flat rubber roofs [RE-wrenches]

[Jeff Clearwater]

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Hi Ray,

I'm not an expert on ballasted roof systems. 
Just have some limited experience with  a 
handfull of flat roof jobs.  I didn't mean to 
imply I had written some exhaustive review.  But 
I do have a project now that - like many medium 
to small commercial jobs on a small commercial 
roof has to deal with compound drainage slopes in 
both dimensions.  The limited  systems I've used 
and researched deal with these in different ways. 
On another job I had also looked at obtaining 
some decent tilt on a small commercial system and 
worked with DP&W to determine the best balance of 
slope vs weight etc.

I'm also sensitive to promoting or critiquing 
products on the List without definitive 
conclusive experience which is why I said to 
contact me off-list.  But my experience is 
limited.  I thought it applicable to Geoff's 
small system though which is why I invited the 
inquiry.

But I'm glad to start a discussion so that others 
with more experience might chime in.

Flat roof systems that I am aware of are:

DP&W
(http://www.directpower.com/products/racks/brmphotos.html)

Evergreen's Sunplicity System
http://www.evergreensolar.com/products/

Sunlink
http://www.eastwoodenergy.com/jadworks/sunlink/jwsuite.nsf/ViewSelection/EB9998CC579FF38F882570740069FD97?Open&site=Home*ViewSelection=Product_Info**

Solar Quilt (Canada) (new product)
http://www.arisetech.com/Projects/CCIW.php

Schott's SunRoof System (both flat and tilted roof models)
http://www.us.schott.com/photovoltaic/english/products/systems/commercial_rooftop/index.html

Powerlight
http://www.powerlight.com/products/roof_top.shtml

The nice thing about DP&Ws system is that it's 
inexpensive and can be custom sized for small to 
medium systems.  It will also take a good amount 
of non-flatness.  Most of the other system rely 
on larger expanses of panels to achieve the 
engineered uplift requirements and are more 
dependent on the roof being truly flat.

The folks at Sunlink have a nice product - the 
supports are perpendicular to the rows and thus 
also allow some roof curvature to be taken up. 
The Sunplicity system has the supports going 
along the row line - but I have not direct 
experience with their ability to take up 
curvature but I imagine it to be less.  Schott 
and Powerlight are really for bigger projects 
although I see that Schott now has a tilted roof 
solution - no experience with it.

That's about all I know!

Perhaps someone with more experience would care to comment.

Best,

Jeff C.
Village Power Design










>HI Jeff;
>
>I too would like to see your reviews of 
>different brands of racks. Can you post it to 
>the list (I think many others would be 
>interested) or is it too much info to post? At 
>least CC me on this if you don't mind.
>Thanks for doing the review too. We need more unbiased sources of info.
>
>Ray Walters
>
>Jeff Clearwater wrote:
>
>>Hey Geoff,
>>
>>You should definitely consider ballasted 
>>systems and with that -  lower your tilt angle 
>>if it's negotiable.  You still get in the 90 % 
>>range of optimal output as low as 7-10º tilt. 
>>Most commercial flat roof systems have gone 
>>down to 5º or even less so as to get more 
>>panels on the roof, lower ballast weight and 
>>simplify design. The little you lose in tilt is 
>>easily made up for in those factors.
>>
>>That said,  contact Jeff Randall at DPW.  They 
>>have a simple ballasted rack system based on 
>>concrete paver blocks that can be engineered to 
>>any tilt and panel.  I have received quotes 
>>from them for ballasted systems up to 15º tilt 
>>- but if you go with a lower angle still you'll 
>>have less ballast.  That can be critical in 
>>terms of the weight loading capability of your 
>>roof - that's your first point of research - 
>>how many lbs/ft2 can be safely added to that 
>>roof -  (if you are at 5-10º, most roofs can 
>>easily handle the extra ballast, above that, 
>>the weight rises exponentially) (But in snow 
>>country you really need to know the safety 
>>margin you are working with!) - then call DP&W 
>>or any other manufacturer of ballasted roof 
>>systems of which there are now at least 5. 
>>Contact me off list if you want my reviews of 
>>them.  Most are not oriented to doing small 
>>systems like yours.
>>
>>Hope that helps,
>>
>>Jeff C.
>>Village Powerr Design
>>
>
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-- 
~~~~~~~~~~~~~
Jeff Clearwater
Village Power Design Associates
Sustainable Energy & Water Solutions for Home & Village
http://www.villagepower.com
gosolar at villagepower.com

530-470-9166
877-SOLARVillage
877-765-2784
425 Nimrod St.
Nevada City, CA 95959
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`~

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