PV roofing material [RE-wrenches]

[William Miller]

Matt:

What were your expectations, and given that the GC1000 has no display
(other than a blinking light), how were you able to tell the installation
met them?

I am looking for hard data to answer the old
"dual-different-direction-facing-arrays-into-one-MPPT" question once and
for all.  It was my understanding from this forum (or speculation,
possibly) that two arrays facing different directions would confuse one
MPPT controller, possibly significantly reducing the output.  Based on this
assumption, all of the systems we have designed with this scenario, we have
specified separate MPPT controllers for separate facing roofs.  This was
probably the conservative approach, but we would like more specific data if
you or others have it.

Thanks,

William Miller


At 10:21 AM 8/18/02 -0700, you wrote:
>William,
>
>It was a grid-tie, and I used a GC-1000 with two 15 mod strings. It has
>worked flawlessly (so far!) for about 9 months, meeting or exceeding my
>expectations. Because the roof pitch is only a 3 in 12, the system starts
>producing very early and runs very late in the day, Summer and Winter.
>
>But, according to John Berdner, if the install is with a Sunny Boy, the
>string inputs MUST be exactly balanced or something mysterious and terrible
>will occur! I have to assume (assume nothing is my motto these days)
>that an east-west array works very much like any array which has the
>possibility of being partially shaded
>because of too-tight spacing, shadows from obstructions or whatever. I
>haven't heard of any problems (beside low power output) because of this type
>of arrangement as long as all the mods have their diodes intact.
>
>Matt
>
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