MPPT arrays in different directions [RE-wrenches]

[douglas bath]

Rainman sez,

"Definitely go with the MultiMode. Can't miss with the Multimode. Wopner
says "simpler is better." Rainman says MPPT will work with extended solar
day, flatter peak but better in the early and late. Definitely go with the
simpler. Judge Wopner on at 5 o'clock." 

Can't argue with the Rainman.

Douglas B. Bath, 
Gaiam- Real Goods & Jade Mountain
800-919-2400 x6903 voice
303-222-8700 fax
http://www.realgoods.com
Building a Sustainable World Since 1978


-----Original Message-----
From: Gary Higbee, Solutions from the Land [mailto:ghigbee at efn.org]
Sent: Tuesday, March 19, 2002 2:30 PM
To: RE-wrenches at topica.com
Subject: MPPT arrays in different directions [RE-wrenches]


Hi Wrenches,

I'd appreciate your thoughts on a large install I'm working on. We've got
about 5kW of PV, though it is divided into South, East, and West fixed roof
arrays. Not optimum, but the architect got to my client before we did.

We're setting up a 48-volt grid-tied system with battery backup. The only
viable inverter solutions I'm aware of for almost immediate delivery are the
Vanner RE48-4500 and the AEI MM-5000. I love the way the MM-5000 is packaged
(built-in 5kW MMPT, ground fault, etc.) but I am concerned about using one
MPPT unit on three different PV orientations. I think I heard that each
different orientation should have its own MPPT controller. Is this true?

If I use the Vanner I'll need 5 combiner boxes, 5 Solar Boost 3048 units,
and all the ground fault and main breakers (the 5 units encompassing 3
directions and current limitations). I'd likely use two Outback DC boxes and
mount the PV controllers in a row above a raceway. I think this could be
done in a clean manner, but the AEI is sure attractive.

So, what do you think--lump the whole roof (East, South, West) into one
giant array with one MPPT and go with the AEI, or break down the roof and
MPPT each direction, using the Vanner/Outback solution?

THANK YOU!

Gary

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           Gary Higbee  (ghigbee at efn.org)
              (541)607-1818 (Eugene)
             (541)902-8544 (Florence)
Solar, wind, and hydro site analysis and system design
    Components dealer and installation assistance
              ~Solutions from the Land~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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