[RE-wrenches] Dealing with snow

[Darryl Thayer]

Hi I have a large array that I mounted at 45 deg.  it mostly clears itself. however two years ago it held ice and snow for 3 Weeks.  I wanted to try BoB Gudgel's snow melt routine, but he was to busy to give me details, then the snow melted.  I have never had problems with  the snow build up behind modules.  But in Minnesota we have 40 to 50 lb snow load, and some places in Main or Vermont have 100 or more.
Darryl  

--- On Fri, 8/14/09, penobscotsolar at midmaine.com <penobscotsolar at midmaine.com> wrote:

> From: penobscotsolar at midmaine.com <penobscotsolar at midmaine.com>
> Subject: Re: [RE-wrenches] Dealing with snow
> To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
> Date: Friday, August 14, 2009, 3:48 PM
> Hi August,
>    Here in Maine we get pretty decent
> amounts of snow. There isn't any
> foolproof way to keep your panels clear without doing it
> manually
> because we sometimes get sticky, half ice, half snow type
> of
> precipitation, but here's some of the things we do.
> >
> >
> >
> > 1. Do you typically mount arrays flush to the roof? If
> so, I'm assuming
> > that roof pitches are generally designed to handle the
> various snow load
> > and snow-shed scenarios depending on how much snow the
> area sees?
> 
>   We do typically flush mount, providing the roof
> pitch is the typical
> 10-12 pitch. If it is less we have used tilt up racks, but
> that
> seriously cuts down the available usable array sq.footage.
> The roofs
> here are built to handle snow loads exceeding what we would
> normally
> get, but you will still often see people on less than 10
> pitched roofs
> cleaning them off in the middle of Feb.
> 
> 
> >
> > 2. Does the height off the roof matter? In other
> words, is it better to
> > mount low to the roof or higher above the roof. Does
> snow wedge under the
> > array?
> 
> We have always mounted as close to the peak as possible. I
> have seen
> arrays, not installed by my company, in which the snow has
> built up over
> time on the top of an array mounted too far below the roof
> line/peak. The
> snow melts and refreezes and quickly becomes a liability to
> the
> effectiveness of the array, at least. We have moved the
> entire array to
> the top of the roof line and the clients no longer had that
> problem. Of
> course, for customers that rely on a roof rake to remove
> snow from their
> array, moving the panels to the highest point on the roof
> essentially
> removes that option.
> 
> 
> >
> > 3. Are there products out there designed to help shed
> snow?
> 
>    We have used Rain-X. It does seem to
> help. Occasional re-application is
> necessary. Beside that, I haven't used any other option.
> Maybe a solar
> powered electric heater :-) would work?
> 
> 
>    With pole or frame mounts that are
> adjustable we tend to tilt them up
> to 80 or 85 degrees to facilitate snow shedding.
> >
> 
>    I'm sure you'll hear a lot more from
> other NE wrenches, amongst,
> geographically, others.
> 
> Daryl DeJoy
> NABCEP Certified PV installer
> Penobscot Solar Design
> 
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