Mark, Although these are tough issues, I don't see that the sky is falling or that systems are too dangerous to install in residential applications.
That being said, I think we are still a ways off from safe PV systems. My opinion is that some type of "smart PV modules" that can do ground-fault and arc-fault detection will become the practical solution to safety issues related to buildings and people. The critical things with module level control is reliability, efficiency, and cost. It is too soon to broadly require these technologies, but safety concerns will push the development. It is not unlikely that the 2014 NEC will have requirements that the PV industry has not widely adopted on its own. The 2011 NEC already requires series arc fault detection, which is not currently available nor are there published standards to evaluate them. It is an interesting time with lots of changes currently underway. Bill. -----Original Message----- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Frye Sent: Friday, October 22, 2010 9:24 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] Ground Mount Screening Thanks for the response Bill. It's a tough nut to crack and we are all doing our best to move the industry forward. It is interesting that you bring up the issue of vermin. Unfortunately, I had to address squirrel damage on one of my own residential roof top installations. Not pretty. But the one thing I can say is that a squirrel can eat right through both wood or plastic lattice in a heart beat. For that matter, a squirrel can move right through a standard steel chain link fence. So where does that really leave residential level PV installations in the US. It appears that everywhere we turn we see more and more issue being brought up, with ad hoc solutions that make installation more and more difficult. Are we really moving in a direction that PV is so complicated and dangerous that I can only be installed in commercial and industrial venues where these concerns can be managed in the context of "access by qualified personnel only"? Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 www.berkeleysolar.com -----Original Message----- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Bill Brooks Sent: Friday, October 22, 2010 8:27 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] Ground Mount Screening Mark, I certainly was not implying that you were in any way unintelligent. I was merely suggesting that fences or only one means of compliance. You have a different opinion, and you are entitled to it. However, if all jurisdictions viewed prevention of ready access to mean fences, that would not be good for the PV industry as a whole. Both crawl spaces and unfinished basements can have numerous hazards so these locations are generally not seen as habitable and should not be readily accessible locations. However, a garage does require that NM be above 8' or protected--usually by sheetrock--below 8 feet. Under a PV array that is lower than 8' would be like a crawl space only if access to the underside were protected as crawl spaces should be. We tried to get specific language in the NEC on types of guards that were permitted, but the Code Making Panel rejected the proposal stating that it was well-understood in the electrical industry how to prevent ready access--maybe not so much. The much bigger problem is that installers put not protection around their wiring systems so that children can use the "black vines" to play Tarzan on them. I think you would agree that is not good--but we see it all the time in rural areas. Animals are another big problem in certain places. While this thread is about ground mount systems, roof mounting in wooded areas populated by squirrels is a serious problem--as discussed many times in this forum. The code currently does not address this problem, but perimeter screening may be a requirement in the future to prevent both squirrels and debris from creating a fire hazard under a PV array. Just yesterday I was talking to a contractor that had just come back from an installation with a fully eaten 6-foot section of USE-2 where they had to remove the array to repair the wiring. Fortunately, the ground fault protection activated and prevented a fire. Bill. _______________________________________________ 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
