PV Inverters module strings (Last Call) [RE-wrenches]

[Bill Brooks]

Carl,

No self-respecting PV manufacturer is going to share eventual
underperformance numbers. They are non-the-less very real and are fairly
consistent with all PV technologies available. No special conspiracy theory
for a-Si. All systems degrade at 1-2% per year and most of the degradation
seems to occur in voltage. Documented at PVUSA with over 20 systems of all
types over 10 years.

Initial overperformance is probably only an issue if you start a system
during the colder time of year. Most inverters, I believe this includes
Trace Tech (Kent please chime in) will stay offline with a DC overvoltage
condition should the Voc get over 600 Volts initially. As the array warms in
the sun and degrades, that voltage will settle into the proper range and the
inverter will start.

Bill.

> -----Original Message-----
> From: Carl Emerson [mailto:freepower at freepower.co.nz]
> Sent: Thursday, May 10, 2001 12:04 PM
> To: RE-wrenches at topica.com
> Subject: Re: PV Inverters module strings (Last Call) [RE-wrenches]
>
>
> Bill
>
> My understanding is that the voltages stated on the web site are after
> stabilization. Unisolar warn of initial over performance not
> eventual under
> performance.
>
> > Like you I would be more comfortable with more data, I have
> asked Qudrat for
> > MPPT vs. temp and VOC vs. temp.
>
> I usually allow the array to exceed the max. voltage in the first
> summer season
> if the inverter will handle the over voltage condition and simply
> regulate the
> extra power. The SEA from Australia does this beautifully.
> In the first season a new US64 will give up to 100 watts at 1300 W/sqM.
> It is important to know how the Trace will react to over
> voltage... can someone
> comment on this ??
>
> Carl Emerson
>
>
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