On 1/17/2012 6:32 PM, Bill Hoffer wrote:
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
Hey Bill !!
Don't worry, I wouldn't dream of doing something that is outside the
module's specifications.
Most PV module manufacturers don't quite understand how this works
either but one particular
manufacturer liked the idea when I brought it up to them a couple years
ago at SPI.
This mode of operation is also done in part of the UL testing. There
are certain rules
that have to be followed for this and luckily, most properly installed
systems are already protected.
It's actually much easier on the modules than you might think.
boB
On Tue, Jan 17, 2012 at 4:37 PM, b...@midnitesolar.com
<mailto:b...@midnitesolar.com> <b...@midnitesolar.com
<mailto:b...@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.
b...@daystarsolar.ca <mailto:b...@daystarsolar.ca>
780-906-7807 <tel: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: b...@midnitesolar.com <mailto:b...@midnitesolar.com>
To: re-wrenches@lists.re-wrenches.org
<mailto:re-wrenches@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:m...@oasismontana.com]
*Sent*: Monday, January 16, 2012 10:00 AM
*To*: 'RE-wrenches' <re-wrenches@lists.re-wrenches.org>
<mailto:re-wrenches@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 ^(TM)
Oasis Montana Inc.
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Bill Hoffer PE
NABCEP Certified Solar PV Installer^(TM)
Sunergy Engineering Services PLLC
2504 Columbia Ave NW
East Wenatchee WA 98802-3941
suneng...@gmail.com <mailto:suneng...@gmail.com> Cell:(509)679-6165
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