[RE-wrenches] Matching modules into Xantrex GT

[Andrew Truitt]

Allan - Good point.  With that in mind I would revise my loss estimate
upwards.   I would be very curious to hear from anyone with actual
experience with this type of situation.

Andrew Truitt
Truitt Renewable Energy Consulting
202 486-7507
http://www.linkedin.com/pub/andrew-truitt/8/622/713

Please excuse brevity and typos - this message was typed on tiny keys.

On Jan 15, 2011 11:02 PM, "Allan Sindelar" <allan at positiveenergysolar.com>
wrote:

 A little more musing here...and I'm looking for others' opinions on this
theoretical piece.

If you have two unmatched strings, won't the string with the larger Imp
define the MPP of the inverter?

If so, I would expect that the weaker string would be forced to operate at
the Imp of the stronger string.

If the stronger string operates at a higher Vmp, it will pull the weaker
string's operating voltage above its own MPP, which could pull the current
down substantially as voltage moved from Vmp toward Voc.

Conversely, if the stronger string operates at a lower Vmp, it will pull the
weaker string's operating voltage back toward its own MPP, which would
maintain approximately the same current at a slightly lower voltage. This
would reduce output slightly, but not nearly as much as in the other
direction.

Does this make sense? And does real-world experience bear this out?



Allan Sindelar
Allan at positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
EE98J Journey...


>
> Friends:
>
> I have a client with a Xantrex GT2.8 inverter.  Feeding it are 8 Solar
World SW175...


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