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.
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. 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. Mick Abraham, Proprietor www.abrahamsolar.com Voice: 970-731-4675 ---------- Original Message ----------- From: "Allan Sindelar" <[EMAIL PROTECTED]> To: "RE Wrenches" <RE-wrenches@lists.re-wrenches.org> Sent: Wed, 6 Aug 2008 08:55:54 -0600 Subject: [RE-wrenches] Inverter for Switch to GT > 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 > NABCEP certified solar PV installer > Positive Energy, Inc. > 3225A Richards Lane > Santa Fe NM 87507 > 505 424-1112 ------- End of Original Message -------
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