[RE-wrenches] Evergreen

Sun Jan 3 11:35:28 PST 2010

Since modules are getting so inexpensive, the big questions is what is 
the best way to get 33% more power? Is it better to use 33% more modules 
on a fixed array, or use a tracker?  Which one costs less?  It costs 
$1.50 to $2.00 per watt for a tracker.   If modules cost $3 per watt and 
a fixed mount costs $.040 per watt , 33% of $3.40 per watt is $1.12 per 
watt.   And trackers don't come with a 25 year power output warranty.  I 
see tackers making sense when the array is powering a centrifugal pump 
in the summer or possible a time-of-use grid tie that pays more in the 
summer.  You are definitely better off with more modules on a fixed 
array in an off grid situation because you always need more power in the 
winter when the tracker is least effective.
David

David Katz

Chief Technical Officer

AEE Solar

1155 Redway Drive

P.O. Box 339

Redway, CA  95560

Tel (707) 825-1200

Fax (707) 825-1202

dkatz at aeesolar.com <mailto:david at aeesolar.com>

www.aeesolar.com <http://www.aeesolar.com/>

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Dana wrote:
>
> You got it!
>
>  
>
> It boggles my mind to watch the two OB FM60s and see the difference 
> each day and then to go back and see the data over time. It is a very 
> good argument for tracking. We have a Durango client that we installed 
> 12 KW GIT tracked and it is outperforming the expectations of our 
> client too.
>
>  
>
> Dana Orzel
>
>  
>
> Great Solar Works, Inc
>
> www.solarwork.com
>
> E - dana at solarwork.com
>
> V - 970.626.5253
>
> F - 970.626.4140
>
> C - 970.209.4076
>
>  
>
> I will be the shift in how the world uses power! - Dana Orzel
>
>  
>
> *From:* re-wrenches-bounces at lists.re-wrenches.org 
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of 
> *Allan Sindelar
> *Sent:* Thursday, December 31, 2009 8:13 PM
> *To:* RE-wrenches
> *Subject:* Re: [RE-wrenches] Evergreen
>
>  
>
> Dana,
> Thank you for this information. I would like to clarify what you 
> wrote. We have long accepted that trackers may be expected to increase 
> daily output by about 35-40% in the summer and 10-15% in the winter, 
> due to the differences in the sun's seasonal elevation and the 
> resultant length of the solar day. It sounds as if you measured the 
> effective increase from approximately summer solstice - winter 
> solstice and got a 32% gain. You previously got the same gain (33%) 
> measuring from last winter solstice to summer solstice. This makes 
> sense, as it averages winter and summer gains over two roughly equal 
> periods, with variations (summer monsoons, etc.) being within 
> acceptable error.
> And whether grid-tied, grid-tied with backup, or off-grid is 
> irrelevant as long as you can compare and record the outputs of the 
> two otherwise identical arrays, one tracked and one fixed.
> Do I understand this right? If so, it's good real-world data for 
> design purposes.
> Allan
>
> *Allan** Sindelar*
> Allan at positiveenergysolar.com <mailto:Allan at positiveenergysolar.com>
> NABCEP Certified Photovoltaic Installer
> EE98J Journeyman Electrician
> *Positive Energy, Inc.*
> 3201 Calle Marie
> Santa Fe, New Mexico 87507
> *505 424-1112*
> www.positiveenergysolar.com <http://www.positiveenergysolar.com/>
>
>
>
> Dana Orzel wrote:
>
> This is for a grid tied with battery backup Outback system.
>
> The 32% increased gain for the tracker VS. fixed mount production is 
> an average of the last 180 days and I checked it in the spring for the 
> last 180 days [over the winter] and it was 33%. The 12 -- Evergreen 
> 180 watt modules produce about 65 -70% of our home and office's 
> electrical requirements.
>
> Thanks,
>
> Dana Orzel
>
>     Dana,
>
>     That 32% is a very useful number, and it matches with our
>     experience as well. But I need to verify a couple of assumptions,
>     please:
>
>     Does this represent average annual production, rather than peak
>     seasonal? And is it a grid-tied system?
>
>     Thanks,
>
>     Allan
>
>      
>
>     Allan Sindelar
>
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