[RE-wrenches] Inverter for Switch to GT

[David Brearley]

Hello, Allan.

I¹m actually just sitting at my desk looking at a grid-direct string
inverter guide we¹re going to publish in the first issue of SolarPro
magazine. 

The SMA 700, of course , is three inverters in one box. It looks to me like
you¹d be operating it in the middle setting w/ 9 modules in series. You¹d
have 675Wstc in to a 600W inverter w/ a MPPT range of 100-200Vdc. The
smallest Fronius inverter has a MPPT range of 150-450.

There are actually two string inverter products with MPPT ranges between
these devices:

1. the Kaco 1501xi has a MPPT range of 125-300Vdc
2. the PV Powered 1100EVR (extended voltage range) has a MPPT range of 115
­450Vdc

Maybe one of these works for you?

Mick Abraham¹s idea about using the Enphase micro-inverter (1 per every 2
modules) is very interesting and worth exploring. This device has a MPPT
range of 25 ­ 40Vdc and is rated at 175 watts continuous. These inverters
are shipping, so maybe we¹ll get some installer feedback.

Regards,

David Brearley, Technical Editor
SolarPro magazine 
NABCEP Certified PV Installer 
david.brearley at solarprofessional.com
Direct: 541.261.6545
Fax:  541.512.0343

Visit our Web site at solarprofessional.com

On 8/6/08 9:55 AM, "Allan Sindelar" <allan at positiveenergysolar.com> wrote:

> 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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