HI Doug,
Thanks, If memory serves, they were replaced, inverters were changed
and the results were the same.
Most of my other experience is with battery based applications and I
just haven't seen any advantage. I have seen no real lack of
performance, but not the advantages that others are now stating. I
will certainly put this new information to use.
That said, I think they have many great attributes. For me the
biggest is the peal and stick on the metal roof, best mounting
system out there.
Would I use them on my house, sure.
But given that most of my jobs being off-grid battery based, many on
pole mounts, its just too expensive to use thin film, unless the price
does come down a lot.
peace,
jay
peltz power
On Nov 1, 2008, at 1:15 PM, Doug Pratt wrote:
Hi Guys,
I might be able to shed some light on the Uni-Solar performance
disparity bouncing back and forth here. Uni-Solar put out a low-
performing (some might call them defective?) batch of US-64’s back
around 2004 I believe. As an employee of Uni-Solar’s primary North
American distributor I’ve seen a couple of these cases crop up.
Jay, if this system was installed in the 2003-2005 time frame, and
the cells have the slightly reddish outer edges, then they’re
suspicious. Collect serial numbers and contact Uni-Solar.
The reddish edges disappeared when Uni-Solar’s 2nd generation
deposition machine came online in late 2004. Wattage ratings on
most modules went up a little bit at this time also. Most folks
experiences with Uni-Solar have been like Joel’s. They perform just
a little bit better than crystalline…5%-7% is typical, although it
depends on temperature. Hot climates favor amorphous silicon, cold
climates favor crystalline silicon.
Cheers,
Doug Pratt
DC Power Systems
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
] On Behalf Of Joel Davidson
Sent: Saturday, November 01, 2008 10:00 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] crystalline VS uni-solar and beyond
Hi Jay,
My experience was the exact opposite with Unisolar triple-junction
structural standing seam systems in 1996 and megawatts of Unisolar
from 2003 to 2007. My Unisolar tests and installations exceeded
PVWATTS kWh estimates by approx 5% (PVWATTS uses crystalline PV
temperature coefficient). PVWATTS is a reliable estimator for
crystalline PV systems when 0.65 dc-to-ac derate factor for battery
based systems and 0.75 to 0.82 for batteryless systems was used. See http://www.uni-solar.com/uploadedFiles/0.4.2_white_paper_3.pdf
a-Si degradation is no mystery. See http://www.nrel.gov/docs/fy00osti/28333.pdf
NREL on-going tests since 1997 validates Unisolar's 20-year 80%
warranty claim. It is interesting that the time of year Unisolar is
deployed affects its light induced degradation. See "Recovery of
Light Induced Degradation in Amorphous Silicon Solar Cells and
Modules."
I think that Unisolar modules are suitable:
when high power density is not required
if flexibility and/or conformability are wanted
if partial shading is an issue
if high cell temperature is an issue
if building integration is wanted
if no glass is wanted
if its unique appearance is wanted.
The "aluminum-frame-glass-module" monopoly has been broken.
Unisolar's persistence, First Solar's CdTe success, and the re-
appearance of CIGS (remember Arco/Siemens 1998 ST modules?) along
with "see through" and other flexible PV modules is changing PV. The
lowest price per watt (initial cost) is gradually giving way to
lowest price per kilowatt-hour (lifecycle cost). It's still a neck-n-
neck which PV technology will win, but there is no doubt that PV is
winning almost everyone's heart and mind.
Best regards,
Joel Davidson
"Not all change is for the better, but nothing gets better without
change." So vote for change!
----- Original Message -----
From: jay peltz
To: RE-wrenches
Sent: Friday, October 31, 2008 10:23 PM
Subject: Re: [RE-wrenches] crystalline VS uni-solar
Hi Joel,
1. unisolar 64's and sharp single cystal
2. SMA inverters
3. Arcata California
4. exact, I mean side by side with no shading, same azimuth ( south)
same tilt ( can't remember)
5. As to the unisolar producing more, I must stress that I have
never seen the Unisolar produce more than SC, never.
jay
peltz power
On Oct 31, 2008, at 1:01 PM, Joel Davidson wrote:
Hello Jay,
Sounds like something is wrong other than Unisolar vs. crystalline.
All things being equal, the Unisolar should produce more kWh per kW
than crystalline. Questions:
1. What modules and how many of each?
2. What inverter or inverters?
3. Geographic location?
4. Array azimuth and tilt?
Best regards,
Joel Davidson
----- Original Message ----
From: jay peltz <[EMAIL PROTECTED]>
To: RE-wrenches <re-wrenches@lists.re-wrenches.org>
Sent: Friday, October 31, 2008 8:27:19 AM
Subject: Re: [RE-wrenches] crystalline VS uni-solar
Hi Geoff,
In regards to the performance between Unisolar and crystalline,
there is a side by side ( same watts, batteryless intertie with
metering) installation up here on the North coast of California, and
the the Unisolar is the constant under-performer. This includes
cloudy, sunny, warm, cold weather.
I have seen nothing in the field to support the Unisolar claims
about better performance in low light etc. That said, they do work
better in very hot conditions, if thats what you have.
jay
peltz power
On Oct 31, 2008, at 8:08 AM, Geoff Greenfield wrote:
As a follow up to my uni-solar post (and thanks to all who provided
feedback), I have a second request:
Any references to recent side-by side "shoot-outs" between Unisolar
and conventional crystaline PV? Scientific studies? Your own
wrench thoughts?
I am more and more often encountering confused customers that are
considering unisolar systems at zero-tilt (we are at 40 degrees N),
with plenty of partial shading, after getting a pitch about all
sorts of advantages of Uni-Solar. I think that this product has
it's role and I occasionally sell it... But I am frustrated when I
truly believe I can deliver a better net energy production with a
tilted crystalline solution (avoiding the shaded areas).
For a brighter energy future,
Geoff Greenfield
Founder and CEO
Third Sun Solar & Wind Power Ltd.
340 West State Street, Unit 25
Athens, OH 45701
740.597.3111 Fax 740.597.1548
www.Third-Sun.com
Clean Energy - Expertly Installed
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