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

Sat Mar 28 11:27:24 PDT 2015

Several years ago I think someone was talking about using Rain-X on the glass of the modules so the snow would come off easier. I never have tried this. Anyone who has? Results?

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] On Behalf Of dana at solarwork.com
Sent: Saturday, March 28, 2015 9:17 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Tilt Racking vs Roof Mount for Shedding snow

I would be curious to hear if there's a difference in how different manufacturers modules hold snow and ice,

Has anyone seen particular module manufacturers that tend to hold more snow ?

this would be really good information for those of us in snow country

Dana Orzel 208.721.7003

Encourage Free Thinking Self Responsible Free Range Children

On Mar 27, 2015, at 9:59 AM, <dan at foxfire-energy.com> <dan at foxfire-energy.com> wrote:

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
 <http://www.Foxfire-Energy.com> www.Foxfire-Energy.com
NABCEP #092907-44

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-------- Original Message --------
Subject: Re: [RE-wrenches] Tilt Racking vs Roof Mount for Shedding snow
From: "Dave" < <mailto:dave at independentpowerllc.com> dave at independentpowerllc.com>
Date: Fri, March 27, 2015 10:32 am
To: "'RE-wrenches'" < <mailto:re-wrenches at lists.re-wrenches.org> 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> mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of  <mailto: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
 <http://www.Foxfire-Energy.com> www.Foxfire-Energy.com
NABCEP #092907-44

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