[RE-wrenches] Tilt Racking vs Roof Mount for Shedding snow

Fri Mar 27 10:25:17 PDT 2015

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 <dave at 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-bounces at lists.re-wrenches.org] *On
> Behalf Of *dan at 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
> www.Foxfire-Energy.com
> NABCEP #092907-44
>
>
>
> -------- Original Message --------
> Subject: Re: [RE-wrenches] Tilt Racking vs Roof Mount for Shedding snow
> From: "Dave" <dave at independentpowerllc.com>
> Date: Fri, March 27, 2015 10:32 am
> To: "'RE-wrenches'" <re-wrenches at 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-bounces at lists.re-wrenches.org*
> <re-wrenches-bounces at lists.re-wrenches.org>] *On Behalf Of *
> *dan at foxfire-energy.com* <dan at 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
> *www.Foxfire-Energy.com* <http://www.Foxfire-Energy.com>
> NABCEP #092907-44
>
>
> ------------------------------
>
> _______________________________________________
> List sponsored by Redwood Alliance
>
> List Address: *RE-wrenches at lists.re-wrenches.org*
> <RE-wrenches at lists.re-wrenches.org>
>
> 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/re-wrenches@lists.re-wrenches.org/maillist.html*
> <http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html>
>
> List rules & etiquette:
> *www.re-wrenches.org/etiquette.htm*
> <http://www.re-wrenches.org/etiquette.htm>
>
> Check out or update participant bios:
> *www.members.re-wrenches.org* <http://www.members.re-wrenches.org>
>
>
> _______________________________________________
> List sponsored by Redwood Alliance
>
> List Address: RE-wrenches at 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*
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20150327/52b4dc13/attachment-0002.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 25138 bytes
Desc: not available
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20150327/52b4dc13/attachment-0005.png>