Mismatch module losses? [RE-wrenches]

[Sky Sims]

3 different module types nice. No one will recommend doing this, but if
I wanted to maximize the performance my guess would be to series string
the 2 80watt modules and series string the 2 120watt panels then put the
175watt module in its own series string. Then I would parallel all 3
strings together. My experience when playing around with this type of
scenario is that the voltages will hit some sort of parity that allows
all the strings to contribute to the overall wattage and the amps will
simply add together. After you hook it all up prudence would require
that you verify with an amp probe under load whether or not all the
panels are actually feeding power to the charge controller.
Disconnecting strings and doing voltage and amperage checks and
reconnecting strings will give you a definitive answer as to whether or
not the power is being clipped to any significant degree. 

Sky Sims
Ecological Systems
www.ecologicalsystems.biz
220 County Road 522
Manalapan, NJ 07726
ph)732-462-3858  fax)732-462-3962
 
-----Original Message-----
From: Alex Cozine [mailto:acdc.cozine at gmail.com] 
Sent: Wednesday, October 31, 2007 11:45 AM
To: RE-wrenches at topica.com
Subject: Mismatch module losses? [RE-wrenches]



    Is there really that much difference?  I have a Solar Service
upgrade
for a off grid cabin near Mt. Rainier.  They need to move their
trace2524
inverter, c40 charge controller 125vdc input, and bank of 8 batteries in
24
volt conf.
The array consists of --2- 80watt 21.8Voc 4.85 Isc shells-- and --2- 120
watt 21.5Voc 7.45 Isc kyoceras--.  Plus they bought one new module
--175watt
44.4Voc 5.3 Isc sunworld--.  This is all on a hill 160 feet away.

What is the most efficient way to wire up these modules for this 24 volt
system?
We put one 80watt module in series with one 120watt module and to the
combiner box.
Then the other 80watt in series with the other 120 to the combiner
Then the 175 to the combiner.
Paralleled all 160' down to the power shed into the c40.

Is there a big loss putting an 80 watt module in series with a 120 watt
module?
I was thinking the amperages would average out.  Is that true?  or does
the
120 watt module act like a 80 in that conf.?
Does anyone have an explanation for why I could've chosen to put the
80's in
series and the 120's in series?


Thanks,


Alex and Dave Cozine
Brothers Electric & Solar
Tacoma Washington
brotherselectricsolar.com

[Non-text portions of this message have been removed]


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