PV degradation [RE-wrenches]

[Darryl Thayer]

Why not use your solar monitor? Solar radiation
measuring device to measure the solar radiation and
then determine the module performance degradation, and
by the way what solar monitor do you use and where did
you get it?
Darryl
--- Allan Sindelar <allan at positiveenergysolar.com>
wrote:

> 
> Bill,
> Thank you for correcting my mistake about EVA, as
> opposed to Tedlar, being
> the component causing the browning. I am surprised
> that it was only 10-12
> years ago, but I guess I am regularly reminded by
> things like this just how
> young this industry really is.
> 
> The 50% was not lack of voltage, though. It's an old
> 12V system, and one
> upgrade several years ago was a Solar Boost 50
> running 24V in/12V out, in
> order to minimize line losses and the very problem
> you describe. The
> combined output to the batteries is reduced by
> roughly that amount.
> 
> Allan
> 
> ----- Original Message ----- 
> From: "Bill Brooks" <bill at brooksolar.com>
> >
> > The browning is due to the clear EVA in the module
> turning brown. This
> > problem was fixed about 10-12 years ago when
> manufacturers realized that
> the
> > slow-cure EVA was the source of the problem. As
> far as I know, no
> > manufacturer uses that type of EVA anymore. There
> have been some isolated
> > reports of EVA browning, but nothing compared with
> what used to happen
> with
> > the M-55.
> >
> > The EVA browning effects both current (light
> hitting cell) and cell
> voltage.
> > Typical reports were about 20-30 loss due to
> browning. It is likely the
> 50%
> > you discovered was due to the fact that the array
> max power voltage was
> > below the operating voltage of the battery.
> >
> > Bill.
> >
> > > -----Original Message-----
> > > From: Allan Sindelar
> [mailto:allan at positiveenergysolar.com]
> > >
> > > I have not found a lot of consistency regarding
> degradation. I have seen
> > > numerous first-generation Photowatts (imported
> from France by Windy in
> the
> > > early 80s) still at 100% of rated power. Most of
> the ASI 16-2000s I see
> > > are
> > > close to original output, depending on degree of
> discoloration. At the
> > > same
> > > time, I have one long-time off-grid customer
> with 16 tracked Arco M55s
> > > (which at one time were Arco's premium 36-cell
> module at 53/55 watts)
> that
> > > are seriously browned and putting out about 50%
> of rated power (loosely
> > > measured).
> > >
> > > The 0.6%/year I heard as a ROT from some NREL
> study is a statistical
> > > average
> > > based on many varied module specimens, not a
> predictable structural
> > > degradation common to all crystalline silicon
> modules. I suspect that
> > > early
> > > Tedlar browning is the cause of much of that
> figure.
> > >
> > > Allan at PosE
> >
> 
> 
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