Wind-Loading and Tilted panels on roofs [RE-wrenches]

[Dean T. Newberry]

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Hello Justine,
Let me echo Don Loweberg's advice to use plane of roof mounting.
Also your local building officials know what wind loading to use for 
your area.
The penalty for east or west facing modules may be less than you think.
You can test your assumptions with the spreadsheet at this URL
http://www.dcn.davis.ca.us/go/deant/EnergyCalc.xlt 
Use medium security in Excel and enable macros.

In Denver a 1kW array facing south at 6 in 12 slope would generate 
1.78MWh/Yr. The same array facing  east or west would  generate 
1.43 MWh/Yr.  a 20% penalty.  Seldom is the house on a true rotational 
axis, you could pick the slope which favors the south. Small azimuth 
increments make a difference. If the azimuth is south of west  by only 
11degrees, the penalty is only 11%.

If Time Of Use (TOU) metering is not an issue face the modules east for 
cooler operation. If TOU is available a west facing array may be more 
economically favorable.

Justine Sanchez wrote:

>Hi folks,
> 
>Justine from SEI here...we have a question regarding wind loading on roof mounted  panels at a tilt. We have seen some structural damage to a local home here with panels mounted at a tilt and are wondering if anyone else has had this experience. On a new project we need to mount some modules to a roof that has an East/West orientation (ie the ridge line runs N-S)....so that to face our modules south we would have to mount them on either the east or west roof space tilted to the south. Unfortunately this is the only good solar access on the property...but we have concerns about the wind-loading.
> 
>Any comments?
> 
>Thanks!
>-Justine Sanchez
>Solar Energy International
>  
>

-- 
Dean T. Newberry
Marketing and Sales

Quantum Energy Group
265 Applegate School Road, P.O. Box 158
Applegate, Ca. 95703

Email:  deant at dcn.org

Cell:      530 867-2392
Office:  530-878-4585
Fax:      530-878-6685 

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