PV power tolerance [RE-wrenches]

[Bill Brooks]

Your free subscription is supported by today's sponsor:
-------------------------------------------------------------------
Claim your companion air fare now!
http://click.topica.com/caacJzhbz8Qcsbz9JC9a/PermissionData
-------------------------------------------------------------------

Marco,

You like to pick fun topics don't you. It is always best to take the low end
of any tolerance as the assumed power. However, another issue that nobody
talks about is that all manufacturers test and provide their tolerances
before Light Induced Degradation (aka LID).

Not many people have ever heard of LID in crystalline silicon modules, but
all crystalline modules lose 2-5% of their output in the first few hours of
full light exposure. If a module starts out at -3% below STC spec, it will
likely end up more than -5% below rating after seeing the sun for a few
hours. It is so expensive and difficult to make a claim on a module power
warranty that it is usually not worth it, unless you know there is a real
significant problem with the module (more than 20% out of rating).

All these issue are starting to become very important as we see larger and
larger systems installed.

Good luck in your quest for the truth. Remember the PIER website to look at
the actual performance from most manufacturers available today.
http://pierminigrid.showdata.org/

Bill.

-----Original Message-----
From: Marco Mangelsdorf [mailto:marco at pvthawaii.com]
Sent: Sunday, October 10, 2004 12:01 PM
To: RE-wrenches at topica.com
Subject: PV power tolerance [RE-wrenches]




Your free subscription is supported by today's sponsor:
-------------------------------------------------------------------
Is Unemployment on the rise? Answer and Win!
http://click.topica.com/caacHNhbz8QcsbaaVcJa/PermissionData
-------------------------------------------------------------------

My understanding of the term "power tolerance" as it relates to module
output: when a PV manufacturer claims that their nominal 100-watt module has
a power tolerance of +/- 5 percent, this means that the module is guaranteed
to have put out a minimum 95 watts under STC (it's relatively rare that
we're going to see a 100-watt module put out 105 watts STC); if it did they
would call it a 105-watt module and charge us accordingly.

Looking at different manufacturers yields different power tolerance ranges:
BP Solar, for their larger output modules, claims a 5 percent PT and even a
0 percent PT for their not-available-in-the-U.S. 7180 180-watt module; Shell
has 5 percent; RWESS, for their ASE300s, has a practical 0 percent PT as
well; Sharp has a 10 percent PT (now, who would want to go with a Sharp
array with that kind of PT when one can likely get more real power from a
BPS, Shell or RWESS array?), etc.

My interest: what kind of performance (real world kW DC and AC kWhs) are you
all getting from your various PV installations?  Are you generally satisfied
with your PV manufacturers' output claims?  Have many of you had
low-performing systems which are due to disappointing array output due to
under-performing modules?

Unfortunately, with the sky-high global demand for modules these days, the
manufacturers can sell virtually everything that rolls out of their assembly
lines and not necessarily be all that concerned about power tolerance
issues.  Not only that, but prices have gone up this year with more price
increases to come.  Still, I think that it's important to get some more real
world empirical data on performance; simply using the CEC derate number per
module doesn't cut it for me.


Marco Mangelsdorf
President
ProVision Technologies, Inc.
69 Railroad Avenue, A-7
Hilo, Hawai'i 96720
(808) 969-3281, 934-7462 facsimile
www.provisiontechnologies.com

Your free subscription is supported by today's sponsor:
-------------------------------------------------------------------
Get 4 Free low-fat, low-carb recipes
http://click.topica.com/caacHMObz8QcsbaaVcJf/PermissionData
-------------------------------------------------------------------

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read

List rules & etiquette: www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

Your free subscription is supported by today's sponsor:
-------------------------------------------------------------------
Give your opinion on Abortion and Win!
http://click.topica.com/caacHMZbz8Qcsbz9JC9f/PermissionData
-------------------------------------------------------------------

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read

List rules & etiquette: www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------