Re: [RE-wrenches] Microfractures in PV Modules
Does this suggest that it is better to buy monocrystalline cell modules instead of poly; and that those modules that flash test with the highest output for a given production run have the best printed connections and therefore the higher probability of long term life and performance? Bill Dorsett Manhattan, KS -Original Message- From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Christopher Warfel Sent: Saturday, October 04, 2014 10:21 AM To: re-wrenches@lists.re-wrenches.org Subject: [RE-wrenches] Microfractures in PV Modules Recently a inspector raised the issue of microfractures in pv modules, and that the existence of such fractures would require replacement of the modules and a failing of the system inspection. I found information from NREL confirming the existence of microfractures in poly crystalline. However, I have not seen any information on how to detect them (ie, what they look like). Does anyone have a reference that shows this, and is this a valid concern for the industry? Thank you, Chris -- Christopher Warfel, President ENTECH Engineering, Inc. PO Box 871, Block Island, RI 02807 401-466-8978 ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
[RE-wrenches] Microfractures in PV Modules
Recently a inspector raised the issue of microfractures in pv modules, and that the existence of such fractures would require replacement of the modules and a failing of the system inspection. I found information from NREL confirming the existence of microfractures in poly crystalline. However, I have not seen any information on how to detect them (ie, what they look like). Does anyone have a reference that shows this, and is this a valid concern for the industry? Thank you, Chris -- Christopher Warfel, President ENTECH Engineering, Inc. PO Box 871, Block Island, RI 02807 401-466-8978 ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] Microfractures in PV Modules
Hi Chris, Do you mean the AHJ? jay On Oct 4, 2014, at 8:20 AM, Christopher Warfel wrote: Recently a inspector raised the issue of microfractures in pv modules, and that the existence of such fractures would require replacement of the modules and a failing of the system inspection. I found information from NREL confirming the existence of microfractures in poly crystalline. However, I have not seen any information on how to detect them (ie, what they look like). Does anyone have a reference that shows this, and is this a valid concern for the industry? Thank you, Chris -- Christopher Warfel, President ENTECH Engineering, Inc. PO Box 871, Block Island, RI 02807 401-466-8978 ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] Microfractures in PV Modules
No, this is a third party quality assurance inspector for a rate payer funded program. The issue is most likely proper use of ratepayer funds towards these projects. I would think that the AHJ wouldn't be concerned unless there was a safety issue My question is more along the lines of: is this a real issue, and if so, how does one see the defect? On 10/4/2014 12:21 PM, jay peltz wrote: Hi Chris, Do you mean the AHJ? jay On Oct 4, 2014, at 8:20 AM, Christopher Warfel wrote: Recently a inspector raised the issue of microfractures in pv modules, and that the existence of such fractures would require replacement of the modules and a failing of the system inspection. I found information from NREL confirming the existence of microfractures in poly crystalline. However, I have not seen any information on how to detect them (ie, what they look like). Does anyone have a reference that shows this, and is this a valid concern for the industry? Thank you, Chris -- Christopher Warfel, President ENTECH Engineering, Inc. PO Box 871, Block Island, RI 02807 401-466-8978 ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org -- Christopher Warfel, President ENTECH Engineering, Inc. PO Box 871, Block Island, RI 02807 401-466-8978 ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] Microfractures in PV Modules
Christopher There are some level of micro fractures that are always present in cells and not visible to the naked eye. Some of these will produce visible fractures over time from loading and flexing of the module from weather and temperature changes. The micro fractures can be an issue with performance, but may not show up until later, they are not necessarily an issue with safety. If the encapsulation is intact and the there is not a specific internal fault caused by the separation the only issue would be loss of conducting surface between the broken piece and the internal string wiring resulting in a loss of performance. Bottom line as long as there is not a fault, your AHJ does not have much to say about performance, the NEC says nothing about performance, only if the installation is safe. All modules are flash tested and sorted for performance and checked for faults ( insulation resistance tested at a voltage significantly higher than the operational rating, 2x max voltage + 1000V). This is required before a module manufacturer can place a UL sticker on it. IMHO as long as the damage and is not causing leakage current during an insulation resistance test at the factory the AHJ really cannot say anything about it legally, he is not an inspector for UL and really only needs to be able to read the UL sticker and certify it is being used according to the listing. That being said some module manufacturers do add an additional Electroluminescence test that does detect micro cracks by placing a small reverse current through the module that causes the active material to act as a Light Emitting Diode in the near infrared spectrum that it is possible to detect with a special camera calibrated for that light spectrum. Usually done in a lab, although there are expensive field units available now. These test will show micro-cracks, bad print screening and bad spots on the cells from the doping process. I have done tests were we purposely damage cells in a module and we have been able to detect micro cracks that did not necessarily result in a reduced flash test at the factory. Over time I assume that will not be the case and reduced output may be the. So IMHO your AHJ does not have the equipment nor does he have the expertise to perform these tests, nor does the NEC or UL1703 require it! Good Luck with the inspector, but I think he is way out of his league on this one, until it becomes a safety issue, even a visible crack in a cell is not an issue of his concern. Bill On Sat, Oct 4, 2014 at 8:20 AM, Christopher Warfel cwar...@entech-engineering.com wrote: Recently a inspector raised the issue of microfractures in pv modules, and that the existence of such fractures would require replacement of the modules and a failing of the system inspection. I found information from NREL confirming the existence of microfractures in poly crystalline. However, I have not seen any information on how to detect them (ie, what they look like). Does anyone have a reference that shows this, and is this a valid concern for the industry? Thank you, Chris -- Christopher Warfel, President ENTECH Engineering, Inc. PO Box 871, Block Island, RI 02807 401-466-8978 ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches. org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org -- William Hoffer 161 SE Fourth Ave P.O. Box 1823 White Salmon, WA 98672-1823 suneng...@gmail.com bhof...@sunergyengineeringservices.com ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] Microfractures in PV Modules
Hi Chris, There are a number of test methods, but the best two are. Electroluminescence imagining ELI thermal imaging IR From what I read at Photon, the ELI is the best for micro cracks before they really happen. After they are visible, thermal imaging can be helpful. As to it being a real issue, I believe so. The cause has not been confirmed, but contributing factors are: cell thickness manufacturing handling shipping/packing field handling. For example I've seen IR photos that show a hand print damage in the middle of module. Or damage that sure looks like it would have been from a shoulder pressing on a cell area ( carrying it like a sheet of plywood). If you are looking for someone who can do these field tests, contact me off site, jay peltz power On Oct 4, 2014, at 10:46 AM, Christopher Warfel wrote: No, this is a third party quality assurance inspector for a rate payer funded program. The issue is most likely proper use of ratepayer funds towards these projects. I would think that the AHJ wouldn't be concerned unless there was a safety issue My question is more along the lines of: is this a real issue, and if so, how does one see the defect? On 10/4/2014 12:21 PM, jay peltz wrote: Hi Chris, Do you mean the AHJ? jay On Oct 4, 2014, at 8:20 AM, Christopher Warfel wrote: Recently a inspector raised the issue of microfractures in pv modules, and that the existence of such fractures would require replacement of the modules and a failing of the system inspection. I found information from NREL confirming the existence of microfractures in poly crystalline. However, I have not seen any information on how to detect them (ie, what they look like). Does anyone have a reference that shows this, and is this a valid concern for the industry? Thank you, Chris -- Christopher Warfel, President ENTECH Engineering, Inc. PO Box 871, Block Island, RI 02807 401-466-8978 ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org -- Christopher Warfel, President ENTECH Engineering, Inc. PO Box 871, Block Island, RI 02807 401-466-8978 ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
