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:[EMAIL PROTECTED]> NABCEP certified solar PV installer Positive Energy, Inc. 3225A Richards Lane Santa Fe NM 87507 505 424-1112
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