[RE-wrenches] Tilt biased....

[R Ray Walters]

A couple of nice things about working on carports:
1) often the ceiling is exposed, making anchoring and finding rafters easy
2) If you did have a leak, its not quite as catastrophic.

Just because you get the wind loading and anchors right for the array, doesn't mean the carport roof will still be there.
I design from the modules all the way to the foundations. I think some good old fashioned overkill will cover you instead of a detailed engineering analysis for such a small project.
A couple of carports I worked on, I actually beefed up the carport itself, by adding hurricane ties, and Simpson ties at the rafters, support structure, and footings.
(just look at the each mechanical connection as if gravity were reversed, and also consider the structure, if gravity were sideways)
I've heard recently that in Florida hurricanes, the only roofs left in some areas were the ones with solar panels on them, so its very likely that your end result will be a net benefit to the entire structure.

R. Walters
ray at solarray.com
Solar Engineer




On Apr 17, 2010, at 10:33 AM, <holtek at sbcglobal.net> <holtek at sbcglobal.net> wrote:

> Searching for opinions.....is this "over design"?
> Designing small system (2.35kW). Customer uses gas for heating. Typical A/C unit. I was thinking of biasing the tilt to summer production for greater offset of summer demand (lat 31.6, proposing 18). No net metering in this part of the world. PVwatts shows a drop of 2% /yr. in production , 5% higher production for A/C months. Feedback?
>  
>  Also, this array will go on a carport. I understand that windloading is actually greater for an open structure than one with walls (another reason for lower tilt) - is there any one that can direct me to data on finding out how much more?
>  
> Lastly, what is a good avg. target derate factor for Enphase inverters (real world)?
>  
> Holt E. Kelly
> Holtek Fireplace & Solar Products
> 500 Jewell Dr.
> Waco TX. 76712
> 254-751-9111
> www.holteksolar.com
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