amorphous pv & high voltage arrays [RE-wrenches]

[Matt Lafferty]

Jerry:

Good question, again.

No, we haven't had to reconfigure any of our arrays.  I can speak from
experience with the Trace Tech inverters and amorphous, though.  On hot
days, if the inverter turns off for any reason, the Open Circuit Voltage of
the strings may not reach the Minimum Open Circuit Voltage setting of the
inverter  (factory set at 300).  It is important to realize that the only
times this happened was during intentional shutdowns for periodic testing
and observation.

In our case, I programmed in 280 VOC as the minimum and everything has been
fine since.

In the case of the array(s) you refer to, I would have to question the
"matching" of the source circuit to the inverter operating voltage window.
(i.e. Glass specs, Series Modules per String, Inverter Model, etc.)  Because
there hasn't been a "standard" developed with regard to Asi voltages in
particular, I can't really respond to the individual situation.

We have had Zero "attenuation" related problems to date.

Regarding Asi with Sunny Boys, yes.  As far as I know, we have done more
than anyone...62 individual systems since September and a couple of Beta
sites prior to mass deployment.  The Glass we have been using matches up
well with the Sunny Boy (8 modules in series).  The Sunny Boy has been very
reliable and power tracks the arrays fabulously.

Regarding "watching out for" differences between amorphous & crystalline:
More fusing & combiners required.

There really are no secrets about Asi.  Electrical principals are electical
principals.  The power curve of Asi is different and the "burning in" is
more substantial initially.  Once the power stabilizes, the long-term
stabilization effects are virtually the same as crystalline.  My viewpoint
is that the additional power you receive initially is "free" since it is
above the rating anyway.

I can go on for days about all this but know you guys have better stuff to
do than watch me type...

Pray for Sun!

-Matt Lafferty
pvpro at attbi.com

> Matt,
>
> The reason I ask this is because I know of a company
> here in California that is in the process of re-wiring
> some of their high voltage amorphous arrays because of
> the decline in voltage over the attenuation period.  I
> understand that it is common practice to leave modules
> out of strings and connect them after they attenuate.
>
> The system I mention utilizes Trace Tech industrial
> inverters.  Has anyone on the list done a Sunny Boy
> system with any amorphous pv?  Is there anything to
> watch out for that is different than crystalline
> arrays?
>
> Jerry Caldwell
> L.E.S.
>
> --- Matt Lafferty <pvpro at attbi.com> wrote:
> > Jerry asks:
> >
> > > What kinds of problems are you encountering that
> > are
> > > exclusive to thin film arrays?  Are these problems
> > due
> > > to the fact that amorphous pv produces higher
> > voltages
> > > during it's breaking in period?
> >
> > > Jerry Caldwell
> > > Light Energy Systems
> >
> > Good question.  We have encountered Zero issues with
> > regard to "breaking
> > in".  This is one of the misunderstandings that
> > still exists relating to
> > thin-films.  (Oh, God, I feel a "book" coming on!)
> >
> > The differences between thin-film arrays and
> > crystalline are many, some
> > positive and others not so positive.
> >
> > The higher voltage of the thin-films is one of the
> > positives.  This requires
> > less modules in series to achieve high-voltage
> > configurations, and
> > therefore, greater flexibility in sizing.
> >
> > The two most significant differences are:
> >
> > 1.  The Series Fuse Rating of thin-films requires
> > more fusing and combining
> > than with crystalline.
> > 2.  The larger surface area required to accomodate
> > an array reduces the
> > number of candidate sites.
> >
> > Thin films are incredibly more forgiving in the
> > heat, shade, non-perfect
> > orientations, fog, cloudy days, etc.
> >
> > My personal perspective is that they are different
> > technologies with
> > different characteristics.  They each have their
> > place and, therefore,
> > should be evaluated on their strengths to determine
> > the appropriate
> > application for the candidate site.
> >
> > Pray for Sun!
> >
> > -Matt Lafferty
> > pvpro at attbi.com
> >

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