jay peltz wrote:
HI Mark,
I've seen a paper from Sunpower that shows their modules are OK for
lower voltages, but above a certain voltage ( around 200 or so) they
start to see the static build up, but interestingly only on the panels
at the high end of the voltage.
I haven't seen anything to indicate that other panels will see an
improvement with doing positive ground, if I understand what you are
saying?
This sorta makes sense, in that, supposedly the Sunpower modules are
less efficient if the positive leg is not at ground potential.
(isn't that right?)... So, the module sitting higher in potential from
ground I guess would not be as efficient ?
My question about these Sunpower modules is, what if you just have some
kind of faraday shield, or add a backing
of grounded aluminum foil ? Does that take care of the efficiency
issue ? Does it really have to be "ground" (earth) ?
Otherwise, you would not be able to use these things on an airplane or
on a satellite (not that you'd use a module of this
sort on a satellite OR an airplane) Sounds like there are some real
issues with these PVs for some applications. Or maybe
the reduction on efficiency isn't that big of a deal ?
Also, why would ANY bypass diode in a module get hot unless that module
was in a string and shaded, OR, the
diodes were just "leaky" ? Are these diodes in the Evergreen modules
discreet diodes, or, embedded in every cell,
or what ?
I'm just curious about all of these things.
boB
But I will forward on the information to the telecom in question.
thanks,
jay
Peltz power
On Sep 20, 2008, at 5:36 PM, Mark Frye wrote:
I am sorry to hear that folks are having these kinds of problems.
As I understand it, only module types made up of back contact cells
such as
the SunPower are run with positive ground.
These modules actually require positive ground to reduce static
charge build
up on the front of the cell which can reverse bias and shut down the
module.
I don't know, but it seems to me that folks have somehow mixed up the
high
yield of the back contact cell with positive grounding so now positive
grounding will increase the yeild other types of cells.
Do I have the story about right? Running front contact cells that have
plenty of collection wire on the face on a positive ground will not
significantly increase yield over a negative ground.
Are there other benefits to running positive ground that I am not
aware of?
Mark Frye
Berkeley Solar Electric Systems
303 Redbud Way
Nevada City, CA 95959
(530) 401-8024
www.berkeleysolar.com
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Doug
Pratt
Sent: Saturday, September 20, 2008 5:25 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] evergreen panels diode problems
Jay, there was a bulletin from Evergreen earlier this year about their
modules being used in positive ground systems. I don't remember the
exact
details (and I'm not at work now), but the gist was avoid positive
ground
till we make some modifications. Please check w/Evergreen on Monday.
-Doug Pratt
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