[RE-wrenches] Evergreen

Dana dana at solarwork.com
Sun Jan 3 09:50:24 PST 2010


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

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