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

[Jerry Shafer]

I designed an array with a tempered glass sheet over the module gilted at
75 degrees, it was vented to prevent the effect of green housing. The glass
area was alot larger then the modules but snow always shed off the glass
and the modules were facing the sun. I designed it to be lifted but the
customer never did never needed to. Note the glass sheets were 4 feet by 10
feet. I expected a hit on performance but has not been an issue. In part
that we dont loose durng the sunny days between storms.
Jerry
On Mar 27, 2015 6:36 AM, "Dave" <dave at independentpowerllc.com> wrote:

> BTW Dan. I have designed and installed power sheds here in the north with
> tilt up arrays using adjustable leg sets that allow up to 80 degree tilt
> angles! Pretty ugly if it's staring you in the face, but quite effective
> when the bottom of the array is directly over the eave of the roof. Allow
> 18" or so distance from roof to bottom of modules to allow the snow on the
> surface of the roof to be cleaned occasionally with a roof rake. Adjustable
> legs will allow experience to be your guide going forward on how much of a
> tilt is needed (and tolerated appearance wise). Of course the wind loads
> are severe with a design like this and must be managed.
>
> 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
>
>
> ------------------------------
>
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