[RE-wrenches] Flat Panels

[Joel Davidson]

Dirt buildup along solar modules' bottom rail is a real problem in locations 
that have a lot of airborne dust and dirt and do not get regular rainfall. 
Los Angeles gets very little rain from April to November. This year I let 
dirt build up on my old array  from January until August. One group of 
modules is at 10 degrees tilt. The other group is at 18 degrees tilt. Both 
groups of modules had the same amount of bottom rail dirt buildup. There was 
about 1 inch of sun-blocking dirt at the bottom rail, but not up to the cell 
tabs, and then uniform dirt on the rest of the modules. See 
http://www.solarsolar.com/ I sprayed the array with a very weak solution of 
Turtle brand ZipWax car wash, wiped it with a sponge mop, and then rinsed 
it. Total time spent cleaning the array was less than 10 minutes. Power 
increased 10%. Next summer when I clean the array, I will just dry wipe the 
dirt at the module bottom rail and report the difference.

----- Original Message ----- 
From: "August Goers" <august at luminalt.com>
To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
Sent: Tuesday, November 04, 2008 6:43 AM
Subject: [RE-wrenches] Flat Panels


> Wrenches -
>
> Lately we've been called out to repair or upgrade several ~5 year old PV
> installations in the Bay Area. It is always interesting to see how they're
> holding up. Apparently it was common to mount panels completely flat
> (horizontal) on flat roofs back then. This poses a serious problem because
> the module frame lip catches water and dirt and prevents the panel from
> washing off in the rain. See a photo here:
>
> http://luminalt.com/temp/flatpanel.JPG
>
>
> Note that two of those panels were broken by a baseball, but you can still
> see the dirt buildup on the adjacent panels right across all three rows of
> bypass diodes.
>
> Any ideas on what percentage loss that dried dirt is causing?
>
> Lesson learned: never tilt panels below 5 degrees, preferably 10 degrees.
>
> Cheers,
>
>
> August Goers
>
> Luminalt Energy Corporation
>
>
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