[RE-wrenches] De-icing panels off grid

[jay pozner]

I have gone around this many times on this one.  It's interesting to hear
all the perspectives of peers whom I greatly respect.  In revisiting this I
think context is really important.  There are so many factors that can add
up to "tip" the scales to favor this idea that one professional might or
might not consider.  I have seen a fair amount of destruction of PV from
snow, and of course the disruption in PV performance which could then of
course cascade to battery destruction.  In trying to avoid the heat idea,
I have made a secondary (small) array mounted vertically on a wall of a
cabin to simply maintain a trickle charge of the batteries of the system
during winter months when the cabin isn't being used, in efforts to keep
the lead acid batteries topped off. Of course it's not perfect if the snow
water content is high, and there is wind, but in an inter-mountain (dry)
snowpack it seems to perform well.

One idea that I am tilting towards more and more in these unique
circumstances is to power the heat source (heat tape, etc) with the
generator circuit.  Of course there needs to be a reasonable sized
generator on site, but for most of my stand alone situations this is more
rule than exception.  We can get fancy with a timer (to keep track of
daylight hours) and a photosensor to automatically determine if the array
is substantially covered, but truthfully I bet a simple switch used in
these situations actuated by the system owner might suffice...




Jay Pozner

(970) 209-0024





On Fri, Dec 6, 2024 at 9:27 AM Todd Cory via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Yes, in deep snow country tall pole mounts can be expensive... especially
> with enough room below so the sliding snow never meets the bottom edge of
> the array. My home system has 5 pole mounts with the bottom edges ~6' above
> the ground.
>
> Now that engineering is mandated, this adds more expense to ensure sure
> the foundation can support the mechanical forces of this configuration. But
> shallow angle roof mounts risk having the bottom edge of the modules get
> ripped off (see attached picture) so here in the Mount Shasta area, this is
> the only thing that works.
>
> There was a thread where people were experimenting with reverse biasing
> modules to cause them to generate heat. I think boB was working on some
> kind of possibility for a charge controller option to do this, but I am not
> sure where that went.
>
> Todd
>
>
>
>
>
>
> On Thursday, December 5, 2024 5:49pm, "Howie Michaelson via RE-wrenches" <
> re-wrenches at lists.re-wrenches.org> said:
>
> Todd,
> In general that had been my philosophy, but sometimes pole mounts are just
> logistically to difficult/ expensive  - especially large ones.  In general,
> if it is a windy location, the snow doesn't stick around that long.
> However, even pole mounts at a steep angle can get encrusted and if it
> doesn't get warm enough or sunny, that can stick on the panels for a week
> or more.  I've never considered anything like heat panels or tape, but if
> there is something that works that doesn't harm the panels, then it might
> be a decent option in some cases.
> Howie
>
> On Thu, Dec 5, 2024, 5:15 PM Todd Cory via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
>> Passive works best. In big snow country here, I learned the hard way to
>> only do pole mounts... and set the angle steep in the winter. The snow
>> slides off and all is fine.
>>
>> Todd
>>
>>
>>
>>
>> On Thursday, December 5, 2024 1:01pm, "Kirk Herander via RE-wrenches" <
>> re-wrenches at lists.re-wrenches.org> said:
>>
>> https://glasscareexperts.com/solar-glass-protection/
>> I’ve never tried it but just heard about these people. From the bio they
>> are the original makers of rain X, but they customized a product, several
>> of them, to clean Pv panels and they also mentioned it can help to shed
>> rain and snow.
>> By the way, Rainx is not  approved for such an application.
>>
>> *Kirk Herander / **kirkh at vermont.solar <kirkh at vermont.solar>*
>>
>> *Owner|Principal, VT Solar, LLC*
>>
>> *Celebrating our 33st Anniversary 1991-2024!!*
>>
>> dba Vermont Solar Engineering
>>
>> 802.559.1225
>>
>> On Thu, Dec 5, 2024 at 2:19 PM Howie Michaelson via RE-wrenches <
>> re-wrenches at lists.re-wrenches.org> wrote:
>>
>>> Has anyone successfully used heat panels or cables to melt iced-over
>>> panels (ie. without damaging the panels)? In heavy snow country, or over
>>> periods of freeze/thaw when pelty slushy snow sticks and freezes to panels,
>>> it would be nice to have a safe method of clearing them, especially
>>> off-grid.  I remember discussions of the futility of backfeeding panels to
>>> heat them up to accomplish the same, but not about heat tape or pans that
>>> might be worth trying.
>>> Thanks,
>>> Howie Michaelson
>>> Sun Catcher
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