[RE-wrenches] Flat Panels

[Bill Loesch]

Hi August,

For what it is worth, Velux, one of the premier skylight manufacturers,
limits the minimum angle of the roof (and the parallel skylight) to 15
degrees. With the roof windows/skylights the customer has direct observation
of how much puddling and subsequent dirt is blocking the window.

Anyone care to estimate just how much performance is lost with 5-10 degrees
off optimum tilt vs.no "ring around the collar" improved performance?

Bill Loesch
Solar 1 - Saint Louis Solar


----- Original Message ----- 
From: "August Goers" <august at luminalt.com>
To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
Sent: Tuesday, November 04, 2008 8:43 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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