[RE-wrenches] PV testing

[Bill Loesch]

Fellow RE-Wrenches,

What offerings exist for curve tracers like Glen refers to? Comments on 
specific models?

Thanks,

-- 
Bill Loesch
Solar 1 - Saint Louis Solar
314 631 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 <mailto:frenergy at psln.com>
> Sent: ‎10/‎4/‎2015 21:56
> To: RE-wrenches <mailto: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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