[RE-wrenches] SunPower modules

[Jeff Irish]

Word of caution... don't wire the bigger SunPower modules with the
negative conductor grounded.  With the metal frame grounded, as it
should be, this combination causes a strange surface polarization effect
that will discolor the cells and cause the power output to drop by about
half.  Fortunately the polarization and discoloring are totally
reversible if the system is re-wired with the positive conductor
grounded (as we found out, even after 6 months of being wired
incorrectly), but it takes a few days to correct.  For this same reason,
SunPower modules can't be used with bipolar inverters.

 

Jeff Irish

Hudson Valley Clean Energy

 

________________________________

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of jay
peltz
Sent: Friday, March 20, 2009 9:39 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Sunpower modules

 

Hi Larry,

 

 I was under the impression that Sunpower were only for on grid?

 

And for off grid with the low voltages that we use, they are still
requiring you to use positive ground?  I've seen the white paper they
did and it showed at lower voltages there is no need to positive ground,
thats why for example those 90 watt panels using Sunpower cells are used
with Negative ground.

 

curious,

 

jay

 

peltz power

On Mar 19, 2009, at 9:14 PM, Larry Crutcher, Starlight Solar wrote:





William,

 

I know you asked Jeff but thought I would respond as all we do are off
grid, battery based systems. I typically see that the Vmp voltage of
Sunpower modules is closer to spec with than with Kyocera, Sharp or
Mitsubishi. In my opinion Sunpower modules are only surpassed by Sanyo.
I realize this is anecdotal but after hundreds of installs you begin to
notice these things.

 

Larry Crutcher

 

On Mar 19, 2009, at 5:46 PM, William Miller wrote:





Jeff:

Have these modules worked for you in battery based systems?

William Mill


At 01:27 PM 3/19/2009, you wrote:




Hiya Jeff,
You are correct that the sunpower modules are positively grounded.  You
are
also correct that sunpower only deals with dedicated "dealers".  That
means
that if you are not one of their dealers you cannot get their panels.
It is
my understanding that sunpower is always looking for new dealers, so you
may
want to check in with them.  As far as architectural review committees
and
such, we have never had a problem using SPR modules in the areas where
review is an issue.  The positive ground really does not affect
aanything.
Instead of your negative wire being the grounded (white) conductor it is
your positive conductor that is grounded.  This means you are switching
the
negative instead of the positive in the DC disco.  Sunpower sells
packaged
systems, so they provide positive ground inverters from different
manufacturers.

Evergreen now has a black framed module, and I believe Sharp does too.
I
hope this helps, any other questions feel free to contact me.  
Jeff Blick
Lead PV Installer

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