[RE-wrenches] Evergreen

Doug Pratt dmpratt at sbcglobal.net
Sun Jan 3 15:01:57 PST 2010


I'm with you on this one David.  15 years ago (when PV cost about 3 times as
much as today) I was a great believer in tracking mounts, and I'm sorry to
say I sold a lot of Wattsun and Zomeworks mounts.  But after experiencing
almost yearly repairs to every Wattsun, and watching folks tie down their
Zomeworks so they didn't get blown to the western stop every afternoon, I
gradually became less enthusiastic.  With the price of PV now, I can't make
any kind of financial case for the purchase of a mounting structure that's
sure to cause service callbacks for dealers.  Save yourself the callbacks
from clients. You want more watthours?  Just put a few more modules on a
fixed rack and never have to think about it again!

 

Cheers,

Doug Pratt

Technical Support

DC Power Systems 

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of David Katz
Sent: Sunday, January 03, 2010 11:35 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Evergreen

 

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/> 

 

DISCLAIMER: 
This communication, along with any documents, files or attachments, is
intended for the use of only the addressee and contains privileged and
confidential information. If you are not the intended recipient, you are
hereby notified that any dissemination, distribution or copying of any
information contained in or attached to this communication is strictly
prohibited.  If you have received this message in error, please notify the
sender immediately by e-mail reply and destroy the original communication
and its attachments without reading, printing or saving in any manner.

 



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
 <mailto:Allan at positiveenergysolar.com> 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

No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.725 / Virus Database: 270.14.124/2596 - Release Date: 01/01/10
02:20:00

 



  _____  



 
_______________________________________________
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/20100103/992b6dc2/attachment-0004.html>


More information about the RE-wrenches mailing list