[RE-wrenches] crystalline VS uni-solar and beyond
Joel Davidson
joel.davidson at sbcglobal.net
Sat Nov 1 10:00:12 PDT 2008
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 <jay at asis.com>
To: RE-wrenches <re-wrenches at 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
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches at lists.re-wrenches.org
Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches at lists.re-wrenches.org
Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
------------------------------------------------------------------------------
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches at lists.re-wrenches.org
Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20081101/341023c2/attachment-0003.html>
More information about the RE-wrenches
mailing list