Allan, According to Unirac tech, the code manual only addresses solid wall structures. He was also the one who told me about the greater windloads on open structures. His suggestion was to get an engineer involved, but on a system this size I am hoping to avoid that additional cost. I did fill out their online design parameter form, so I'm hoping to get enough feedback from that to come up with an over-engineered way to anchor the array to the frame structure of the carport.......... Holt E. Kelly Holtek Fireplace & Solar Products 500 Jewell Dr. Waco TX. 76712 254-751-9111 www.holteksolar.com
----- Original Message ----- From: Allan Sindelar To: RE-wrenches Sent: Sunday, April 18, 2010 2:17 AM Subject: Re: [RE-wrenches] Tilt biased.... Holt, Feedback re the low tilt angle: Go for it, you're good. Re wind loading: check out UniRac's Code Compliant Installation Manual, http://www.unirac.com/pdf/ii227.pdf, especially pages 3-9. Less wind loading is one of the main reasons for going with a lower tilt angle. Another is closer module row spacing (at 3X height RoT) without inter-row shading. No experience with Enphase. Allan <![endif]--> Allan Sindelar al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com hol...@sbcglobal.net wrote: Searching for opinions.....is this "over design"? Designing small system (2.35kW). Customer uses gas for heating. Typical A/C unit. I was thinking of biasing the tilt to summer production for greater offset of summer demand (lat 31.6, proposing 18). No net metering in this part of the world. PVwatts shows a drop of 2% /yr. in production , 5% higher production for A/C months. Feedback? Also, this array will go on a carport. I understand that windloading is actually greater for an open structure than one with walls (another reason for lower tilt) - is there any one that can direct me to data on finding out how much more? Lastly, what is a good avg. target derate factor for Enphase inverters (real world)? Holt E. Kelly Holtek Fireplace & Solar Products 500 Jewell Dr. Waco TX. 76712 254-751-9111 www.holteksolar.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
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