Evacuated Tubes [RE-wrenches]

[Joel Davidson]

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Howie,

Sun Utility Network used evacuated tubes at the off-grid(!) urban Pasadena 
California Audubon Society Center. See 
http://www.californiasolarcenter.org/solareclips/2004.02/20040210-10.html

Les Hamasaki at Sun Utility Network 323-478-0866 will give you accurate 
information but may not be familiar with tubes in snow country. See 
http://www.sunutility.com/index.htm

Joel Davidson

----- Original Message ----- 
From: "Howie Michaelson" <howie at suncatchervt.com>
To: <RE-wrenches at topica.com>
Sent: Saturday, November 17, 2007 12:07 PM
Subject: Evacuated Tubes [RE-wrenches]



Hi All,

I'm looking for experiential as well as "non-biased" info on Evacuated
tubes.  I have installed them a few times in the past, but have pretty
much steered clear of them since for several reasons:

1. Here in snow country, I've seen them not shed snow for significant
periods of time, and have also seen them break from ice/snow movement down
the roof.

2. From what I've seen/heard their output is in most cases not any better
than flat plate collectors, and due to lack of snow shedding capabilities,
sometimes substantially worse.

3.  They are more expensive than flat plates, and are rated lower by SRCC
so in Vermont are given less incentive money (which is based on the
ratings).

A client saw the Solar Decathlon and noticed that almost all the
competitors used evacuated tubes (ET's).  He also said that one
manufacturer was whacking a tube very vigorously against hard objects with
no damage resulting.  He wants to put in the reasonably best collectors he
can with an eye toward Return on Investment, but is now enamored with
Evacuated tubes since they would fit well on the south wall of his home at
a very steep angle (near vertical), and was told that there is virtually
no output penalty for doing so.  Placing them near vertical probably goes
a long way toward answering the snow shedding issue, but I'm mostly
ignorant about the rest of these issues.

Any info about any of these concerns or leads to a place where I can get
good comparative info on ET's vs. flat plate collectors would be much
appreciated.

Thanks,
Howie
-- 
Howie Michaelson
NABCEP Certified Solar PV InstallerT

Sun Catcher, LLC
Renewable Energy Systems Sales and Service
http://www.SunCatcherVT.com
(cell) 802-272-0004
(home) 802-439-6096


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