[RE-wrenches] crystalline VS uni-solar

Fri Oct 31 10:23:14 PDT 2008

In 2006, I managed a research project here in Hawaii sponsored by our local utility and the Electric Power Research Institute (EPRI) that did a  6-month side-by-side comparison of Uni-solar 64-watt modules and a leading single-crystal module.  Utilizing detailed system monitoring (Fat Spaniel), we found that the triple-junction Uni solar outperformed 7.6% during early morning low-light conditions, 10.3% under cloudy mid-day conditions and 7.2% during sunny mid-day conditions.  When it was predominantly cloudy most of the day, we saw the Unis producing 12% more across the whole day.Across the whole 6-month test period, we saw the Unis producing about 5% more overall, across all conditions.  For reference, this is a relatively cloudy site - typical of many places in Hawaii - it had a daily average of 4.2 peak hours during the 6-month test period.

Of course a characteristic of the Unisolar modules is that their output is considerably over spec. when out of the box and they then go through a burn-in period when light-soaking slowly reduces their output -supposedly down to a steady state output.  It was hard to get really specific information on this burn-in period from the manufacturer but we were told that most of the burn-in should happen over 100 hours of full sun.  To allow for this, we didn't start testing until 2 months after the installation was complete.  However, our data indicated that even after 8 months, the output per watt of sunlight was still slowly dropping (but still above the name-plate rating).  Obviously, some follow-up evaluation needs to be done now 2 years later.  The funding is gone but I plan to do it on a volunteer basis when time permits.

As someone else mentioned, output isn't the only bottom line, the extra real estate needed by the less efficient Unisolars need to be considered as well as the price per watt.  In my experience, it's pretty common to find single or poly modules that are more than 5% less per watt than the Unisolars.

Jeff Lahl
Project Director,
Solar Electric Light Fund (SELF)
155 Keonekai Rd
Kihei, HI 96753 USA
808 874-5706 (Phone and Fax)
808 283-0875 (Mobile)

--- On Fri, 10/31/08, ASAP POWER! 2 <info at asappower.com> wrote:

From: ASAP POWER! 2 <info at asappower.com>
Subject: Re: [RE-wrenches] crystalline VS uni-solar
To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
Date: Friday, October 31, 2008, 6:01 AM

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We have UniSolar on an East face and Kyocera on a West face.   UniSolar outperforms Kyocera in my opinion, but we will stick to solid crystalline Si for residential/commercial work for space efficiency and racking/mounting ease.   Nothing scientific because it's not side-by-side, but the lower energy early morning to mid-peak sun vs. afternoon peak to dusk contest is about neck and neck.  16,625kwh (Uni-Solar) vs. 16,893 (Kyocera) this morning on the monitor totals for both channels/systems.

Triple-junction thin-film is awesome compared to 1-j or 2-j thin-film, but by mid-2009 the market will be full of 1-J thin-film offerings going into 2-J production.  Trying to catch up they are -- to Stan.  Sharp has some interesting news about their exciting thin-film product for Europe this morning, but we won't see that here in the US anytime soon apparently.

However, the problem for me with UniSolar is that all their claims would be perfectly ok with me if their one dreamy promise of lower cost per watt also came true.

PD 

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Geoff Greenfield
Sent: Friday, October 31, 2008 8:09 AM
To: RE-wrenches
Subject: [RE-wrenches] crystalline VS uni-solar

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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