PV Module Degradation (was PV Inverters module strings) [RE-wrenches]

Tue May 15 06:49:44 PDT 2001

Hi Lynne,

thanks for the response.  Personally I'm not sure what is the correct path to
take, I  pose the question because I don't know the answer.

But I have one for you.  You say $3.5 per watt, thats what you are paying for
panels? What brand, tell more!!

Thanks,

jay
Peltz Power

Lynne A Carter wrote:

> Jay I hear this question a lot from my customers.  It is a good question but
> when I do the math on the prices why not go top of the line,  3.50 per w
> now, or ??? in five years. maybe by then we will be powered by the septic
> tank.
> Lyn
> Lyn at solarvillage.com
> Solar Village Institute inc.
> PO Box 14
> Saxapahaw, NC  27340
> Tel. 336-376-9530
> Fax. 336-376-1809
> www.solarvillage.com
>
> ----- Original Message -----
> From: jay peltz <jay at asis.com>
> To: <RE-wrenches at topica.com>
> Sent: Monday, May 14, 2001 9:25 PM
> Subject: Re: PV Module Degradation (was PV Inverters module strings)
> [RE-wrenches]
>
> > Hi Bill,
> >
> > The issue with warranty is a a big one.  I find that as with most things
> it
> > depends on whom you buy it from.  When I buy a car I don't call the
> manufacuter
> > directly, I go through the dealer as that is there job.
> >
> > When I have a problem with a panel, I go through the supplier and they put
> the
> > screws to the problem.  If they don't do that then time to look for a new
> > supplier.
> >
> > In my experience I have seen manufactures replace out of warranty panels,
> and
> > some give real problems with in warranty situations.  And yes most folks
> don't
> > understand that out of spec panels get you the difference in watts not a
> new
> > panel, but hay watts is watts.
> >
> > I'd like to pose a question.  Since the industry is changing so fast, and
> panel
> > prices will most likely come down a lot in the next 5 years does it
> warrant
> > having a 25yr warranty? or going for less expensive panels with shorter
> warranty
> > with replacement by significantly cheaper panels in some 5-10 yrs?
> >
> > Thanks,
> >
> > jay
> >
> > peltz power
> >
> > Bill Brooks wrote:
> >
> > > Pat,
> > >
> > > It is not 1-2% module degradation. PVUSA proved that all system degrade
> 1-2%
> > > per year as a system. This requires 6-8 years of constant monitoring to
> > > actually detect. This is due to the fact that measurement uncertainties
> are
> > > higher than the degradation rates.
> > >
> > > How much of that is module, is hard to say. It is likely more than 0.5%
> for
> > > most modules. The system degradation is likely 75% of the system
> degradation
> > > if not more. This means that modules could be degrading slightly faster
> than
> > > their warranties allow (0.75%-1.5% per year). For a 20-year warranty
> > > degradation to 80% of rating, this allows for a 1.1% degradation. A 1.5%
> > > degradation will result in a final performance of 74%. Looks like you're
> > > entitled to 6% from the warranty.
> > >
> > > However, have you ever tried to make a claim on a PV warranty from a
> power
> > > point of view (not failure)? Module warranties are great for module
> failures
> > > and very difficult for underperformance. It requires, removing the array
> and
> > > shipping it back to the manufacturer for flash testing. Then you have to
> > > live with their results.
> > >
> > > Most people have the erroneous idea that if their array underperforms
> that
> > > they'll either get a new array or automatically get some new modules.
> Not
> > > so. These warranties are very carefully written and it will cost the
> > > installer or system owner far more to collect on the warranty than the
> > > warranty is worth. I went through the warranty process just to confirm
> this
> > > fact.
> > >
> > > Case in point as to why third party testing is so critical. We are at
> the
> > > mercy of manufacturers information and there is very little muscle any
> one
> > > customer (unless you buy Megawatts of PV) can bear to get satisfaction.
> > >
> > > This is not to say that manufacturers are routinely dishonest or trying
> to
> > > scam folks. They are trying to make money and until recently, this has
> not
> > > been a major issue. When you operate on-grid PV systems, you can more
> > > accurately measure the performance of the PV system and show good or bad
> > > performance with a simple meter. Off-grid systems are a little more
> > > challenging in that regard, so we overdesign for a variety of reasons
> > > (phantom loads--both real and imaginary) and it all comes out in the
> wash.
> > > Welcome to the real world of real-life performance.
> > >
> > > Our industry needs to grow up, but it is going to take all our help. The
> > > federal DOE program unknowingly contributes to the problem because they
> must
> > > show continued improvement on costs and performance. To change the
> > > performance metrics in mid-stream (kinda like Wag the Dog), this could
> cause
> > > some problems with explaining why the numbers all of a sudden got worse
> > > instead of better.
> > >
> > > Bill.
> > >
> > > > -----Original Message-----
> > > > From: Pat Kiernan, Eco Electric, Inc. [mailto:ecoelec at rof.net]
> > > > Sent: Monday, May 14, 2001 6:00 PM
> > > > To: RE-wrenches at topica.com
> > > > Subject: PV Module Degradation (was PV Inverters module strings)
> > > > [RE-wrenches]
> > > >
> > > >
> > > > Bill Brooks,
> > > >
> > > > I would really like to see the PVUSA documentation you mention if it
> is
> > > > available. The reports I've seen indicate 0.5% power degradation per
> year
> > > > with voltage degradation largely due to increasing resistance in
> > > > connections
> > > > and current degradation due to optical degradation in the
> > > > encapsulant/lamination.
> > > >
> > > > If 1-2% module power degradation per year is real than most PV
> warranties
> > > > are a hoax and RE is a little closer to snake oil than I would like.
> > > >
> > > >
> > > > Pat Kiernan
> > > >
> > > > Eco Electric, Inc.
> > > > PO Box 550
> > > > Carbondale, CO 81623
> > > > tel/fax (970) 963-3132
> > > > e-mail: ecoelec at rof.net
> > > > ----- Original Message -----
> > > > From: Bill Brooks <billbrooks7 at earthlink.net>
> > > > To: <RE-wrenches at topica.com>
> > > > Sent: Thursday, May 10, 2001 1:40 PM
> > > > Subject: RE: PV Inverters module strings (Last Call) [RE-wrenches]
> > > >
> > > >
> > > > > 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.
> > > > >
> > > >
> > > >
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