[RE-wrenches] PV testing

[Jerry Shafer]

We use the solmetric 600 and the 1000 and save the data. It the testing you
are doing do you see and modules that stand out as bigger effenders
Jerry
On Oct 5, 2015 2:35 AM, "Bill Loesch" <solar1online at charter.net> wrote:

> Fellow RE-Wrenches,
>
> What offerings exist for curve tracers like Glen refers to? Comments on
> specific models?
>
> Thanks,
>
> --
> Bill Loesch
> Solar 1 - Saint Louis Solar314 631 1094
>
>
>
> On 10/4/2015 9:52 PM, Glenn Burt wrote:
>
> Why wouldn't you invest in an I-V curve tester like the Solmetric PVA
> series and let it do the heavy lifting of the testing you are looking for?
> Or am I missing something in what you are looking for?
>
> Sincerely,
> Glenn Burt
> Sent from my 'smart' phone so please excuse grammar and typos.
> ------------------------------
> From: frenergy <frenergy at psln.com>
> Sent: ‎10/‎4/‎2015 21:56
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
> Subject: [RE-wrenches] PV testing
>
> Wrenches,
>
>         As time passeth, we're bumping more into older PVs/arrays that
> have
> questionable outputs.  After minimizing the variables (dust, temps, sun
> angle, wiring, expected deterioration with age, etc) and still coming up
> with low numbers.  Testing individual PVs' Voc and Isc don't seem to tell
> the whole story as they often look good.
>
>         Would not a definitive test be to wire a suspect PV to an
> inexpensive mppt CC (oxymoron?) and then to an orphaned battery.  The
> battery would have to have a mondo (surplus) rheostat paralleled to it to
> maintain a steady voltage during the test.  With appropriate metering in
> place, you would then have Vmmp and Immp as the rheostat is tweaked to
> hold
> a steady batt voltage and the CC finds the knee.
>
>         Help me here.  I know its a little spendy to cobble up but the
> value
> of nailing an offender might be worth it.  Am I missing something?  Is it
> common for inverters to fall off in output gradually?
>
> Bill
> Feather River Solar Electric
>
>
>
>
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