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<font size="2">If two of the BP75's are connected in series, that's electrically the same as one 150 watt module with peak power around 34 volts. The new Enphase inverter system could devote a mini-inverter to each of these 72 cell pairs & combine the outputs on the AC side, so that's a way to use all the existing PV modules.
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<br />Enphase is so new that one must worry about reliability, but if one unit should fail the others would still work. By that same token, if one pair of solar modules should be partially shaded, it would not affect the power delivery of the other pairs.
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<br />I have no hands on experience with Enphase but I think some wholesalers are now shipping the product. I look forward to Wrench Wreports on this product line.
<br />
<br />Mick Abraham, Proprietor
<br />
<a target="_blank" href="http://www.abrahamsolar.com/">www.abrahamsolar.com</a>
<br />
Voice: 970-731-4675
<br />
<br /><b>---------- Original Message
-----------</b>
<br />
From: "Allan Sindelar" <allan@positiveenergysolar.com>
<br />
To: "RE Wrenches" <RE-wrenches@lists.re-wrenches.org>
<br />
Sent: Wed, 6 Aug 2008 08:55:54 -0600
<br />
Subject: [RE-wrenches] Inverter for Switch to GT
<br />
<br />> <font face="Arial">Wrenches,</font>
<br />> <font face="Arial">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.</font>
<br />> <font face="Arial">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.</font>
<br />> <font face="Arial">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.</font>
<br />> <font face="Arial">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.</font>
<br />> <font face="Arial">What will work with these existing arrays,
please?</font>
<br />> <font face="g">Allan
Sindelar</font>
<br />> <a href="mailto:allan@positiveenergysolar.com"><u><font size="2" face="g" color="#0000ff">allan_(at)_positiveenergysolar.com</font></u></a>
<br />> <font size="2" face="g">NABCEP certified solar PV
installer</font>
<br />> <font size="2" face="g">Positive Energy,
Inc.</font>
<br />> <font size="2" face="g">3225A Richards
Lane</font>
<br />> <font size="2" face="g">Santa Fe NM
87507</font>
<br />> <font size="2" face="g">505
424-1112</font>
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