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Today's Topics:
1. Re: losses to competing angles in single strings (Wilco
Vercoelen)
----------------------------------------------------------------------
Message: 1
Date: Fri, 11 Sep 2009 20:03:29 -0400
From: "Wilco Vercoelen" <w.vercoe...@dommelvalley.ca>
To: "'RE-wrenches'" <re-wrenches@lists.re-wrenches.org>
Subject: Re: [RE-wrenches] losses to competing angles in single
strings
Message-ID: <662021e7cd9644f088ef6fe609b18...@laptop>
Content-Type: text/plain; charset="us-ascii"
Dear wrenches,
We would recommend the PowerOne inverters with two separate MPPT
Tables.
The only thing, they have to raise the warranty to 10 years.
Kind regards,
Wilco Vercoelen
President
new-logo-email.gif
Dommelvalley Green Power Inc.
Solar Energy Solutions
Utopia, Ontario, Canada
<http://www.dommelvalley.ca/> http://www.dommelvalley.ca
Tel. 705-423-9699
Fax. 705-423-9880
Toll Free 1-877-889-7657
This e-mail message is intended only for the person or entity to
which it is
addressed and is confidential, subject to copyright and may be legally
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_____
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Peter
Parrish
Sent: September-11-09 19:53
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] losses to competing angles in single
strings
In principle, two strings with different orientations should not be
wired in
parallel into the same inverter. However, when the mismatch is minor
(15
degrees in pitch or 15 degrees in azimuth) there is practically no
degradation. Fronius circulated a white paper for a while that
argued that
their inverters did maximum power point tracking on the string with
the
greatest irradiance and therefore did an optimum mppt job on the
string
with the greatest "available power". This part of the argument makes
sense.
What I have never been clear about is how close to "optimum" this
arrangement is (optimum being two separate monitors one for each
string).
Fronius appears to be backing away from this white paper, as I was
told
about six months ago from a member of their tech support staff that
they
recommended two separate inverters.
- Peter
Peter T. Parrish, Ph.D., President
California Solar Engineering, Inc.
820 Cynthia Ave., Los Angeles, CA 90065
CA Lic. 854779, NABCEP Cert. 031806-26
peter.parr...@calsolareng.com
Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885
_____
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Nick
Vida
Sent: Wednesday, September 09, 2009 6:38 PM
To: wrenches
Subject: [RE-wrenches] losses to competing angles in single strings
hello wrenches.
I was wondering if any of you have any data on what the losses would
be if
you had your string split with 2 different angles, but at the same
azimuth.
For instance, string of 11 with 8 facing 180 south at 30 degrees,
and 3
facing south 180 at 45 degrees. I have heard that the voltages and
currents
would differ and the IV curve would be inefficient as a string, but
I don't
know how much of a loss would be expected.
thanks in advance, and hopefully I didn't miss anything in the
archives.
thanks,
nick
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