MPPT arrays in different directions [RE-wrenches]

[Joel Davidson]

In 1994, I did a house in Sacramento with two separate systems using separate
4kW Omnion inverters. One array faced south. The other array faced west (which
by the way produces 80% of the south facing array). The Los Angeles Department
of Water and Power did multiple arrays around the curving wall of the convention
center. As the sun strikes and goes off various facing arrays, they perform
differently. You can try one inverter, but I suspect that it will perform the
same as if parts of the total array are partially shaded which is definitely not
MPPT. Please keep us informed and report your results.

"Gary Higbee, Solutions from the Land" wrote:

> 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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