Black on black modules help a little but not really enough here where it can be really cold for many weeks at a time. I have a black on black array (55 degree tilt on a 6/12 roof) on a rental house that needs to be roof raked after every snow, OR, run the generator. I much prefer to use the roof rake.
From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mac Lewis Sent: Friday, March 27, 2015 1:25 PM To: RE-wrenches Subject: Re: [RE-wrenches] Tilt Racking vs Roof Mount for Shedding snow Another thing that makes a big difference here in Colorado is to use dark colored frames and cells as opposed to silver frames and lighter colored cells. We get a lot of cold but clear days and dark color makes a huge difference in how quickly shedding will occur. This same phenomenon will work against you in the summer but for off-grid our design day is mid-winter typically. We prefer pole mounts where snow can be broomed off and tilts optimized throughout the winter. Cheers On Fri, Mar 27, 2015 at 10:15 AM, Dave <d...@independentpowerllc.com> wrote: I will back up your opinion that open back has not a lot to do with it. I have several arrays that I care for here in my off grid neighborhood and some are tilted 20 degrees off of roofs to 45 degree array angle and one is a TPM that is set at 60 degrees for winter and all of these experience severe snow cover problems unless it warms up for a significant amount of time, or the roof rake is used. As you know, building the rack far off of the roof AND minimize costs do not go together. Extra material and extra strength for wind loads. Dave From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of d...@foxfire-energy.com Sent: Friday, March 27, 2015 12:00 PM To: RE-wrenches Subject: Re: [RE-wrenches] Tilt Racking vs Roof Mount for Shedding snow My customers neighbor has 1.1k of 110W panels on a tilt up rack set at about 45° (Some 20° from the roof). Her array pretty much stayed clear all winter with minimal futzing. My customer has a 7.2k array (Four rows of six) in portrait, mounted on unirack solar mount on an asphalt tile roof at around 45° (Off Grid), on an unheated garage. My customers panels got a thin coat of ice on the array early on that held some 12'' of snow all winter. We did set it up so the bottom two rows were on their own CC and could be cleared from the ground, but they never did totally clear. The neighbor now wants to expand her system, is willing to build a shed for the array, but wants me to elevate the array as far off the roof as possible (and minimize costs). I'm working on my diplomacey here. I suggested it might be a combination of factors that contributed to my customers array not sheding, but the neighbor insists it has something to do with the array being open backed. I offered to put it out to the group for opinions. Thanks db Dan Brown Foxfire Energy Corp. Renewable Energy Systems (802)-483-2564 <tel:%28802%29-483-2564> <http://www.Foxfire-Energy.com> www.Foxfire-Energy.com NABCEP #092907-44 -------- Original Message -------- Subject: Re: [RE-wrenches] Tilt Racking vs Roof Mount for Shedding snow From: "Dave" < <mailto:d...@independentpowerllc.com> d...@independentpowerllc.com> Date: Fri, March 27, 2015 10:32 am To: "'RE-wrenches'" < <mailto:re-wrenches@lists.re-wrenches.org> re-wrenches@lists.re-wrenches.org> Dan, What do you mean by "tilt up racking". Would an example be a rack that adds 15 degrees to a 5/12 roof? Good idea (as long as wind load is taken care of) for cold snow country (certainly for off grid) to get the tilt angle higher which helps with snow shedding. BUT if it's super cold like this winter here in northern New England nothing helps as much as a snow rake. On a side note. I had a couple of monitored grid tied systems with second story roof top arrays that produced very little power from January through second week of March. 80% less kWh than similar first story roof top arrays where the homeowner raked off snow. It was so cold that in one period this winter that it did not get over 30 degrees F for 48 consecutive days here, with many nights at 15 to 30 below zero. February was the coldest on record (since 1886) with temps that were 15 degrees below average for the month. No snow shedding going on at all. On another type of array. My adjustable ground mount here set at 90 degrees had a great winter as I regularly saw 1,750 to 1,950W out of my Apollo CC from a 1,440W array on sunny days because of MPPT and the reflective bounce of sunlight off the snow in front of the array. I never have to touch those modules from mid November, when I tilt them to 90 degrees, until after it stops snowing significantly (mid April usually). Best, Dave David Palumbo Independent Power LLC 462 Solar Way Drive Hyde Park, VT 05655 802-888-7194 From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of d...@foxfire-energy.com Sent: Friday, March 27, 2015 8:19 AM To: RE-wrenches Subject: [RE-wrenches] Tilt Racking vs Roof Mount for Shedding snow Hi Guys, I have a customer who seems convinced that tilt up racking sheds snow better than conventional roof mounted arrays (irregardless of angle or panel manufacturer). Anyone else find this is true? Thanks db Dan Brown Foxfire Energy Corp. Renewable Energy Systems (802)-483-2564 <tel:%28802%29-483-2564> www.Foxfire-Energy.com NABCEP #092907-44 _____ _______________________________________________ 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 -- Mac Lewis "Yo solo sé que no sé nada." -Sócrates
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