[RE-wrenches] [Fwd: Inverter for Switch to GT]

[bbassett at hei.net]

Allan,

You should consider the enphase inverters. They could be used with two of
the 36 cell modules in series. Wiring from the roof down is all AC and
dead if the disconnect is open. They also have a monitoring option that
looks pretty nice.

Brad Bassett
AEE


---------------------------- Original Message ----------------------------
Subject: [RE-wrenches] Inverter for Switch to GT
From:    "Allan Sindelar" <allan at positiveenergysolar.com>
Date:    Wed, August 6, 2008 7:55 am
To:      "RE Wrenches" <RE-wrenches at lists.re-wrenches.org>
--------------------------------------------------------------------------

Wrenches,
Occasionally, but more frequently recently, we get requests to turn
off-grid systems into grid-tie systems. Usually this involves sale of a
property to a new owner, and either grid is brought in to facilitate an
easier sale or the new owner brings it in. Once grid is in, the
off-grid-based system is of limited utility, as the equipment won't sell
back. Most of these new owners want a maintenance-free batteryless system.

Unfortunately, most off-grid arrays don't easily convert, as the string
sizing doesn't match. Here's my question: I have two of these requests
right now. Both are systems we installed in the late 90s. One has ten BP
275s, one has twelve. These are standard 12V 75W modules common to that
time. I need advice on inverters that will work with these strings.

The Sunny Boy 700, which is the only small inverter model SMA still
offers, will handle one string of up to nine of these in our temperature
range. Larger models require higher string voltage. Fronius also requires
higher voltage.

You know, it's a real problem to have to explain to new green-oriented
homeowners that there's nothing I can do with their ten-year-old PV system
to make it spin their new meter backward. It doesn't do much for the
mainstream perception of PV for these folks.

What will work with these existing arrays, please?

Allan Sindelar
allan_(at)_positiveenergysolar.com <mailto:allan at positiveenergysolar.com> 
NABCEP certified solar PV installer
Positive Energy, Inc.
3225A Richards Lane
Santa Fe NM 87507
505 424-1112

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