrenches] PV and Roof Flammability Wrenches, See http://www.solarabcs.org/flammability/ and the report at http://www.solarabcs.org/flammability/Flammability_Interimreport.pdf Is there any flammability difference between PV equipment on a roof and HVAC or air handling equipment on a roof? My concern is whether PV
Re: [RE-wrenches] PV and Roof Flammability
Hello Bill, Thanks for the feedback. I need to learn more about this issue. I plan to attend the October 15th SolarABC meeting after the LA conference. Is 2012 IBC draft available? How can PV systems be classified, let alone fire-rated, when there is a seemingly infinite combination of module, mount, wiring, inverter, and safety devices possible? Will system classification require system certification like Florida? Is the air gap considered a problem only for tilted PV arrays? The reasons I ask are (1) because stand-off arrays parallel to low-pitched roof are mounted like HVAC equipment and (2) HVAC and other roof-mounted equipment do not change the building's occupancy group, construction type and minimum roof class. Best regards, Joel Davidson - Original Message - From: Bill Brooks billbroo...@yahoo.com To: 'RE-wrenches' re-wrenches@lists.re-wrenches.org Sent: Thursday, September 23, 2010 8:29 AM Subject: Re: [RE-wrenches] PV and Roof Flammability Joel, The problem is not with the rating of the modules. It is with the way we install them. The air gap is a problem. If HVAC systems were installed like PV modules, they would have the same problem. There will be changes of some sort coming in the next year or so. The IBC in 2012 will require PV systems to have a fire rating. Module fire rating may become irrelevant. Time will tell. This is in a very preliminary stage. All we know is that changes are likely with this new IBC language. There is a group working on this issue that includes several representatives from the PV manufacturing and PV installing industries. If this is something you want to put a lot of personal effort into, there are ways to accommodate good input. The SolarABCs will be helping coordinate ongoing efforts. Bill. -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Joel Davidson Sent: Wednesday, September 22, 2010 7:12 PM To: RE-wrenches Subject: [RE-wrenches] PV and Roof Flammability Wrenches, See http://www.solarabcs.org/flammability/ and the report at http://www.solarabcs.org/flammability/Flammability_Interimreport.pdf Is there any flammability difference between PV equipment on a roof and HVAC or air handling equipment on a roof? My concern is whether PV is being singled out as a flammability concern while other more established industries with more powerful lobbyists are not. Joel Davidson ___ 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
Re: [RE-wrenches] PV and Roof Flammability
Good points all, Has anyone had an experience where you've seen new shingles and PV installed at the same time, where the shingles became prematurely brittle beneath the array, where you could say for sure it was PV's fault? I too have tried to keep an eye on that, but I never can pin it on PV, most are still retrofits, not lending any credible data. As long as the PV doesn't cause the fire, due to: - Ground-faulted or otherwise compromised wiring - Melted cheap-o junction boxes (lowest cost import products) - Improperly wired roof mounted combiners (reverse polarity) - Conduit/expansion fitting errors (like the TARGET fire) - The fact that they simply will be in the way if firefighters have to vent... Are we saying there is evidence that the PV shade structure can increase the flammability of the roof product from combustion, due to proximity? Trapping a combustible level of heat beneath the array that can dry out and set fire to comp shingle? Hypothesis = 1 in a billion, necessary to look at, sure. Maybe 1 in a 1/2 billion for wood shake. Solutions I see then: -They can be stuck to the roof, no air gap no problem. Well, except no possibility of removal for firefighters. -Integrated into the roof, then maintenance and wiring is buried. -0-5 (or whatever), no go due to too close. -5 (or whatever) and higher, Ok, due to adequate airflow and lack of proximity. So now we're going to need PV compatible roof product ratings? PV has a great track record ratio of installs to related fires, and this is with a majority of installers NOT really knowing what their doing, me included. I hope we don't have to get more expensive as a result, let's make the roofers tell us which ones are not compatible, and then we can just tell them to stop installing it. PV is too important. :o) I have to believe that having a roof covered by PV, especially in CA, could also Help Prevent fires from falling embers from forest and field fires, the occasional PGE GAS LINE EXPLOSION BLOWING UP WHOLE NEIGHBORHOODS, etc. Most material science would indicate that shading of the roof, the overwhelming majority of the time, will extend roofing product lifespan, often significantly, and help keep the attic a bit cooler. Let's not let officials overdo it, as I get more frustrated and educated about this overly passive and tolerant society of ours, I'm beginning to believe a little collateral damage is completely acceptable. It obviously is for the big boys of energy, money, automobiles, policy, etc. *See BURNING THE FUTURE (Coal), GASLAND (Natural Gas), FLOW (For Love of Water), all the oil movies (oil), The Cove (Dolphins)... etc. We could probably have a roof fire per day, and still be doing better than these A for alternative holes, except we'd get blitzed by the bad guys. Thanks again for keeping watch guys. $.0001 P.S. WHERE IS OUR FEED-IN TARIFF?... oh what, the PPA's have it covered, oh yeah, they don't want one, great for us. Is anyone watch-dogging these PV finance guys? They're the ones that scare me the most, you know, the ones that get lost at the T for truth-in-lending. Thanks for your relentless service to the industry that could save America, if only they would let us. Ryan J. LeBlanc NABCEPT Certified Solar PV Installer Cell: 707.591.1950 Direct: 707.536.9839 r...@naturalenergyworks.com http://www.NaturalEnergyWorks.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
Re: [RE-wrenches] PV and Roof Flammability
Hi gang. It seems to me that an upward sloping gap between the flammable roofing materials and the PV modules would result in a chimney effect for any fire in the roofing materials whether the fire is a result of the PV system or not. Combine that with the modules blocking access to a roofing fire, and maybe you have their concern. Just guessing here. Ryan LeBlanc wrote at 12:43 PM 9/23/2010: Good points all, Has anyone had an experience where you've seen new shingles and PV installed at the same time, where the shingles became prematurely brittle beneath the array, where you could say for sure it was PV's fault? I too have tried to keep an eye on that, but I never can pin it on PV, most are still retrofits, not lending any credible data. As long as the PV doesn't cause the fire, due to: - Ground-faulted or otherwise compromised wiring - Melted cheap-o junction boxes (lowest cost import products) - Improperly wired roof mounted combiners (reverse polarity) - Conduit/expansion fitting errors (like the TARGET fire) - The fact that they simply will be in the way if firefighters have to vent... Are we saying there is evidence that the PV shade structure can increase the flammability of the roof product from combustion, due to proximity? Trapping a combustible level of heat beneath the array that can dry out and set fire to comp shingle? Hypothesis = 1 in a billion, necessary to look at, sure. Maybe 1 in a 1/2 billion for wood shake. Solutions I see then: -They can be stuck to the roof, no air gap no problem. Well, except no possibility of removal for firefighters. -Integrated into the roof, then maintenance and wiring is buried. -0-5 (or whatever), no go due to too close. -5 (or whatever) and higher, Ok, due to adequate airflow and lack of proximity. So now we're going to need PV compatible roof product ratings? PV has a great track record ratio of installs to related fires, and this is with a majority of installers NOT really knowing what their doing, me included. I hope we don't have to get more expensive as a result, let's make the roofers tell us which ones are not compatible, and then we can just tell them to stop installing it. PV is too important. :o) I have to believe that having a roof covered by PV, especially in CA, could also Help Prevent fires from falling embers from forest and field fires, the occasional PGE GAS LINE EXPLOSION BLOWING UP WHOLE NEIGHBORHOODS, etc. Most material science would indicate that shading of the roof, the overwhelming majority of the time, will extend roofing product lifespan, often significantly, and help keep the attic a bit cooler. Let's not let officials overdo it, as I get more frustrated and educated about this overly passive and tolerant society of ours, I'm beginning to believe a little collateral damage is completely acceptable. It obviously is for the big boys of energy, money, automobiles, policy, etc. *See BURNING THE FUTURE (Coal), GASLAND (Natural Gas), FLOW (For Love of Water), all the oil movies (oil), The Cove (Dolphins)... etc. We could probably have a roof fire per day, and still be doing better than these A for alternative holes, except we'd get blitzed by the bad guys. Thanks again for keeping watch guys. $.0001 P.S. WHERE IS OUR FEED-IN TARIFF?... oh what, the PPA's have it covered, oh yeah, they don't want one, great for us. Is anyone watch-dogging these PV finance guys? They're the ones that scare me the most, you know, the ones that get lost at the T for truth-in-lending. Thanks for your relentless service to the industry that could save America, if only they would let us. Ryan J. LeBlanc NABCEPT Certified Solar PV Installer Cell: 707.591.1950 Direct: 707.536.9839 r...@naturalenergyworks.com http://www.NaturalEnergyWorks.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
Re: [RE-wrenches] PV and Roof Flammability
a similar definition when we get right down to it. Which sort of causes a problem, doesn't it? This is at the heart of why I am in favor of responsible testing to determine the truth in this matter. Because we all want it to be somebody else's customer and we can't make sure it's not our customer unless we understand how to do that. We won't really understand how to do that unless somebody goes thru the exercise of testing stuff and telling us what the results are. I suspect that testing will show that most common sloped-roof materials will maintain their UL rating as long as there is something like a 6 clearance up-slope for convection. Meaning 6 between the roof surface and any horizontal rails. I don't think one can honestly argue that there's an array over that piece of roof so hot embers can't get onto the roof surface in that area. Sort of like having a disaster response plan composed of It will never happen. I say be proactive on this issue or somebody else will make decisions for us. We just might learn something important along the way and avoid some really hard lessons in the future. Even if it's somebody else's customer. Like all of us, I am concerned about further limitations on PV deployments. The CalFire guidelines pretty much strangle a lot of potential residential installations and, in my opinion, are overkill that provides very limited benefit. That sucks. Bonehead AHJs cause a lot of grief. That sucks. Uncertainty about materials supply or incentives... That sucks too. Big oak tree in the neighbor's yard. That sucks. Foreman quits to go into business for himself. That sucks. Third microinverter failure in a week. That sucks. When it comes down to it, we have to deal with all kinds of things that suck on a daily basis. Some avoidable and some not. Let's avoid the avoidable ones. $0.02001 Solar Janitor PS... On a brainstorm note: It occurs to me that laying a corrugated metal roof skin over the top of an existing roof material should effectively increase the fire resistant characteristics to an acceptable level. A physical barrier. A roof condom. I figure that you wouldn't need to attach it to the roof... Just secure it to the standoffs and rails, attach some stiffener system to eliminate the wind-rattle, and you're golden. Just a thought. -Original Message- From: Michael Welch Sent: Thursday, September 23, 2010 12:50 PM To: RE-wrenches Subject: Re: [RE-wrenches] PV and Roof Flammability Hi gang. It seems to me that an upward sloping gap between the flammable roofing materials and the PV modules would result in a chimney effect for any fire in the roofing materials whether the fire is a result of the PV system or not. Combine that with the modules blocking access to a roofing fire, and maybe you have their concern. Just guessing here. Ryan LeBlanc wrote at 12:43 PM 9/23/2010: Good points all, Has anyone had an experience where you've seen new shingles and PV installed at the same time, where the shingles became prematurely brittle beneath the array, where you could say for sure it was PV's fault? I too have tried to keep an eye on that, but I never can pin it on PV, most are still retrofits, not lending any credible data. As long as the PV doesn't cause the fire, due to: - Ground-faulted or otherwise compromised wiring - Melted cheap-o junction boxes (lowest cost import products) - Improperly wired roof mounted combiners (reverse polarity) - Conduit/expansion fitting errors (like the TARGET fire) - The fact that they simply will be in the way if firefighters have to vent... Are we saying there is evidence that the PV shade structure can increase the flammability of the roof product from combustion, due to proximity? Trapping a combustible level of heat beneath the array that can dry out and set fire to comp shingle? Hypothesis = 1 in a billion, necessary to look at, sure. Maybe 1 in a 1/2 billion for wood shake. Solutions I see then: -They can be stuck to the roof, no air gap no problem. Well, except no possibility of removal for firefighters. -Integrated into the roof, then maintenance and wiring is buried. -0-5 (or whatever), no go due to too close. -5 (or whatever) and higher, Ok, due to adequate airflow and lack of proximity. So now we're going to need PV compatible roof product ratings? PV has a great track record ratio of installs to related fires, and this is with a majority of installers NOT really knowing what their doing, me included. I hope we don't have to get more expensive as a result, let's make the roofers tell us which ones are not compatible, and then we can just tell them to stop installing it. PV is too important. :o) I have to believe that having a roof covered by PV, especially in CA, could also Help Prevent fires from falling embers from forest and field fires, the occasional PGE GAS LINE EXPLOSION BLOWING UP WHOLE NEIGHBORHOODS, etc. Most material science would indicate that shading of the roof, the overwhelming
Re: [RE-wrenches] PV and Roof Flammability
Hi I forgot last summer I removed some modules that I had installed in the 1996? the roof had been damaged by hail. No damage to the modules, and the shingles under the modules looked great, and they did not look or feel brittle and the rest of the roof was beat up. --- On Thu, 9/23/10, Darryl Thayer daryl_so...@yahoo.com wrote: From: Darryl Thayer daryl_so...@yahoo.com Subject: Re: [RE-wrenches] PV and Roof Flammability To: RE-wrenches re-wrenches@lists.re-wrenches.org Date: Thursday, September 23, 2010, 8:39 PM Hi all Of course there were some fires with thermal collectors where the wood and shingles cought fire with inadaquite venting. No venting was the case. But I have measured the temperature under PV when it was vented and the roof was cooler under the array than elsewhere. ___ 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
