Jarmo,
The sun’s geometry is not nearly that simple. To understand the impact of north-facing arrays, you have to perform a simulation. PV:WATTS does this just fine and it is easy to show that a 18-degreed North-facing tilt produces 75% of a perfect 30-degree south-facing array. Far more than your assumption of 50%. To compare 15-degrees South to 15-degrees North, the numbers are slightly better at 77%. We are going to see a lot of north-facing arrays once people understand that low tilt angles are very forgiving on North slopes. Steep slopes are a totally different story and you have to run the numbers…. Bill. From: RE-wrenches [mailto:[email protected]] On Behalf Of [email protected] Sent: Tuesday, July 28, 2015 8:04 AM To: RE-wrenches <[email protected]> Subject: Re: [RE-wrenches] Using the North Facing Roof I did a slide on the effect of North facing modules. For even a fairly aggressive rotation North as shown, the effect is "only" a 50% reduction. The questions of whether or not to do it, are, - is the mounting structure simpler, lower cost - security against wind - can I put a larger array on the roof (typically yes, if you make back to back pyramid shaped structures) - overall, what is the cost versus benefit JARMO _____________________________________________________________________________________ Jarmo Venalainen | Schneider Electric | Xantrex Brand | CANADA | Sales Application Engineer Phone: +604-422-2528 | Tech Support: 800-670-0707 | Mobile: +604-505-0291 Email: <mailto:[email protected]> [email protected] | Site: <http://www.xantrex.com/> www.Xantrex.com | Address: 3700 Gilmore Way, Burnaby, BC V5G4M1 <http://www.xantrexrebate.com/> <http://www.xantrex.com/> <https://www.facebook.com/Xantrex> <https://twitter.com/Xantrex> <https://twitter.com/Xantrex> *** Please consider the environment before printing this e-mail From: "Peter Parrish" <[email protected] <mailto:[email protected]> > To: "'RE-wrenches'" <[email protected] <mailto:[email protected]> >, Date: 07/28/2015 12:22 AM Subject: [RE-wrenches] Using the North Facing Roof Sent by: "RE-wrenches" <[email protected] <mailto:[email protected]> > _____ I recently read a short piece that caught me up short, and I quote: “The fast dropping cost of solar, while a huge boon to the adoption of solar PV, has counter-intuitively altered design parameters. No longer is the north-facing roof considered unusable because limited application in less-than optimal orientations can still show a positive net benefit. Arrays are thus designed now with elements or sub-arrays in these locations, increasing overall kW installation while reducing the energy production per capacity installed. This might have been anticipated based on sheer economic analysis from a users perspective, but so long has solar been expensive that these less optimal orientations were never seriously considered.” I doubt that the individual who wrote this piece came to these conclusions him/herself. Does anyone know of a recent article that argued this perspective? Is this an emerging design practice? If so, I’d like to know more about it. - Peter Peter T. Parrish, Ph.D. President, SolarGnosis 1107 Fair Oaks Ave., Suite 351 South Pasadena, CA 91030 (323) 839-6108 [email protected] <mailto:[email protected]> ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. _____________________________________________________________________________________________________________________ List sponsored by Redwood Alliance List Address: [email protected] <mailto:[email protected]> Change listserver email address & settings: <http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: <http://www.mail-archive.com/[email protected]/maillist.html> http://www.mail-archive.com/[email protected]/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
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