[RE-wrenches] Shedding ice

[Bill Hoffer]

Bob

Wonder how Module manufacturer warranties will handle applying reverse
current to the module , especially if it is more than the power rating of
the module???  I would want that one in writing before risking having to
write off an array in order to melt a little snow!

Bill

On Tue, Jan 17, 2012 at 4:37 PM, boB at midnitesolar.com
<boB at midnitesolar.com>wrote:

>  On 1/17/2012 4:18 PM, benn kilburn wrote:
>
>  boB,
> If this concept were to become a working option for the Classic, would the
> modules have to be modified in any way?  Why are the diodes not blocking
> the reverse current?
> benn
>
> DayStar Renewable Energy Inc.
> benn at daystarsolar.ca
> 780-906-7807
> HAVE A SUNNY DAY
>
>
>
>
> No mods.  However, as you can see, if the controller is maxed out as far as
> array size, that could limit the snow melting effect.   I don't have any
> hard
> data as for the minimum power needed to apply to the array for snow
> melting,
> but it could be around twice the power to melt snow as the power rating of
> the array.   Yesterday's experiment was less than 2wice the power rating
> and it may have been fine with with even less, so that's a very good sign.
>
> How much power does it take to melt snow off of a car's rear window from
> the electric defroster ?  It's a similar kind thing.
>
> Diodes ??  You mean the bypass diodes ??   No problem.  Those don't
> conduct in this case.
>
> boB
>
>
>
>
>
>
>
>  ------------------------------
> Date: Mon, 16 Jan 2012 13:14:36 -0800
> From: boB at midnitesolar.com
> To: re-wrenches at lists.re-wrenches.org
> Subject: Re: [RE-wrenches] Shedding ice
>
> On 1/16/2012 11:39 AM, David Katz wrote:
>
> Mark,
> I believe the Midnite Classic has this feature built in. Check with them.
> David Katz
>
>
>
>
> It just snowed up here in Arlington, Washington A.C.  and we were just
> starting to melt some snow
> on a couple of modules on our roof just now with one of our charge
> controllers here in the lab.
>
> This feature is not yet in the Classic, BUT, check out this experiment
> that I did about 3 years ago
> in my front yard with an animated gif time lapse.
>
> One module is being powered and the other is not powered, just sitting
> there for comparison.
> These are KC125s.
>
> The time involved here was about 3 hours and took about 1 kW-hour of
> energy but gives you
> an idea of what may be done with this idea.  One thing not in our favor
> here is that the module
> that is being powered is resting on the ground, in the snow, which would
> significantly
> hinder snow melting I would think rather than being properly mounted.
>
> Oh what fun it is to melt some PV snow tonight !
>
> http://fusion.midnitesolar.com/PVsnowMelt3.gif
>
> boB
>
>
>
>
>
>
>
>
>  *From*: Mark Dickson [mailto:Mark at OasisMontana.com<Mark at OasisMontana.com>]
>
> *Sent*: Monday, January 16, 2012 10:00 AM
> *To*: 'RE-wrenches' <re-wrenches at lists.re-wrenches.org><re-wrenches at lists.re-wrenches.org>
> *Subject*: [RE-wrenches] Shedding ice
>
>
> I recall a conversation a while back about the possibility of “reversing”
> the current in a solar module to increase the cell temp enough to shed
> ice/rime.  To follow-up, has anybody been successful at this?  I am
> guessing, if so, it would entail, removal of diodes, increasing PV and
> battery capacity and some way to sense the ice at the very least. . . It
> sounds good in theory, but I am skeptical as to whether it will work in
> reality. . .
>
>
>
> Best regards,
>
>
>
> Mark Dickson,
>
> NABCEP Certified Solar PV Installer ™
>
> Oasis Montana Inc.
>
>
>
>
>
> _______________________________________________ List sponsored by Home
> Power magazine List Address: RE-wrenches at lists.re-wrenches.org Options &
> settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.orgList-Archive:
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List
> rules & etiquette: www.re-wrenches.org/etiquette.htm Check out
> participant bios: www.members.re-wrenches.org
>
>
> _______________________________________________
> List sponsored by Home Power magazine
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Options & settings:http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:www.re-wrenches.org/etiquette.htm
>
> Check out participant bios:www.members.re-wrenches.org
>
>
>
> _______________________________________________
> List sponsored by Home Power magazine
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Options & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive:
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out participant bios:
> www.members.re-wrenches.org
>
>
>


-- 
Bill Hoffer PE
NABCEP Certified Solar PV Installer™
Sunergy Engineering Services PLLC
2504 Columbia Ave NW
East Wenatchee WA 98802-3941
SunEngSer at gmail.com Cell:(509)679-6165
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20120117/1d15e2e9/attachment-0003.html>